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Physiology 31071

Module 7-13 Lecture Exam unit 2

QuestionAnswer
Module 7 Central Nervous System (CNS): Brain and spinal cord, responsible for integration and processing of sensory information.
Peripheral Nervous System (PNS): Nerves extending from the CNS.
Peripheral Nervous System (PNS): Divided to two divisions -Afferent Division - Efferent Division
Afferent Division : Sensory input from somatic and special senses.
Efferent Division: Motor output controlling skeletal muscles (somatic nervous system) and involuntary organs (autonomic nervous system).
Module 7 Central Nervous System (CNS): Brain and spinal cord, responsible for integration and processing of sensory information.
Peripheral Nervous System (PNS): Nerves extending from the CNS.
Peripheral Nervous System (PNS): Divided to two divisions Afferent Division & Efferent Division
Afferent Division : Sensory input from somatic and special senses.
Efferent Division: Motor output controlling skeletal muscles (somatic nervous system) and involuntary organs (autonomic nervous system).
Types Functions of the Nervous System: -Sensory Function, -Intergration, -Motor Funtion
Functions of the Nervous System: Sensory Function Detects external and internal stimuli through sensory receptors and sends information to the CNS.
Functions of the Nervous System: Intergration The CNS processes sensory information and makes decisions on how to respond.
Functions of the Nervous System: Motor Funtion CNS sends motor commands to effectors (muscles and glands) through cranial and spinal nerves.
Cells of the Nervous System: -Neurons -Neuroglia (Supporting Cells) -PNS Neuroglia
"Nuerons"- Cells of the Nervous System:
"Neuroglia (Supporting Cells)"- Cells of the Nervous System:
"PNS Neuroglia"- Cells of the Nervous System:
Types Functions of the Nervous System: -Sensory Function, -Intergration, -Motor Funtion
Functions of the Nervous System: Sensory Function Detects external and internal stimuli through sensory receptors and sends information to the CNS.
Functions of the Nervous System: Intergration The CNS processes sensory information and makes decisions on how to respond.
Functions of the Nervous System: Motor Funtion CNS sends motor commands to effectors (muscles and glands) through cranial and spinal nerves.
Cells of the Nervous System: -Neurons -Neuroglia (Supporting Cells) -PNS Neuroglia
Sturcture of "Neurons"- Composed of dendrites (receive signals), a cell body (contains the nucleus), and an axon (transmits signals).
Function of "Neurons"- Neurons transmit electrical impulses to communicate information throughout the nervous system.
Neuron Types: -Sensory Neurons -Motor Neurons -Interneurons
Sensory Neurons: Transmit sensory input to the CNS.
Motor Neurons: Send motor outputs to effectors.
Interneurons: Facilitate communication within the CNS.
Neuroglia (Supporting Cells) CNS: -Astrocytes -Oligodendrocytes -Microglia -Ependymal Cells
Astrocytes: Most numerous, maintain the blood-brain barrier, guide neuron development.
Oligodendrocytes: Form and maintain the myelin sheath, which insulates axons.
Microglia: Act as phagocytes, removing debris and pathogens.
Ependymal Cells: Produce cerebrospinal fluid (CSF).
Neuroglia (Supporting Cells) PNS: -Schwann Cells
Schwann Cells: Form myelin sheath in PNS, aid in regeneration of damaged axons.
Neurons and muscle cells : produce electrical signals through changes in membrane potential.
Action Potentials: Electrical impulses that propagate along the axon, triggering neurotransmitter release at synapses.
Graded Potentials: Small, localized changes in membrane potential.
Types of Ion Channels: Leak Channels -Ligand-Gated Channels -Mechanically-Gated Channels -Voltage-Gated Channels - -
Leak Channels: Open randomly to allow ions to cross the membrane.
Ligand-Gated Channels: Open in response to binding of a specific chemical stimulus
Mechanically-Gated Channels: Open due to mechanical stimulation such as pressure or vibration.
Voltage-Gated Channels: Open in response to changes in membrane potential.
Resting Membrane Potential (RMP): -voltage across the plasma membrane of a resting neuron (approximately -70 mV in neurons). -Created by the unequal distribution of ions, primarily sodium (Na⁺) and potassium (K⁺), across the membrane, and maintained by the Na⁺/K⁺ pump
Action Potential Phases: -Depolarization -Repolarization -Hyperpolarization
Depolarization: Voltage-gated Na⁺ channels open, Na⁺ enters the cell, making the inside more positive.
Repolarization: Voltage-gated K⁺ channels open, K⁺ exits, restoring the negative charge inside the cell.
Hyperpolarization: Membrane becomes more negative than the resting potential before stabilizing.
Neurotransmitters "chemicals": Neurotransmitter chemicals released by neurons to transmit signals across a synapse to another cell.
Neurotransmitters includes: acetylcholine, dopamine, serotonin, and glutamate.
Synaptic Transmission: - Neurotransmitters are stored in vesicles within the axon terminals. -When an action potential reaches the terminal, vesicles release neurotransmitters into the synaptic cleft. -The neurotransmitter binds to receptors on the postsynaptic cell, trigger
Plasticity: The nervous system’s ability to change, grow, and adapt based on experiences. This includes forming new connections and modifying existing ones. - Neurons can increase the number of dendrites and receptors in response to stimuli.
