A&P bone and muscle physiology

Synaptic cleft

- Gap between nerve and muscle

Thick filaments contain

- myosin filaments - Contain ATPase enzymes - Possess myosin heads

Sites of muscle attachment

-Bones -Cartilages -Connective tissue coverings

Three ways to generate ATP

-Direct phosphorylation of ADP by creatine phosphate -Aerobic respiration -Anaerobic glycolysis and lactic acid formation

Smooth Muscle Characteristics

-Lacks striations -Spindle-shaped cells -Single nucleus -Involuntary—no conscious control

Cell returns to its resting state when:

-Potassium ions diffuse out of the cell -Sodium-potassium pump moves sodium and potassium ions back to their original positions

Skeletal Muscle Functions

-Produce movement -Maintain posture -Stabilize joints -Generate heat

Direct phosphorylation of ADP by creatine phosphate (CP)

CP transfers a phosphate group to ADP to regenerate ATP CP supplies are exhausted in less than 15 seconds About 1 ATP is created per CP molecule

At rest, within the A band there is a zone that lacks actin filaments

Called the H zone

Aerobic respiration

Glucose is broken down to carbon dioxide and water, releasing energy (about 32 ATP)

The first step in bone healing involves the formation of a blood filled swelling known as ____

Hematoma

ATP

Immediate source of energy for muscle contraction Stored in muscle fibers in small amounts that are quickly used up

Center of H zone is

M line

Twitch

Single, brief contraction Not a normal muscle function

Three basic muscle types are found in the body

Skeletal muscle Cardiac muscle Smooth muscle

Unfused (incomplete) tetanus

Some relaxation occurs between contractions, but nerve stimuli arrive at an even faster rate than during summing of contractions Unless the muscle contraction is smooth and sustained, it is said to be in unfused tetanus

Skeletal Muscles are

Striated Voluntary

Cardiac Muscle Characteristics

Striations Involuntary

Types of Graded Responses

Twitch Summing of contractions Unfused (incomplete) tetanus Fused (complete) tetanus

Extensibility

ability of muscle cells to be stretched

Irritability (also called responsiveness)—

ability to receive and respond to a stimulus

Elasticity

ability to recoil and resume resting length after stretching

Contractility

ability to shorten when an adequate stimulus is received

Thin filaments contain

actin filaments Composed of the contractile protein actin Actin is anchored to the Z disc

Muscle fiber contraction is

all or none

The skull vertebral column and thoracic cage form the __ skeleton

axial

Sarcoplasmic reticulum (SR) stores and releases

calcium

Small canals that connect osteocytes and their lacunae to the central canal are known as

canaliculi

Striated involuntary muscle tissue is classified as ___ muscle

cardiac

Sarcomere

contractile unit of a muscle fiber

Epimysium

covers the entire skeletal muscle

the heads of the myosin myofilaments are called ___ when they link the thick and thin filaments together during skeletal muscle contraction

cross bridges

Endomysium

encloses a single muscle fiber

An incomplete bone break known as a ___ fracture is commonly seen in children

green stick

Blood cell formation is called

hematopoesis

Skeletal muscles must be stimulated by a ____ to contract

motor neuron (nerve cell)

One neuron and all the skeletal muscles it stimulates is known as ____

motor unit

Fascia

on the outside of the epimysium

Motor unit

one motor neuron and all the skeletal muscle cells stimulated by that neuron

The process of bone formation is known as

ossification

The ____ is an organelle that wraps and surrounds the myofibril and stores calcium.

sarcoplasmic reticulum

Cubed-shaped bones that contain mostly spongey bones are called ___ bones

short

The gap between motor neuron and the muscle fiber it supplies at the neuromuscular junction is called the ___

synaptic cleft

Epimysium covering on the outside of the muscle can blend into cord like ___ or sheet like ____

tendons, aponeuroses

What bones protect the spinal cord

vertabrae

Perimysium

wraps around a fascicle (bundle) of muscle fibers

Neurotransmitter associated with muscle movement

Acetylcholine (ACh)

I band = light band

Contains only thin filaments

A band = dark band

Contains the entire length of the thick filaments

Muscle tissue has the ability to shorten when adiquitely stimulated a characteristic known as ____

Contractility

Which is the fastest way to generate ATP?

Direct phosphorylation of ADP by creatine phosphate (CP)

Fused (complete) tetanus

No evidence of relaxation before the following contractions Frequency of stimulations does not allow for relaxation between contractions The result is a smooth and sustained muscle contraction

Summing of contractions

One contraction is immediately followed by another Because stimulations are more frequent, the muscle does not completely return to a resting state The effects are "summed" (added)

Bone destroying cells known as osteoclasts are activated by the hormone ____

PTH parathyroid hormone

Isometric contractions

The muscle is unable to shorten or produce movement Example: pushing against a wall with bent elbows

Isotonic contractions

The muscle shortens, and movement occurs Example: bending the knee; rotating the arm