Chapter 9 – Muscle Tissue Overview

These flashcards cover essential vocabulary related to muscle tissue, including types of muscles, their properties, anatomy, functions, physiology, and more.

Voluntary Muscle

Muscle that is consciously controlled.

Involuntary Muscle

Muscle that is automatically controlled.

Striated Muscle

Muscle with visible stripes or bands under a microscope.(cardiac, skeletal)

Nonstriated Muscle

Muscle without visible stripes.(smooth)

Myo- & mys-

Prefixes meaning muscle.

Sacro

flesh

Inos

fiber

Example:

Break down sarcolemma

Sarco: flesh

Lemma: Husk

Its the muscle cell version of a regular cells plasma membrane

Skeletal Muscle

Organs attached to bone; elongated cells (myocytes); striated, voluntary, fast, andpowerful but tires easily.

Cardiac Muscle

Muscle found only in the heart; striated, involuntary, and rhythmic.

Smooth Muscle

Located in walls of hollow visceral organs (e.g., stomach, bladder); elongated, nonstriated, involuntary, and slow.

General Functions

Movement of bones/fluids, maintaining posture, stabilizing joints, and heat generation (especially skeletal muscle).

Excitability

The ability of muscle tissue to respond to stimuli.

Contractility

The ability of muscle tissue to shorten forcibly.

Extensibility

The ability of muscle tissue to be stretched.

Elasticity

The ability of muscle tissue to recoil.

Connective Tissue Sheaths (external to internal

Epinesium

Perinesium

Endomesium

Prefix:

Epi

on , upon, over

Prefix:

Peri

around or near

Prefix:

Endo

within, inner

Suffix:

Mysium:

Derived from the Greek word mys, meaning "muscle."

Epimysium

Connective tissue sheath that surrounds the entire muscle.

Perimysium

Connective tissue sheath that surrounds fascicles, or groups of muscle fibers.

Endomysium

Connective tissue sheath that surrounds individual muscle fibers.

Microscopic Anatomy:

Sarcolemma:

Plasma membrane.

Microscopic Anatomy:

Sarcoplasm:

Cytoplasm containing glycosomes (glycogen storage) and myoglobin (O2 storage).

Microscopic Anatomy

Myofibrils: Rod like elements taking up 80% of cell volume contain sarcomeres

Microscopic Anatomy:

Sarcoplasmic Reticulum (SR)

Structure that regulates intracellular Ca2+ levels and stores/release Ca2+.

Microscopic Anatomy:

T Tubules

Continuations of sarcolemma that penetrate the cell to allow coordination between sarcomeres

A Sarcomere is a region between two ____ _____

Z discs

These 4 markers are present in a sarcomere:

A band

I band

H zone

M line

Sarcomere:

A band:

dark region, entire length of the filament

Sarcomere:

I band

Light region(thin filaments only, thin as in ac-thin>actin)

Sarcomere:

H zone:

Lighter midsection of A band where filaments don’t overlap

Sarcomere

M line:

Bisects the H zone

Myofilaments:

Myosin(thick)

Actin(thin like acthin)

Regulatory proteins(tropomyosin)

Myofilaments:

Thick (Myosin):

Features globular heads that act as cross bridges; contains binding sites for actin and ATP.

Myofilaments:

Thin (Actin)

Twisted double strand of F actin; bears active sites for myosin attachment.

Myofilaments:

Regulatory Proteins

Tropomyosin (blocks active sites) and Troponin (binds Ca2+ to move tropomyosin).

Describe the sliding filament model

During contraction, thin filaments slide past thick filaments, causing actin and myosin to overlap more; I bands shorten, H zones disappear, and Z discs move closer.

Fill in the blank

During contraction, _____ _____ slide past _____ ______, causing actin and myosin to overlap _______ ; I bands ______, H zones ______ , and Z discs move _____.

During contraction, thin filaments slide past thick filaments, causing actin and myosin to overlap more; I bands shorten, H zones disappear, and Z discs move closer.

Action Potential (AP)

A neural impulse that travels along the axon and triggers muscle contraction.

Neuromuscular Junction (NMJ)

The synapse where a motor neuron connects with a muscle fiber.

Phase 1: Activation at Neuromuscular Junction (NMJ):

1. Action potential (AP) arrives at axon terminal; voltage-gated Ca2+ channels open.

2. ACh (Acetylcholine) is released and binds to sarcolemma receptors.

3. Ligand-gated ion channels open, causing local depolarization (end plate potential)

Phase 2: Excitation-Contraction (E-C) Coupling:

1. AP travels across sarcolemma and down T tubules.

2. Voltage-sensitive proteins in T tubules change shape, triggering SR to release Ca2+.

3. Ca2+ binds to troponin, moving tropomyosin and exposing actin active sites.

Cross Bridge Cycle:

1. Formation: Energized myosin head attaches to actin.

2. Power Stroke: Myosin head pivots, pulling the thin filament toward the M line.

3. Detachment: ATP binds to myosin, causing it to release from actin.

Rigor Mortis

After death, Ca2+ leaks into cells causing cross bridges to form, but lack of ATP prevents detachment, resulting in muscle stiffness.