Repair in the CNS: Limited ability for repair due to inhibitory proteins and scar tissue formation. Damage is often permanent.
Repair in the PNS: Axons can regenerate if the cell body remains intact and Schwann cells are active. Schwann cells form a regeneration tube to guide axonal regrowth.
Review – Multiple Choice 1. Which of the following is NOT a function of the nervous system? C) Hormonal secretion
2. The central nervous system consists of: A) Brain and spinal cord
3. The afferent division of the peripheral nervous system is responsible for: B) Sensory input
4. Which glial cell is responsible for forming the myelin sheath in the central nervous system? C) Oligodendrocytes
5. Which type of neuron transmits information from sensory receptors to the CNS? B) Sensory neuron
6. The function of microglia in the nervous system is: B) Removing cellular debris and pathogens
What is the typical resting membrane potential of a neuron? C) -70 mV
8. Which ion is primarily responsible for the depolarization phase of an action potential? B) Sodium (Na⁺)
9. Voltage-gated ion channels open in response to: B) Changes in membrane potential
10. Neurotransmitters are released from the: C) Synaptic End Bulbs
11. The space between two neurons where neurotransmitters are released is called the: A) Synapse
12. Which of the following statements about neuronal repair is true? B) PNS neurons can regenerate if the cell body is intact.
13. Neuronal plasticity refers to the nervous system's ability to: B) Change and adapt based on experience
14. Which glial cell forms a regeneration tube to help repair damaged axons in the PNS? B) Schwann cells
Module 8: Nervous System and Neuronal Excitability. Graded Potentials: Generated on dendrites and cell bodies. o Signal short distances. o Can be depolarizing (membrane potential becomes less negative) or hyperpolarizing (more negative). o Have decremental conduction—amplitude decreases with distance. o Their amplitude
Action Potentials (APs): Initiated at the axon hillock and propagate down the axon. o Long-distance signaling without decrement. o Follows an all-or-none law: once threshold is reached, the AP happens. o Phases: Depolarization , Repolarization, After-Hyperpolarization
Depolarizing phase: rapid increase in Na+ permeability, making the inside more positive.
Repolarization phase: K+ exits the cell, restoring negative charge inside.
After-Hyperpolarization phase: membrane potential temporarily dips below resting potential.
Refactory period "Absolute": no new AP can occur because Na+ channels are inactivated.
Refactory period "Relative": a stronger-than-normal stimulus is required to trigger an AP
Voltage-Gated Na+ Channels: Three states: 1. closed but capable of opening, 2. open, and 3. closed/inactivated. o Na+ channels are crucial in the depolarization phase of AP
Voltage-Gated K+ Channels: Open more slowly than Na+ channels, aiding in repolarization by allowing K+ out of the cell
Synapse: The connection between neurons or between a neuron and another cell (e.g., muscle or gland). Involves the release of neurotransmitters from the presynaptic neuron, which bind to receptors on the postsynaptic neuron
Neurotransmitter Release 1st Mechanism: 1. AP arrives at the axon terminal, opening voltage-gated Ca2+ channels
Neurotransmitter Release 2ndMechanism: 2. Ca2+ influx triggers vesicles containing neurotransmitters to fuse with the membrane.
Neurotransmitter Release 3rd Mechanism: 3. Neurotransmitters are released into the synaptic cleft, binding to receptors on the postsynaptic cell.
Neurotransmitter Release 4th Mechanism: Ligand-gated ion channels open in response, initiating graded potentials in the postsynaptic cell
Termination of Signal: Neurotransmitters are removed by diffusion, enzymatic degradation, or reuptake into the presynaptic neuron
Excitatory Post-Synaptic Potentials (EPSPs): Depolarization occurs due to the influx of Na+ ions. o Moves the membrane potential closer to the threshold for an AP
Inhibitory Post-Synaptic Potentials (IPSPs): Hyperpolarization occurs due to the influx of Cl- ions or efflux of K+. o Moves the membrane potential away from the threshold
Neurotransmitter Types: -Acetylcholine (ACh) -Endocannabinoids -Glutamate -Dopamine -Serotonin:
Acetylcholine (ACh) Can be excitatory or inhibitory depending on receptor type (e.g., nicotinic or muscarinic).
Endocannabinoids Affect pain processing and appetite.
Glutamate Most prevalent excitatory neurotransmitter in the brain.
Dopamine mportant in reward pathways
Serotonin Regulates mood, involved in depression treatment (SSRIs)
Types of Neural Circuit -Diverging Circuit -Converging Circuit -Reverberating Circuit - - - -
Diverging Circuit: A single presynaptic neuron connects with multiple postsynaptic neurons.
Converging Circuit: Multiple presynaptic neurons synapse with one postsynaptic neuron.
Reverberating Circuit: Neurons stimulate each other in a loop, maintaining the signal.
Parallel After-Discharge Circuit: One presynaptic neuron stimulates several chains of neurons, which converge onto a single postsynaptic neuron
Drugs and Toxins Affecting Neuromuscular Transmission: -Botulinum Toxin (Botox) -Curare -Sarin Gas
Botulinum Toxin (Botox): Inhibits ACh release, leading to muscle paralysis.
Curare: Blocks ACh receptors, preventing muscle contraction.
