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PHYSIOLOGY FINAL 1
UNITS 1-4
| Question | Answer |
|---|---|
| what is physiology? | study of how systems function in living organisms. |
| main variables of homeostasis? | temp, blood sugar, pH, O2/CO2, BP, electrolytes, water |
| what are the components of a negative feedback loop? | Control center -> effector -> regulated variable -> sensor -> CC… |
| difference between negative and positive feedback loop? | negative shuts off the loop @ certain point, positive amplifies it until a certain point |
| what is the concentration of Na, K, Cl, and proteins in the INTERSTITIAL FLUID? | TONS of Na, little K, lots of diff ions |
| what is the concentration of Na, K, Cl, and proteins in the INTRACELLULAR FLUID? | TONS of K and proteins. |
| what is the concentration of Na, K, Cl, and proteins in the PLASMA FLUID? | MOSTLY water, proteins, gas, nutrients, waste. a COLOIDAL suspension (tons of stuff, nothing bonded just floating) |
| How are ions distributed across a cell membrane ? | SALTY BANANA! NaCl on the outside, TONS of K+ inside. |
| what are the 6 functions of membrane proteins? | cell ID, receptor, ion channel, transporters (3 types), enzymes, CELL-CELL adhesion |
| what are the 5 major ways substances cross the PM? | simple diffusion, facilitated diffusion, pumps, endocytosis, exocytosis |
| what are the 3 factors affecting water across a membrane? | membrane permeability, conc of solutes, pressure |
| what is osmolality? | osmoles per KG |
| what is osmolarity? | osmoles per L |
| what are osmoles? | solute concentration compared to H2O concentration - more osmoles = less water |
| tonicity? | ability of solution to cause movement of water |
| isotonic? | same amount of solute all over |
| hypertonic solution? | MORE SOLUTE OUTSIDE OF CELL, water moves out of cel |
| hypotonic solution? | LESS solute outside of cell, water moves INTO cell |
| osmotic pressure? | pressure required to STOP movement of water |
| what are 6 factors affecting rate of movement thru cell membrane? | concentration and electrical gradient, solubility of molecule, size, surface area of cell, composition of cell membrane |
| what is resting membrane potential in a cell? | -70 mV |
| how is electrical gradient in cell formed? | charge difference, ion distribution, ion channels / pumps for maintenance |
| What is the electrochemical equilibrium potential for Na+? | +60mV to keep Na+ from wanting INSIDE the cell |
| What is the electrochemical equilibrium potential for K+ ? | -90mV to keep K+ from wanting OUT of cell |
| what is the Na/K pump for? | maintaining electrochemical gradients essential for cellular functions |
| what is an excitable cell? | uses electrochemical gradient to do WORK, generated by depolarizing event |
| what are the stages of action potential? | stimulus, depolarization, repolarization, hyperpolarization |
| when can NO AP be formed after an AP? (ABSOULTE refractory period) | during the depolarization and repolarization phase |
| when can an AP be formed again? (relative refractory period) | during the hyperpolarization |
| what is saltatory conduction? | myelinated axon uses this, makes signal 'jump' btwn nodes of Ranvier |
| what are glial cells? | the brains version of myelin cells, make up 90% of the brain |
| what channels open during depolarization? | sodium, K+ stays closed |
| what channels open during repolarization? | K+, Na+ close |
| what ion is leaking during hyperpolarization? | K+! |
| what are the 3 types of neurons present in the Brain? | bipolar, unipolar, multipolar (classic neuron shape). |
| what glial cell creates CSF, lines ventricles/spinal cord and distributes hormones? | ependymal cells |
| what glial cell forms myelin and CANNOT be repaired once injured? | oligodendrocytes |
| what glial cell is most abundant and does many things? | astrocytes |
| what glial cell is the immune cell? | microglia |
| What is the main function of astrocytes? | They support and protect neurons, maintain the blood-brain barrier, and regulate the chemical environment in the CNS. (Think “Astro |
| What is the main function of microglia? | They act as the brain’s immune cells, cleaning up debris and fighting infection. (Think “Microglia munch microbes.”) |
