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AP1 > AP1 Exam 2 > Flashcards

AP1 Exam 2 Flashcards

1
Q

Hypodermis

A

aka subcutaneous layer

NOT part of the skin

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2
Q

Functions of the skin

A

Protection

Absorbs

Excretion

Thermoregulation

Cutaneous sensation

Synthesis of Vitamin D

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3
Q

A mole:

A

aka Nevus

benign overgrowth of melanocytes

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4
Q

Most cells in the epidermis are:

A

Keratinocytes

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5
Q

Melanocytes

A

contain special organelle called melanosome: synthesize melanin from the amino acid tyrosine in the presence of the enzyme tyrosinase

produce melanin and transfer to keratinocytes

melanin protect the DNA within keratinocytes

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6
Q

Merkel cells and tactile discs function in the:

A

sensation of touch

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7
Q

Layers of the epidermis

A

Stratum corneum

Stratum lucidum (not present everywhere)

Stratum granulosum

Stratum spinosum

Stratum basale

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8
Q

Keratinocytes

A

have intermediate filaments called tonofilaments composed of a protein that will later form keratin

continuously undergo mitosis and migrate to more superficial layers

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9
Q

Transition between the deeper living cells and the more superficial dead cells: which layer?

A

Stratum granulosum

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10
Q

Stratum granulosum

A

transition from living to dead keratinocytes

filled with granules of keratin

lamellar granules release a waterproofing lipid solution

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11
Q

Where is stratum lucidum located?

A

Fingertips

Palms

Soles

*cells are lucid/clear

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12
Q

Dermis consists of:

A

irregular CT with collagen and elastic

contains blood vessels, nerves, glands, hair follicles, and Arrectores pilorum muscles

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13
Q

Dermis is divided into two regions:

A

Papillary region (more superficial): connects the dermis to the epidermis

Reticular region

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14
Q

Sudoriferous gland

A

aka sweat gland

two types: eccrine and apocrine

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15
Q

Dermal papillae within the papillary region of the dermis greatly increase ______ ______.

A

surface area

allows for better adhesion to epidermis

more SA for diffusion

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16
Q

Touch corpuscles

A

Meissner corpuscles

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17
Q

Free nerve endings:

A

sensation of warmth, coolness, pain, tickle, itch

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18
Q

Subcutaneous layer

A

aka hypodermis

more fibers than cells: attach dermis to deeper tissues

larger blood vessels

pacinian aka lamellated corpuscles: sense pressure

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19
Q

lamellated corpuscle

A

aka pacinian corpuscle

sense pressure

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20
Q

Epidermal ridges

A

aka fingerprints

develop during 3rd and 4th fetal months as the epidermis conforms to the contours of the underlying dermal papillae

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21
Q

Skin color is due to the combination of these 3 pigments:

A

Melanin: amount and expression is genetically determined

Carotene: amount and expression is genetically determined

Hemoglobin

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22
Q

The number of ______ is about the same in all races. It is the amount of ______ produced and distributed that contributes to differences in skin color. Increased exposure to UV light increases enzymatic activity of ______.

A

melanocytes

melanin

melanosome: increased melanin production leads to tan

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23
Q

Carotene:

A

yellow-orange pigment

precursor to vitamin A (used to synthesize pigments for vision)

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24
Q

Hair picture

A
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25
Q

The hair follicle is located in the:

A

dermis

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26
Q

Hair matrix

A

produces new hair cells and push the growing hair through the pilary canal

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27
Q

Associated with hairs are:

A

sebaceous glands

arrector pili muscle

hair root plexuses: group of dendrites and nerve fibers endings that form a network around a hair follicle; sensitive to touch when hair shaft is moved

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28
Q

Each nails consists of:

A

nail body

free edge

nail root

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29
Q

Nail picture

A
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30
Q

Nail matrix:

A

epithelium deep to the nail root

produce new keratinocytes

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31
Q

Sebum

A

secreted by sebaceous glands

keeps hair from drying

prevents excessive evaporation of H2O

inhibits growth of some bacteria

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32
Q

Eccrine sweat glands

A

merocrine glands

more common and found in most places

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33
Q

Apocrine sweat glands

A

apocrine gland

found in association with hair that develops at puberty (axilla, groin, beard)

