Human Physiology Exam 2

What is the center of the spinal cord made of?

gray matter

Is gray matter myelinated or unmyelinated?

unmyelinated

What surrounds the center of the spinal cord?

white matter

What is white matter composed of?

myelinated axons

How many pairs of spinal nerves are there per segment of the spinal cord?

one pair of nerves

What does the dorsal root do?

carries sensory information into the spinal cord

What does the ventral root do?

carries motor information away from the spinal cord

What does the spinal cord control?

processing and response to sensory input

What is a flexor muscle?

muscle that brings a limb closer to the body

What is an extensor muscle?

muscle that take limbs away from the body

What does ipsilateral mean?

the same side

What does contralateral mean?

the opposite side

What are spinal reflexes?

the simplest motor response by the nervous system

What route does a stretch reflex follow?

goes in the dorsal route and out the ventral route

What is an example of the stretch reflex?

the knee jerk reflex

What is a flexor withdrawal reflex?

withdrawal of a limb from a painful stimulus to prevent damage

Which muscles are stimulated and inhibited during the flexor withdrawal reflex?

flexor muscle is stimulated and extensor muscle is inhibited

What is the cross extensor reflex?

involves the stimulation of both legs

Which leg is flexed or extended during the cross extensor reflex?

ipsilateral leg is flexed and contralateral leg is extended

What is the inverse myotatic reflex?

too much tension on the muscle causes the muscle to relax which is the opposite of what the muscle was originally trying to do

What is the function of the meninges?

to be protective and nourishing

What is the dura mater?

tough outer membrane that contains blood sinuses

What is the arachnoid mater?

highly vascularized middle layer that is web-like in appearance

What is the subarachnoid space?

space between the arachnoid mater and pia mater

What does the subarachnoid space contain?

cerebral spinal fluid

What is the pia mater?

innermost membrane located on the surface of the brain and spinal cord that adheres to the surface of the cortex

Does the brain contain pain receptors?

no

What can headache pain be associated with?

inflammation of the meninges or blood vessels

What is meningitis?

inflammation of the meninges usually caused by infection

What is the most common form of meningitis?

viral meningitis

Which is the more severe form of meningitis?

bacterial meningitis

What is cerebral spinal fluid?

clear watery fluid that contains many of the same constituents as plasma but at different concentrations

What does CSF fill?

the space between arachnoid and pia maters of brain and spinal cord as well as the ventricles of the brain and the central canal of the spinal cord

Is the CSF the same as the brain’s interstitial fluid?

no

What is the total volume of the CSF usually?

125 to 150 mL

What is hydrocephalus?

the enlarging of the skull caused by excess CSF

Why is the CSF important?

acts as a cushion of water for the brain thus reducing the brain’s weight by 97% and helps exchange materials between blood and brain interstitial fluid

What forms the blood brain barrier?

endothelial cells of capillary walls in the brain

What do the endothelial cells have?

tight junctions that force material to go through cells in the capillary wall

How do astrocyte glial cells help form the blood brain barrier?

by surrounding the capillaries

What regions of the CNS are not protected by the blood brain barrier?

portion of the hypothalamus

How does the blood brain barrier make it hard to treat certain diseases?

some materials cannot get through the blood brain barrier and into the brain

What are Parkinson’s patients treated with?

L-dopa because dopamine cannot get through the blood brain barrier

How much energy does the brain require?

about 20% of the body’s energy needs

Why does the brain need a constant flow of blood?

for oxygen and glucose

What do neurons in the CNS rely on?

aerobic metabolism

Do neurons in the CNS store glycogen?

no

What can diabetics experience after taking an insulin shot?

insulin shock due to low blood glucose

What does insulin shock cause?

increased excitability of CNS and possibly seizures

What is a stroke?

it is a loss of blood flow to an area of the brain

What is a transient ischemic attack?

brief blockage of blood flow to an area of the brain; mini stroke

What is a hemorrhagic stroke?

blood vessel ruptures and causes a clot resulting in ischemia

How many segments does the spinal cord have?

