biol114 - ch.9

Cardiac Muscle Tissue

Involuntary, striated muscle

Skeletal Muscle Tissue

Voluntary, striated muscle

Smooth Muscle Tissue

Involuntary, non-striated muscle

Tendon

Connective tissue that attaches muscle to bone.

Aponeurosis

Broad sheet of connective tissue that provides stability and connects muscles to bones. Ex- on frontal and occipital bone, and abdomen

Epimysium

Outermost connective tissue layer that surrounds a muscle.

Perimysium

Middle connective tissue layer that surrounds a fascicle (bundle of muscle fibers).

Endomysium

Innermost connective tissue layer that surrounds individual muscle fibers.

Sarcolemma

Plasma membrane of a muscle fiber.

Sarcoplasm

Cytoplasm of a muscle fiber.

Sarcomere

Contractile unit of a muscle fiber.

The Muscle

muscle as an organ → muscle fascicle → muscle fiber → myofibrils → myofilaments

Muscle Fibers (muscle cells)

Huge, many nuclei, sarcolemma, sarcoplasm.

T-tubule

Extends across the muscle fiber and surrounds each myofibril; opening at sarcolemma

Sarcoplasmic Reticulum

Membrane-bound structure that stores calcium ions.

Terminal Cisterna

End of the sarcoplasmic reticulum that stores the most calcium ions.

Triad

Terminal Cisterna → T-tubule → Terminal Cisterna

Myofilaments

Actin Proteins & Myosin Proteins

Thin Filaments

Actin proteins that make up part of the myofibrils.

Thick Filaments

Myosin proteins that make up part of the myofibrils.

G-actin

Active sites

F-actin

Twisted strands of G-actin to be functional

Tropomyosin

Covers active site

Troponin

Calcium receptor

Thin Filaments

G-actin, F-actin, Tropomyosin, Troponin

Myosin

Head & Tail

Titin

Molecular Spring

Needed for Contraction

Stimulation (nervous system), Calcium, and ATP

Thick Filaments

Contains Myosin & Titin

Resting Membrane Potential

Polarized state of a cell with a negative charge inside and a positive charge outside, maintained by the Na+/K+ pump, and found in Neurons & Skeletal muscle fibers.

Action Potential

Resting Potential → Depolarization (Na+ channels open with ACh neurotransmitters → Na+ enters cell → cell becomes positive) → Peak: Action Potential → Repolarization (AChE close the Na+ channels → K+ channels open → K+ exits cell → cell becomes negative) → Refractory Period →Resting Potential

Neuromuscular Junction

Connection between a motor neuron and a muscle fiber.

Axon terminals

Expanded end of axon

Motor End Plate

Neuron meets muscle fiber

ACh

Attaches to Na+ channel

AChE

Breaks down ACh; an enzyme

Isotonic

Muscle contraction where the length changes, either shortening (concentric) or elongating (eccentric).

Concentric

Shortening length

Eccentric

Elongating length

Isometric

Muscle length stays constant

ATP

Aerobic- Requires Oxygen

Glycolysis

Creates ATP; Anaerobic- Does NOT Require Oxygen

Sources of Stored Energy

ATP, Creatine Phosphate (C.P.), & Glycogen

Muscles At Rest

Use some remaining ATP to create Creatine P. and Glycogen

Active Muscles

Use ATP

Peak Activity Muscles

Use ATP from Glycogen

Oxygen Debt

Need extra oxygen during recovery period for ATP, it uses energy that doesn’t need oxygen to produce lactate. Glycolysis→ Converted by liver→ Lactate

Muscle Fatigue

Recovery tie depends on the amount of activity

High activity time

High recovery time

Low activity time

Low recovery time

Trophy

How something grows

Hypertrophy

Excessive muscle growth; muscles grew big

Atrophy

Absence of growth; muscles deteriorating away

Muscular Dystrophy

Muscle grows abnormally; genetic, sex recessive