Sarin Gas: Inhibits acetylcholinesterase, causing continuous muscle contraction
Review – Multiple Choice pt2 1. Which of the following statements about graded potentials is TRUE? C) Graded potentials have decremental conduction
2. During an action potential, what happens during the depolarization phase? B) Na+ ions enter the cell, making the inside more positive.
3. What is the function of voltage-gated calcium channels at the axon terminal? B) They allow Ca2+ to enter and facilitate neurotransmitter release.
4. Which of the following occurs during the absolute refractory period? B) No action potential can occur because Na+ channels are inactivated.
5. Which neurotransmitter is described as the most common excitatory neurotransmitter in the brain? B) Glutamate
6. Which neurotransmitter binds to nicotinic receptors and can be either excitatory or inhibitory, depending on the receptor subtype? B) Acetylcholine
7. Which type of neural circuit allows one presynaptic neuron to connect with multiple postsynaptic neurons? B) Diverging circuit
8. What causes the release of neurotransmitters at a synapse? B) The arrival of an action potential and the opening of voltage-gated calcium channels.
9. How is the strength of a stimulus encoded by action potentials? B) The frequency of action potentials increases.
10. Which of the following drugs inhibits the release of acetylcholine, leading to muscle paralysis? C) Botulinum toxin (Botox)
Module 9: The Central Nervous System Components Brain and Spinal Cord
Central Nervous System (CNS) Major Functions: Processing sensory information, controlling motor functions, regulating bodily processes, and housing the brain's higher cognitive functions.
Spinal Cord Protection by vertebrae and three layers of meninges: -Dura mater - Arachnoid mater -Pia mater
Spinal Cord Nerves: 31 pairs (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal), each responsible for sensory input and motor output.
Gray Matter: Contains neurons that process sensory input (dorsal gray horns) and send motor output (ventral and lateral gray horns).
White Matter: Consists of myelinated axons in bundles called tracts: -Ascending tracts -Descending tracts
Ascending tract: Carry sensory signals to the brain.
Descending tract Send motor commands from the brain.
Spinal Reflex Arc Components: - Sensory receptor - Sensory neuron - Integrating center (spinal cord or brain) - Motor neuron - Effector (muscle or gland)
Reflexes ; Reflexes are automatic responses to stimuli, processed in the spinal cord.
Brain Protection: -Skull and meninges protect the brain. brain's ventricles and subarachnoid space, providing protection, nutrition, and waste removal.
Brain Protection pt2: Blood-Brain Barrier (BBB): Highly selective barrier that prevents harmful substances from entering the brain, consisting of tight junctions and astrocytes.
Brain Protection pt3: Cerebrospinal Fluid (CSF): Produced by the choroid plexus, it circulates through the brain's ventricles and subarachnoid space, providing protection, nutrition, and waste removal.
Brainstem consist: -Midbrain -Pons -Medulla Oblongata
Midbrain: Movement control (substantia nigra, red nucleus), sensory-motor integration.
Pons: Regulates respiration, controls communication between brain areas.
Medulla Oblongata: Controls autonomic functions like heart rate and breathing.
Cerebellum: Coordinates movement, evaluates performance of motor activities, and helps with learning movement patterns.
Diencephalon consist: -Thalamus -Hypothalamus -Pineal Gland -
Thalamus: Relay center for sensory information, filters stimuli before it reaches the cerebral cortex.
Hypothalamus: Regulates autonomic nervous system, emotions, hunger, thirst, body temperature, and circadian rhythms.
Pineal Gland: Secretes melatonin to regulate sleep-wake cycles.
Types of Lobes -Frontal Lobe -Parietal Lobe -Occipital Lobe -Temporal -Insula
Frontal Lobe: Motor control, reasoning, speech (Broca's area).
Parietal Lobe: Sensory processing (primary somatosensory cortex).
Occipital Lobe: Visual processing (primary visual cortex).
Temporal Lobe: Auditory processing, language comprehension (Wernicke's area).
Insula: Taste and smell processing (gustatory and olfactory cortices).
Sleep Cycles Wakefulness- Controlled by the Reticular Activating System (RAS), which increases cortical activity.
Sleep Cycles: Non-REM (NREM) 4 stages; heart rate, breathing, and brain activity decrease progressively.
Sleep Cycles: REM Sleep Brain is active, associated with dreaming, rapid eye movements, and muscle paralysis.
Broca’s Area: Motor speech area; plans the muscle movements required for speech.
Wernicke’s Area: Interprets the meaning of spoken and written language.
Limbic System: limbic system (including the hypothalamus and amygdala) governs emotional responses, such as fear and pleasure.
