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Neuronal
| Question | Answer |
|---|---|
| What is the role of neuron? | They transmit electrical impulses rapidly around the body to react to changes in the internal and external environment |
| What are the parts of neuron structure? | Cell body, dendron, dendrites, axon, myelin sheath, nodes of ranvier |
| What factors increase the rate of electrical impulse? | Saltatory conduction, myelination, increased temperature, increased temperature, increased axon diameter, fewer synapses |
| What are the types of neuron and their features? | Sensory (long dendrites, short axon), Relay (short dendrites, short axon), Motor (short dendrites, long axon) |
| Role of Schwann cells | Produce layers of phospholipid bilayer membrane which wrap around and insulate the axon |
| Why does myelination (saltatory conduction) increase the speed of electrical impulse? | Myelination blocks Na+ voltage gated ion channels to opening, creating a steeper electrochemical and concentration gradient. The distance creates longer localised circuits. |
| What's the role of sensory receptors? | to convert a detected stimulus into a nerve impulse. |
| What are the types of sensory receptor? | Photoreceptors, mechanoreceptors, chemoreceptors, thermoreceptors. |
| What is the pacinian corpuscle? | Sensory receptor detecting mechanical pressure in the skin |
| How does the pacinian corpuscle convert mechanical pressure into nervous impulse? | When pressure is applied the corpuscle changes shape, causing the membrane to change shape. This causes the stretch-mediated sodium ion channels to stretch, allowing Na+ to diffuse into the neuron generating an action potential |
| How is resting potential maintained? | - Leaky K+ channels move K+ions out of the axon - Leaky Na+ channels allowing Na+ ions into the axon - The sodium potassium pump moves 2Na+ ions out and brings 3K+ ions in using ATP |
| What is resting potential? | It's -70mV, the membrane is said to be polarised. |
| What is an action potential? | The temporary reversal of potential difference caused by a change in the distribution of ions |
| Process of the generation of an action potential | 1. voltage-gated Na+ ion channels open at -55mV, causing Na+ to flow into the axon (depolarisation) 2. At +35mV the Na+ion channels close and the K+ ions channels open, causing K+ions to move out of the axon |
| What is hyperpolarisation? | K+ ion channels are slow to close, causing action potential to drop below -70mV. |
| What is the all-or-nothing principle? | A certain level of stimulus will always trigger a response, the size of the stimulus does not affect the size of the action potential |
| What are the two types of neurotransmitter? | Excitatory (triggers an action potential), Inhibitory (prevents an action potential) |
| What makes up the synapse structure? | mitochondria, SER, calcium ion channels, vesicle (containing NTs),synaptic knob, synaptic cleft, NT receptor. |
| Process of synaptic transmission | depolarisation causes Ca2+ ion channels to open. Ca binds to vesicles causing them to bind to membrane and release NTs. NTs bind to receptors (Na+ ion channels), causing them to open so Na+ ions move into post-synaptic neuron. |
| What neurotransmitter is found in cholinergic synapses? | Acetylcholine |
| What happens to leftover acetylcholine in the synaptic cleft? | Broken down by acetylcholinesterase into acetyl and choline for reabsorbtion |
| What is the nervous system? | network of cells, tissues and organs which are responsible for controlling and coordinating the functions of the body |
| What are the functions of the nervous system? | Responding to changes in the environment, Transmits electrical impulses, Interpret nerve impulses, Assimilates experiences in memory and learning, Initiates glandular secretion and muscle contraction, Promotes instinctual behaviour. |
| Branches of CNS | Brain and spinal cord |
| Branches of peripheral nervous system | somatic and autonomic |
| Branches of autonomic nervous system | Sympathetic and parasympathetic |
| What neurons are in the peripheral nervous system? | Motor and sensory neurons |
| What does the somatic nervous system control and where does the input come from? | Behaviour under conscious control, input from sense organs |
| Characteristics of neuron in somatic nervous system | Heavily myelinated |
| Characteristics of neuron in autonomic nervous system | Either lightly myelinated or unmyelinated |
| What does the autonomic nervous system control and where does the input come from? | unconscious actions, input from internal receptors |
| What are ganglia? | Swellings where two motor neurons meet in the autonomic nervous system. Found between pre-ganglionic and post-ganglionic neurons. |
| Characteristics of ganglionic neurons in sympathetic motor system | Short pre-ganglionic neurons which are lightly myelinated. Long post-ganglionic neurons which are unmyelinated. |
| Role of sympathetic nervous system | Initiates the fight or flight response |
| Neurons used in sympathetic nervous system | thoracolumber neurons |
| Neurotransmitters used in sympathetic nervous system | Acetylcholine (relay to motor), noradrenaline (motor to effector) |
