WKU ANATOMY/ PHYSIOLOGY EXAM 2

length-tension relationship

Amount of tension generated depends on length of muscle before it was stimulated

epiphyseal line

in adults, a bony scar that marks where growth plate used to be

Perimysium

Connective tissue surrounding a fascicle

Endomysium

Connective tissue surrounding a muscle fiber

Tendon

Connects muscle to bone

osteoclasts

break down bone

osteogenesis imperfecta

brittle bone disease; excessively brittle bones due to lack of protein, collagen

Eumelanin

brownish black pigment

Facicle

bundle of muscle fibers

PTH (parathyroid hormone)

Secreted by the parathyroid gland and raises blood calcium levels

What are the functions of skin?

Sensation, heat regulation, absorption, protection, excretion, secretion

Triad

a T tubule and two terminal cisternae associated with it

cyanosis

a bluish discoloration of the skin resulting from poor circulation or inadequate oxygenation of the blood.

second degree burn

a burn involving the epidermis and the dermis; characterized by erythema, hyperesthesia, and vesications (blisters)

myogram

a chart of the timing and strength of a muscle's contraction

Fractures

a crack or break in a bone

terminal cisterns

dilated end-sacs of SR which cross the muscle fiber from one side to the other

autorythmic

able to contract rhythmically and independently

Neoplasms

abnormal growths of new tissue that are classified as benign (nonharmful) or malignant (harmful)

what does inadequate calcitriol result in?

abnormal softness of bones in children (rickets) and in adults (osteomalacia)

resting membrane potential

about -90 mV in skeletal muscle cells *maintained by sodium-potassium pump

Growth in Length of Long Bones

function of chondrocytes and osteoblasts

vestigial hair

kept ancestors warm; found on trunk and limbs

I band

light band, thin filaments

mucous membrane

lines cavities that open to the outside ex: mouth, nasal passages, vagina, & urethra

what does the epithelium do?

lines cavities/covers organs

synovial membrane

lines closed cavities of joints do not have a layer of epithelium

flexion lines

lines on the flexor surfaces of the digits, palms, wrists, elbows; where skin folds

What does estrogen do?

maintains bone density in both sexes; inhibits resorption by osteoclasts

contractile proteins

myosin and actin do the work of contraction

somatic motor neurons

nerve cells whose cell bodies are in the brainstem and spinal cord that serve skeletal muscles

What does the dermis contain?

nerve fibers, sensory fibers, hair follicles, sebaceous glands, and sweat glands

What do gap junctions allow?

passage of nutrients, wastes, signals

hemangioma

patches of discolored skin caused by benign tumors of dermal capillaries; also known as birthmarks

mammary glands

produce milk; modified apocrine sweat glands

What do muscles do?

produce movement

muscle fatigue

progressive weakness from prolonged use of muscles

What does the integumentary system consist of?

skin, hair, nails, cutaneous glands

Lacunae

small cavities that contain osteocytes

cartilaginous joints

two bones are linked by cartilage two types: synchondroses & symphyses

Where do you find keratinocytes and what does it do?

epidermis & synthesizes keratin

all threshold intensity and above

twitch produced

cerumen

(earwax) yellow waxy material that lubricates and protects the ear canal

Excitability

(responsiveness) to chemical signals, stretch, and electrical changes across the plasma membrane

synovial joints

*(diarthrotic joints) freely movable joints *joint in which two bones are separated by a joint cavity *most structurally complex type of joint

Dystrophin

**links thin filaments to the sarcolemma *clinically important protein

regulatory proteins

**tropomyosin and troponin *act like a switch to determine when the fiber can contract and when it cannot *contraction activated by the release of calcium into sarcoplasm and its binding to troponin *troponin changes shape and moves tropomyosin off the active sites on actin

contraction of muscle

*ATPase in myosin head hydrolyzes an ATP molecule *activates the head "cocking" it in an extended position *head binds to actin active site forming a myosin actin cross bridge *myosin releases ADP and P and flexes pulling thin filaments with it- power stroke *upon binding more ATP, myosin releases actin

synchondrosis joint

*Bones are joined by Hyaline cartilage *bind epiphysis and diaphysis

treatments of osteoporosis

*Estrogen replacement therapy (ERT) slows bone resorption, but increases risk of breast cancer, stroke, and heart disease *Drugs Fosamax, Actonel destroy osteoclasts *Best treatment is prevention: exercise and a good bone-building diet between ages 25 and 40

bony joints

*Immoveable joint formed when gap between two bones ossify *synostosis *Examples: frontal and mandibular bones in infants; cranial sutures in elderly; attachment of first rib and sternum with old age

spongy bone consists of

*Lattice of bone covered with endosteum *Slivers of bone called spicules *Thin plates of bone called trabeculae *Spaces filled with red bone marrow

