A&P Unit 2: Quick Study

Endomysium

Surronds a muscle fiber

Epimysium

Surrounds whole muscle

Perimysium

Surrounds fascicle

I band

Has thin filaments only, shortens during contraction

A band

entire length of the thick (myosin) filaments, stays same length during contraction

H zone

central part of the A band containing thick filaments only, shortens/narrow during contraction

Z disc

anchors thin (actin) filaments, move closer together during contraction

M line

center of the sarcomere, holds thick filaments/myosin in place,

Sodium (Na⁺)

Enters the muscle fiber after ACh binds, causing depolarization, generates the muscle action potential

Potassium (K⁺)

Leaves the muscle cell during repolarization, helping the membrane return toward its resting state

Isotonic

Muscle lenght changes, tension constant and movement occurs, lifting a weight

Isometric

Muscle length doesn’t change, tension rises without movement, pressing palms together

Recruitment

Increasing force by activating more motor units, smaller units are generally recruited first, increasing force as you lift

Increased stimulation frequency

motor units stimulated more frequently, Ca can’t be completely removed between stimuli

Why does botulism causes flaccid paralysis?

toxin prevents the motor neuron from releasing ACh, muscle fiber doesn't receive the signal, no muscle contraction happens so flaccid occurs

Why does myasthenia gravis worsens with activity?

ACh can’t effectively bind, repeated stimulation causes repeated release of ACh, fewer receptors avaible so muscle response becomes weaker

Hamstring injury

flex the knee and extend the hip, injury makes running, jumping, or bending difficult

Rotator cuff rehabilitation

Stabilize the shoulder joint, assist with rotation/abduction, rehab focuses on gradually restoring strength and stability

Fall risk

Weak quadriceps, glutes, and ankle muscles can reduce the ability to control movements and maintain balance, increasing fall risk.

extensibility

Can be stretched beyond resting length without damage.

agonist/prime mover

Has the major responsibility for a movement, biceps brachii during elbow flexion

antagonist

Opposes or reverses the agonist's movement, triceps brachii during elbow flexion

aponeurosis

Broad, sheetlike attachment that distributes force over a wider area

contractility

Develops tension and can shorten when stimulated.

fascicle

bundle of muscle fibers

fixator

A synergist (agent, substance, muscle) that stabilizes an origin or bone

irritability

Receives and responds to a stimulus.

motor end plate

folded region of sarcolemma containing ACh receptors.

motor unit

one motor neuron and every skeletal muscle fiber it innervates, contracts all-or-none, whole muscle produces graded force by changing stimulation frequency and recruiting different numbers of motor units

myofibril

Long contractile organelle that occupies most of the muscle fiber, made of sarcomeres

sarcolemma

Specialized plasma membrane of a muscle fiber, contains receptors and conducts the action potential.

Small motor unit

Few fibers per neuron, precise control

Large motor unit

Many fibers per neuron, powerful, less precise movement

sarcomere

basic contractile unit of skeletal muscle and extends from one Z disc to the next Z disc

sarcoplasmic reticulum

Specialized smooth ER that stores, releases, and reabsorbs calcium ions

satellite cell

allow limited repair of skeletal muscle, but this ability declines with age.

synergist

Adds force or reduces unwanted movement, wrist stabilizers

tendon

Cordlike collagen structure that connects muscle to bone and transmits force.

tetanus

Tetanus toxin disrupts inhibitory signaling to motor neurons, Motor neurons become overactive, causing sustained muscle spasms and spastic paralysis.

Unfused tetanus

Frequent stimulation produces a strong, sustained contraction with partial relaxation

Fused tetanus

Very frequent stimulation produces smooth, sustained contraction with no visible relaxation

What is 1?

Muscle bundle

What is 2?

Fascicle

What is 3?

Muscle fiber

What is 4?

Endomysium

What is 5?

Perimysium

What is 6?

Epimysium

What is 1?

I Band

What is 2?

A band

WHat is 3?

I band

What is 4?