1. Which of the following is NOT a protective structure of the brain? B) Vertebrae
2. The spinal cord processes sensory information in which part of the gray matter? B) Dorsal gray horns
3. How many pairs of spinal nerves are there in the human body? C) 31 pairs
4. Which of the following tracks sends sensory information to the brain? C) Ascending tracts
5. What is the primary function of the cerebellum? B) Coordinate voluntary movements and balance
6. Which brain structure acts as the relay center for most sensory information? B) Thalamus
7. The blood-brain barrier is mainly composed of which type of cells? B) Endothelial cells with tight junctions
8. During REM sleep, which of the following occurs? B) Rapid eye movements and vivid dreaming
9. Which cranial nerve is associated with smell? B) Olfactory nerve
10. Broca’s area is primarily responsible for which of the following? C) Planning and coordinating muscle movements for speech
11. The hypothalamus is involved in all of the following functions EXCEPT: C) Producing melatonin
12. The limbic system is primarily associated with which of the following? B) Emotional responses
13. Which brain region is responsible for filtering sensory information before it reaches conscious awareness? C) Thalamus
14. Which brainstem structure plays a key role in regulating heart rate and respiration? B) Medulla oblongata
15. Which of the following best describes the role of the reticular activating system (RAS)? C) Maintains wakefulness and regulates sleep cycles
Module 10 : Sensation Conscious or unconscious awareness of changes in the environment (internal or external). Sensory information may not always reach conscious awareness (e.g., blood pressure regulation)
Perception: Conscious awareness and interpretation of sensory input, requiring processing by the cerebral cortex. Sensation without perception occurs when sensory input doesn’t reach the cortex.
(4 Steps) Process of Sensation: Step 1: Stimulation Sensory receptors are activated by a stimulus.
(4 Steps) Process of Sensation: Step 2: Transduction The stimulus is converted into electrical signals, producing a receptor or generator potential.
(4 Steps) Process of Sensation: Step 3: Action Potential Generated if the stimulus surpasses a threshold.
(4 Steps) Process of Sensation: Step 4: Integration Sensory input is processed in the central nervous system, often in the thalamus before reaching the cerebral cortex.
Sensory Receptors Types: -Mechnoreceptor -Theromoreceptors -Photoreceptors -Chemoreceptors -Nicoceptors - -
Mechnoreceptors Detect mechanical stimuli (e.g., pressure, stretch).
Thermoreceptors Detect changes in temperature (e.g. cold, hot)
Photoreceptors Detect light in the retina
Chemoreceptors Detect chemicals (taste, smell, etc.).
Nicoceptors Detect painful stimuli (e.g., extreme temperatures, tissue damage).
Adequate Stimulus Each sensory receptor responds best to a specific type of stimulus, referred to as the “adequate stimulus.” For example, thermoreceptors respond to temperature changes but not to mechanical deformation.
Transduction Sensory receptors convert non-electrical stimuli into electrical signals. This process typically involves opening ion channels, resulting in a receptor potential that leads to action potentials if strong enough.
Law of Specific Nerve Energies Sensory nerves carry one type of information. Regardless of how a nerve is stimulated, the brain interprets it according to the type of receptor it comes from (e.g., mechanical pressure on the eye leading to visual flashes).
Receptive field: The area a sensory receptor is sensitive to
Larger receptive fields: (e.g., back, thighs) lead to less precise perception, while smaller fields (e.g., fingers, lips) provide higher sensitivity
Sensory Coding: -Modality -Location -Intensity -Duration -
Sensory Coding for"Modality": Type of stimulus (e.g., mechanical, chemical).
Sensory Coding for "Location": Where the stimulus originates, determined by the receptor's receptive field.
Sensory Coding for "Intensity": Coded by the frequency of action potentials.
Sensory Coding for "Duration": How long the stimulus persists, with some receptors adapting over time.
Tonic receptors: Slowly adapting; monitor stimuli that require constant attention (e.g.,pain, proprioception).
Phasic receptors: Rapidly adapting; detect changes in stimulus intensity (e.g., touch, olfactory receptors).
Pain and Nociception 5 responses for 1. "Transduction": Nociceptors activated by noxious stimuli.
Mechanical: Respond to pinch, puncture.
Thermal: Respond to extreme temperatures.
Polymodal: Respond to multiple types of stimuli (e.g., heat, chemical stimuli like capsaicin)
2. "Conduction": Pain signals travel through fast (Aδ fibers) or slow (C fibers) pathways.
3. "Transmission": Neurotransmitters like glutamate and substance P transmit pain signals to the brain
4. "Perception": Pain is perceived consciously in the brain, but reflexes can act before pain is perceived.
5." Modulation": Gate Control Theory allows mechanical stimuli to suppress pain (e.g., rubbing a sore spot). Endogenous opioids like enkephalins help modulate pain.
Referred Pain: Pain perceived in a different location from its source, due to convergence of sensory pathways (e.g., heart pain felt in the left arm).
Proprioception: Awareness of body and limb position, mediated by slow-adapting receptors in muscles and tendons.
Review – Multiple Choice 1. Which of the following best describes sensation? C. Conscious or unconscious awareness of changes in the environment.
2. What is the correct sequence of events in the process of sensation? B. Stimulation → Transduction → Action potential → Integration
3. Nociceptors are specialized to detect: C. Painful stimuli
4. Which of the following types of receptors responds to mechanical stimuli such as pressure or stretching? B. Mechanoreceptors
5. The adequate stimulus refers to: B. The stimulus that a receptor responds to best
6. The Law of Specific Nerve Energies means: B. Each nerve fiber carries information that the brain interprets as one specific type of stimulus
7. Which of the following is a tonic receptor that adapts slowly or not at all? C. Nociceptor
8. What best explains referred pain? A. Pain that is felt far away from the actual site of the injury
9. Gate Control Theory explains how: B. Mechanoreceptor stimulation can suppress pain sensations
10. Which of the following types of pain fibers is responsible for fast, well-localized pain? B. Aδ (A-delta) fibers
11. Phasic receptors are important for: C. Detecting rapid changes in stimuli, such as touch or smell
12. Proprioception is the sensory system responsible for: B. Understanding body and limb position in space
Module 11 Sensory systems: Sensory systems detect stimuli from the environment and send signals to the brain for interpretation.