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34
Q

Psoriasis

A

keratinocytes divide and move more quickly than normal from the stratum basale to the stratum corneum and are shed prematurely

make an abnormal keratin: forms flaky, silvery scales (most common on knees, elbows, and scalp)

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35
Q

Most common carcinoma:

A

basal cell carcinoma

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36
Q

Three forms of skin cancer:

A

Basal cell carcinoma (most common)

Squamous cell carcinoma

Malignant melanoma (least common, most threatening)

*all are attributed to excessive sun exposure

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37
Q

Albinism

A

inherited INABILITY of an indiv. to produce melanin

most cases: unable to synthesize tyrosinase

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38
Q

Vitiligo

A

partial/complete loss of melanocytes from patches of skin

irregular which spots

may be an autoimmune disorder attacking melanocytes (no apparent genetic link)

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39
Q

Jaundice caused by a buildup of ______

A

bilirubin

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40
Q

Striae are caused by:

A

aka streaks aka stretch marks

rapid stretching and tearing of dermis (puberty, weight gain, pregnancy)

first appear as purple or reddish lines (tearing of vessels in dermis)

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41
Q

Alopecia

A

partial/complete lack of hair (from aging, chemo, etc.)

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42
Q

Wound healing

A

Epidermal wound healing: return to normal function

Deep wound healing: loss of some function; scar tissue formation (fibrosis)

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43
Q

Epidermal wound healing

A

only epidermal involvement

basal cells break away from basement membrane

they migrate into the wound until they are in full contact (as a sheet moving up from the bottom)

contact inhibition: once they are in contact they stop migrating; mitosis of basal cells is stimulated

return to normal function

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44
Q

Stages of deep wound healing

A

Inflammatory phase: blood clot, increased blood flow and permeability, WBCs and mesenchymal cells move into the area; scab formed

Migration phase: epithelial cells form bridge, fibroblasts move into area and produce collagen

Proliferative phase: growth of epidermal cells, increased collagen, regeneration of blood vessels

Maturation phase: collagen fibers become organized, fibroblasts decrease, blood vessels normal, scab sloughs off

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45
Q

Degrees of burns

A

First degree: only epidermal involvement; no blisters

Second degree (partial thickness): part of dermis involved, blisters, scarring

Third degree (full thickness): deep into dermis, lose deep nerve endings (numbness), edema, vary in appearance

*rule of 9’s is only for 2nd and 3rd degree burns

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46
Q

Eczema

A

inflammation of the skin

characterized by patches of red, blistering, dry, extremely itchy

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47
Q

Wart

A

mass produced by uncontrolled growth of epithelial skin cells

caused by papillomavirus

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48
Q

Hirsutism

A

condition of excessive body hair

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49
Q

Lanugo

A

cover the body of the fetus

fine, nonpigmented, downy hairs

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50
Q

Terminal hairs

A

coarse, heavily pigmented hair

hair of head, eyebrows, eyelashes (secondary characteristic)

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51
Q

Vellus hairs

A

short, fine, pale hairs

develop on most of the body during childhood

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52
Q

Cartilage consists of:

A

ground substance of chondroitin sulfate (provides plasticity)

dense network of collagen (provides strength) and elastic fibers

chondrocytes reside in spaces called lacunae (little lakes)

no blood vessels (slow healing and growth)

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53
Q

Cartilage is covered by CT called ______

A

Perichondrium>>once vascularized, this becomes periosteum

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54
Q

Types of cartilage

A

Hyaline: most abundant, ends of long bones, smooth surface for joint movement

Fibrocartilage: very strong, long thick bundles of collage, disc shaped segment between bones (think intervertebral discs, pubic symphysis)

Elastic: threadlike network of elastic fibers, malleable parts of body (auricle, epiglottis)

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55
Q

Yellow bone marrow is:

A

adipose connective tissue

triglyceride storage: function of bone tissue

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56
Q

Structure of long bone picture:

A

*epiphyseal plate (growth plate) in children

*articular cartilage is hyaline cartilage

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57
Q

The bone matrix is made up of:

A

50% hydroxyapatite (calcium phosphate and carbonate) for hardness

25% water

25% collagen

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58
Q

Osteogenic cells:

A

mesenchyme

*differentiates into osteoblast

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59
Q

Osteoclasts come from ______ lineage.

