Anatomy and Physiology Exam 3

nervous tissue function: sensory input

gather information about changes in stimuli

nervous tissue function: integration

process, interpret, make decisions

nervous tissue function: motor output

cause response by activating muscles or glands

neuron: cell body

contains nucleus

neuron: dendrites

extensions receives signal and send to cell body

neuron: axon

extension conducts signal away from cell body

neuron: axon terminal

ending of neuron communicates w/ another neuron/muscle cell. uses calcium to release neurotransmitter into synaptic cleft

neuron: schwann cells

cells wrap around axons of nerves in the PNS, produce myelin

neuron: myelin

insulates fibers and increase speed of impulse. unmyelinated areas easily depolarize and stimulate next unmyelinated section easily

oligodendrocytes

insulates fibers and increases speed of impulse for neuronal axons of brain and spinal cord (CNS). makes tissue appear white

neuron: nodes of ranvier

space between myelin sheaths allow impulse to jump along axon quicker

nerve

axons bundled together. convred in connective tissue, blood vessels integrated

resting nerve impulse

• polarized

• positive Na+ ions have greater concentration outside

• negative charge inside maintained by anions

anions

negatively charged particles

sodium-potassium pump

maintains resting state by pumping Na+ out

what happens during stimulus and depolarization in a neuron?

stimulus causes Na+ channels to open, allows Na+ to come inside cell, causing depolarization. this triggers Na+ channels in next section to depolarize if strong enough (all or nothing)

where are the ions during depolarization?

positive on inside, negative on outside

neurotransmitter

chemical substances fit into receptor sites on next nerve/muscle cell (effector). it causes sitmulus or inhibition of action potential in receiving neuron/muscle cell

local anesthetics

block Na+ channels, stopping impulse from traveling down axon

sedative and gerneral anesthesia

increases GABA

GABA

inhibit neurotransmission activity, increasing Cl- movement, keeping it negative on the inside

Reflex

rapid, predictable, involuntary responses to a stimulus

5 steps of Reflex

1. sensory receptor

2. sensory neuron

3. integration center

4. motor neuron

5. effector organ

multiple sclerosis (MS)

• myelin shealths gradually destoryed and axons degenerate

• impulse doesn’t pass along axon efficiently

• causes control of muscles to diminish, increase in fatigue, loss of balance, sensory deficits, numbness/tingling

• has relapse-remit episodes

• high levels of protein + WBCs in cerebrospinal fluid

Herpes simplex virus (HSV)

• enters sensory neurons through either oral (1) or genital (2) mucosa.

• it travels via microtubules to cell body to latency. stress causes virus to travel to mucosa and replicate, causing blisters

shingles

• caused by varicella zoster

• causes chicken pox

• when virus over, viral particles gain access to sensory nerves and lay dormant

• reactivation causes it to travel to skin and cause rashes

central nervous system

brain and spinal cord, all info occurs here

peripheral nervous system

nerves carry impulses to and from CNS and rest of body. sensory and motor functions

what is the brain and spinal cord protected by?

skull, vertebrae, blood brain barrier, meninges, and cerebrospinal fluid

meninges

3 layers (dura mater, arachnoid mater, pita mater) of connective tissue wrap around brain and spinal cord. provides space for fluid and connects it fo inner skull

cerebrospinal fluid

watery plasma full of nutrients and oxygen to supply brain and cushions it. formed by choroid plexuses (capillaries) in ventricles of brain.

gyri of brain

ridges

sulci of brain

grooves

inner white matter

tracts of myelinated axons relay signals to and from outer cortex

corpus callosum

2 hemispheres connected by white fiber tracts

outer cortex gray matter

cell bodies functions in speech, memory, logical and emotional responses, consciousness, voluntary movement, and interpretation of sensation

basal nuclei

island of gray matter inside cerebrum, subcortical motor center function in regulating skeletal muscle movements

thalamus

encloses ventricle of CSF, serves as relay station for sensory impulses

epithalamus

relays signals from the limbic system

limbic system function

involes w/ emotions and pleasure centers

pineal gland function

secretes melatonin

hypothalamus function

regulation body temp, water balance, and metabolism communicates with pituiutary gland

mamillary bodies function

serve as memory consolidation relays for the hippocampus

cerebral peduncles function

relay info to upper brain areas

corpora quadrigemia

optic and auditory reflexes centers

pons

rounded structure of fiber tracts relays info from cerebrum to cerebellum. controls respiratory rate and depth with the medulla. contains nuclei of cranial nerves V-VII, contains projection fibers

medulla oblongata

visceral activities controlled such as heart rate, breathing, and blood pressure

arbor vitae

outer grey matter cortex and inner region of white matter provides timing of muscle activity, balance control, and monitors body position