Somatic sensory systems: (touch, pressure, pain)
Special senses: (smell,taste, sight, hearing, and balance).
Olfactory System (Smell) Location of receptors: Olfactory epithelium in the upper part of the nasal cavity.
Olfactory System (Smell) Receptors: Chemoreceptors called olfactory cilia located on non-motile cilia.
Olfactory System (Smell) Olfactory transduction: -Odorants bind to receptors. - Binding activates G protein (G olf) → adenylyl cyclase → cyclic AMP (cAMP). -cAMP opens ion channels (Na+ and Ca2+) → depolarization → action potential.
Olfactory System (Smell) Olfactory Pathway: -Olfactory nerve (Cranial Nerve I) → Olfactory bulbs → Glomeruli (mitral cells). -Mitral cells send signals to the olfactory cortex in the temporal lobe and the limbic system (emotional responses to smells).
Olfactory System (Smell Adaptation: Olfactory system adapts quickly, reducing sensitivity by 50% within the first second of stimulation
The Gustatory System (Taste) Taste receptors: Located in taste buds, which are mainly found on papillae on the tongue.
The Gustatory System (Taste) Five primary tastes: Salty, sour, sweet, bitter, umami.
The Gustatory System (Taste) Transduction: -Salty and sour: Sodium and hydrogen ions enter receptor cells → depolarization → neurotransmitter release.
The Gustatory System (Taste) Transduction: Sweet, bitter, umami: Tastants bind to G-protein-coupled receptors (gustducin) → activate IP3 → depolarization and Ca2+ release → neurotransmitter release.
The Gustatory System (Taste) Pathway: Taste information travels via Cranial Nerves VII (facial), IX (glossopharyngeal), and X (vagus) to the gustatory cortex in the insula
The Visual System (Sight) Main Components: Retina Contains photoreceptors (rods and cones).
The Visual System (Sight) Main Components: Fovea Region of highest visual acuity, with the highest concentration of cones.
The Visual System (Sight) Main Components: Lens Adjusts to focus light on the retina for image formation (accommodation).
The Visual System (Sight) Main Components: Pupil Controls light entry.
The Visual System (Sight) Photoreceptors: -Rods -Cones
The Visual System (Sight) Rods: Sensitive to low light; good for night vision.
The Visual System (Sight) Cones: Sensitive to bright light; involved in color vision.
The Visual System (Sight) Visual Pathway: Light → Retina → Photoreceptors (rods and cones) → Optic nerve → Optic chiasm → Thalamus → Primary visual cortex
The Auditory System (Hearing) Components: Ear Structure External auditory canal, tympanic membrane (eardrum), ossicles (malleus, incus, stapes), cochlea, semicircular canals.
The Auditory System (Hearing) Components: Sound Transduction Sound waves → Tympanic membrane → Ossicles vibrate → Pressure waves in cochlear fluid (perilymph) → Bend hair cells in the cochlea (organ of Corti). - Inner hair cells transduce sound, outer hair cells enhance sensitivity. - Tip-link proteins connect st
The Auditory System (Hearing) Components: Pitch Determined by which region of the basilar membrane vibrates.
The Auditory System (Hearing) Components: Loudness Determined by the extent of basilar membrane vibration.
The Auditory System (Hearing) Components: Auditory Pathway: Sound Waves Sound signals travel via Cranial Nerve VIII (vestibulocochlear) → Pons → Thalamus → Auditory cortex
Vestibular System (Balance): Otolithic organs (utricle and saccule): Detect linear acceleration and head tilt.
Vestibular System (Balance): Semicircular ducts Detect rotational movement.
Vestibular System (Balance): Sensory information Sensory information from vestibular organs travels via the vestibular branch of Cranial Nerve VIII → Brainstem → Thalamus → Vestibular cortex.
Vestibular System (Balance): Vestibular system Vestibular system also communicates with areas controlling eye movement to help maintain balance and orientation
Autonomic Nervous System (ANS) • Purpose: Regulates involuntary actions, controlling smooth muscle, cardiac muscle, and glands (visceral organs).
Autonomic Nervous System (ANS) Sympathetic Nervous System: "Fight or flight" response. Increases heart rate, dilates pupils, and promotes energy mobilization.
Autonomic Nervous System (ANS) Parasympathetic Nervous System "Rest and digest" response. Promotes energy conservation and supports digestion and bodily repair.
Autonomic Nervous System (ANS) Enteric: Controls gastrointestinal function.
Autonomic Nervous System (ANS) Preganglionic neuron (releases acetylcholine) → Ganglion → Postganglionic neuron → Effector organ.
Autonomic Nervous System (ANS) Sympathetic postganglionic neurons release norepinephrine, while parasympathetic postganglionic neurons release acetylcholine.
Autonomic Nervous System (ANS) Nicotinic receptors (excitatory, found on postganglionic neurons).