| What is the main function of oligodendrocytes? | They form the myelin sheath around CNS axons to speed up nerve signals. (Think “Oligo |
| What is the main function of ependymal cells? | They line the brain’s ventricles and produce and circulate cerebrospinal fluid (CSF). (Think “Ependymal |
| What is the main function of Schwann cells? | They myelinate axons in the peripheral nervous system (PNS), one Schwann cell per axon. (Think “Schwann |
| What is the main function of satellite cells? | They support and protect neurons in the PNS ganglia. (Think “Satellite |
| Mnemonic for main CNS glial cells | “A M.O.E. makes your brain GO!” → Astrocytes, Microglia, Oligodendrocytes, Ependymal cells. |
| Difference between oligodendrocytes and Schwann cells? | Oligodendrocytes myelinate multiple CNS axons; Schwann cells myelinate a single PNS axon. |
| what are the 2 PNS glial cells? | Schwann and satellite |
| what is MS? | multiple scleorsis. a degenerative disease of myelin |
| What are the bumps on the brain called? | Gyri |
| What are the valleys or grooves on the brain called? | Sulci |
| Which lobe of the brain is associated with motor control? | Frontal lobe |
| What are the three main areas of the frontal lobe? | Primary motor cortex, premotor cortex, and prefrontal cortex |
| What does the primary motor cortex do? | processes input from skeletal muscle for voluntary movement |
| What does the premotor cortex (motor association area) do? | Works with the prefrontal cortex to integrate movement information with sensory inputs to form perceptions |
| What does the prefrontal cortex do? | Involved in decision-making, personality, and planning movements |
| Which lobe of the brain processes sensory input (senses)? | the parietal lobe |
| What is the function of the parietal association areas? | Integrate sensory info with other areas to form meaningful perceptions |
| Which lobe of the brain is responsible for vision? | Occipital lobe |
| What does the primary visual cortex do? | Receives input directly from the optic nerve |
| What do the visual association areas do? | Process and integrate visual information with other sensory inputs |
| What is the main function of the cerebellum? | Coordinates movement and balance; processes sensory input to fine-tune motor activity |
| What special feature does the cerebellum have? | Contains the largest number of neurons in the brain |
| Which lobe of the brain processes hearing and smell? | Temporal lobe |
| What does the primary auditory cortex do? | Receives signals from the auditory nerve |
| What do the auditory association areas do? | Process and integrate sound information with other sensory inputs |
| What other functions are linked to the temporal lobe? | Olfaction (smell), short-term memory storage, and recall |
| What is the corpus callosum? | A bundle of nerve fibers connecting the two cerebral hemispheres |
| What is the function of the corpus callosum? | Allows integration of sensory and motor information and coordination of movement between both sides of the body |
| What is the diencephalon? | A brain region containing the thalamus and hypothalamus |
| What is the function of the thalamus? | Receives sensory input from spinal cord and relays it to cerebral cortex |
| What is the function of the hypothalamus? | Regulates endocrine functions = body temp, thirst, food intake through hormone control= HOMEOSTASIS |
| What is the midbrain (mesencephalon)? | The bridge between brainstem and diencephalon that controls eye movements and visual/auditory reflexes |
| What is the function of the pons? | relay station between the cerebellum and cerebral cortex; helps coordinate breathing |
| What is the function of the medulla oblongata? | Controls breathing, blood pressure, and swallowing |
| What important event occurs in the medulla related to motor control? | Corticospinal tract fibers cross over to the opposite side, causing each hemisphere to control opposite-side muscles |
| What does the pituitary gland (hypophysis) do? | Regulates other endocrine organs under direction from the hypothalamus |
| What are the two parts of the pituitary gland? | Anterior pituitary (from epithelial tissue) and posterior pituitary (from neural tissue) |