A

WBC (macrophage of bone)

breaks down bone

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60
Q

Compact bone

A

aka cortical bone

most of the skeleton is compact bone

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61
Q

Spongy bone

A

aka cancellous bone, trabecular bone

site of hematopoiesis>red bone marrow

spongy bone lessens the overall bone weight

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62
Q

Compact bone picture

A

Compact bone is arranged in osteons aka Haversian systems: form concentric lamellae

Interstitial lamellae: between osteons

Outer (external) circumferential lamellae: directly deep to the periosteum

Inner circumferential lamellae: line the medullary cavity

Lacunae: small spaces between lamellae housing osteocytes

Canaliculi: channels connecting lacunae, filled with ECF, contain fingerlike projections of osteocytes

Central (osteonic) canal: blood and lymph. vessels run through here

Perforating (Volkmann’s) canals: blood and lymph. vessels run from central canal to outer cortex of the bone

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63
Q

Spongey bone picture

A

Spongey bone are arranged in a lattice of thin columns called trabeculae.

Still have lamellae, lacunae, and canaliculi just in a different layout

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64
Q

Ossification

A

aka osteogenesis

process of forming new bone

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65
Q

Osteogenesis occurs by two different methods:

A

Intramembranous ossification: spongy bone, can be remodeled to form compact, forms flat bones

Endochondral ossification: cartilage (cartilage model) is replaced by bone, forms both compact and spongy bone, formation of most bones, 1 primary and 2 secondary centers of growth

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66
Q

Intramembranous ossification picture

A

does not go through cartilage stage

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67
Q

Endochondral ossification picture

A

*1 primary and 2 secondary centers of growth

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68
Q

Ossification contributing to bone length is usually complete by ___to ___ years of age.

A

18-21

*bones can still continue to thicken and are capable of repair even after epiphyseal plate closure

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69
Q

Bone fractures

A

Open

Comminuted

Greenstick

Impacted

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70
Q

Vitamin A for bones:

A

stimulates osteoblasts

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71
Q

Vitamin C for bones:

A

needed for synthesis of collagen

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72
Q

Vitamin D for bones:

A

promotes absorption of calcium from foods in the GI tract into the blood

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73
Q

Vitamin K and B12 for bones:

A

needed for synthesis of bone proteins

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74
Q

Bone resorption

A

minerals (calcium, phosphate) into the blood

removal of minerals and collagen fibers from bone by osteoclasts

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75
Q

Bone deposition

A

deposit minerals into bone (calcium, phosphate)

addition of minerals and collagen to the bone by osteoblasts

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76
Q

Abnormally thick and heavy bones

A

too much new bone tissue is formed (osteoblasts)

acromegaly

77
Q

Bones are too “soft” or weak

A

excessive calcium loss from bone (osteoclasts)

osteoporosis, rickets, osteomalacia

78
Q

Fracture repair

A

First step: formation of hematoma

2nd/3rd steps: phagocytes remove cellular debris, fibroblasts deposit collagen, formation of fibro-cartilaginous callus followed by a bony callus of spongy bone (osteoblasts from bony callus)

Final step: spongy bone is replaced by compact bone, fracture line disappears but evidence of fracture remains, takes several months

79
Q

PTH and calcitriol

A

increase blood Ca2+ levels (osteoclasts)

parathyroid hormone (PTH) produced in the parathyroid glands

calcitriol (active form of Vit. D3) is produced by the kidneys after being stimulated by PTH (causes retention of calcium in kidneys)

80
Q

Calcitonin

A

decreases blood calcium levels (osteoblasts)

produced by parafollicular cells of thyroid gland

81
Q

Joint

A

a point of contact between:

2 bones

bone and cartilage

bone and tooth

82
Q

Syndesmoses

A

more space than a suture; more connective tissue

between tib. fib.