Autonomic Nervous System (ANS) Muscarinic receptors (found on target organs, can be excitatory or inhibitory).
Autonomic Nervous System (ANS) Beta-blockers (beta antagonists) used to reduce sympathetic responses, e.g., to slow heart rate.
Autonomic Nervous System (ANS) Beta-agonists used to induce sympathetic responses, e.g., bronchodilation for asthmatics.
Autonomic Nervous System (ANS) Parasympathetic Function SLUDD (Salivation, Lacrimation, Urination, Digestion, Defecation).
Autonomic Nervous System (ANS) Sypathetic Function Fight or flight response (Excitement, Emergency, Exercise, Embarrassment).
Autonomic Nervous System (ANS) Key Point ANS helps maintain autonomic tone, controlled by the hypothalamus, keeping balance between sympathetic and parasympathetic input.
Autonomic Nervous System (ANS) Autonomic reflexes maintain homeostasis (e.g., heart rate, breathing).
Somatic Nervous System (SNS) • Purpose: Controls voluntary movements by regulating skeletal muscles.
Somatic Nervous System (SNS) Somatic motor neuron (from spinal cord) → Skeletal muscle → Contraction.
Somatic Nervous System (SNS) Neurotransmitter Acetylcholine, acting on nicotinic receptors at the neuromuscular junction (NMJ).
Somatic Nervous System (SNS) Neuromuscular Junction (NMJ) site where motor neurons synapse with skeletal muscle fibers.
Somatic Nervous System (SNS) Signal transmission: Acetylcholine released into the synapse binds to nicotinic receptors, causing sodium influx and muscle depolarization (end plate potential).
Somatic Nervous System (SNS) Action potential spreads across the muscle membrane, initiating contraction.
Somatic Nervous System (SNS) Drugs Affecting NMJ -Botulinum toxin - Curare -Organophosphates (e.g., Sarin gas) -
Somatic Nervous System (SNS) Botulinum toxin Blocks acetylcholine release, causing paralysis.
Somatic Nervous System (SNS) Curare: Nicotinic receptor antagonist, preventing acetylcholine from binding, inhibiting contraction.
Somatic Nervous System (SNS) Organophosphates (e.g., Sarin gas) Inhibit acetylcholinesterase, causing continuous muscle contraction.
Review – Multiple Choice 1. Where are the olfactory receptors located? c. On olfactory cilia
2. What activates the G protein (Golf) during olfactory transduction? c. Odorant molecules binding to receptors
3. Which part of the brain receives olfactory signals for conscious smell perception? c. Temporal lobe
4. Which of the following is not one of the five primary tastes? b. Spicy
5. How do salty tastants trigger taste transduction? b. By entering the taste cell through sodium channels
6. Taste information from the posterior third of the tongue is carried by which cranial nerve? b. Glossopharyngeal nerve (Cranial Nerve IX)
7. Which structure is responsible for adjusting the shape of the lens for focusing? d. Ciliary muscles
8. What type of photoreceptors are responsible for color vision? b. Cones
9. What is the region of the retina with the highest visual acuity? b. Fovea
10. The malleus, incus, and stapes transmit sound waves by: b. Converting sound waves into pressure waves in the cochlear fluid
11. Which structure in the cochlea is responsible for sound transduction? b. Organ of Corti
12. What determines the pitch of a sound in the auditory system? b. The region of the basilar membrane that vibrates
13. Which structure detects rotational movement? c. Semicircular canals
14. The utricle and saccule help to detect: b. Linear acceleration and head tilt
15. Information from the vestibular system is carried to the brain by which cranial nerve? b. Vestibulocochlear nerve (Cranial Nerve VIII)
16. Which of the following is a primary function of the autonomic nervous system? c. Regulating smooth muscle, cardiac muscle, and glands
17. Which neurotransmitter is released by sympathetic postganglionic neurons? c. Norepinephrine
18. What type of receptor does acetylcholine bind to in parasympathetic target tissues? d. Muscarinic cholinergic
19. The parasympathetic division is responsible for which of the following actions? c. Stimulating digestion and energy conservation
20. Which branch of the autonomic nervous system is most active during the "fight or flight" response? b. Sympathetic
21. What neurotransmitter is released at the neuromuscular junction to stimulate skeletal muscle contraction? c. Acetylcholine
22. Where does the motor neuron of the somatic nervous system synapse with skeletal muscle? c. Neuromuscular junction (NMJ)
23. Which toxin blocks the release of acetylcholine at the neuromuscular junction, causing muscle paralysis? c. Botulinum toxin
24. Which of the following drugs acts as a nicotinic receptor antagonist, preventing muscle contraction? b. Curare
25. What effect does a beta-agonist, like albuterol, have on the body? c. Opens respiratory airways by inducing sympathetic response
Module 12 Muscle Types -Skeletal Muscle -Cardiac Muscle -Smooth Muscle -
Skeletal Muscle -Striated, voluntary, attached to bones. -Responsible for body movements, posture, and heat production (thermogenesis).
Cardiac Muscle -Striated, involuntary, found in the heart. - Responsible for pumping blood through the body.
Smooth Muscle -Non-striated, involuntary, found in hollow organs. - Moves substances within the body (e.g., food in the digestive tract).
