anatomy and physiology exam 3

central nervous system

brain and spinal cord; integrating and control center of the nervous system, interprets sensory input and dictates motor output based on reflexes, current conditions, and past experience

peripheral nervous system

nerves outside CNS; serves as communication lines that link all parts of the body to the CNS

sensory (afferent) division

sensory receptors convey nerve impulses to CNS; keeps CNS informed of events going on inside and outside the body

somatic sensory nerves

convey impulses from skin, skeletal muscles, and joints

visceral sensory fibers

transmit impulses from the visceral organs (organs within the ventral body cavity)

motor (efferent) division

CNS to receptors, activate muscles to contract and glands to secrete

somatic nervous system

aka voluntary nervous system; has somatic nerve fibers that conduct impulses from CNS to skeletal muscles; voluntary control of skeletal muscles

autonomic nervous system

aka involuntary nervous system; has visceral motor nerves that regulate activity of smooth muscle, cardiac muscle, and glands

sympathetic division

”fight or flight” mobilizes systems during body activity

parasympathetic division

”rest and digest” conserves energy; promotes house-keeping functions during rest

dendrites

short, tapering, diffusely branching extensions; receives signals and conveys graded potentials to cell body

cell body

aka soma; consists of a spherical nucleus surrounded by cytoplasm; integrates info from dendrites and decides whether to fire an action potential down the axon to transmit signals to other cells

axon

arises from a cone-shaped area of the body called the axon hillock; generates nerve impulses and transmits them along the axolemma

synaptic knob

aka axon terminal, knob-like distal endings of the terminal branches; releases neurotransmitter

acetylcholine

primary neurotransmitter at neuromuscular junction; used in autonomic nervous system; can be excitatory or inhibitory depending on receptor

resting state

all voltage-gated K⁺ and Na⁺ channels are closed; -70 mV, Na⁺ mostly outside, K⁺ inside

depolarization

voltage-gated Na⁺ channels open and Na⁺ rushes in and membrane patch becomes less negative

repolarization

Na⁺ channels are inactivating, and voltage-gated K⁺ channels open which restores the internal negativity of the resting neuron

hyperpolarization

some K⁺ channels remain open, and Na⁺ channels reset and resting electrical conditions restored by sodium-potassium pump

saltatory conduction

action potentials generated in the myelin sheath gaps and APs jump rapidly from gap to gap. made possible by myelinated axons, because the myelin keeps current insulated in the axons

sulci

shallow grooves that separate gyri

gyri

elevated ridges of tissue

brain stem

controls basic life functions

pons

regulates breathing rhythm, sleep and arousal

medulla oblongata

heart rate, breathing, blood pressure

midbrain

visual and auditory reflexes

cerebrum

conscious thought, memory, sensation, voluntary movement

left hemisphere

language, logic, math

right hemisphere

creativity, spatial awareness, emotion

frontal lobe

motor control, personality, decision-making, speech

parietal lobe

sensory perception, spatial awareness

temporal lobe

hearing, memory, language comprehension

occipital lobe

vision

thalamus

sensory relay station

epithalamus

pineal gland, melatonin, circadian rhythms

hypothalamus

homeostasis, hunger, thirst, temperature, endocrine control

cerebellum

balance, posture, coordination, motor learning

longitudinal fissure

separates left/right hemispheres (sagittal plane)

central sulcus

separates frontal/parietal lobes

transverse cerebral fissure

separates the cerebral hemispheres from the cerebellum below

broca’s area

responsible for speech production (motor speech); located in frontal lobe

blood brain barrier

protective mechanism that helps maintain the brain’s stable environment; prevent toxins and pathogens from entering CNS

reflex

rapid, automatic (involuntary) responses to stimuli

somatic sensory association area

interprets sensory input

visceral sensory cortex

internal organ sensations

olfactory cortex

smell

gustatory cortex

taste

primary motor cortex

voluntary movement

premotor cortex

helps plans movement

nociceptors

respond to potentially damaging stimuli that result in pain

mechanoreceptors

respond to mechanical force such as touch, pressure, vibration, and stretch

thermoreceptors

respond to temperature changes

chemoreceptors

respond to chemicals in solution (molecules smelled or tasted, changes in blood or interstitial fluid chemistry)

proprioceptors

respond to internal stimuli and advise the brain of the body’s position and movements

olfactory (I)

smell

optic (II)

vision

oculomotor (III)

eye movement, pupil constriction, eyelid movement

trochlear (IV)

moves superior oblique eye muscle (down and in)

trigeminal (V)

sensation to the face, chewing muscles

abducens (VI)

lateral eye movement (abduction)

facial (VII)

facial expression, taste (front ⅔ tongue), tear/saliva production

vestibulocochlear (VIII)

hearing and balance

glossipharyngeal (IX)

taste (back ⅓ tongue), swallowing, salivary glands

vagus (X)

swallowing, speech, heart rate, digestion (widest range)

accessory (XI)

neck and shoulder muscle movement (turning head, shrugging)

hypoglossal (XII)

tongue movement for speech and swallowing

somatic reflex

has one motor neuron, afferent fibers are somatic sensory neurons, and effectors are skeletal muscles

autonomic reflex

has two motor neurons, afferent fibers are visceral sensory neurons, effectors are smooth/cardiac muscle and glands

rods

see in dim light and black and white, mostly in peripheral retina

cones

see in bright light and color, mostly in central retina

iris

controls pupil size therefore the amount of light entering the eye; made of two smooth muscle layers

gustation

the sense of taste

outer ear

pinna and auditory canal

middle ear

ossicles (malleus, incus, stapes)

inner ear

cochlea, semicircular canals