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Nervous System
| Question | Answer |
|---|---|
| What is a sensory (afferent) neuron? | Receives initial stimulus from the environment |
| What is an association neuron (interneuron)? | Receives input from sensory neurons and sends it to motor neurons; makes up 99% of the body's neurons |
| What is a motor (efferent) neuron? | Receives signals from the brain and stimulates target cells (effectors) to elicit a response |
| What is a key limitation of neurons regarding cell division? | Neurons cannot divide |
| What is the function of dendrites? | Receive information and transfer it to the cell body |
| What is the axon hillock? | The site of action potential generation |
| What is the function of the axon? | Transfers impulses away from the cell body |
| How do diameter and myelination affect nerve conduction? | Increased diameter and increased myelination both result in quicker propagation of the impulse |
| What are the three types of neurons? | Sensory, association neuron, and motor neuron |
| What are the 6 types of glial cells | Oligodendrocytes, Schwann cells, Microglia, Ependymal cells, Satellite cells, Astrocytes |
| What makes glial cells different from neurons? | Glial cells are capable of dividing; neurons cannot |
| What do oligodendrocytes do? | Produce myelin in the CNS |
| What do Schwann cells do? | Produce myelin in the PNS |
| What do microglia do? | Act as CNS phagocytes |
| What do ependymal cells do? | Circulate CSF using cilia |
| What do satellite cells do? | Serve as support cells in the PNS |
| What do astrocytes do? | Physically support CNS neurons and maintain nutrient and mineral balance |
| What does "all or nothing" mean for action potentials? | The strength of a neural signal is based on factors like frequency of firing or how many neurons contribute — not the size of the stimulus itself |
| What are the 5 stages of an action potential in order? | 1. Resting Potential, 2. Depolarization, 3. Repolarization, 4. Hyperpolarization, 5. Refractory Period |
| What is the resting potential? | −70 mV; K⁺ is higher inside the cell, Na⁺ is higher outside |
| What happens during depolarization? | A stimulus opens gated ion channels; Na⁺ enters and depolarizes the axon; if the −50 mV threshold is reached, voltage-gated Na⁺ channels open down the entire neuron (all-or-nothing) |
| What is the threshold for an action potential? | −50 mV |
| What happens during repolarization? | K⁺ moves out of gated ion channels, restoring polarization |
| What happens during hyperpolarization? | Excess K⁺ leaves the neuron before the channels fully close |
| What is the refractory period? | The neuron is unresponsive to new stimuli until the Na⁺/K⁺ pump returns ions to resting potential locations |
| What is the role of the Na⁺/K⁺ pump? | Maintains the resting potential of −70 mV using ATP |
| What is the ion exchange ratio of the Na⁺/K⁺ pump? | 3 Na⁺ pumped out for every 2 K⁺ pumped in |
| What is step 1 of synaptic transmission? | The action potential reaches the synaptic region |
| What is step 2 of synaptic transmission? | The action potential activates voltage-gated Ca²⁺ channels, allowing Ca²⁺ to enter |
| What is step 3 of synaptic transmission? | Ca²⁺ entry causes the presynaptic neuron to release neurotransmitters from synaptic vesicles into the synaptic cleft |
| What is step 4 of synaptic transmission? | Neurotransmitters bind to receptors on the postsynaptic neuron |
| What is step 5 of synaptic transmission? | The postsynaptic membrane is either excited or inhibited depending on which neurotransmitter binds |
| What is the general rule about how sensory receptors respond? | They respond strongly to their own specific stimuli and weakly to others |
| What do mechanoreceptors detect? | Touch |
| What do thermoreceptors detect? | Temperature |
| What do nociceptors detect? | Pain |
| What do electromagnetic receptors detect? | Light |
| What do chemoreceptors detect? | Taste, smell, and blood chemistry |
| Where does ACh bind and what does it do? | Binds to ACh receptors on the post-synaptic membrane for nerve transmission |
| What does ACh do at neuromuscular junctions? | Its secretion causes contraction or relaxation of muscles (PNS) |
| How is ACh recycled and what does that do? | It is recycled back to the presynaptic vesicle via acetylcholinesterase, which terminates the nerve signal and prevents the postsynaptic neuron from depolarizing |
| What is glutamate and what does it do? | The most common CNS neurotransmitter in vertebrates; excitatory |
