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