| What controls the pituitary gland? | The hypothalamus |
| what are the 2 types of synapse? | electrical and chemical |
| what are electrical synapse? | CELL-CELL connection where ions are transmitted |
| what are chemical synapses? | has a synaptic cleft and releases neurotransmitters, no cell-cell connection |
| What triggers the start of neurotransmitter release at a chemical synapse? | An action potential reaches the axon terminal and depolarizes the pre-synaptic membrane. |
| What causes calcium channels to open in the pre-synaptic membrane? | Depolarization from the action potential opens voltage-gated Ca2+ channels. |
| What does calcium do once it enters the pre-synaptic cell? | It triggers synaptic vesicles to fuse with the membrane and release neurotransmitters. |
| What are the four possible fates of neurotransmitters in the synaptic cleft? | 1. Bind to receptors; 2. Diffuse ; 3. Broken down; 4. Reuptake |
| How do neurotransmitters affect the post-synaptic cell? | They bind to ligand-gated receptors, which can open ion channels and cause depolarization or hyperpolarization. |
| What ends the effect of neurotransmitters at the synapse? | They trigger a response by binding to receptors or removed by diffusion, degradation, or reuptake. |
| Why do different neurotransmitters cause different effects? | Each neurotransmitter binds to specific receptors, leading to different intracellular responses and downstream effects. |
| what are graded potentials? | action potentials that vary in amplitude based on STRENGTH of stimulus |
| What does EPSP stand for? | Excitatory post-synaptic potential. |
| What does an EPSP do to the neuron? | It depolarizes the membrane and brings the neuron closer to firing an action potential. (SUB threshold) |
| What does IPSP stand for? | Inhibitory post-synaptic potential. |
| What does an IPSP do to the neuron? | hyperpolarizes membrane and moves neuron further from firing AP |
| How are EPSPs and IPSPs similar? | Both are localized, graded, can be summed, and DECAY as they spread. |
| What causes an EPSP? | Neurotransmitters that open Na+ and K+ channels. |
| What causes an IPSP? | Neurotransmitters that open K+ (out) or Cl- (in) channels. |
| Why are EPSPs graded? | Their size depends on stimulus strength — stronger stimulus |
| where do IPSP and EPSP meet? | at the axon hillock, this sum will determine fate of neuron |
| why does the axon hillock control AP? | contains all the voltage gated channels that will produce AP (Na+) |
| What is temporal summation? | Additive effect- many IPSP/EPSPs at 1 synapse caused by high-frequency firing of one neuron. |
| What is spatial summation? | Additive effect from EPSPs at multiple synapses on the same post-synaptic neuron at the same time. |
| What does temporal summation involve? | One neuron firing rapidly to build up EPSPs or IPSPs. |
| What does spatial summation involve? | Many neurons firing simultaneously to produce EPSPs or IPSPs. |
| Acetylcholine | Excitatory; muscle control and memory; location: CNS and PNS |
| Epinephrine/Norepinephrine | Biogenic amines; excitatory; fight-or-flight response; location: adrenal medulla (PNS) |
| Dopamine | amine; excitatory; voluntary movement and reward; location: hypothalamus and CNS pathways |
| Serotonin | amine; inhibitory; mood, sleep, cognition, GI motility; location: gut (~90%) and CNS |
| Glutamate + Aspartate | Amino acids; excitatory; memory; CNS and PNS |
| GABA + glycine | Amino acid; inhibitory; inhibits CNS; location: cerebellum, brain stem, basal ganglia, hippocampus |
| Endogenous opioids (endorphins) | NEUROpeptides; inhibitory; pain relief and mood elevation; location: pituitary and hypothalamus |
| Vasoactive Intestinal Peptide (VIP) | Neuropeptide; excitatory or inhibitory depending on site; intestinal and smooth muscle; location: pancreas, intestine, CNS |
| Path from CNS to muscle? | Upper motor neuron (primary motor cortex) → spinal cord → lower motor neuron → muscle (effector). |
| What is the neurotransmitter at the NMJ? | Acetylcholine only. |
| Step 1 at the NMJ (presynaptic) | Action potential reaches the presynaptic terminal. |