Regarding Muscle Mechanics,

Define a Motor Unit

A motor neuron and all the muscle fibers it supplies; small units provide fine control, largeunits provide strength.

Muscle Twitch Phases:

1. ________ period : E-C coupling occurs; no visible tension.

2. ___________ : Cross bridges cycle; tension rises to peak.

3. _________ : Ca2+ re-enters SR; tension declines.

1. Latent period: E-C coupling occurs; no visible tension.

2. Contraction: Cross bridges cycle; tension rises to peak.

3. Relaxation: Ca2+ re-enters SR; tension declines.

Muscle Twitch Phases:

1. Latent period: _______________________________________

2. Contraction: ________________________________________

3. Relaxation: _________________________________________

1. Latent period: E-C coupling occurs; no visible tension.

2. Contraction: Cross bridges cycle; tension rises to peak.

3. Relaxation: Ca2+ re-enters SR; tension declines.

Graded Muscle Responses consist of

Frequency change and Strength change, they are variations in muscle contractions based on frequency or strength of stimuli.

Graded Muscle Responses:

Frequency Change

Increased stimulus frequency leads to temporal summation, unfused tetanus, and eventually fused (complete) tetanus.

Graded Muscle Responses:

Strength Change

Recruitment (multiple motor unit summation) activates more fibers via the size principle (smallest fibers first).

Contraction Types:

Isotonic and Isometric

Isotonic Contraction

Muscle changes length to move a load; can be concentric (shortening) or eccentric (lengthening).

Isometric Contraction

Tension increases but muscle doesn't shorten (load exceeds tension).

Muscle Tone:

Constant, slightly contracted state of muscles due to spinal reflexes; keeps muscles healthy and ready.

Types of ATP generation in muscle cells ______ , _____ , _____

Direct Phosphorylation

Anaerobic Pathway

Aerobic Respiration

Describe

Direct Phosphorylation

Creatine Phosphate (CP) + ADP yields 1 ATP (lasts about 15 sec)

Describe Anaerobic pathway

Glycolysis converts glucose to lactic acid; it yeilds 2 ATP (last 30-40 seconds.)

Describe Aerobic Respiration

Occurs in the mitochondria requires O2 to breakdown glucose into CO2, H20, and 32 ATP (lasts for hours)

What is Muscle fatigue

Physiological inability to contract due to ionic imbalances (K+ and Ca2) rather than total lack of ATP

What is EPOC (O2 debt)

Extra O2 needed post-excercise to replenish O2 reserves, convert lactic acid and replace glycogen/ ATP stores

Skeletal Muscle Fiber Types

1.) ________

2.) ________

3.) ________

1.) Slow Oxidative

2.) Fast Oxidative

3.) Fast Glycostic

Describe slow oxidative skeletal muscle fibers

Aerobic, fatigue-resistant, high myoglobin (red), used for endurance (e.g., marathons).

Describe fast oxidative skeletal muscle fibers

Aerobic (some anaerobic), intermediate fatigue resistance, used for sprinting/walking.

Describe Fast Glycolytic skeletal muscle fibers

Anaerobic, fast to fatigue, low myoglobin (pale), used for powerful movements (e.g., hitting a baseball).

Fill in the blank/ Smooth Muscle structure

-________-shaped

-_______ nucleus

-___ striations

-___ T tubules

-___ sarcomeres

-features _______ ( _____ pouches) and _____ bodies (anchoring points).

-Spindle-shaped

-single nucleus

-no striations

-no T tubules

-no sarcomeres

-features caveolae (Ca2+ pouches) and dense bodies (anchoring points).

Describe smooth muscle physiology/structure

-Spindle-shaped

-single nucleus

-no striations

-no T tubules

-no sarcomeres

-features caveolae (Ca2+ pouches) and dense bodies (anchoring points).

Fill in the blank/ Contraction of a Smooth muscle

1. Ca2+ enters from ____ and ____.

2. Ca2+ binds to _______.

3. Activated _______ activates _______ light chain ______.

4. Kinase phosphorylates myosin, allowing _________ formation.

1. Ca2+ enters from ECF and SR.

2. Ca2+ binds to calmodulin.

3. Activated calmodulin activates myosin light chain kinase.

4. Kinase phosphorylates myosin, allowing cross bridge formation.

There are two types of smooth muscle fibers ______ (_____) and ________

Unitary (visceral) and Multiunit

Despl-[-[