Osteoporosis

*a condition in which the bones become fragile and break easily *most common bone disease *postmenopausal women at greater risk due to ovaries ceasing estrogen secretion

bursa

*a fibrous sac filled with synovial fluid, located between adjacent muscles, where tendon passes over bone, or between bone and skin *cushions muscles, helps tendons slide more easily over joints, modifies direction of tendon pull

muscle fibers in one unit:

*dispersed throughout muscle *contract in unison *produce weak contraction over wide area *provide ability to sustain long term contraction as *motor units take turns contracting

tendon sheath

*elongated cylindrical bursa wrapped around a tendon *in hand and foot

Hypercalcemia

*excessive calcium in the blood *can cause weak muscles, sluggish reflexes, emotional disturbance *not as common

Structural Ways to Classify Joints

*fibrous- thin strands of fibers/ collagen *cartilaginous- pads of cartilage *synovial- joint cavity *bony - bones joined together

Calcitriol

*increases amount of calcium in the blood *causes osteoclasts to be more active *most active form of vitamin d *produced by actions of skin, liver, and kidneys

Calcitonin

*lowers blood calcium levels *causes osteoblasts to be more active *stimulates osteoblasts to deposit calcium into bone *important in children

Meniscus

*moon-shaped cartilage in knee; in each knee, menisci extend inward from the left and right *absorb shock and pressure *guide bones across each other and improve their fit together

synovial fluid

*rich in albumin and hyaluronic acid *slippery texture *nourishes articular cartilage and removes waste *makes movement of synovial joints almost friction free

What does collagen do?

*stretch slightly under tension and recoils when released *somewhat extensible and elastic *returns muscle to its resting length

kyphosis

*hunchback *deformity of spine due to vertebral bone loss

freckles

flat, melanized patches

Symphyses (cartilaginous)

two bones joined by fibrocartilage Example: pubic symphysis joins right and left pubic bones with interpubic disc; bodies of vertebrae joined by intervertebral joints

satellite cells

unspecialized myoblasts remaining between the muscle fiber and endomysium -play a role in regeneration of damaged skeletal muscle tissue

skeletal muscle

voluntary, striated muscle usually attached to bones

nueromuscular junction (NMJ)

when target cell is a muscle fiber each terminal branch of NMJ forms a separate synapse

Albanism

white skin from lack of melanin

Exercise and Articular Cartilage

-Exercise warms synovial fluid *Becomes less viscous, more easily absorbed by cartilage -Cartilage then swells and provides a more effective cushion *Warm-up period before vigorous exercise helps protect cartilage from undue wear and tear -Repetitive compression of nonvascular cartilage during exercise squeezes fluid and metabolic waste out of the cartilage -When weight removed, cartilage absorbs synovial fluid like a sponge taking in oxygen and nutrients to the chondrocytes -Without exercise, cartilage deteriorates more rapidly from inadequate nutrition and waste removal

isotonic muscle contraction

-Muscle changes in length with no change in tension *Concentric contraction: muscle shortens as it maintains tension (example: lifting weight) *Eccentric contraction: muscle lengthens as it maintains tension (example: slowly lowering weight)

physiological classes of muscle fibers

-Slow oxidative (SO), slow-twitch, red, or type I fibers *well adapted for endurance; resist fatigue by oxidative ATP production *important for muscles that maintain posture -Fast glycolytic (FG), fast-twitch, white, or type II fibers *fibers are well adapted for quick responses *important for quick and powerful muscles: eye and hand muscles -Fast twitch, intermediate, or type IIA fibers *fast twitch but fatigue resistant *known in other animals but rare in humans

response to stretch (smooth muscle)