.Functions of Muscles Movement: Skeletal muscles move the skeleton; smooth muscles move internal contents
.Functions of Muscles Stabilization: Helps in maintaining body posture and stabilizing joints.
Functions of Muscles Storage: Smooth muscle sphincters help store substances like urine
Functions of Muscles Heat Generation: Muscles generate heat through contractions (thermogenesis).
Properties of Muscle Electrical Excitability: Ability to respond to stimuli by generating action potentials
Properties of Muscle Contractility: Ability to contract forcefully when stimulated.
Properties of Muscle Extensibility: Ability to stretch without damage.
Skeletal Muscle Fibers Structure Sarcomeres: Functional units of contraction.
Skeletal Muscle Fibers Structure Thick (myosin) & Thin (actin) Filaments: Contractile proteins responsible for muscle movement.
Skeletal Muscle Fibers Structure Sarcoplasmic Reticulum (SR): Stores and releases calcium, essential for muscle contraction.
Skeletal Muscle Fibers Structure Hypertrophy: Increase in muscle fiber size due to an increase in myofibrils.
Skeletal Muscle Fibers Structure Atrophy: Decrease in muscle fiber size due to disuse or nerve loss.
Muscle Contraction Mechanism Sliding Filament Mechanism: -Muscle contraction occurs as actin and myosin filaments slide past each other, shortening the sarcomere. -Requires ATP for the power stroke and detachment of myosin from actin.
Contraction Cycle Steps: ATP Hydrolysis: Myosin head gets energized.
Contraction Cycle Steps: Cross-Bridge Formation Myosin binds to actin.
Contraction Cycle Steps: Power Stroke: Myosin head pivots, pulling actin toward the center of the sarcomere.
Contraction Cycle Steps: Detachment ATP binds to myosin, causing it to detach from actin.
Neuromuscular Junction (NMJ) process: Acetylcholine (ACh) is released from a motor neuron, binds to receptors on the muscle, and generates an end-plate potential (EPP), which triggers an action potential for muscle contraction
Excitation-Contraction Coupling: Action potential travels down the T-tubules, triggering calcium release from the SR, which binds to troponin, allowing contraction.
Creatine Phosphate: Provides the first source of ATP during short bursts of activity.
Anaerobic Glycolysis: Generates ATP without oxygen, leading to lactic acid buildup.
Aerobic Respiration: Produces more ATP using oxygen, primarily for endurance activities.
Muscle Fatigue: Produces more ATP using oxygen, primarily for endurance activities.
Muscle Recovery Oxygen Debt: Post-exercise elevated oxygen consumption helps recover and restore energy reserves
Skeletal Muscle Mechanics Motor Unit: A motor unit includes a motor neuron and the muscle fibers it innervates.
Skeletal Muscle Mechanics Small Motor Units: Precise movements (e.g., fingers).
Skeletal Muscle Mechanics Large Motor Units: Gross movements (e.g., legs)
Skeletal Muscle Mechanics Twitch Contraction: A single contraction-relaxation cycle in response to a stimulus.
Skeletal Muscle Mechanics Twitch Contraction Phases: Latent, contraction, relaxation.
Skeletal Muscle Mechanics Tetany: Sustained muscle contraction due to rapid stimulation without relaxation.
Types of Skeletal Muscle Fibers -Slow Oxidative (SO) Fibers -Fast Oxidative-Glycolytic (FOG) Fibers -Fast Glycolytic (FG) Fibers -
Types of Skeletal Muscle Fibers Slow Oxidative (SO) Fibers: High endurance, used for posture and endurance activities.
Types of Skeletal Muscle Fibers Fast Oxidative-Glycolytic (FOG) Fibers Moderate endurance, used for walking and sprinting
Types of Skeletal Muscle Fibers Fast Glycolytic (FG) Fibers: Quick bursts of power, fatigue rapidly
Cardiac Muscle -Contracts as a functional syncytium due to intercalated discs. -Contains autorhythmic cells, meaning it can generate its own electrical impulses.
Smooth Muscle: -Contracts slower than skeletal muscle but can sustain contraction for longer. -Two types: Single-unit (contracts as one unit) and multi-unit (fibers contract independently)
Review – Multiple Choice 1. Which of the following is NOT a type of muscle tissue? d. Epthelial muscle
2. What is the primary role of the sarcoplasmic reticulum in skeletal muscle fibers? b. Storing calcium for muscle contraction
3. During muscle contraction, which of the following proteins directly binds to calcium? c. Troponin
4. In the sliding filament mechanism, which of the following events requires ATP? d. Detachment of myosin from actin
5. Which of the following describes a characteristic of slow oxidative (SO) fibers? a. High resistance to fatigue
6. What happens when acetylcholine binds to receptors at the neuromuscular junction? b. Sodium channels open, leading to depolarization
7. Which type of motor unit would most likely be used for fine motor control, such as writing? a. A motor unit with 10-20 muscle fibers
8. Which of the following is a function of smooth muscle? d. Moving substances through hollow organs
9. Which molecule is the first source of ATP during muscle contraction? a. Creatine phosphate
10. What causes rigor mortis to occur after death? b. Lack of ATP preventing myosin from detaching from actin
11. Which of the following best describes a “twitch” contraction in skeletal muscle? b. A brief contraction followed by complete relaxation
12. Which type of skeletal muscle fiber is primarily recruited during activities like sprinting? c. Fast glycolytic (FG) fibers
13. In skeletal muscle contraction, what triggers the opening of voltage-gated calcium channels on the sarcoplasmic reticulum? a. Depolarization of the T-tubules
14. What happens during the power stroke of muscle contraction? b. Myosin pulls actin filaments toward the center of the sarcomere
15. What is the role of creatine kinase in skeletal muscle? b. It catalyzes the formation of ATP from creatine phosphate.
