Anatomy and Physiology Chapter 9: Muscles and Muscle Tissues

What are the three types of muscle tissue?

Skeletal, cardiac, smooth

Skeletal muscle

Organs that attach to/cover bony skeleton

Rapid contraction, but tires easily (bunny)

Striations

voluntary

Cardiac Muscle

In the heart

Involuntary

Striated

Steady and constant rate of contraction

Smooth Muscle

In walls of visceral organs: hollow organs

Involuntary

No striations

Slow, sustained rate of contraction (turtle)

Another name for muscle cells

Muscle fibers

What are the two types of myofilaments?

actin

myosin

What is a myofilament?

Long strands of muscle

4 Characteristics of muscle tissue

Excitability/Responsiveness/Irritability

Contractility

Extensibility

Elasticity

Excitability/Responsiveness/irritability

Ability to receive and respond to a stimulus (usually a chemical); the response is "conductivity"

Conductivity

Response; generation of electrical impulse that passes along plasma membrane of muscle cell and causes cell to contract

Contractility

Ability to shorten forcibly when stimulated; sets muscles abort from others (muscles are only tissue with this ability)

Extensibility

Ability to be stretched or extended

1. Cell shorten when contracting

2. But can be stretched when relaxing

Elasticity

Ability of a muscle cell to recoil and resume resting length after being streched

Muscle functions

Producing body movement (locomotion, manipulation)

Maintaining postures and body positions

Stabilizing joints

Generating heat (40% of body mass; most responsible for heat)

Other functions of muscle

Skeletal muscles protect inner organs

Smooth muscle forms valves for passage (sphincters)

Dilate pupils of eyes

Each muscle is served by one ___, ____, and more than one ____

Nerve, artery...vein

Nerve endings controls ____

activity

Rich blood supply because (2)

1. Uses huge mounts of energy

2. Removes numerous amounts of metabolic wastes

Endomysium

Whisky fine areolar connective tissue sheath around each individual muscle fiery; sheaths are continuous with each other; when muscle fibers contract, pull on sheath, pull on bone to be moved

Perimysium

Around each fascicles, is a layer of fibrous connective tissue

fascicle

Muscle fibers grouped together; wrapped in perimysium

Muscle's insertion

When muscle contracts: moveable

Muscle's origin

When muscle contracts: immovable

Direct/fleshy attachments

epimysium of muscle fuses to periosteum of bone/pericardium of cartilage

steroids

Synthetic male hormones

Indirect attachments

Muscle's connective tissue extents as tendon (or aponeurosis) anchors to the bone/cartilage/other-muscle-fascia; more common; smaller, durable

tendons

Tough collagen fibers that withstand touch bony protections; small size-conserve space

Myosin (from notes)

Most abundant muscle protein (2/3's); one molecule is made of 2 twisted protein strands with globular corssbridges (heads) that project outward

Many myosin ____ make up a myosin ______

Molecules, filament

cross bridges (from notes)

In the presence of Ca (calcium) ions react with actin filaments and shorten the myofibrils - contraction; contain ATP binding sites

Actin (from notes)

1/4 total protein in skeletal muscle; globular structure with myosin binding sites attached to surface

Actin molecules arranged in a ____ ___ to form an actin filament

Double helix

Actin filament has two other proteins associated with it

tropomyosin; troponin

tropomyosin

Rod shaped; in longitudinal grooves of actin helix (longitudinal groove: Paige's hair)

troponin

Attached to tropomyosin surface

At rest tropomyosin and troponin _____ active sites on actin so linkages between actin and myosin ____ be formed

inhibit; CANNOT

There must be a high concentration of Cs ions for ____

contraction

What happens when CA ions bind to troponin?

It changes the position of the tropomyosin and they move so that the active sites of actin are exposed and then linkages can form between actin and myosin filaments

sarcoplasmic reticulum

"endoplasmic reticulum" of a muscle fiber; membranous channels that run parallel to and surround each myofibril

Transverse tubules

"t-tubules"; membranous channels that go from the sarcolemma all the way through the muscle fiber; open to the outside of the muscle fiber; invaginations of the sarcolemma; contain extracellular fluid

both the sarcoplasmic reticulum and transverse tumbles function to___________________________

To activate the muscle contraction mechanism

Terminal cisternae

Enlarged portions of the sarcoplasmic reticulum; where calcium ions are stored

triad

Sarcoplasmic reticulum

Transverse tubules

Terminal cisternae

Neuromuscular junction

Site where motor nerve fibers and muscle fires meet; also called myoneural junction

Stimulation of what causes contraction?