-Stretch can open mechanically gated calcium channels in the sarcolemma causing contraction -When stretched, tissue briefly contracts then relaxes; helps prevent emptying while filling

characteristics of cardiac muscle cells

-Striated like skeletal muscle, but myocytes (cardiocytes) are shorter and thicker; Sarcoplasmic reticulum less developed, but T tubules are larger and admit Ca2+ from the extracellular fluid -Myocyte is joined at its ends to other myocytes by intercalated discs; Appear as thick, dark lines in stained tissue sections; Electrical gap junctions allow each myocyte to directly stimulate its neighbors; Mechanical junctions that keep the myocytes from pulling apart -Damaged cardiac muscle cells repair by fibrosis; Unfortunately, after a heart attack, functional muscle is not regenerated

smooth muscle

-capable of mitosis and hyperplasia -takes longer to contract, but can remain contracted longer without becoming fatigue -smooth muscle of iris controls pupil size -smooth muscles can contract forcefully even when greatly stretched *Allows hollow organs such as the stomach and bladder to fill and then expel their contents efficiently

cardiac muscle

-contracts with regular rhythm -Can contract without need for nervous stimulation -works in sleep and wakefulness -highly resistant to fatigue -muscle cells of a given chamber must contract in unison -contractions must last long enough to expel blood

Fatigue in low-intensity (long duration) exercise is thought to result from:

-fuel depletion as glycogen and glucose levels decline -electrolyte loss through sweat can decrease muscle excitability -central fatigue when loss motor signals are issued from brain *brain cells inhibited by exercising muscles release of ammonia *phycological will to persevere- not well understood

cardiac and smooth muscle

-involuntary muscles *cells are myocytes- not as long and fibrous as skeletal muscles; they have 1 nucleus

types of smooth muscle

-multiunit: occurs in some of the largest arteries and air passages (piloerector muscle & iris in eye) *autonomic innervation forms motor units -single unit: occurs in most blood vessels, in digestive, respiratory, urinary, and reproductive tracts *more common *also called visceral muscle: often in 2 layers (inner circular & outer longitudinal) *myocytes of this cell type are electrically coupled to each other by gap junctions *directly stimulate each other & a large number of cells contract as one

isometric muscle contraction

-muscle produces internal tension but external resistance causes it to stay the same length *important in postural muscle function and antagonistic muscle joint stabilization

relaxation of muscle

-nerve stimulation and ACH release stops -AChE breaks down ACh and fragments are reabsorbed into knob stimulation by ACh stops -Ca+2 pumped back into SR by active transport -Ca+2 binds to calsequestrin while in storage in SR - Ca+2 removed from troponin is pumped back into SR -Tropomyosin reblocks the active sites of actin -Muscle fiber returns it to its resting length

Fatigue in high-intensity exercise is thought to result from:

-potassium accumulation in the T tubules reduces excitability -excess ADP and Pi slow cross bridge movements, inhibits calcium release and decrease force production in myofibrils

rigor mortis

-stiffness of the body that sets in 3-4 hours after death *deteriorating sarcoplasmic reticulum releases Ca+2 and deteriorating sarcolemma allows Ca+2 to enter cytosol

plasticity of smooth muscle

-the ability to adjust its tension to the degree of stretch *a hollow organ such as the bladder can be greatly stretched yet not become flabby when empty

contraction strength of twitches

-the muscles starting length influences tension generation -muscles fatigue after continual use -warmer muscles enzymes work more quickly -muscle cell's hydration level influences cross- bridge formation -increasing the frequency of stimulus delivery increases tension output *stimulating the nerve with higher voltages produces stronger contractions

VO2 max

-the point at which the rate of oxygen consumption plateaus and does not increase further with added workload *usually greater in males than females *can be twice as great in trained endurance athlete as an untrained person

what is the structure of smooth muscle myocytes?

-they have a fusiform shape -one nucleus -thick and thin filaments present -z discs are absent and replaced by dense bodies

contraction phase

-time when muscle generates external tension *Force generated can overcome the load and cause movement

relaxation phase

-time when tension declines to baseline *SR reabsorbs Ca2+, myosin releases actin and tension decreases *Takes longer than contraction

latent period

-very brief delay between stimulus and contraction *Time required for excitation, excitation-contraction coupling, and tensing of elastic components of muscle (generating internal tension)

Peristalsis (smooth muscle)

-waves of contraction brought about by food distending the esophagus or feces distending the colon *propels contents along the organ

2 ways to classify joints

1. Structure ( describes what holds the bones together) 2. Function ( degree of movement permitted)

Excitation of muscle fiber

1. arrival of nerve signal: Ca2+ enters axon terminal- voltage-gated Ca2+ channels open, Ca2+ flows into neuron 2. acetylcholine (ACh) release via exocytosis of synaptic vesicles 3. binding of ACh to receptor 4. opening of ligand (chemical)-regulated ion gate, creation of end-plate potential, Na+ flows in then K+ flows out, causes local voltage change called end plate potential (EPP) 5. EPP causes opening of voltage-regulated ion gates; creation of action potentials, AP voltage change that spread across entire membrane (muscle=excited)

stratum granulosum

3rd layer of the epidermis that secretes a waterproofing for skin

inorganic matter of matrix

85% hydroxyapatite (crystallized calcium phosphate salt) 10% calcium carbonate Other minerals (fluoride, sodium, potassium, magnesium)

Axes of Rotation

A moving bone has a relatively stationary axis of rotation that passes through the bone in a direction perpendicular to the plane of movement

bone marrow

A soft tissue inside the bone that produces blood cells

Osteoblasts

Bone building cells

what is the leading cause of accidental deaths?

