Term
| What are the functions of the nervous system (5)? |
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Definition
-sensory
-integration
-motor functions
-regulate glandular secretions
-maintain appropriate state of consciouness |
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Term
| What is required for the nervous system to function? |
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Definition
| rapid transmission of information from one site in the body to another by electrochemical impulse |
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Term
| What are the two main classes of cells in the nervous system? |
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Definition
neuroglial (glial) cells
neurons |
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Term
| How does myelin affect information transfer? |
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Definition
| speeds of propagation of the electrical impulse |
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Term
| Which class of cells is involved in transmission of information/impulses? |
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Definition
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Term
| What are the functions of neuroglial cells? (6) |
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Definition
-form myelin (sheath around axon)
-provide nutrients & oxygen
-anchor neurons
-destroy pathogens
-remove dead neurons
-protect nervous system |
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Term
| What is the function of neurons? |
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Definition
-develop & propagate action potentials to carry information throughout the CNS
- |
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Term
| From where do cardiac cells gain their action potential? |
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Definition
| they can generate their own AP |
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Term
| What is the term for the central body of the neuron? |
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Definition
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Term
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Definition
-multibranched projections from the soma
-receive impulses from other neurons & transmit the info to the soma |
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Term
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Definition
-single unbranched projections from the soma
-conducts impulse from the soma to another neuron or cell |
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Term
| What is the length of an axon? |
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Definition
| ranges from less than 1mm to greater than 1m |
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Term
| How many axons project from each neuron? |
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Definition
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Term
| Which contains a high proportion of myelinated axons, white matter or grey matter? |
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Definition
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Term
| What is the term for specialized glial cells found inside the brain & spinal cord? |
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Definition
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Term
| What is the term for specialized glial cells found outside the brain & spinal cord? |
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Definition
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Term
| What is the term for the gaps found between adjacent glial cells? |
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Definition
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Term
| Is the speed of transmission greater for myelinated or unmyelinated cells? |
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Definition
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Term
| What is the function of the nodes of Ranvier? |
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Definition
| work with myelin sheaths to speed up transmission of impulses |
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Term
| What axis/regions of the body is the central nervous system concerned with? |
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Definition
-brain & spinal cord
-central (cranial-caudal) axis of the body |
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Term
| What PNS nerves originate from the brain? The spinal cord? |
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Definition
cranial nerves
spinal nerves |
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Term
| What type of nerves are afferent nerves, and in which direction to they carry information? |
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Definition
sensory nerves (information from sensory receptors)
carry impulses towards CNS |
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Term
| What type of nerves are efferent nerves, and in which direction to they carry information? |
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Definition
motor nerves (cause skeletal contractions)
carry impulses away from CNS |
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Term
| Is somatic NS function voluntary or involuntary? |
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Definition
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Term
True or False
Impulses controlled by the ANS travel to skeletal muscle |
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Definition
False
Involuntary nerve function is found in smooth muscle, cardiac muscle, endocrine glands etc. |
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Term
| What are some functions of the Autonomic Nervous System? |
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Definition
-contract intestines
-increase heart rate in response to threat
-stimulate secretion of digestive juices |
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Term
| Describe the polarization of a resting neuron |
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Definition
-Na/K pump transports Na+ outside the cell, and K+ inside against [%] gradient
-generates a difference in electrical charge across the membrane |
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Term
| What is the resting membrane potential? |
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Definition
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Term
| Does an unstimulated neuron have a greater [K+] on the inside or outside of the membrane? |
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Definition
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Term
| Describe what happens when a neuron receives an impulse from an adjoining neuron |
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Definition
-Na channels in the membrane open
-Na+ passively diffuse to the inside of the cell
-RMP becomes positive
-Na channels close, K+ channels open
-K+ flows out of cell |
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Term
| Why do Na+ ions diffuse into the cell passively once the sodium channels are opened? |
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Definition
-travel down a concentration gradient
-resting mmb potential is -70mV inside the cell, Na+ are attracted to it |
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Term
| An neuron's action potential is... |
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Definition
| the change in electrical charge aacross the membrane from negative to positive |
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Term
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Definition
| opening of Na channels and influx of Na into the neuron cell |
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Term
| Why do K+ ions travel outside of the neuron cell after the potassium channels have opened? |
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Definition
-inflow of Na+ creates positive charge
-like charges repel, K+ moves out |
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Term
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Definition
| opening of potassium channels and outflow of K+ from the neuron cell |
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Term
| Describe the concentration of K and Na between the end of repolarization and the establishment of RMP |
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Definition
| high K outside, high Na inside |
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Term
True or False
The 'strength' of depolarization depends on the strength of the stimulus received |
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Definition
False
As long as the stimulus is above the threshold minimum, depolarization will occur, always at 'maximum strength' |
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Term
| What is the refractory period? |
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Definition
| -when a 2nd stimulus arrive at the time Na channels or K channels are open ("in action") the neuron is insensitive to this new stimulus |
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Term
| What is an absolute refractory period, when does it occur? |
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Definition
no depolarization under any circumstances
-during Na influx or early stages of K outflow |
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Term
| What is a relative refractory period, when does it occur? |
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Definition
we see depolarization
-occurs if a larger than normal stimulus arrives at the tail end of repolarization |
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Term
| What is saltatory conduction? |
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Definition
-myelin sheath prevents flow of Na+ across the membrane, depolarization is limited to the Nodes of Ranvier, skipping from one node to another
-speeds up conduction of the action potential along the neuron |
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Term
| What causes Multiple Sclerosis? |
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Definition
| damage to the myelin sheath, slows rate of conduction and results in loss of normal muscle control |
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Term
| How does an AP travel to the next neuron/target cells after it has traveled the length of an entire axon? |
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Definition
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Term
| Describe synaptic transmission |
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Definition
-AP reaches presynaptic neuron
-at presynaptic knob, Ca2+ channels open
-Ca2+ flows in, neurotransmitter fuses with cell membrane
-synaptic cleft secretes neurotransmitter
-postsynaptic neuron receives neurotransmitter via diffusion |
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Term
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Definition
| junction between a neuron and another neuron, or a neuron and a target cell |
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Term
| What is a the physical gap between a neuron and a receptor cell? |
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Definition
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Term
| What is a presynaptic neuron? |
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Definition
| the neuron that brings the AP to the synapse & releases a neurotransmitter |
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Term
| What is a postsynaptic neuron? |
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Definition
| the neuron that receives the neurotransmitter from the synapse |
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Term
| What is the knob at the end of the presynaptic neuron? |
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Definition
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Term
| What is the function of a neurotransmitter |
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Definition
| to stimulate depolarization of the membrane across a synaptic cleft |
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Term
True or False
Membranes on the postsynaptic neuron bind to all forms of neurotransmitters |
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Definition
False
They usually bind a specific neurotransmitter |
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Term
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Definition
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