physiology of exercise ch.3

What are the two structures of the nervous system?

the central nervous system (CNS) and peripheral nervous system (PNS)

What is in the CNS?

the brain and spinal cord

What is in the PNS?

sensory and motor functions

What is the sensory system?

afferent: incoming

What is the motor system?

efferent: outgoing

What are the two systems within the motor system?

the somatic and autonomic

What is the somatic system?

voluntary; to skeletal muscles

What is the autonomic system?

involuntary; to viscera

What is a neuron?

The basic structural unit of the nervous system. It has the same basic structure as everywhere else in the body and has three major regions.

What are the three major regions of the neuron?

cell body (soma), dendrites, and axon

What is the cell body?

it contains a nucleus and cell processes (dendrites, axon) radiate out

What are the dendrites?

they handle receiver cell processes and carry impulse toward cell body

What is the axon?

It handles sender cell processes; it starts at the axon hillock. It has end branches, terminals, and neurotransmitters

What is the function of the nervous system?

The electrical signal enables communication between the periphery and the brain. It must be generated by a stimulus, be propagated down an axon, and be transmitted to next cell in line

What is resting membrane potential?

difference in electrical charges between outside and inside of cell

What is involved in resting membrane potential?

• high number positively charged ions (Na+) - outside cell

• less number positiviely charged ions (K+) - inside cell

how does resting membrane potential happen?

-Na+ incoming channels closed - Na+ wanting to enter cell but can’t

-K+ channels open - K+ leaving cell (down concentration gradient) and offset by Na+-K+ pumps (moves 3 Na+ for each 2K+ in)

What are graded potentials?

(GPs) help cell body decide whether to pass signal to axon. It can excite or inhibit a neuron.

What are action potentials?

(APs) Begin as GP, rapid and substantial depolarization, pass signal down axon, and are only excitatory

What is depolarization?

It occurs when inside of cell becomes les negative. If more Na+ channels open, Na+ enters cell. It is required for nerve impulse to arise and travel.

What is hyperpolarization?

It occurs when inside of cell becomes more negative. With more K+ channels open, K+ leaves cell. It is more difficult for nerve impulse to arise.

What does the GP do for the signal transmission?

GP = localized changes in membrane potential. Strong GP → AP

What does the inhibitory signal equate to for a signal transmission?

K+ efflax = hyperpolarization

What does an excitatory signal equate to for signal transmission?

Na+ influx = depolarization

How strong does GP have to be for a signal transmission?

It must depolarize to threshold mV. Depolarization → AP will be propagated down axon → AP will be transmitted to next cell

What happens if GP reaches the threshold?

AP will occur. If threshold millivolts not reached, no AP. All or none principle.

What is the propagation down the axon?

myelin sheath up propagation. Fatty sheath around axon (Schwann cells), not continuous (nodes of ranvier), and saltatory conduction

What is multiple sclerosis?

degeneration of myelin

What is needed to transmit AP?

A junction or gap between neurons, axon-synapse-dendrites, AP can move in only one direction, axon terminals contain neurotransmitters.

What happens at the junction or gap between neurons when transmitting APs?

It serves as a site of neuron to neuron communication. AP must jump across synapse.

What happens at the axon-synapse-dendrite when transmitting APs?

presynaptic cell-synaptic cleft-postsynaptic cell.

signal changes form across synapse. It is electrical-chemical-electrical.

What happens at the axon terminals that contain neurotransmitters when transmitting APs?

They serve as chemical messengers and carry electrical AP signal across synaptic cleft. They bind to receptor on postsynaptic neuron and stimulate GPs in postsynaptic surface. The muscles go to acetylcholine (ACh).

How do you stimulate/alter the sympathetic nervous system?

norepinephrine (NE) mediates sympathetic nervous system effects

In a specialized synapse, what happens at the site of the neuron to muscle communication?

It uses ACh as its neurotransmitter and is excitatory and passes AP along to muscle.

In a specialized synapse, what happens in a postsynaptic cell=muscle fiber?

ACh binds to receptor at motor end plate, causes depolarization, AP moves along plasmalemma and down T-tubules, and undergoes repolarization which is the refractory period.

What happens in the left and right hemisphere?

They are connected by the corpus callosum and have inter-hemisphere communication

What happens in the cerebral cortex?

The outermost layer of cerebrum. gray matter (nonmyelinated) and conscious brain (mind, intellect, and awareness)

What is the function of the frontal lobe?

general intellect, motor control

What is the function of the temporal lobe?

auditory input, interpretation

What is the function of the parietal lobe?

general sensory input, interpretation

What is the function of the occipital lobe?

visual input, interpretation

What is the one central lobe?