| Step 2 at the NMJ (calcium entry) | Depolarization opens voltage-gated Ca2+ channels on the presyn; Ca2+ enters presynaptic terminal. |
| Step 3 at the NMJ (vesicle fusion) | Ca2+ triggers ACh-containing vesicles to fuse with the presynaptic membrane and release ACh. |
| Step 4 at the NMJ (postsynaptic response) | ACh binds nicotinic receptors (ligand-gated ion channels) causing Na+ influx and depolarization. |
| Step 5 at the NMJ (termination) | ACh is broken down by acetylcholinesterase into acetate and choline; choline is recycled. |
| Nicotinic receptor properties | Ionotropic (ligand-gated); located at NMJ and autonomic postganglionic cells; FAST!! response. |
| Muscarinic receptor properties | Metabotropic (G-protein coupled); not ion channels directly; SLOW!! found on smooth and cardiac muscle. |
| how many motor neurons innervate a muscle fibre? | ONE! |
| what is resting membrane potential of MUSCLE? | -90mV |
| what are receptors called that bind acetylcholine? | cholinergic receptors |
| What is an end plate current (EPC)? | A graded current in skeletal muscle produced at the motor end plate when ACh opens nicotinic receptors. |
| What is an end plate potential (EPP)? | The graded depolarization of muscle membrane produced by the EPC that can trigger an action potential if it reaches threshold. |
| How can an EPP lead to an action potential? | If muscles depol past threshold, voltage-gated Na+ channels open and AP is generated. |
| What ion movements produce the EPP? | Nicotinic receptors open cation channels allowing mostly Na+ influx and some K+ efflux, causing depolarization. |
| Where on the muscle cell are nicotinic receptors concentrated? | At the motor end plate, especially in the folded membrane regions that increase receptor surface area. |
| What is the motor end plate? | The specialized, indented region of the muscle membrane where the axon terminal contacts the muscle and densely packs ACh receptors. |
| Are EPPs graded or all-or-none? | EPPs are graded; their magnitude varies with the amount of ACh released. |
| What is the resting membrane potential of skeletal muscle and how does it compare to neurons? | Muscle RMP ≈ -90 mV compared to neuronal RMP ≈ -70 mV. |
| What is myasthenia gravis? | A disease where antibodies target & degrade nicotinic ACh receptors at the NMJ. |
| What are common symptoms of myasthenia gravis? | Muscle weakness; Cogan's eyelid twitch, weak responses on repetitive nerve stimulation. |
| How do antibodies affect the NMJ in myasthenia gravis? | They bind nicotinic receptors, reducing receptor number and impairing ACh binding. |
| What structural change occurs at the motor end plate in myasthenia gravis? | Loss of folds and fewer nicotinic receptors at the motor end plate. |
| How does myasthenia gravis change the muscle response to ACh release? | Reduced postsynaptic response to ACh, producing smaller muscle contractions. |
| What is a main symptomatic treatment for myasthenia gravis? | Acetylcholinesterase inhibitors to slow ACh breakdown and increase its availability at the NMJ. |
| How do acetylcholinesterase inhibitors help symptoms? | They prolong ACh presence in the cleft, increasing chance of receptor binding and improving muscle strength. |
| Is there a cure for myasthenia gravis? | No cure; treatments manage symptoms and delay progression. |
| Order of muscle from largest to smallest | Muscle -> Fascicle bundle -> Muscle cell/fiber -> Myofibril -> Myofilaments |
| List six key properties of skeletal muscle fibers | Long and cylindrical; Length 1–12 cm; Striated; Multinucleated; Many mitochondria; Number varies by muscle |
| What is the sarcolemma | The plasma membrane of the muscle cell |
| What are transverse T tubules | Indentations of the sarcolemma that conduct action potentials into MUSCLE fiber |
| What are terminal cisternae | end sections of the sarcoplasmic reticulum that store Ca2+ |
| What is the triad | A T-tubule flanked by two terminal cisternae |
| What are myofibrils | Bundles of contractile organelles within the muscle cell composed of repeating sarcomeres containing myofilaments |
| Describe thick myofilaments | Composed of myosin; long tail with two heads; myosin head has actin-binding site and ATPase site |