Burns

thin filaments

Fibrous (F) actin: two intertwined strands String of globular (G) actin subunits each with an active site that can bind to head of myosin molecule Tropomyosin molecules Each blocking six or seven active sites on G actin subunits Troponin molecule: small, calcium-binding protein on each tropomyosin molecule

Bromhidrosis

Foul-smelling perspiration, usually noticeable in the armpits or on the feet; produced by bacterial action on sweat from apocrine glands

epiphyseal plate

Growth plate, made of cartilage, gradually ossifies; hyaline cartilage that separates epiphyses and diaphysis

what do long bones act as?

Levers to enhance the speed or power of limb movement

terminal hair

Long, coarse, pigmented hair found on the scalp, legs, arms, and bodies of males and females.

basal cell carcinoma

Most common and least severe type of skin cancer; forms in stratum basale

Functions of the muscular system

Movement: body movement and movement of substance through body parts Maintenance of posture Respiration Production of body heat

Hemoglobin

Oxygen carrying pigment in red blood cells; adds reddish to pink hue to skin

intramembranous ossification

Produces flat bones of skull, clavicle and part of the mandible in fetus; thickens long bone throughout life

Small motor units vs. large motor units

Small: fine motor activities (fine degree of control) --> facial expression Large: gross muscular activities (more strength than control) --> quadriceps used for running

excitation of smooth muscle

Smooth muscle is involuntary and can contract (or relax) in response to a variety of stimuli • Autonomic activity—for example, parasympathetic nerves secrete acetylcholine stimulating GI tract smooth muscle and sympathetic nerves secrete norepinephrine relaxing smooth muscle in bronchioles (dilating them) • Hormones, carbon dioxide, oxygen, and pH—for example, hormone oxytocin stimulates uterine contractions • Temperature—for example, cold excites piloerector muscles and warmth relaxes muscle in skin blood vessels • Stretch—for example, stomach contracts when stretched by food • Autorhythmicity—for example, some single-unit smooth muscle cells in GI tract depolarize at regular intervals

range of motion determined by

Structure of the articular surfaces Elbow—olecranon of ulna fits into olecranon fossa of humerus Strength and tautness of ligaments and joint capsules Stretching of ligaments increases range of motion Double-jointed people have long or slack ligaments Action of the muscles and tendons Nervous system monitors joint position and muscle tone Muscle tone—state of tension maintained in resting muscles

Functional Ways to Classify Joints

Synostosis: no movement Synarthrosis: very little movement Amphiarthrosis: slightly movable Diarthrosis: freely movable

malignant melanoma

The most serious form of skin cancer; arises from melanocytes; highest incident in men, redheads, people who had severe sunburn as a child

Rickets

Vitamin D deficiency resulting in soft, deformed bones

voltage (electrical potential)

a difference in electrical charge from one point to another

syndesmosis joint

a fibrous joint at which two bones are bound by long collagen fibers Example: joint between radius & ulna

dermal papillae

a fingerlike projection of the dermis

twitch

a quick cycle of contraction and relaxation when stimulus is at threshold or higher

motor unit

a single motor neuron and all the muscle fibers it innervates *an average motor unit contains 200 muscle fibers*

Pilus

a slender filament of keratinized cells growing from a tube in the skin called a hair follicle

sarcomere

a structural unit of a myofibril in striated muscle, consisting of a dark band and the nearer half of each adjacent pale band

serous membrane

a thin membrane lining the closed cavities of the body ex: pericardium, pleura, peritoneum, tunica vaginalis

Extensibility

ability to be stretched

Contractility

ability to shorten

two types of myofilaments

actin (thin) myosin (thick)

subcutaneous fat

adipose tissue; proves insulation for body, energy reserver; thinner in elderly and infants; thicker in women

fibrous joints

adjacent bones are bound by collagen fibers that emerge from one bone and penetrate into the other three kinds: sutures, gomphoses, syndesmoses