The (deep) insular lobe. It is emotion and self-perception

What is the primary motor cortex?

conscious control of skeletal muscle movement. pyramidal cells- corticospinal tract- spinal cord

What is the basal ganglia (cerebrum white matter)?

Clusters of cell bodies deep in cerebral cortex. initiation of sustained or repetitive movements such as walking or running.

What is the primary sensory cortex?

The parietal lobe

What makes up the diencephalon?

The thalamus and hypothalamus

What does the thalamus do?

It serves as a major sensory relay center. It determines what we are consciously aware of.

What does the hypothalamus do?

maintains homeostasis; regulates internal environment. Neuroendocrine control, appetite, food intake, thirst, blood pressure, heart rate, and breathing.

What does the cerebellum do?

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

What does the brain stem do?

It relays info between the brain and spinal cord.

What does the brain stem consist of?

midbrain, pons, medulla oblongata. Also contains reticular formation and analgesia system.

What is the reticular formation?

It coordinates skeletal muscle function and tone. It controls cardiovascular and respiratory function.

What is the analgesia system?

It is where opioid substances modulate pain. It releases beta endorphin with exercise.

What is the spinal cord?

It is continuous with medulla oblongata. It is tracts of nerve fibers permit two-way conduction of nerve impulses.

What are the two-way nerve impulses?

ascending (afferent) sensory fibers

descending (efferent) motor fibers

What does the PNS consist of?

it is connected to brain and spinal cord. It has cranial nerves that are connected to brain. It has spinal nerves that are connected to spinal cord. It has both types directly supplying skeletal muscles. And has two major divisions.

What are the two major divisions of the PNS?

sensory (afferent) division

motor (efferent) division

What is the sensory division?

It transmits info from periphery to brain. Major families of sensory receptors.

What are the major families of sensory receptors?

mechanoreceptors, thermoreceptors, nociceptors, photoreceptors, and chemoreceptors

What are mechanoreceptors?

physical forces (moving, pushing, proding)

What are thermoreceptors?

temperature

What are nociceptors?

“pain”

They do not sense pain but rather sensations our brain typically translates into pain. Pain is in the brain.

What type of info do nociceptors transmit?

temperature changes (hot/cold), physical pressure or damage (cuts/bruises)

chemical irritants (acids)

What are chemoreceptors?

chemical stimuli

What are the special families of sensory receptors?

Joint kinesthetic receptors, muscle spindles, and golgi tendon organs

What are joint kinesthetic receptors?

They are sensitive to joint angle, rate of angle can change. They sense joint position and movement.

What are muscle spindles?

Are sensitive to muscle length, rate of change.

They sense muscle stretch

What are golgi tendon organs?

They are sensitive to tension in tendon. They sense strength of contraction.

What is motor division?

It transmits info from brain to periphery. It has two subdivisions.

What are the two subdivisions of motor division?

Autonomic - regulates visceral activity

somatic - stimulates skeletal muscle activity

What is the ANS?

It has control of involuntary internal functions and exercise-related autonomic regulation (heart rate, blood pressure, lung function). It also has two complementary divisions.

What are the two complementary divisions of the ANS?

Sympathetic and parasympathetic nervous system.

What is the sympathetic nervous system?

It has the fight or flight: prepares body for exercise. It increases heart rate, blood pressure, blood flow to muscles, airway diameter, metabolic rate, glucose levels, FFA levels, and mental activity.

What is the parasympathetic nervous system?

It is rest and digestion, (conservation of energy) where it is active at rest and opposes sympathetic effects. Stimulation increases digestion and urination. it decreases heart rate, and diameter of vessels and airways.

What are the five sequential steps of the sensory motor integration?

1. stimulus sensed by sensory receptor

2. sensory AP sent on sensory neurons to CNS

3. CNS interprets sensory info, sends out response

4. Motor AP sent out on alpha motor neurons

5. Arrives at skeletal muscle and response occurs

What is Sensory Motor Integration?

It is communication and interaction between sensory and motor systems. It has five steps.

What is sensory Input?

Group 3, 4 and signal to CNS. It can be integrated at many points in the CNS. The complexity of integration increases with ascent through CNS. It can evoke motor response regardless of point of integration.

How does sensory input get signal to CNS?

It facilitates oxygen (ATP) delivery to muscle. It stimulates and maintains responses to exercise. It prevents fatigue.

Where is the complexity of integration in the CNS?

The spinal cord, lower brain stem, cerebellum, thalamus, and cerebral cortex (primary sensory cortex)

Where does the sensory input evoke motor response?

Spinal cord, lower region of brain, motor area of cerebral cortex. As level of control moves from spinal cord to cerebral cortex, movement complexity increases