Module 13 Motor control : involves interaction between the nervous system and muscles to produce movement.
Lower motor neurons are essential for initiating voluntary skeletal muscle movements.
Lower motor neuron receive input from: - Local circuit neurons - Upper motor neurons (brainstem and cortex) - Basal nuclei (via the thalamus) -Cerebellum (monitors and corrects movement)
Key Concept: Lower motor neurons Lower motor neurons are the "final common pathway" because all signals for muscle movement eventually reach them.
Somatic reflexes Somatic reflexes are involuntary, fast responses to stimuli that protect the body from injury or help maintain posture.
Stretch Reflex (Myotatic Reflex): Keeps us upright and helps maintain muscle tone
Stretch Reflex (Myotatic Reflex): Monosynaptic: (one synapse between sensory and motor neurons).
Stretch Reflex (Myotatic Reflex): Ipsilateral: (occurs on the same side of the body).
Stretch Reflex (Myotatic Reflex): Receptor: Muscle spindle.
Stretch Reflex (Myotatic Reflex): Response: Muscle contraction in response to muscle stretch (e.g., patellar tendon reflex).
Tendon Reflex: Prevents excessive tension in muscles.
Tendon Reflex: Polysynaptic (multiple synapses).
Tendon Reflex: Ipsilateral.
Tendon Reflex: Receptor: Golgi tendon organs (GTOs) in tendons.
Tendon Reflex: Response: Muscle relaxation to prevent over-contraction
Flexor (Withdrawal) Reflex: Removes a limb from a harmful stimulus (e.g., pulling your hand away from a hot stove).
Flexor (Withdrawal) Reflex: Polysynaptic.
Flexor (Withdrawal) Reflex: Ipsilateral but can include contralateral pathways.
Flexor (Withdrawal) Reflex: Receptor: Nociceptors (pain receptors).
Flexor (Withdrawal) Reflex: Response: Withdrawal of the limb.
Crossed Extensor Reflex When a limb withdraws from a harmful stimulus, the opposite limb compensates (e.g., stepping on a sharp object causes the other leg to extend to maintain balance).
Crossed Extensor Reflex Contralateral (stimulus on one side, response on the other).
Central Pattern Generators (CPGs) CPGs are neural networks that produce rhythmic patterns of movement, such as walking or swimming
Central Pattern Generators (CPGs) network: These networks operate without sensory input and are crucial for coordinating locomotion.
Control of Movement by the Cerebral Cortex Primary Motor Cortex Controls the execution of voluntary movements.
Control of Movement by the Cerebral Cortex Premotor Cortex: Involved in planning movements before they occur.
Control of Movement by the Cerebral Cortex Corticospinal and Corticobulbar tracts corticospinal and corticobulbar tracts relay motor commands from the cortex to the muscles.
Modulation of Movement by the Cerebellum The cerebellum plays a vital role in comparing planned movements with executed movements.  It communicates with various brain regions (pons, thalamus, and cortex) and integrates feedback from proprioceptors to fine-tune movements
Modulation of Movement by the Cerebellum Function: The cerebellum helps adjust motor actions to ensure smooth and coordinated movement.
Review – Multiple Choice 1. Which of the following best describes lower motor neurons C. Sensory neurons that relay information from muscles to the brain
2. The stretch reflex is characterized by all the following EXCEPT: B. It involves the Golgi tendon organ as its receptor
3. What is the primary function of the Golgi tendon organs (GTOs) in the tendon reflex? B. Detect changes in muscle tension
4. The flexor (withdrawal) reflex is initiated by which type of receptor? C. Nociceptors
5. In the crossed extensor reflex, what occurs on the side opposite to the stimulus? C. Extension of the limb to support body weight
6. Central Pattern Generators (CPGs) are responsible for: C. Rhythmic patterns of movement such as walking
7. Which area of the brain is primarily responsible for planning movements before they occur? 7. Which area of the brain is primarily responsible for planning movements before they occur?
8. The cerebellum contributes to movement by: C. Comparing intended movements with actual movements and adjusting accordingly
9. All the following are sources of input to lower motor neurons EXCEPT: C. Sensory receptors in the skin
10. Which statement about the tendon reflex is TRUE? D. It induces muscle relaxation to prevent over-contraction
11. What is the role of nociceptors in reflex actions? C. Detecting harmful or painful stimuli
12. The primary motor cortex is located in which part of the brain? A. Frontal lobe
13. An ipsilateral reflex arc means that: C. The sensory input and motor output occur on the same side of the body
14. During the flexor (withdrawal) reflex, what happens to the antagonistic muscles? B. They are inhibited and relax
15. Which statement best describes the "final common pathway"? C. It describes how all motor signals ultimately converge on lower motor neurons
Created by: Rodney C
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