M line

What is 5?

Z disc

What is 6?

Thin filament (actin)

What is 7?

Thick filament (myosin)

Chondrocyte

divide and secrete new matrix within cartilage

Lacuna

hollow cavity in bone or cartilage that contains osteocytes,

Perichondrium

dense irregular connective tissue that surrounds most types of cartilage in the body, except for articular cartilage

Hyaline cartilage

Looks like frosted glass, abundant skeletal cartilage, fine collagen fibers only

Elastic cartilage

Contain more stretchy elastic fibers than hyaline, found only in external ear & epiglottis

Fibrocartilage

Highly compressible, great tensile strength, consists of roughly parallel rows of chondrocytes alternating with thick collagen fibers, menisci

Appositional growth

Thickens bones

Interstitial growth

Lengthens bones

Axial bones

Skull, spine, ribs/thoracic

Appendicular bones

Upper limbs, pelvic, pectoral girdle, lower limbs

Long bones

femur, support weight and enable movement, has shaft, bone ends & membranes, Epiphyseal line/Plate

Short bone

Provide high strength, wrist bones, spongy bone covered by compact bone, no marrow cavity

Flat bone

Sternum, protect internal organs and provide large surfaces for muscle attachment, spongy bone covered by compact bone, no marrow cavity

Irregular bone

Vertebrae, spongy bone covered by compact bone, no marrow cavity

Diaphysis

tubular shaft, thick collar of compact bone, contains the medullary cavity.

Epiphysis

separates from the diaphysis along the epiphyseal plate, when the cartilage cells are dying and calcification of the matrix

Medullary cavity

Has red marrow, in the diaphysis

Endosteum

thin membrane of connective tissue that lines the inner surfaces of bones

Articular cartilage

Covers bone ends in synovial joints

Trabeculae

Meshwork of bony spines in spongy bone

Red marrow

Blood cell formation, present in the medullary cavity of the diaphysis and all areas of spongy bone

Yellow marrow

red marrow converted to this in adults, holds fat

Osteon

main structural and functional unit of compact bone, central canal runs through it

Central canal

holds blood vessels, lymph vessels, and nerves to feed the bone

Osteoprogenitor cell

Stem cell, some become osteoblasts

Osteoblast

Matrix-synthesizing cell, responsible for bone growth

Osteocyte

Mature bone cell, monitors and maintains mineralized bone matrix

Osteoclast

Bone-resorbing cell, remodels bone

Perforating canal

small channels in compact bone that transmit blood vessels and nerves from the outer surface (periosteum) inward to the central canals of osteons

Lamellae

layers of mineralized matrix in bone tissue that organize collagen fibers and support the bone’s strength

Lacunae

small cavities within the bone matrix that house osteocytes

Canaliculi

microscopic channels in bone tissue that connect osteocytes to each other and to central blood vessels

Articulation/joint

connection point between two or more bones in the skeletal system

Fibrous joint

connection between two bones that are held together by dense connective tissue, suture, Syndesmosis, Gomphosis

Syndesmosis

Bones connected by a ligament, fibrous joint

Gomphosis

Fibrous joint, anchors the root of a tooth into its bony socket

Cartilaginous joint

Synchondrosis and Symphysis

Synchondrosis

Connected by hyaline cartilage, connects first rib

Symphysis

Connected by fibrocartilage, intervertebrae discs

Synovial joint

Articular cartilage covers the bone ends, joint cavity has synovial fluid, articular capsule with fibrous layer/synovial membrane surrounds the joint.

Synovial membrane

lines the inner surface of joint capsules, tendon sheaths, and bursae

Articular capsule

surrounds the joint

Tendon sheath

Elongated fluid-filled sac that wraps around a tendon to decrease friction

Plane Joint

Synovial joint, nonaxial/gliding, formed between flat bone surfaces, allow the bones to slide past each other

Hinge Joint

Synovial joint, uniaxial, lets bones move back and forth in a single direction

Pivot Joint

Uniaxial, allows for rotation