| Describe thin myofilaments | Made of actin, tropomyosin, and troponin; actin has myosin-binding sites; tropomyosin blocks sites at rest; troponin holds tropomyosin in place. troponin binds Ca+ and moves tropomyosin |
| What is a sarcomere | The contractile unit between two Z-discs made of overlapping thick and thin filaments |
| Name the sarcomere regions from Z-line to M-line | Z line; I band; A band; H band; M line |
| What does the I band contain | thin filaments only |
| what does the triad do? | links electrical signal with calcium release |
| what does the A band contain? | full length of thick filaments with overlap of thin filaments |
| which bands shorten upon muscle contraction? | Z disks, I band, H band |
| what is rigor mortis? | no new ATP supplied cuz no O2 movement, so myosin cant release actin, causing rigidity. NOT permanent |
| how does rigor mortis occur? | happens when Ca+ isnt being held in SR by calcium ATPase (no ATP to pump back into SR), this allows for binding to tropomyosin and contraction after death |
| What is a motor unit? | A motor neuron and all the muscle fibers it innervates. |
| Where is the motor neuron's cell body located? | In the spinal cord. |
| What does one action potential in a motor neuron produce in its muscle fibers? | One action potential in all the muscle fibers of that motor unit. |
| What is a muscle twitch? | A single contraction in response to one motor neuron action potential. |
| What is the latent period of a muscle twitch? | The short delay after an AP before tension appears while Ca2+ is released and cross-bridge sites are exposed. |
| What occurs during the contraction period of a twitch? | Cross-bridge cycling produces tension as actin and myosin interact. |
| What occurs during the relaxation period of a twitch? | Ca2+ is pumped back into the sarcoplasmic reticulum by Ca2+ ATPase and muscle tension falls. |
| Why is the relaxation period longer than the contraction period? | Because Ca2+ must be actively pumped back into the SR against its gradient by Ca2+ ATPase, which is slower than release. |
| How does the intermingled arrangement of motor units affect muscle contraction? | distribute force so contractions remain balanced and smooth. |
| What does asynchronous firing of motor units achieve? | It ensures smooth movement by overlapping contraction and relaxation of different motor units. |
| What is motor unit recruitment? | Increasing the number of active motor units to contract more muscle fibers and raise force output. |
| How does twitch summation increase muscle force? | Higher motor neuron firing frequency prevents full relaxation so successive twitches add together, increasing force. |
| What produces a graded muscle contraction? | Motor unit recruitment and/or summation of twitches to create greater force |
| why does action potential frequency matter in muscle contractoin? | more AP = more twitch = treppe stepladder formation of more and more force being generated. |
| What is treppe | A stepwise increase in contraction force when many action potentials cause progressively larger twitches. |
| What is unfused tetanus | A plateau of tension where action potential frequency allows partial relaxation between twitches. |
| What is fused (complete) tetanus | A smooth, sustained contraction produced when action potential frequency is so high there is no relaxation between twitches. |
| What determines whether tetanus is unfused or fused | The frequency of action potentials and whether twitches can partially relax between stimuli. |
| What is the functional result of fused tetanus | All twitches summate to produce a continuous maximal force and smooth sustained contraction. |
| Which part of the nervous system is the somatic motor system? | Part of the peripheral nervous system (PNS) |
| What is the main function of the somatic motor system? | Allows voluntary movement and control of skeletal muscles. |
| Where are the motor neuron cell bodies for voluntary action located? | In the central nervous system (CNS). |
| How do motor neurons communicate with muscle? | At the neuromuscular junction using acetylcholine. |
| What is the role of the premotor cortex? | DIRECTS MOTOR BEHAVIOUR AND BEHAVIOURAL DECISIONS |
