what makes up CNS?

1. brain
2. forebrain has the cerebrum (80% of weight)
3. diencephalon - thamus and hypothalamus
4. cerebellum
5. brainstem - continuous with spinal cord- medulla, pons, midbrain
6. spinal cord

the peripheral nervous system consists of what?

12 pairs of crainal nervers and 31 spinal nerves

what is the difference between the afferent division and efferent division?

a- conveys info from senser to cns

e- has somatic nerverous system -- nervers from skeletal muscles

ANS - nerves from smooth, cardiac muscles and glands

sympathetic division

parasympathetic

what is neuroglia?

what is the purpose of the nervous system?

90% of cells within CNS

occupies half of the volume of the brain

--- to regulate and coordinate various functions of the body

what 3 classes can neurons be divided into?

afferent - impulses from sensory receoptors to spinal cord/brian

efferent - impulses from CNS out to organs

interneurons - lies in the CNS accounts for 99% of all nerve cells

what happens during a nerve impulse?

high concentration of NA+ on the outside of the membrane cause it to be electrically positive. while the nerves on the inside make it negative

action potential-- stimulus that causes the NA to rush in the nerve

what is neuromuscular junction?

nerve to muscle synapse-- acetycholine is the substance

what two regions of the spinal cord enlarged or innervation of the limbs?

what is a plexus?

1. cervical enlargement -- from c4 to t1

2. lumbosacral enlgarment -- t11 to l1

--- network of converging and diverging nerve fibers or blood vessels

where are the cell bodies of the motor axons that make up the ventral root located?

ventral gray horn of the spinal cord

what is a ganglion?

a collectino of never cell bodies located outside the CNS

what happens when you damage your spinal cord?

loss of all sensation and voluntary movements inferior to the pint of damage.

what is ischemia?

deficiency of blood supply to the spinal cord.

what are proprioceptors?

what else is it called?

they conduct sensory information to CNS to muscles, tendons, ligaments and joints

also called the kinesthetic sense

what is the funciton of the muscle spindle?

- sends info to CNS regarding the degree of muscle stretch--- the greater the strectch the greater the impose up the afferent to spinal cord increases

what are the three ways that muscle spindles can activate the alpha motor neurons to cause the muscle to contract?

1. tonic stretch--- final length of the muscle fiber
2. phasic stretch -- rate of length change -- overshoots
3. gamma system -- mainitn the spindle @peak operation for all muscle lengths

where is the golgi tendon organ located?

encapsulated in tendon fibers near the junction of muscle and tendon

what muscle contract GTO is stretched. what happens?

- the firing rate of GTO is sensitive to change in the tension of the mscle

1. maintaining a steady grip

2. causes contracted muscles to relax - protects the muscles and its cnnective tissue harness from excessive loads

what are joint receptors?

they supply info tothe CNS concerning join angles..

what ar the two main centers that are associated with learning new motor skills.

voluntary control of movement patterns?

cerebral cortex and cerebellum

what is the functionof the primary motor cortex?

where is it found?

brings movement in diffent areas of the body

contains homunculus

its on both sides of the brain. each side controls the opposite

located near the frontal lobe.

what is the system that controls the movements of hands and fingers?

corticospinal system -- fine, discretes and voluntary movements.

where is the premotor cortex?

lateral surface of each cerebral hemisphere -- in front of the primary motor cortex

what is the extrapyramidal tract?

what are they mostly concerned with ?

multineural pathway - sends impulses from premotor areas down to the motorneuron of the spinal cord.

posture and coordinatin or large m groups.

where can you find the cerebellum?

what is its function?

behind the brainstem

-- motor control.

locomotion

maintaining equilibrium

postural adjustments