Motor nerve fibers

Motor end plate

Specialized part of sarcolemma/muscle at the neuromuscular junction; sarcolemma is extensible folded; area has many nuclei and mitochondria

Synaptic vesicles

Tiny bubbles that contain neurotransmitters; main neurotransmitter acetylcholine (green balls in hook page 286)

Synaptic clefts

Recesses of muscle fiber that motor fiber branches into; the nerve ending and motor end plate don't touch, this is the space between them

Motor unit

A motor neuron and the muscle fiber it controls; page 286-7

___ motor nerve fiber is connected to ____ muscle fibers so ___ muscle fibers connected to the same nerve fiber contract ______

One; many; all; simultaneously

The ____ muscle fibers in a motor unit, the ___ movements of the muscle (example:__)

Fewer; finer; eye muscles

Acetylcholine

neurotransmitter; made in cytoplasm at distal end of a motor neuronal and stored in synaptic vesicles

Steps for Contraction

1. Acetylcholine released and diffuses across gap at neuromuscular junction

2. Sarcolemma is stimulated, muscle impulse travels deep into fiber through t-tubules to sarcoplasmic reticulum

3. Ca ions from Saco ret are released into sarcoplasm and bind to troponin molecules

4. tropomyosin molecules move and expose binding (active) sites on actin

5. Linkages form between actin and myosin... actin filaments slide inward along myosin filaments...muscle fiber shortens-contraction

Cholinesterase

enzyme that decomposes acetylcholine, located at neuromuscular junction in the membranes of the motor end plate

Steps for Relaxation

1. cholinesterase decomposes acetylcholine so sarcolemma is o longer stimulated

2. CA ions are actively transported back into the Saco ret

3. Linkages between actin and myosin are broken

4. Troponin and tropomysocin molecules inhibit the binding (active) sites of actin

5. Actin and myosin filaments slide apart...muscle fiber lengthens-relaxation

Energy for contractions comes from what?

ATP

Equation for formation of ATP

ATP <=> ADP + P + energy

ATPase

enzyme in myosin that breaks the ATP into DP and P so energy is released

Anything that ends in ose =

sugar

Anything that ends in ase =

enzymes

Creatine phosphate

High energy molecule stored in muscles; tapped to regulate ATP while metabolic pathways are adjusting to higher demands for ATP; short-lived

Equation for creating phosphate

Creatine phosphate + ADP => creatine + ATP

Glucose is stored into the form of___

glycogen

Cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen; eating and breathing to get energy

Glucose molecule gives enough energy for __ ATP

36

Cellular respiration formula

Glucose + oxygen => carbon dioxide + water + ATP

C6H12O6 + 6O2 => 6CO2 + 6H2O + Energy/ATP

Two steps of cellular respiration

1. Glycolysis (2 ATP)

2. Aerobic respiration (34 ATP)

- Citric Acid Cycle (Krebs's) (2 ATP)

- Electron Transport Chain (32 ATP)

Glycolysis

Anaerobic; first phase of cellular respiration that breaks glucose down into tow pyruvic acid molecules and tow ATP; occurs in cytoplasm (2 ATP)

Aerobic respiration

Aerobic; sequence of chemical reactions in which the bonds of fuel molecules are broken and the energy releases is used to make ATP (34 ATP); includes Citric Acid Cycle and Electron Transport Chain

Citric Acid Cycle

2 ATP; waste: carbon dioxide

Electron Transport Chain

32 ATP; waste: water

Lactic Acid formation

Occurs when not enough oxygen is available to send pyruvic acid into aerobic respiration; due to extreme exercise; ex: muscles working hard due to running so can't get enough oxygen into body (lung capacity) so blood can't get to lungs to pick up more oxygen so causes oxygen deficit/debt

Oxygen Deficit/Debt

When have less than amount of oxygen a body must take in for restorative process; causes arctic acid buildup; occurs when you don have enough oxygen in you body to send all the pyruvic acid into the aerobic part of cell respiration

Muscle fatigue

State of physiological inability to contract even though the muscle still may be receiving stimuli; results from a relative deficit of ATP; not its total absence

contractures

State of continuous contractions; ex: writer's cramp

____ is a byproduct of cellular respiration

heat

__-__% of energy available from cellular respiration and ___% is lost as heat

20-25%; 75%

Slow twitch/red muscle

"dark meat" lots of myoglobin and lots of mitochondria so does lots of cellular respiration to get ATP; does NOT fatigue easily; ex: back muscles (for posture) and thigh muscles

Fast twitch/white muscles

Few mitochondria and less myoglobin; gets most of its ATP through creating phosphate and Glycolysis and; DOES fatigue easily; found in muscles used in rapid movement

Muscles "can" or "cannot" have both?

can

hypertrophy

increase size/muscle mass; working out, exercising

atrophy

Decrease in size/muscle mass

myoblasts

A cell that builds muscles

Gap junction is aka ____

Synaptic clefts

Skeletal muscle fibers are contracting by what week?

Week 7

Smooth and cardiac do not do what?

They don't fuse

Heart is pumping blood by what week?

Week 3

Babies' movements are ____ and ____

Uncoordinated and reflexive

__ movements precede __ ones

Gross, fine

Development in a kid begins in ___ and radiates ___

Starts in head, radiates outward

When is the natural peak of motor control?

Mid adolescence

Women's skeletal muscles make up approx. __% of body mass

36%

Men's skeletal muscles make up approx.. __% of body mass

42%

Why are muscles not infected easily?

Rich blood supply

Muscular dystrophy

Inherited muscle-destroying diseases that appear in childhood; initially enlarge (due to fat) but then atrophy

Duchesne muscular dystrophy

Sex-linked recessive disease; females carry and transmit; almost always males have it; 2-7 years old; healthy people become clumsy and fall as skeletal muscles fail; usually die in 20s

As we age, our amount of connective tissue _____and number of muscle fibers ___

Increases, decreases

sarcopenia

Gradual loss of muscle mass

Muscle strength has usually decreased by ___% at 80 y/o

50%

How can old people get muscle strength back/maintain it?

Lightly working out