| What is the role of the supplementary motor cortex? | Programs motor sequences and orients for FINE motor control. |
| What is the role of the primary motor cortex? | activates appropriate neurons for certain muscles |
| What is the motor homunculus? | map of the body |
| How is the body arranged on the motor homunculus? | Medial to lateral: foot → ankle → knee → thigh → trunk → shoulder → elbow → wrist → hand → fingers → face → lips → jaw → tongue. |
| what is the role of the prefrontal cortex? | decision making - the first thought to pick up a cup |
| What major input does the primary somatosensory cortex receive? | Sensory info relay from the thalamus (homeostasis sensor). |
| What functions does the primary somatosensory cortex do? | Detects touch, temperature, texture, pain, and proprioception. |
| What is the sensory homunculus? | A map on the primary somatosensory cortex showing which cortical areas receive input from specific body parts. |
| How does the sensory homunculus relate to sensation? | Larger cortical areas on the homunculus correspond to body regions with finer sensory discrimination. |
| what are the two homonculus? | sensory and motor |
| what are the other things in the somatic motor system? | basal ganglia, spinal pathways, |
| what is the corticospinal tract? | bundles of nerves going from primary motor cortex to the muscles it innervates via the spine |
| why is the corticospinal tract important? | similar to a highway used to send AP to specific muscles. |
| what is the decussation of the pyramids? | at the bottom of the medulla, the corticospinal tract from both sides of brain cross 80%, so left brain controls right body etc |
| What is proprioception? | Your brain's ability to sense limb position and muscle contraction without seeing them. AKA muscle sense |
| How does proprioception work? | Skeletal muscles send signals to the brain about their position and movement. |
| What do muscle spindles detect? | Muscle stretch, length, and rate of change in length (velocity). |
| Where are muscle spindles located? | Between muscle fibers (INTRAfusal) |
| What are intrafusal fibers? | Specialized fibers inside muscle spindles; different from contractile extrafusal fibers. |
| What do muscle spindles signal? | Need for more muscle power if they are stretched too far |
| How does the brain respond to spindle signals? | Increases action potential frequency or recruits more motor units. |
| What triggers APs in muscle spindles? | Stretching the central sensory region lacking myofibrils. |
| Role of muscle spindles in proprioception? | They help the brain know limb position and movement. |
| What do Golgi tendon organs detect? | Muscle tension and load/force. |
| Where are Golgi tendon organs located? | At the junction between muscle and tendon. |
| Function of Golgi tendon organs? | Fine-tune force output and prevent overload. |
| Structure of Golgi tendon organs? | Capsule with collagen fibers, innervated by ib afferent nerves. |
| How do Golgi tendon organs signal? | Stretch squeezes collagen, distorts sensory endings, triggers AP to CNS. |
| Muscle spindle vs Golgi tendon organ? | one detect length/velocity; one detects force/load. |
| What do primary afferents (Ia) detect? | Length changes and velocity; fire rapidly during stretch. |
| What do secondary afferents (II) detect? | Only length changes; steady firing during stretch. |
| what neurons does the muscle spindle use? | gamma motor neurons to communicate back to the brain |
| sensory fibres in muscle spindle? | LA and IL fibres (primary and secondary afferens) |
| sensory fibre in golgi tendon organ? | ib fibres, primary afferent nerves |
| What are the two types of motor neurons? | Alpha motor neurons and gamma motor neurons. |
| What do alpha motor neurons do? | innervate EXTRAFUSAL muscle fibers to generate power and cause muscle contraction. aka muscle cells |
| Where do alpha motor neurons send signals? | From the CNS to skeletal muscle at the NMJ. |
| What do gamma motor neurons do? | They innervate intrafusal fibers to keep muscle spindles sensitive to stretch. |
| Do gamma motor neurons cause strong contractions? | No, they cause slight contractions just to maintain spindle sensitivity. |
