Advanced A& P - Unit 2b Study Guide: Physiology II

tracts

a bundle of myelinated axons within the central nervous system

ascending tract

group of axons in spinal cord that conducts sensory impulses upward to the brain; typically involves 2 neurons between sensory receptor and final destination of impulse

descending tract

group of axons that conducts impulses downward from the brain thru the spinal cord to motor neurons controlling muscles and glands

fasciculus cuneatus/gracilis tract

• ascending

• starts at skin, muscles, tendons, joints, ends at primary sensory area

• sensory: relays sensory impulses regarding touch, pressure, and body movement

spinothalamic tract

• ascending

• starts at sensory receptors in various body regions, ends at primary sensory area

• sensory: relay sensory impulses regarding pain, temp, touch, and pressure

corticospinal tract

• descending

• starts at brain synapse (primary motor area), ends at skeletal muscles

• motor: causes voluntary movement

UMN syndrome (spastic paralysis)

paralysis is characterized by increased muscle tone, exaggerated reflexes, and little to no muscle atrophy

LMN syndrome (flaccid paraylsis)

paralysis is characterized by no muscle tone, absent reflexes, and significant muscle atrophy

decussation

crossing over of nerve fibers; much of the sensory information from the right side of the body is processed by the left side of the brain and vice versa. Most motor commands affecting the right side of the body originate from the left side of the brain, and vice versa.

basal nuclei

masses of gray matter deep within cerebral hemispheres, produces dopamine, interact with other brain areas through combination of stimulation and inhibition to facilitate voluntary movement

parkinson’s disease

rigidity, shuffling/off balance gait, poor small motor control, hypomimia, hypophia (effort to speak), micorgraphia, dementia, depression, sleep problems, etc

huntington’s disease

uncontrollable jerkin movements, mental deterioration, sometimes addiction and mental health issues. Causes proteins to accumulate in the brain, leading to degeneration of the neurons and a deficiency in GABA, which usually works to inhibit antagonistic movements

Autonomic Nervous System (ANS)

motor part of the PNS that functions without conscious effort (heart rate, blood pressure, breathing rate, body temp, and other visceral activities that aid in maintaining homeostasis)

characteristics of autonomic nervous system

• two neurons motor pathway links CNS to visceral effector

• involuntary

• utilizes both acetylcholine and norepinephrine

characteristics of somatic nervous system

• single neuron motor pathway links CNS & skeletal muscle

• voluntary

• relies on acetylcholine

preganglionic fiber (autonomic neurons/nerve fibers)

leaves the CNS and synapses with one or more neurons who cell bodies are within the autonomic ganglion

postganglionic fiber (autonomic neurons/nerve fibers)

axon of the cell bodies inhe autonomic ganglion; extend to visceral effector

cranial nerves that carry out parasympathetic impulses

• III (oculomotor)

• VII (facial)

• IX (glossopharyngeal)

• X (vagus - carries the most)

thoracolumbar division

• sympathetic

• preganglionic fibers originate from neurons in lateral horn of spinal cord (T1-L2)

• postganglionic fibers @ paravertebral ganglia or collateral ganglia

paravertebral ganglia (aka sympathetic chain ganglia)

ganglia located alongside the spinal cord

collateral ganglia

gnaglie closer to effectors

cardiosacral division

• parasympathetic

• preganglionic fibers originate from neurons in the brain and spinal cord (S2-4) (most are myelinated)

• postganglionic fibers (shorter) @ terminal ganglia

terminal ganglia

ganglia near or in various organs

effects of sympathetic impulses

• pupils: dilate

• digestion: decrease

• bronchioles: dilate

• heart rate: increase

• vessels to skin: constrict

• adrenal medulla: secrete epinephrine and norepinephrine

effects of parasympathetic impulses

• pupils: constrict

• digestion: increase

• bronchioles: constrict

• heart rate: decrease

• vessels to skin: no effect

• adrenal medulla: no effect

cholinergic fibers

secrete acetylcholine, preganglionic neuerons of sympathetic and parasympathetic divisions, postganglionic neurons of parasympathetic divisions

adrenergic fibers

secrete norepinephrine, postganglionic neurons of sympathetic division

nicotinic receptor

• cholinergic

• in synapses between preganglionic and postganglionic neurons of parasympathetic and sympathetic pathways

• produce rapid, excitatory responses

muscarinic receptor

• cholinergic

• in membranes of effector cells

acetylcholinesterase

prevents continuous muscle contractions and allows nervous system to process signals normally

monoamine oxidase

plays a major role in regulating mood and emotion

how knowledge of neurotransmitters and receptors may be applied to pharmacology

we can use knowledge of neurotransmitters, their effects, receptors, and breakdown of them to develop medications that will alter neurotransmitter levels or their effects.

Example: MAOIs (antidepressants) reduce the effect of monoamine oxidase and can increase levels of norepinephrine

pain receptors

free nerve endings throughout the body; can be stimulated by tissue damage, chemicals, mechanical forces, and extremes in temp

enkephalins, serotonin, and endorphins

substances in the body that decrease pain