83
Q

Cartilaginous joints

A

Synchondroses: hyaline cartilage connecting bones (“bone to bone”); may ossify with age

Symphyses: fibrocartilage connecting bones

Epiphyseal cartilage:

composed of fibrocartilage or hyaline cartilage

no synovial cavity

little or no movement

84
Q

Synovial joint

A

articular capsule: dense irregular and regular CT

synovial membrane

synovial fluid

articular cartilage: covers epiphyses of bone; not covered by synovial membrane

may contain articular discs: (menisci)

85
Q

Fibrous joints

A

Sutures: thin layer of fibrous CT

Syndesmoses: more space than a suture; more fibrous CT

Gomphoses: teeth in sockets

86
Q

Rickets and osteomalacia

A

Results from inadequate calcification of extracellular bone matrix

usually caused by Vit. D deficiency (fix this for prevention and treatment)

Rickets: in children, growing bones become “soft” and are easily deformed; epiphyseal plates fail to ossify resulting in bowed legs and deformities of the skull, rib cage, and pelvis

Osteomalacia: “adult rickets”; new bone formed during remodeling fails to calcify

87
Q

Myofibril

A

an organelle in a muscle fiber (myocyte)

basic functional unit of the muscle fiber (made of filaments: actin, myosin)

88
Q

Muscle arrangement (superficial to deep)

A

Entire muscle: covered by epimysium

Fascicle: covered by perimysium

Muscle fiber (myocyte): covered by endomysium

Myofibril: full of filaments

89
Q

Motor unit

A

group of muscle fibers supplied by a somatic motor neuron

*each muscle fiber is only supplied by 1 neuron thus 1 NMJ

90
Q

Embryonic muscle development

A

myoblasts fuse to form one muscle fiber (why they are multinucleated and they cannot undergo mitosis)

91
Q

Calsequestrin

A

calcium binding protein inside SR

allows calcium concentration to be 10K times higher than in sarcoplasm (relaxed muscle)

92
Q

T tubules are open to the outside of the muscle fiber, so they are filled with ______ ______.

A

Interstitial fluid

93
Q

Contractile proteins:

A

actin

myosin

94
Q

Sarcomere

A

M line: center of sarcomere

Z discs: end of sarcomere (middle of I band)

A band: length of myosin (never changes length)

H zone: between ends of actin (center of A band); only thick filaments

I band: between ends of myosin (crosses Z line)

95
Q

Titin

A

helps sarcomere return to its resting length

connects Z disc to M line

attaches thick filaments to Z discs and M lines

96
Q

Myomesin

A

structural protein associated with the M line

97
Q

Dystrophin

A

links the thin filaments of the sarcomeres to sarcolemmal proteins (integral membrane proteins)

transmits the tensive forces of the sarcomeres

98
Q

Sarcolemmal proteins

A

integral membrane proteins that dystrophin attaches to

99
Q

How many molecules of Ach cause the Na+ channels to open?

A

2

100
Q

Regulatory proteins

A

Troponin

Tropomyosin

101
Q

Structural proteins

A

Titin

Myomesin

Dystrophin

Sarcolemmal proteins

102
Q

Rigor mortis

A

“rigidity of death”

cell membranes leak Ca2+ bind to troponin: cross bridges attach

ATP is no longer being produced: cross bridges cannot detach

starts 3-4 hrs after death

disappears ~24 hrs after death: proteolytic enzymes digest cross bridges

103
Q

Hypertrophy is an increase in the ______ of muscle fibers.

A

diameter

organelles increase in number

contain more myofibrils from repetitive muscular activity

atrophy is opposite

104
Q

Hyperplasia

A

increase in number of cells

105
Q

Growth of skeletal muscle is stimulated by ______ during childhood.

A

hormones

106
Q

ATP production

A

cells do NOT store significant amounts; must be made at same rate that it is used

production via: creatine phosphate, glycolysis, aerobic respiration

107
Q

Creatine

A

need 2g/day

synthesized in liver, kidneys, pancreas and ingested (supplements, milk, red meat, some fish)

more ingested (supplements), less synthesized (can cause dehydration and kidney dysfunction)

108
Q

Control of contraction

A

1 nerve impulse= 1 AP in that motor unit

amplitude of AP is always the same but the frequency of stimulation is what increases the force the fibers can produce

109
Q

Twitch

A

a brief contraction of all the muscle fibers in a motor unit

110
Q

What is a myograph?

A

device used to measure the force generated by a contracting muscle

111
Q

Myogram:

A

record of muscle contraction

112
Q

Wave summation:

A

when a second stimulus is applied after the refractory period, skeletal muscle will respond to both stimuli

second stimulus occurs (after refractory period) before the muscle is relaxed= second contraction stronger than the first

more Ca2+ is released from SR

113
Q

Motor unit recruitment:

A

process whereby the number of active motor units is increased according to need

more neurons stimulated= more motor units stimulated =more motor tension

smallest, weakest motor units are recruited first

114
Q

Cardiac muscle is regulated by the ANS and the ______ system.