31

How many pairs of nerves does the spinal cord have?

31

Where do spinal nerves carry sensory information?

in the back

Where do spinal nerves carry motor information?

in the front

What are dermatomes?

skin areas the cover each pair of spinal nerves

What is referred pain?

pain corresponding to the dermatome of a specific region and not necessarily where the problem is happening

What is an example of referred pain?

heart attacks can cause a pain sensation in left arm and chest

What is cauda equina?

the “horse’s tail” of nerves that fill the vertebral canal after the L2

Why are spinal taps performed?

to detect infection or disease or administer anesthetics

What is the brainstem composed of?

medulla, pons, and midbrain

What is the brainstem the origin of?

most of the cranial nerves

What is the brainstem involved in?

initial processing and organization of information from the spinal cord

True or false: the brainstem is an important autonomic control center.

true

What is the reticular activating system?

diffuse network or neurons throughout the brainstem

How do general anesthetics work?

by suppressing activity of the RAS

True or false: the reticular activating system is a distinct group of neurons located in a specific area of the brainstem.

false

What happens when there are lesions or damage to the RAS?

a coma can result because it cannot arouse the higher levels of the brain

What is the structure of the cerebellum?

outer gray matter, inner white matter, convolutions to increase surface area

What does increased surface area of the cerebellum allow for?

more neurons

How much of the brain’s neurons does the cerebellum contain?

over 50%

What is the cerebellum involved in?

subconscious control of motor activity, including the coordination and planning of skilled voluntary movements

True or false: the cerebellum directly controls the muscles.

false

What does the cerebellum do?

monitors and indicates adjustments needed in movements

What can damage to the cerebellum result in?

difficulties in movement, speech, and abnormal eye movements

How does alcohol affect the cerebellum?

causes slurred speech and unsteady movements

What is the hypothalamus?

collection of specific nuclei located above the pituitary and below the thalamus

What does nuclei refer to?

large groups of gray matter (dendrites, cell bodies, and some axons)

What is the hypothalamus involved in?

control of many homeostatic functions

True or false: the hypothalamus is an important autonomic control system

true

What does the hypothalamus help control?

basic functions such as thirst, urine production, body temperature, gastrointestinal activity, cardiovascular activity, and appetite

What does the hypothalamic pituitary gonadal axis do?

important in the control of reproduction and reproductive cycles

What is the hypothalamus the link between?

the nervous system and endocrine system

What does the hypothalamus control?

the release of hormones from the anterior pituitary

What does the hypothalamus produce?

hormones released by the posterior pituitary

What is the thalamus?

mass of gray matter in the center of the brain that has a lot of neurons packed into it

What does the thalamus act as?

relay station for sensory information going to the cortex

True or false: almost all sensory information passes through the thalamus on the way to the cortex.

true

What does the thalamus do?

projects sensory information to specific areas of the cortex and screens/filters sensory information before relaying it to the cortex

What are the basal nuclei?

series of gray matter nuclei that are subcortical (under the cortex)

What does the basal nuclei do?

help maintain purposeful motor activity while inhibiting unwanted motor activity

What has been posited to be the cause of Tourette’s Syndrome?

loss of inhibition by the basal ganglia

What is the cerebral cortex?

the most advanced portion of the brain

What is the cerebral cortex responsible for?

sensory perception, control of voluntary movements, language, personality, higher level thinking, and executive functions

How is the cerebral cortex composed?

outer gray matter and inner white matter

What does the occipital lobe contain?

primary visual cortex; association areas for recognizing shapes, faces, etc

What does the parietal lobe contain?

somatosensory cortex; association areas for sensory information

What does the temporal lobe contain?

primary auditory cortex and primary olfactory cortex; association areas for recognizing smells and sounds

What is the temporal lobe important for?

the process of memory storage and incorporating thoughts into long term memory storage