What do hair receptors do?

alert us of parasites crawling on skin

What does the ceramic portion of the bone do?

allows the bone to support the body weight

Striations

alternate dark and light bands found on skeletal and cardiac muscle

Joint (articulation)

any point where two bones meet, whether or not the bones are movable at that interface

wolf's law of bone

architecture of bone determined by mechanical stresses placed on it

Tendons

attach muscle to bone

Gomphosis (fibrous joint)

attachment of a tooth to its socket, held in place by fibrous periodontal ligament

where would you find stem cells?

deepest layer of the epidermis (stratum basale)

endochondral ossification

bone forms by replacing hyaline cartilage

Calcium homeostasis is regulated by three hormones:

calcitriol, calcitonin, and parathyroid hormone (PTH)

Gycogen

carbohydrate stored to provide some oxygen needed for muscle activity

what fills outer region of dense bone?

circumferential lamellae

what is a composite material?

combination of a ceramic and a polymer

what does the nervous tissue do?

communication

What is calcium needed for?

communication between neurons, muscle contraction, blood clotting, exocytosis

skeletal system

composed of bones, cartilages, and ligaments

joint (articular) capsule

connective tissue that encloses the cavity and retains the fluid

red marrow

contains hematopoietic tissue which produces blood cells; in nearly every bone in a child; in skull, vertebrae, ribs, sternum, and others

what is very slow in smooth muscles in comparison to skeletal muscles?

contraction and relaxation

Cartilage

covers many joint surfaces of mature bone

Sarcoplasm

cytoplasm of a muscle fiber

a band

dark area A stands for anistropic

reticular layer

deep & thicker layer of dermis; dense irregular connective tissue

Where do you find melanocytes and what do they do?

deepest part of the epidermis & shields DNA from ultraviolet radiation

Hypocalcemia

deficient calcium in the blood caused by vitamin d deficiency, diarrhea, thyroid tumors pregnancy and lactation increases risk

compact bone

dense outer shell of bone

osteolysis

dissolving of bone

epidermal ridges

downward waves of epidermis; fingerprints

moles

elevated, melanized patches often with hair

Epiphyses

ends of long bone; strength

what are the layers of the skin?

epidermis, dermis, hypodermis

short bones

equal in length and width, glide across one another in multiple directions

What is the most common cause of skin cancer?

exposure to UV radiation

Periosteum

external sheath that covers bone except where there is articular cartilage important for bone growth and healing of fractions

what hair allows for nonverbal communication?

eyebrows and eyelashes

Lanugo hair

fine, downy, unpigmented hair that appears on the fetus in the last 3 months of development

what causes people to die from burns?

fluid loss, infection, or toxic effects of eschar

synaptic cleft

gap between axon terminal and sarcolemma

what does the polymer portion on the matrix do?

gives flexibility

interstitual growth

growth from within

appositional growth

growth in width

What are guard hairs responsible for?

guarding nostrils & ear canals

What are the accessory organs?

hair, nails, and cutaneous glands

elastic filaments

help stabilize position of thick filaments prevent overstretching and provide recoil

Stress-relaxation response (receptive relaxation)

helps hollow organs gradually fill (urinary bladder)

Steps of healing a fracture

hematoma formation, fibrocartilage callus formation, bony callus formation, bone remodeling

Ligaments

hold bones together at joints; bone to bone

Titin

huge, springy protein that makes elastic filament

What layer is not actually part of skin?

hypodermis

open reduction

involves surgical exposure of the bone and the use of plates, screws, or pins to realign the fragments

What are the 3 layers of the hair?

lanugo, vellus, terminal

articular cartilage

layer of hyaline cartilage that covers the facing surfaces of two bones

What two directions do bones grow?

length and width

Canaliculi

little channels that connect lacunae

Conductivity

local electrical excitation sets off a wave of excitation that travels along the muscle fiber

Myofibrils

long protein cords occupying most of sarcoplasm

long bones

longer than they are wide; responsible for movement

spongy (cancellous) bone

loosely organized bone tissue

thick filaments

made of several hundred myosin molecules

squamous cell carcinoma

malignant tumor of the squamous epithelial cells in the epidermis; arises from keratinocytes of stratum spinosum

Osteocytes

mature bone cells

what do muscle cells contain?

millions of ACh receptor which are proteins incorporated into its membrane

threshold

minimum voltage necessary to generate an action potential in the muscle fiber and produce a contraction