| Why is alpha-gamma coactivation important? | It ensures the brain receives continuous proprioceptive feedback during muscle contraction. |
| What happens without alpha-gamma coactivation? | Intrafusal fibers go slack, spindle stops sending info, and the brain loses track of muscle position and force. |
| How does alpha-gamma coactivation work? | the neurons fire together so extrafusal and intrafusal fibers contract simultaneously. |
| Why do intrafusal fibers contract during coactivation? | To maintain stretch on the sensory region of the spindle and keep sending signals to the CNS. |
| What does alpha-gamma coactivation preserve? | Proprioception and accurate muscle control during movement. |
| What components make up a reflex arc? | Sensory receptor, afferent neuron, synapse, interneuron, efferent neuron, effector organ. |
| Is the brain involved in a reflex arc? | No, reflexes bypass the brain. |
| Example of a reflex arc? | Touching a flame and pulling your hand away. |
| How does the reflex arc work? | Pain signal travels via afferent neuron to spinal cord, activates interneuron, which triggers efferent neuron to move muscle. |
| What triggers the stretch reflex? | Tapping the patellar tendon stretches the quadriceps. |
| What detects the stretch in the muscle? | Muscle spindles. |
| What happens when muscle spindles stretch during stretch reflex? | They send an action potential through the afferent neuron to the spinal cord. |
| What does the afferent neuron do in the stretch reflex? | It synapses with the motor neuron of the quadriceps. |
| What is reciprocal innervation? | Activation of one muscle while its opposing muscle is inhibited. |
| What is the result of the stretch reflex? | Quadriceps contract, hamstring relaxes, and the leg kicks out. AKA reciprocal innervation |
| Main function of the cerebellum? | Coordinates movement and processes sensory information. |
| What kind of input does the cerebellum receive? | From somatic receptors, balance/equilibrium receptors, and motor neurons. |
| What does the pons do? | Relays info between the cerebellum and cerebral cortex; and helps control breathing. |
| How does the cerebellum ensure accurate movement? | It compares motor cortex signals with proprioceptor feedback and adjusts movement. |
| What is the vestibular ocular reflex (VOR)? | A reflex that stabilizes vision during head movement, coordinated by the cerebellum. |
| What are the two main input sources to the cerebellum? | Motor cortex and proprioceptors. |
| What does the cerebellum do if movement is incorrect? | Modifies motor cortex signals to correct the movement. |
| What is the limbic system? | The emotional center of the brain. |
| Main components of the limbic system? | Corpus callosum, cingulate gyrus, olfactory bulb, hippocampus, hypothalamus, thalamus, amygdaloid nucleus. |
| Role of the hypothalamus? | Controls ENDOCRINE functions like temperature, hunger, thirst, and hormone release. aka homeostasis |
| Role of the thalamus? | Receives and integrates sensory input before sending it to the cortex. (hallway of info) |
| What is the diencephalon? | The thalamus and hypothalamus together. |
| Function of the amygdaloid nucleus? | Processes emotions and strengthens emotional memories. |
| What behaviors are linked to the limbic system and hypothalamus? | Eating, drinking, movement, heart rate, blood pressure, sex, and memory. |
| What is the pituitary gland also called? | Hypophyse. |
| Function of the pituitary gland? | Regulates other endocrine organs, controlled by hypothalamus |
| Origin of anterior vs posterior pituitary? | Anterior from pharynx epithelium; posterior from hypothalamic neural tissue. |
| What does the pituitary secrete hormones for? | Stress, lactation, growth, development, and reproduction. |
| What regulates the pituitary gland? | The hypothalamus. |
| Where is the hypothalamus located? | Just in front of the brainstem. |
| Functions of the hypothalamus? | Regulates temperature, water, food intake, heart rate, circadian rhythms, emotions, and hormones. |
| What control system does the hypothalamus use? | Negative feedback control. |
| How does negative feedback work? | Stimulus triggers change, sensor detects it, sends signal to control center, effector responds to restore balance. |