| What is GABA and what does it do? | An inhibitory neurotransmitter found in the brain |
| What is glycine and what does it do? | An inhibitory neurotransmitter found in the CNS outside the brain |
| What is unique about gaseous neurotransmitters? | They are synthesized and released on demand and are not stored in vesicles (e.g., nitric oxide/NO) |
| What are biogenic amines? | Neurotransmitters derived from amino acids; include epinephrine (E) and norepinephrine (NE), which act in the sympathetic nervous system |
| What are the effects of epinephrine? | Bronchodilation and vasodilation to lungs and skeletal muscles; vasoconstriction to the digestive system and kidneys |
| What does the somatic nervous system innervate? | Skeletal muscle |
| What movements does the somatic nervous system control? | Both voluntary and involuntary movements |
| What neurotransmitter does the somatic nervous system use and where? | ACh at neuromuscular junctions (synapse between motor neuron and skeletal muscle cell); effect is stimulatory |
| How many neurons does the somatic nervous system use from CNS to effector? | One neuron (heavily myelinated axon) |
| What are the effector targets of the autonomic nervous system? | Smooth muscle, glands, and cardiac muscle |
| How many neurons does the autonomic nervous system use from CNS to effector? | A two-neuron chain |
| What is the overall role of the parasympathetic branch? | Rest and digest |
| What neurotransmitters does the parasympathetic system use and where? | ACh at both the ganglion and at the effector organ |
| What type of axons does the parasympathetic system use? | Lightly myelinated preganglionic axon; non-myelinated postganglionic axon |
| What are the key effects of parasympathetic activation? | Lowered heart rate; increased digestion, relaxation, and sexual arousal |
| What is the overall role of the sympathetic branch? | Fight or flight |
| What neurotransmitters does the sympathetic system use and where? | ACh at the ganglion; norepinephrine (NE) and epinephrine (E) at the effector organ; also stimulates the adrenal medulla |
| What type of axons does the sympathetic system use? | Lightly myelinated preganglionic axon; non-myelinated postganglionic axon |
| What are the key effects of sympathetic activation? | Increased blood pressure and heart rate, ejaculation, energy generation; inhibition of digestion, urination, and salivary secretion |
| What three structures make up the CNS? | Brain, spinal cord, and interneurons |
| What is the blood-brain barrier? | A blockade of cells that prevents or slows the passage of drugs, ions, and pathogens into the CNS |
| What substances can pass through the blood-brain barrier? | O₂, CO₂, glucose, and small non-polar molecules |
| What is the forebrain and what does it contain? | The largest part of the brain; contains the olfactory bulb, thalamus, hypothalamus, basal ganglia, and hippocampus |
| What are the three major divisions of the brain? | Forebrain, Midbrain, Hindbrain |
| What is the function of the thalamus? | Relay station between the spinal cord and cerebral cortex |
| What is the function of the hypothalamus? | Controls visceral functions such as sleep, hunger, and temperature regulation |
| What is the function of the basal ganglia? | Planning and learning movement sequences |
| What is the function of the hippocampus? | Memory |
| What is the olfactory bulb responsible for? | Smell |
| What is the limbic system and what does it control? | Hippocampus + amygdala + hypothalamus; controls behavioral and emotional responses |
| What is the diencephalon? | A subdivision of the forebrain containing the thalamus, hypothalamus, and pineal gland |
| What is the telencephalon? | The subdivision containing the cerebrum and cerebral cortex, divided into lobes |
| What is the function of the frontal lobe? | Conscious thought and attention |
| What is the function of the parietal lobe? | Sensory processing, somatosensation, and proprioception |
| What is the function of the temporal lobe? | Sound processing and interpretation |
| What is the function of the occipital lobe? | Visual input |
| What are the functions of the midbrain? | Relay center for visual and auditory impulses; motor control |
| What is the function of the cerebellum? | Balance and coordination |
| What is the brainstem and what does it connect? | Connects the cerebrum to the spinal cord; made up of midbrain + medulla oblongata + pons |
| What is the function of the pons? | Relay center between the cortex and cerebellum |
| What is the function of the medulla oblongata? | Controls breathing, heart rate, and GI activity |
Created by:
smurtab