With subthreshold stimuli

no contraction at all (but tension develops)

Matrix

nonliving part of bone

What is a cast used for?

normally used to stabilize and immobilize healing bone

H band

not as dark; middle of A band; thick filaments only

what is remodeling of bone?

ongoing replacement of old bone tissue by new bone tissue

first degree burn

only epidermis is damaged; heals within days

stratum lucidum

only in thick skin - palms, soles *not always present*

what are the 2 zones of the dermis?

papillary layer and reticular layer

stratum corneum

outermost layer of the epidermis, which consists of flattened, keratinized cells

Mitochondria

packed into spaces between myofibrils

vellus hair

pale, fine body hair of children and adult females (peach fuzz)

pallor

paleness due to decreased blood flow to skin

Sarcolemma

plasma membrane of a muscle fiber

Synapse

point where a nerve fiber meets its target cell

what are langerhaan cells responsible for and where do you find them?

prevents things from getting into the skin & found in epidermis

closed reduction

procedure in which the bone fragments are manipulated into their normal positions without surgery

osteogenesis

process of bone formation

Myoglobin

red pigment; provides some oxygen needed for muscle activity

Pheomelanin

reddish-yellow pigment

erythema

redness of the skin due to capillary dilation (increased blood flow)

bone remodeling

repairs microfractures, releases minerals into blood, reshapes bones in response to use and disuse 10% of the skeleton per year

Elasticity

returns to its original resting length after being stretched

Arthrology

science of joint structure, function, and dysfunction

Diaphysis

shaft of a long bone

multiaxial joint

shoulder joint has three degrees of freedom or axes of rotation

denervation atrophy

shrinkage of paralyzed muscle when nerve remains disconnected

What are the three types of muscle tissue?

skeletal, cardiac, and smooth muscle

What is the body's largest organ?

skin

sarcoplasmic reticulum

smooth ER that forms a network around each myofibril

yellow marrow

soft, fatty material found in the medullary cavity of long bones; found in adults

medullary cavity

space in the diaphysis of a long bone that contains bone marrow

stratum spinosum

spiny layer above stratum basale

muscle tone

state of partial contraction

myoblasts

stem cells that fused to form each muscle fiber early in development

osteogenic cells

stem cells; found in endosteum and inner layer of periosteum

Kinesiology

study of musculoskeletal movement

papillary layer

superficial layer of dermis rich in blood vessels and allows for mobility of leukocytes and other defense cells

Functions of the skeleton

support, protection, movement, electrolyte balance, acid-base balance, blood formation

Epimysium

surrounds entire muscle

axon terminal

swollen end of nerve fiber Contains synaptic vesicles with acetylcholine (ACh)

organic matter of matrix

synthesized by osteoblasts; Collagen, carbohydrate-protein complexes, such as glycosaminoglycans, proteoglycans, and glycoproteins

What are stretch marks?

tears in the collagen fibers caused by stretching of the skin due to pregnancy or obesity

stratum basale

the deepest layer of the epidermis consisting of stem cells and keratinocytes *only layer with mitotic activity*

third degree burn

the destruction of the epidermis and dermis, with damage or destruction of subcutaneous tissue; often requires skin grafts

friction ridges

the markings on the fingertips that leave oily fingerprints on surfaces we touch

what happens if nerve connections are severed or poisoned?

the muscle becomes paralyzed

zero position of synovial joints

the position of a joint when a person is in the standard anatomical position

recruitment or multiple motor unit summation

the process of bringing more motor units into play with a stronger stimuli

Electrophysiology

the study of the electrical activity of cells

what causes people to be darker than others?

they produce greater quantities of melanin, melanin breaks down slower, melanin granules more spread out in keratinocytes

basal lamina

thin layer of collagen and glycoprotein separates nerve cell and muscle cell from surrounding tissues *contains acetylcholinesterase (AChE) that breaks down ACh allowing for relaxation

Endosteum

thin layer of reticular connective tissue lining marrow cavity; contains osteoclast and some osteoblasts

flat bones

thin, flattened, and usually curved; protects soft organs

What is the building unit of spongy bone?

trabeculae; thin plate like units in netlike arrangement; found in center of ends and center of shafts of long bones

T tubules

tubular infoldings of the sarcolemma which penetrate through the cell and emerge on the other side

Carotene

yellow-orange pigment acquired from yellow-orange vegetables

jaundice

yellowing of the skin from bilirubin in blood

metaphysis

zone of transition facing the marrow cavity