KIN 400 Exam 2

central nervous system and peripheral nervous system

two major divisions of the nervous system

brain and spinal cord

the central nervous system consists of what two things?

sensory and motor

the peripheral nervous system can be divided into what two divisions?

sensory

afferent; incoming nerves of the peripheral nervous system belong to what division?

motor

efferent; outgoing nerves of the peripheral nervous system can be divided into what division?

somatic and autonomic

the motor division of the peripheral nervous system can be divided into what two subdivisions?

somatic

voluntary subdivision of the motor division of the peripheral nervous system; to skeletal muscles

autonomic

involuntary subdivision of the motor division of the peripheral nervous system; to viscera

sympathetic and parasympathetiic

the autonomic subdivision of the motor division can be further divided into what?

sympathetic

fight, flight, or freeze

parasympathetic

rest and digest

neuron

basic structural unit of the nervous system; she basic structure everywhere in the body

cell body (soma), dendrites, axon

three major regions of the neuron

cell body

region of the neuron that contains the nucleus; cell processes radiate out

dentrites

region of the neuron that handles receiver cell processes; carry impulse towards cell body

axon

region of the neuron that handles sender cell processes; starts at axon hillock; has end branches, terminals, and neurotransmitters

electrical signal

\_______ enable communication between periphery and brain (must be generated by a stimulus; must be propagated down an axon; must be transmitted to next cell in line)

resting membrane potential

difference in electrical charges between outside and inside of cell; -70 mV; cause: uneven separation of charged ions; polarized

-70 mV

resting membrane potential

Na+; K+

during resting membrane potential there is high \_____ outside the cell and medium \_____ inside the cell; the inside is more negative relative to the outside

closed

during resting membrane potential Na+ channels are \________; Na+ wants to enter the cell but can't; electrical and concentration gradients

open

during resting membrane potential K+ channels are \________; K+ leaving cell (concentration gradient); offset by Na+-K+ pumps

depolarization

occurs when inside of cell becomes LESS negative (-70mV -\> 0mV); with more Na+ channels open Na+ enters the cell; is required for nerve impulse to arise and travel

hyperpolarization

occurs when inside of cell becomes MORE negative (-70mV -\> -90mV); with more K+ channels open, K+ leaves the cell; makes it more difficult for nerve impulse to arise

nervous system

depolarization and hyper polarization contribute to \__________ function

graded potentials

help cell body decide whether to pass signal to axon; can excite or inhibit a neuron

action potentials

pass signal down axon; only excitatory; involve rapid, substantial depolarization; last around 1ms; begin as graded potentials; can move in only one direction

localized

\______ changes in membrane potential are generated by incoming signals from dendrites (inhibitory or excitatory)

inhibitory signal

K+ efflux; hyperpolarization

excitatory signal

Na+ influx; depolarization

action potentials

strong graded potentials become \___________, which will then be propagated down the axon and transmitted to the next cell

-55mV

if graded potential reaches threshold (\__________), an action potential will occur; if threshold millivolts is not reached, no action potential will occur; "all-or-none principle"

-70mV to -55mV

millivolt range where a depolarizing graded potential occurs; Na+ influx

-55mV to +30 mV

millivolt range where a depolarizing action potential occurs, Na+ influx

+30mV to -70mV

millivolt range where a repolarizing action potential occurs; K+ efflux

absolute refractory period

during depolarization; neuron unable to respond to another stimulus; Na+ channels already open, cannot open more

relative refractory period

during depolarization; neuron response only to very strong stimulus; K+ channels open (Na+ closed, could reopen)

myelin

speeds up propagation

Schwann cells

fatty sheath around axon

nodes of ranvier

gaps in the myelin sheath

saltatory conduction

the jumping of action potentials from node to node

multiple sclerosis

degeneration of myelin

larger

\______ axon diameter means faster propagation

gap junction

serves as site of neuron-to-neuron communication; action potential must jump across synapse (axon -\> synapse -\> dendrites); presynaptic cell -\> synaptic cleft -\> postsynaptic cell

\`chemical

signals changes form across synapse from electrical to \________ and back to electrical

neurotransmitters

found in axon terminals; serve as chemical messengers; carry electrical action potential signal across synaptic cleft; bind to receipt on postsynaptic surface; stimulate graded potentials in postsynaptic

neuromuscular junction

specialized synapse; uses acetylcholine (ACh) as its neurotransmitters; is excitatory - passes action potential along to muscle

postsynaptic cell

muscle fiber; ACh binds to receptor at motor end plate; causes depolarization; action potential moves along plasmalemma and down T-tubules; undergoes depolarization; refractory period

exercise

\______ increases release of acetylcholine

Peroxisome proliferator-activated receptor-y coactivator 1a (PHC-1a)

increases branching of the presynaptic terminal motor neuron; increases the number of presynaptic vesicles containing acetylcholine; increases the number of acetylcholine receptors on the cell membrane; decreases the size of the motor end plate

small-molecule (rapid-acting) and large-molecule (neuropeptides/slow-acting)

two major categories of neurotransmitters

50+

how many neurotransmitters are known or suspected?

