Nervous System for Exam 2 Flashcards
list the 6 components of the central nervous system
- gray matter
- white matter
- spinal cord
- cauda equina
- meninges
- cerebrospinal fluid
describe gray matter
groups of cell bodies (nuclei) around brain and in center of spinal cord
describe white matter
groups of myelinated axons (tracts) inside of brain and on the outside of the spinal cord
describe the function of spinal axons (in white matter)
transmit and receive signals from the brain
list the 4 main components of the brain
- cerebrum
- cerebellum
- interbrain
- brain stem
describe the cerebrum
the majority of the brain (big wavy bits), divided into left and right hemispheres, contains the cerebral cortex an cerebral medulla
what is the cerebral cortex?
the outer portion of the cerebrum (gray matter)
what is the cerebral medulla?
the inner portion of the cerebrum (white matter)
where is the cerebellum located?
caudal and ventral to cerebral hemispheres
list the 3 components of the interbrain
- hypothalamus
- thalamus
- epithalamus
what gland is attached to the hypothalamus and what does it do?
the pituitary gland, involved in regulating hormone release
what is the function of the thalamus?
to relay signals to the rest of the brain
what gland is located in the epithalamus and what does it secrete?
the pineal gland, secretes melatonin
list and describe the locations of the 3 components of the brain stem
- midbrain: top of stem
- pons: ventral to midbrain
- medulla oblongata: ventral to pons, attaches to spinal cord
what is the function of the blood-brain barrier?
regulate movement of materials from the blood into the brain
can most drugs easily cross the blood-brain barrier?
no they must be designed specifically
describe the structure of the blood-brain barrier
astrocytes surround capillaries in the brain and push simple squamous cells (endothelial cells lining those capillaries) closer together to form tight junctions between the cells, meaning that anything entering the brain from the blood must now travel through the endothelial cells instead of around them, requiring transport receptors thus providing more protection
can glucose pass through the blood-brain barrier? why or why not?
it can because it’s small
what does the blood-brain barrier mean for infections of the nervous system like rabies or tetanus?
they are much harder to treat
where is the spinal cord found and what makes up its structure?
within white matter, made of different tracts of axons
list and describe the 2 kinds of fibers in the spinal cord
- afferent fibers: relay sensory information from periphery to the brain (AKA sensory fibers)
- efferent fibers: relay motor information from brain to periphery (also called motor fibers)
what do Efferent fibers do?
cause an Effect in the body
what is the cauda equina?
the terminal end of the spinal cord, which gets smaller going down its length and resembles a horse’s tail
what are and how many meninges are there?
protective membranes, 3 layers of connective tissue
what is the most superficial layer of the meninges?
the dura mater
what is the dura mater made of and what is it attached to?
dense irregular connective tissue (the most protective layer), attached directly to the skull
what is the space between the dura mater around the spinal cord and vetebrae called and what is it used for?
the epidural space, where we inject drugs
describe the arachnoid layer of the meninges
thin, wispy, fibrous layer, looks like a spider web, NONVASCULAR
what is the deepest layer of the meninges?
the pia mater
describe the pia mater
bound tightly to the brain and spinal cord, thin, fibrous, also nonvascular
what is the space between the pia mater and the arachnoid space called?
the aubarachnoid space
where is cerebrospinal fluid located?
in the subarachnoid space
what is the function of cerebrospinal fluid?
acts as a protective cushion produced by ependymal cells
what are the 2 components of the peripheral nervous system?
- spinal nerves
2. cranial nerves
name one type of spinal nerve and its function and location
somatic nerves; associated with voluntary control of movement; found in pairs off each side of each vertebra (1L and 1R)
what do dorsal roots do?
carry afferent impulses to spinal cord
name the location and function of the dorsal root ganglion
sits at the base of the dorsal root and receives afferent signals from periphery; sends to CNS
what do ventral roots do?
carry efferent (reactionary) signals (impulses) to periphery
describe a mixed nerve
contains both motor (efferent) and sensory (afferent) axons, both to and away from periphery
where are the cranial nerves located?
innervating the face and neck
how many pairs and what type of nerves are cranial nerves?
12 pairs, afferent. efferent, and mixed
does the autonomic nervous system require conscious perception?
no!
list the 3 parts of the autonomic nervous system
- sympathetic nervous system
- parasympathetic NS
- enteric NS
describe the sympathetic nervous system
associated with the body’s responses to stress
describe the parasympathetic nervous system
associated with the body’s responses to nonstress, during the absence of stress
describe the enteric nervous system
has components of both sympathetic and parasympathetic NS, controls digestive system under stress and nonstress
define potential
a relative electrical charge between 2 points
membrane potential
relative electrical charge between the inside and outside of a cell membrane
what causes a membrane potential?
differences in concentrations of ions across a cell membrane
define resting membrane potential
differences in ion concentrations across the cell membrane when the cell is at rest
describe the general resting membrane potential
slightly more positive charge on the outside of the membrane than on the inside
what do Na+-K+ ATPases do?
transport 3 Na+ outside cell for every 2 K+ that enter
describe the contribution of channels in neurons and other cells
Na+ channels transport Na+ into the cell and K+ channels transport K+ out of the cell; both move along a concentration gradient and are both closed at rest, with no contribution to the membrane potential at rest
name and describe the 1 state of the transmission of a nerve impulse
resting state: cell membrane is at resting potential with slightly more positive charge outside than inside
name and describe the 2nd state of the transmission of a nerve impulse
chemical stimulation of membrane: signals for start of impulse transmission, something binds to receptor neuron to start
name and describe the 3rd state of the transmission of a nerve impulse
depolarization: will occur at the site on the membrane that was stimulated, only at one specific place
Na+ channels OPEN, Na+ enters the cell (K+) channels still closed
membrane potential now more positive on inside of cell
name and describe the 4th state of the transmission of a nerve impulse
repolarization begins: Na+ channels CLOSE, Na+ stops entering cell, K+ channels open at same time, and K+ leaves the cell
Na+ starts moving away from the site of stimulation
name and describe the 5th state of the transmission of a nerve impulse
repolarization continues until: membrane returns to resting potential, which must happen in order for next impulse to occur
Na+-K+ ATPase helps to reestablish Na+ on outside of cell and K+ on inside of cell
where do steps 1-5 of transmission of a nerve impulse occur?
all on one spot on the cell membrane
name and describe the 6th state of the transmission of a nerve impulse
propagation of an action potential: changes in membrane potential travel down length of the membrane
Na+ moving away from site of depolarization results in depolarization at next spot on membrane
name and describe the 7th state of the transmission of a nerve impulse
action potential continues: to terminal end of axon
name and describe the 8th state of the transmission of a nerve impulse
action potential traveling results in the release of a neurotransmitter: into synapse
define saltatory conduction
transmission of a nerve impulse down a myelinated axon, action potential “jumps” from one node of Ranvier to the next
what does saltatory conduction do to the transmission of a nerve impulse?
speeds it up, increases rate of nerve impulse signalling
define neurotransmitters
chemical substances (messengers) released by an axon into synapses, transmit the nerve impulses from one neuron to the next