| How is body temperature regulated? | Hypothalamus detects deviation from set point and activates mechanisms to restore it. |
| Why does temperature set point change when sick? | To help fight off microbes as an evolutionary defense. |
| What are the three divisions of the ANS? | Sympathetic, Parasympathetic, Enteric. |
| Which brain structure primarily controls the ANS? | Hypothalamus. |
| Main function of the sympathetic division? | Fight/flight/freeze: increases HR and BP, dilates airways, redirects blood to muscles. |
| Main function of the parasympathetic division? | Rest and digest: slows HR, lowers BP, increases blood to gut for digestion. |
| What does the enteric nervous system do? | Controls the gut; can operate independently of the CNS. |
| Where do sympathetic nerves exit the spinal cord? | Thoracic and lumbar regions. (LOW) TO BE CLOSE TO EFFECTORS |
| Where do parasympathetic nerves exit the CNS? | Brainstem and lower sacral spinal cord. (UP HIGH) |
| Which organs may have only sympathetic innervation? | Adrenal glands and many blood vessels. |
| Give an example of an organ with both sympathetic and parasympathetic input. | Genitals. |
| What three neuron types are common to both ANS divisions? | Preganglionic neuron, autonomic ganglion, postganglionic neuron. |
| What neurotransmitter is used in autonomic ganglia for both divisions? | Acetylcholine. |
| Primary neurotransmitters at target organs for the parasympathetic division? | Acetylcholine. |
| Primary neurotransmitters at target organs for the sympathetic division? | Norepinephrine and epinephrine (except sweat glands). |
| What is the neurotransmitter in sweat glands? | Acetylcholine - only time sympathetic uses Ach. |
| which preganglionic axon length is longer? sympathetic vs parasympathetic? | parasympathetic |
| where is ganglion located in sympathetic division? | autonomic ganglia are closer to the CNS |
| Compare postganglionic axon length: sympathetic vs parasympathetic? | Sympathetic postganglionic axons are longer; parasympathetic postganglionic axons are shorter. |
| Why do the two ANS divisions sometimes act together? | They coordinate to maintain homeostasis; one division may dominate depending on the situation. |
| where is the autonomic ganglion located in parasympathetic division? | autonomic ganglia are closer to the target organ |
| which division of ANS has longer post ganglion axon? | sympathetic |
| which division of ANS post ganglionic axon is unmyelinated? | parasympathetic - signal can take a bit longer to get there |
| which division of ANS has shorter post ganglion axon? | parasympathetic |
| What neurotransmitter do all preganglionic neurons release? | Acetylcholine (ACh). |
| What receptor does ACh bind to on postganglionic neurons in autonomic ganglia? | Nicotinic receptors |
| How does ACh act at nicotinic receptors? | Fast transmission via ion channel opening and depolarization. |
| What receptors does ACh bind to on target organs in the parasympathetic system? | Muscarinic receptors. |
| How does ACh act at muscarinic receptors? | Slow transmission via G-protein signaling that opens OTHER NEARBY ion channels- TAKES A WHILE |
| What is the main neurotransmitter released by sympathetic postganglionic neurons at most target organs? | Norepinephrine. (BUT SWEAT GLANDS GET ACh) |
| What neurotransmitters are released by the adrenal medulla? | Epinephrine (~80%) and norepinephrine (~20%). |
| Which sympathetic target organ uses ACh instead of norepinephrine? | Sweat glands. |
| What are the two major classes of adrenergic receptors? | Alpha adrenergic receptors; Beta adrenergic receptors. |
| What responses are associated with alpha adrenergic receptor activation? | Smooth muscle contraction and vasoconstriction. |
| What responses are associated with beta adrenergic receptor activation? | Vasodilation, smooth muscle relaxation, bronchodilation, and increased cardiac activity. |
| Why is the adrenal gland medulla considered a modified autonomic ganglion in the sympathetic division? | It releases epinephrine directly into the blood and lacks a postganglionic neuron and parasympathetic connection |
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