midbrain

visual and auditory reflex centers, subcortical motor cortex, contains projection fibers

medulla oblongata function

relays sensory pathway impulses from skin and proprioreceptors. relay sensory info to cerebellum, contains projection fibers

reticular formation function

maintains cerebral cortical alertness, filters out repetitive stimuli, regulates skeletal and visceral muscle activity

cerebellum

processes info from cerebral motor cortex, proprioceptors, and visual + equilibrium pathway. provides instructions for smooth, coordinated skeletal muscle movements

spinal cord

major reflex enclosed within vertebral column, cushions meninges and cerebrospinal fluid. sensory nerves enter spinal cord dorsally, while motor nerve exit spinal cord ventrally

cauda equina

inferior point of spinal nerves

meningitis

inflammation of the meninges due to bacterial or viral infection. diagnosed by lumbar puncture. fever, neck pain, and headache associated

concussion

brain injury due to traumatic movement. dizziness to loss of conscioiusness associated

cerebrovascular accident

CVA/stroke caused by blockage or rupture of blood vessel reducing blood flow to brain area. symptoms based on location of infarct

amyotrophic lateral sclerosis

motor neurons of brain cortex and anterior horn of spinal cord cause abnormal apoptosis of motor neurons. tripping, awkward balance, dysfunction of movements lead to paralysis and death

parkinson’s disease

degeneration of neurons in midbrain that supply dopamine to basal nuclei. overactivity of motor activities leading to tremors, bradykinesia, and ridgidityness

anterior horn

grey matter

bradykinesia

slowless of movement

alzheimer’s disease

reduction in acetylcholine and abnormal buildup of proteins in brain regions responsible for memory. memory and cognitive decline and behavior changes leads to death.

precentral gyrus of cerebral cortex

motor map

postcentral gyrus of cerebral cortex

sensory map

PNS

neurons outside of brain and spinal cord

sensory PNS

bring impulses from sense organs to CNS

motor PNS

bring impulses from CNS to effectors (muslces, glands)

what are the 4 cranial nerves?

olfactory CNI, optic CNII, oculomotor, CNIII, vestibulocochlear CNVIII

spinal nerves

divide after leaving spinal cord into dorsal ramus and ventral ramus

ramus

branch with both motor and sensory fibers

brachial plexus spinal nerve

leave from C5-T1

axillary spinal nerve

shoulder,deltoid

radial spinal nerve

posterior lower arm muscles, and digit extensors

ulnar spinal nerve

flexor carpi ulnaris and digit 4 +5

median spinal nerve

anterior lower arm muscles and intrinsic palm muscles

sacral and lumbar plexuses spinal nerve

leave from L1-S4

femoral spinal nerve

skin sensations and anterior thigh muscles

obturator spinal nerve

medial thigh skin and muscles

sapheneous spinal nerve

medial skin of lower leg

common fibular spinal nerve

wraps around fibula for lateral and anterior lower leg

tibial spinal nerve

posterior leg muscles

somatic division

voluntary control of skeletal muscles

autonomic division

involuntary control, glands, smooth, and cardiac muscles

symapathetic division

fight or flight, increase blood pressure, heart rate, breathing, dilate eyes, liver increases glucose, digestion reduced, constrict blood vessels to skin, dilate blood vessels to skeletal muscle

parasympathetic division

rest and digest, promotes maintenance while conserving energy, decreases blood pressure and heart rate. G1 tract blood shunted toward it to absorb nutrients, secretion of gastric juices

conjunctiva

transparent mucous membrane, prevents eye drying

what does the fibrous layer consist of? (2)

the cornea and sclera

cornea

clear, allows light to pass, bends light, constantly renews epithelial cell layers, lots of pain receptors

sclera

white, shiny, opaque, sturdy, contiguous with dura mater

what does the vascular layer consist of? (3)

choroid, cilary body, and iris

choroid

blood vessel rich, dark brown membrane that absorbs light, prevents scattering, provides nutrients to eye layers

cilary body

holds lens upright and controls lens shape via suspensory ligament

iris

pattern of muscle and elastic fibers, pigmented, opens to allow light to enter through pupil, emotions affect pupil size

what does the sensory layer consist of? (3)

retina, fovea centralis, and optic disc

retina

has rods and cones to see color

pigmented cells

act as phagocytes removing damaged photoreceptors, stores vitamin A, prevents light from scattering

rods

more numerous, dim light, peripheral vision, black-grey-white colors, good for spotting movement, uses pigment rhodospin

cones

bright light, blue-red-green color, central portion of retina, every cone has pathway to ganglion

fovea centralis

only cones and area of greatest visual acuity

optic disc

blind spot, where optic nerve leaves eye and no image produced