A

endocrine

115
Q

Like cardiac muscle, smooth muscle is also ______

A

autorhythmic

116
Q

How does smooth muscle generate ATP?

A

anaerobic respiration (glycolysis)

smooth muscle has a low capacity for generating ATP

117
Q

Smooth muscle fiber picture

A

thick, thin, and intermediate filaments

intermediate filaments are attached to dense bodies (functionally similar to Z discs) and found in sarcoplasm and sarcolemma

contraction of thick and thin filaments generates tension on intermediate filaments

118
Q

What are the two types of smooth muscle?

A

Single unit (aka visceral smooth muscle): connect to one another by gap junctions and contract as a single unit

Multi-unit: lack gap junctions and contract independently

119
Q

DOMS

A

delayed onset muscle soreness

microscopic muscle damage as a major factor (not all contributors are known)

120
Q

Muscle fatigue

A

inability of a muscle to maintain force of contraction after prolonged activity (not enough Ach, decreased release of Ca2+, depletion of nutrients, etc)

central fatigue: feelings of tiredness and desire to cease activity; may be protective mechanism

121
Q

Muscle tone

A

small amount of tension or contraction that a muscle exhibits even at rest

loss of muscle tone= flaccid

122
Q

Neuromuscular disease:

A

somatic motor neuron

NMJ

muscle fiber

term encompasses problems/diseases at any one of these 3 sites

123
Q

Myasthenia gravis

A

autoimmune disease

chronic, progressive damage of NMJ

antibodies bind to and block Ach receptors

decreases overall number of functional Ach receptors

124
Q

Spasm

A

sudden involuntary contraction of a single muscle that is part of a large group of muscles

125
Q

Cramp

A

painful spasmodic contraction

126
Q

Tic

A

spasmodic twitch made involuntarily by muscles that are normally under voluntary control

127
Q

PNS

A

all nervous tissue outside the CNS

Cranial nerves (12 pairs)

Spinal nerves (31 pairs)

Peripheral nerves

  • Divided into two divisions:
    • Sensory (afferent)
    • Motor (efferent)
  • Consists of the: these all have a sensory and motor neurons
    • somatic NS
    • ANS
      • motor portion: SNS and parasympathetic NS
    • enteric NS
128
Q

Somatic nervous system

A

Motor control of voluntary skeletal muscle

Sensation from body wall, limbs, head, and special senses

129
Q

Enteric nervous system

A

Sensation and motor control (smooth muscle, glands) of GI tract

130
Q

The somatic, ANS, and enteric nervous systems all have both a ______ and ______ subdivision.

A

sensory

motor

131
Q

Nerve vs. Tract

A

nerve: a bundle of neuronal axons in the PNS
tract: a bundle of neuronal axons in the CNS

132
Q

Ganglion vs. Nucleus

A

ganglion: a group of neuronal cell bodies in the PNS
nucleus: a group of neural cell bodies (unmyelinated) in the CNS

133
Q

Plexus

A

extensive network of nerves found within the PNS

134
Q

Tremor

A

rhythmic, involuntary, purposeless, contraction

produces a quivering/shaking movement

135
Q

Fibrillation

A

spontaneous contraction of a single muscle fiber

not visible under the skin

can be recorded by electromyography

may signal destruction of motor neurons

136
Q

Muscle strain

A

forceful stretching or tearing of muscle fibers

137
Q

Myotonia

A

slow relaxation or decreased ability to relax muscle after voluntary contraction

may be accompanied by increased muscular excitability and contractility

138
Q

Myomalacia

A

pathological softening of muscle tissue

139
Q

In neuron, axoplasm and axolemma are synonymous with:

A

cytoplasm

cell membrane (NOT the same as neurolemma)

140
Q

Nissl bodies

A

prominent clusters of RER

specialized form of typical organelle

141
Q

Neuron picture

A
  • axon: can approximate 3’ long in humans!
142
Q

In a neuron, impulses (APs) generally arise in the ______ ______.

A

Trigger zone: the junction of the hillock and initial segment

143
Q

Axon contains:

A

Mitochondria

Microtubules: tubulin; participate in moving material between the cell body and axon

Neurofibrils: intermediate filaments; cell shape and support

Does NOT contain RER=no protein synthesis in axon

144
Q

Axon ______ may branch off main axon.