| What are the affects of the sympathetic nervous system? | Increased heart rate, dilated pupils, inhibited digestion, saliva produced |
| Characteristics of ganglionic neurons in parasympathetic motor system | Long pre-ganglionic neurons which are lightly myelinated Short post-ganglionic neurons which are unmyelinated |
| Role of parasympathetic nervous system | Relaxation response |
| What neurons are used in the parasympathetic nervous system | Cranial sacral neurons |
| Neurotransmitters used in the parasympathetic nervous system | Acetylcholine |
| Affects of parasympathetic nervous system | Decreased heart rate, constricted pupils, normal digestion |
| Where is noradrenaline released from? | Adrenal medulla |
| Why do neurotransmitters affect smooth muscle differently? | They bind to different receptors on the blood vessel |
| Role of cerebrum | Controlling voluntary actions (learning, memory, personality) |
| Role of the cerebellum | Controls unconscious functions (balance, posture) |
| Role of medulla oblongata | Autonomic control (heart rate) |
| Role of the hypothalamus | Regulatory centre for temperature and osmoregulation |
| Role of the pituitary gland | Stores and releases hormones to control bodily functions |
| What lobes make up the cerebrum? | Frontal lobe, parietal lobe, temporal lobe, occipital lobe |
| What is the cerebrum split into, what connects them? | Split into two cerebral hemispheres connected by the corpus callosum |
| How is the cerebrum specialised? | Highly convoluted (folded) to give a large surface area. |
| What's meant by contralateral control? | The right side of the brain controls the left side of the body and vice versa |
| What makes up the forebrain? | Cerebrum, thalamus and hypothalamus |
| What makes up the hindbrain? | Pons, medulla oblongata, cerebellum |
| What's the sarcolemma? | Cell membrane in muscle |
| What's the sarcoplasm? | Cytoplasm in muscle |
| What's the sarcoplasmic reticulum? | Endoplasmic reticulum in muscle, releasing Ca2+ ions |
| Structure of smooth muscle cell | No striations, almond shaped, single nucleus, uses actin and myosin for contraction |
| Where is smooth muscle found? | Found in muscle which contract involuntarily (the cell wall of blood vessels and intestines) |
| How is smooth muscle specialised? | Can contract in different directions, contracts and tires slowly (needs less ATP). |
| Structure of cardiac muscle | Specialised striations, each muscle fibre branched, single nucleus, muscle fibres connected by intercalated disks. |
| What are striations formed from? | A sacromere containing actin and myosin |
| How is cardiac muscle specialised? | Branched structure allows the contraction to flow as a whole, lots of mitochondria for high levels of ATP |
| Structure of skeletal muscle | Connected to bone via tendons. Made of bundles of muscle fibres, contain myofibrils enclosed in a sarcolemma. Sarcolemma folds inwards to form T-Tubles to help with electrical conduction. Longer than normal cells, multiple nuclei. Lots of mitochondria |
| What makes up a myofibril? | Many sarcomeres lined up parallel to provide maximum strength |
| What proteins make up a sarcomere? | Actin and myosin |
| What different parts make up a sarcomere? | Light band (I-band), Dark band (A-band), H-zone, Z-line |
| What happens to the sarcomere during contraction? | It shortens, causing I-band and H-band to shorten |
| What does the neuromuscular junction lead to? | Calcium ions being released from the sarcoplasmic reticulum leading to muscle contraction |
| Process of a neuromuscular junction | Acetylcholine binds to Ach receptors (Na ion channels) causing Na ions to enter the sarcolemma causing depolarisation. Depolarisation spreads down the t tubules into the sarcoplasm, leading Ca ions to be released from the sarcoplasmic reticulum |
| What causes the movement of actin in the sliding filament model? | Myosin head binds to exposed myosin binding site, phosphate ion removed causing head (and actin to move). ADP is released and ATP binds - causes myosin head to detach and return to original position |
| What causes the myosin binding site to become available? | Ca2+ ions bind to troponin, causing a conformational change. This causes the tropomyosin to move |
| What is a reflex? | an involuntary response to a sensory stimulus |
| Steps in the reflex arc | Receptor detects the stimulus and converts it to an action potential, sensory neuron carries impulse to relay neuron in spinal cord or brain, motor neuron carries the impulse to the effector |
| How to check the knee-jerk reflex? | Tap the patella tendon just below the kneecap |
| What can the absence of the reflex or multiple oscillations suggest? | Absence = nervous problems Multiple oscillations = cerebellar disease |
| What is the blinking reflex? | involuntary blinking of eyelids when the cornea of stimulated (by light, touch or sound) |
| Where is the relay neuron for the blinking reflex found? | Lower brain stem |
| What is the corneal (blinking) reflex used for? | Assessing brain death, its presence indicates brain functioning in the lower brain stem |
Created by:
Charlotte_05
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