exercise

ACh and norepinephrine (NE) govern \_______

ACh

stimulates muscle contraction; mediates parasympathetic nervous system effects

NE

mediates sympathetic nervous system effects

graded potentials

neurotransmitters trigger \_________ on new cells

excitatory postsynaptic potential (EPSP)

depolarizing and excitatory and promotes action potentials; summation: multiple \___________ \= more depolarizing; if threshold depolarization is reached, action potential occurs

inhibitory postsynaptic potential (IPSP)

hyperpolarizing and inhibitory and prevents action potentials; summation: multiple \________ \= more hyperpolarizing

cerebrum, diencephalon, cerebellum, brainstem

four divisions of the brain

left and right hemispheres

part of cerebrum connected by corpus callous, allowing inter-hemisphere communication

cerebral cortex

outermost layer of cerebrum; gray matter (nonmyelinated); conscious brain (mind, intellect, awareness)

frontal, temporal, parietal, occipital

four superficials (outer) lobes of cerebrum

frontal

lobe of cerebrum used for general intellect and motor neuron

temporal

lobe of cerebrum used for auditory input and interpretation

parietal

lobe of cerebrum used general sensory input and interpretation

occipital

lobe of cerebrum used for visual input and interpretation

insular

one central deep lobe of cerebrum; used for emotion and self-perception

primary motor cortex

located in frontal lobe; conscious control of skeletal muscle movement; pyramidal cells -\> corticospinal tract -\> spinal cord

basal ganglia

cerebral white matter; clusters of cell bodies deep in cerebral cortex; initiation of sustained or repetitive movements; walking, running, posture, muscle tone

primary sensory cortex

regions of the cerebral cortex that initially process information from the senses located in the parietal lobe

thalamus

located in diencephalon; serves as major sensory relay center; determines what we are consciously aware of

hypothalamus

located in the diencephalon; maintains homeostasis, regulates internal environment; neuroendocrine control; appetite, food intake, thirst, fluid balance, sleep; blood pressure, heart rate, breathing, temperature

cerebellum

controls rapid, complex movement; coordinates timing and sequence of movements; compares movements with intentions and initiates corrections; accounts for body position, muscle status; receives input from primary motor cortex; helps execute and refine movements

brain stem

info relay between brain and spinal cord; midbrain, pons, medulla oblongata

reticular formation

a nerve network in the brainstem that coordinates skeletal muscle function and tone; controls cardiovascular and respiratory function

analgesia system

opioid substances modulate pain here; releases B-endorphin with exercise; found in brain stem

spinal cord

continuous with medulla oblongata; tracts of nerve fibers permit two-way conduction of nerve impulses; ascending afferent (sensory) fibers and descending efferent (motor) fibers

peripheral nervous system

connected to brain and spinal cord; 12 pairs of cranial nerves (connected to brain); 31 pairs of spinal nerves (connected to spinal cord); both types directly supplying skeletal muscles; two major divisions: sensory (afferent) division and motor (efferent) division

sensory division

transmits information from periphery to brain; includes major families of sensory receptors (mechanoreceptors, thermoreceptors, nociceptors, photoreceptors, chemoreceptors)

mechanoreceptors

respond to physical forces

thermoreceptors

respond to temperature

nociceptors

respond to pain

photoreceptors

respond to light

chemoreceptors

responds to chemical stimuli

joint kinesthetic receptors

are sensitive to joint angles, rate of angle change; sense joint position and movement

muscle spindles

are sensitive to muscle LENGTH, rate of change; sense muscle length

golgi tendon organs

are sensitive to tension in tendon; sense STENGTH of contraction

motor division

transmits information from brain to periphery; includes two subdivisions: autonomic (regulates visceral activity) and somatic (stimulates skeletal muscle activity)

sympathetic

division of autonomic nervous system; control of involuntary internal functions; exercise-related autonomic regulation (heart rate, blood pressure, lung function); fight or flight: prepares body for exercise; increases blood flow to muscles; air diameter (bronchodilator); metabolic rate, glucose levels, FFA levels, and mental activity

parasympathetic

division of autonomic nervous system; rest and digestion (is active at rest; opposes sympathetic effects); simulates an increase in digestion and urination; conservation of energy; decreases heart rate; decreases diameter of vessels and airways

sensory-motor integration

communication and interaction between sensory and motor systems; five sequential steps (stimulus sensed by sensory receptor; sensory AP sent on sensory neurons to CNS; CNS interprets sensory information, sends out response; motor AP sense out on a-motor neurons; arrives at skeletal muscle and response occurs)

sensory input

can be integrated at many points in CNS; complexity of integration increases with ascent through CNS (spinal cord, lower brain stem, cerebellum, thalamus, cerebral cortex/primary sensory cortex); can evoke motor response regardless of point of integration (spinal cord, lower region of brain, motor area of cerebral cortex)

complexity

as level of control moves from spinal cord to cerebral cortex, movement \_________ increases

motor reflex

instant, preprogrammed response to stimulus; response to stimulus identical each time; before conscious awareness; impulse integrated at lower, simple levels

muscle spindles

specialized intrafusal muscle fibers (different from normal (extramural) muscle fibers; innervated by y-motor neurons; sensory receptors for muscle fiber stretch); if stretched, synapses in spinal cord with a-motor neuron, trigger for reflex muscle contraction, prevention of further (damaging) stretch, stretch reflex

golgi tendon organs

sensory receptor embedded in tendon (associated with 5 to 25 muscle fibers; sensitive to tension in tendon (strain gauge); important in resistance exercise (safety devices)); monitors muscle FORCE; when stimulated by excessive tension, inhibition of agonists, excitation of antagonists, prevention of excessive tension in muscle tendon, reduced potential for injury

endocrine system

communication system; chemical communication; is slower to respond but longer lasting than the nervous system; maintains homeostasis via hormones (controls and regulates cell and organ activity; acts on target cells) constantly monitors internal environment; coordinates integration of physical systems during rest and exercise; maintains homeostasis during exercise (controls substrate metabolism; regulates fluid and electrolyte balance)

nervous system

electrical communication

steroid

derived from cholesterol; lipid soluble, diffuse through membranes; secreted by four major glands: adrenal cortex (cortisol aldosterone), ovaries (estrogen, progesterone), testes (testosterone), placenta (estrogen, progesterone)

nonsteroid

not lipid soluble, unable to cross membranes; two groups: protein or peptide and amino acid derived