A

collaterals

145
Q

Telodendria

A
  • The axon and its collaterals end by dividing into many fine processes
    called axon terminals or axon telodendria end in:
    • synaptic end bulbs
    • varicosities (string of swollen bumps)
146
Q

Axon terminals contain only some:

A

contain only some cytosol, mitochondria, cytoskeleton, SER and synaptic vesicles

147
Q

Things made in the cell body must be transported to axon terminal via:

A
  • Slow axonal transport:
    • one way ( from cell body to axon terminal)
    • trans. of: axoplasm to growing/regenerating axons
  • Fast axonal transport:
    • two way
    • microtubules as tracks and motors for movement of materials
    • trans. of: organelles, materials for axolemma, synaptic vesicles and end bulb
148
Q

Nerve fiber relationship within a nerve (picture)

A

consists of axon plus myelin sheath (if present)

the endoneurium surrounds the nerve fiber (to include the myelin sheath when present)

149
Q

Structural classification of neurons (picture)

A

Multipolar neurons: several dendrites and only one axon; located throughout the brain and spinal cord; majority of neurons in human body

Bipolar neurons: one main dendrite and one axon; utilized/located in special senses (retina, inner ear, olfactory)

Pseudounipolar neurons: one process extends from the body and divides into a central branch that functions as an axon as a dendritic root; employed for general SENSORY neurons that convey touch and stretching information

150
Q

Neuroglia are NOT ______ cells.

A

excitable

*neuroglia will fills the spaces formerly occupied by neurons in cases of injury or disease

151
Q

Neuroglia of CNS

A

Astrocytes

Oligodendrocytes

Microglia

Ependymal cells

152
Q

Neuroglia of PNS

A

Schwann cells (neurolemmocytes)

Satellite cells

153
Q

Neurons do not undergo ______ but neuroglia do.

A

mitosis

154
Q

Myelin

A

multi layered complex of lipids and proteins (layers of plasma membranes)

prevents loss of electrical signal=speeds up conduction of nerve impulses

PNS: Schwann cells

CNS: oligodendrocytes

155
Q

Schwann cell (neurolemmocyte) and myelination

A

Myelinates a segment of an axon in PNS

multiple layers surround the axon

the outer nucleated cytoplasmic layer of the Schwann cell is called the neurolemma (only in PNS)

156
Q

A Schwann cell (neurolemmocyte) or an oligodendrocyte can be associated with neuron, yet the neuron may be unmyelinated: explain

A

If they are just associated (but not wrapped several times) they are just referred to as their cell name: Schwann cell, oligodendrocyte

does NOT = myelination

Schwann cell or oligodendrocyte must be wrapped its plasma membrane around the axon many times= myelination

157
Q

Neurolemma

A

outer layer of myelinating Schwann cells

contains the nucleus and all cytoplasm

found only around axons in PNS

not to be confused with axolemma

158
Q

Nodes of Ranvier

A

gaps between myelinating cells (no myelin)

only on nerve fibers supplied by potentially myelin producing cells

159
Q

Myelination in the CNS:

A

no neurolemma

there are nodes of Ranvier

one oligodendrocyte can myelinate multiple times (several segments or several different axons)

160
Q

White vs. Gray matter

A

White: myelin (myelinated tract fibers)

Gray: no myelin; gray color from Nissl bodies (region predominantly filled with cell bodies)

161
Q

Neurons communicate with one another by using 2 types of electrical signals:

A

Action potentials: short and long distance; all or none

Graded potentials: short distance (localized) communication only; affect the generation of action potentials

162
Q

Resting membrane potential (neuron)

A

-70mV

membrane potential: opposite charges are separated in space; their attractive force is the potential

163
Q

Types of ion channels (picture)

A
164
Q

The cell membrane is impermeable to nearly all ______ charged intracellular molecules

A

negatively

e.g.: proteins, amino acids, phosphates, chloride (slightly permeable to extracellular Cl-)

165
Q

Establishment of resting membrane potential

A

K+ diffuses out of cell

negative particles left inside (neg. charge in cell)

a little Cl- diffuses into the cells

166
Q

Threshold:

A

-55mV

voltage gated Na+ channels open

167
Q

Calcium and membrane potential:

A

Calcium ions appear to bind to exterior surfaces of sodium channel protein molecule

Positive charge of calcium alter the electrical state of the channel protein= increased voltage level required to open the gate

Less calcium means the threshold will be lower than normal (easier to depolarize; highly excitable)

168
Q

Propagation (conduction)

A

nerve impulses must travel from where they arise at a trigger zone down the neuron to the axon terminals

depends on positive feedback

think of it as a wave of depolarization moving toward the axon terminal

169
Q

Continuous conduction:

A

step by step depolarization and repolarization of adjacent segments of the axon

170
Q

Saltatory conduction:

A

special mode of impulse propagation that occurs along myelinated axons

jump from one node of Ranvier to the next where voltage gated channels are concentrated

much faster than continuous

requires less ATP (more efficient)

171
Q

A, B, C fibers

A

A: large, myelinated (fastest)

B: medium, myelinated (fast)

C: small, unmyelinated (slow)

*the greater the diameter the faster the conduction

172
Q

Light touch vs. firm pressure

A

light touch: low frequency, widely spaced impulses; stimulates only a few pressure sensitive neurons

firm pressure: higher frequency; stimulates more pressure sensitive neurons

173
Q

Synapses and homeostasis:

A

contribute to homeostasis by providing evaluation and integration of stimuli

physically changed with repeated use (learning)

most neurons are both pre and post synaptic neurons

174
Q

Types of synapses:

A

electrical: pre and post synaptic neurons are in physical contact; AP/ions flow through gap junctions (heart and GI); faster than chemical

chemical: pre and post s. neurons are NOT in physical contact; AP travels via neurotransmitter

175
Q

Axo-

A

dendritic

somatic

axonic

176
Q

Chemical synapse signal transmission (picture)

A
177
Q

How are neurotransmitters removed?

A

Enzymatic degradation

Reuptake/uptake

Diffusion

178
Q

uptake vs. reuptake

A

uptake: neurotransmitter taken up by a cell that did not release it

reuptake: neurotransmitter take up by the same cell that released it

179
Q

EPSP

A

Excitatory post synaptic potential

potential that brings the membrane closer to threshold (depolarizing)

inside of the cell becomes less negative

180
Q

IPSP

A

inhibitory post synaptic potential

potential that brings the membrane further from threshold (repolarizing)

inside of the cell becomes more negative

181
Q

Summation

A

integration/evaluation of synaptic input

occurs at trigger zone

Spatial summation

Temporal summation

182
Q

Neurotransmitters are divided into 2 classes

A

small molecule neurotransmitters:

  • Ach: can be excitatory or inhibitory (at diff. synapses)
  • Amino acids: CNS; can be both
  • Biogenic amines: both
  • ATP and other purines
  • Nitric oxide: formed on demand; vasodilation

neuropeptides: both CNS and PNS; formed in cell body, packaged into vesicles, transported to axon terminals

  • opioid peptides; (pain control; enkephalins, endorphins, dynorphins>bodies natural pain killers)
183
Q

Plasticity

A

nervous system’s ability to change based on experience and need

neurons can sprout new dendrites, synthesize new proteins, change # of synapses

184
Q

Neural circuits

A

simple series: single pre. neuron to single post. neuron; most are far more complex

diverging: amplification of the original signal

converging: results in more effective stimulation/inhibition; e.g. motor neurons

reverberating: reverberations last longer than usual (perhaps used in breathing, awakening, short term mem.)

parallel after-discharge: if summation is excitatory in post. neuron= stream of impulses; precise activities and timing

185
Q

Regeneration of neurons:

A

to do any regeneration, neurons must:

be in PNS

have intact cell body

be myelinated by functional Schwann cells having a neurolemma: neurolemma forms regeneration tube that guides and stimulates regrowth of the axon

186
Q

Demyelination

A

voltage gated channels are concentrated at nodes of Ranvier

myelin insulates the neuron and allows the depolarization to spread further and faster

destruction of myelin (demyelination) means the depolarization does not reach the next node of Ranvier

examples: MS (CNS; progressive destruction>scleroses) and GBS (PNS; macrophages strip myelin)

187
Q

Local anesthetics work by blocking:

A

block the opening of voltage gated Na+ channels= prevents transmission of pain signals

188
Q

Rabies is caused by a virus that reaches the CNS via:

A

fast axonal transport

AP1 (3 decks)

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