Chapter 8-Muscular System

Case Study # 1

Signs and Symptoms:- Respiratory Acidosis

- Accelerated oxygen consumption

- Extreme heat production

Case Study # 2

Signs and Symptoms:- Muscle weakness

- Easily fatigued

- Muscles eventually cease to function

Case Study # 3

Signs and Symptoms:- Uncoordinated

movements

- Jerky to-and-fro motion of trunk and limbs

Three Types of Muscle Tissue

1) Skeletal Muscle- Striated- Voluntary

2) Cardiac Muscle- Striated- Involuntary

3) Smooth Muscle- Non-striated- Involuntary

Functions of Muscular Tissue

1) Produce body movements

2) Stabilize body positions

3) Store and move substances within the body

4) Produce heat

Skeletal Muscle Tissue

- Each muscle is a separate organ

- Composed of thousands of cells → muscle fibers

- Fibers packed in fascicles

Connective Tissue

- Between Skin and Muscle → Hypodermis- Areolar connective tissue- Adipose tissue

- Individual muscles surrounded by Fascia- Dense irregular connective tissue- Supports muscles- Helps form tendons

Connective Tissue

- Epimysium: surrounds whole muscle

- Perimysium: surrounds fascicle

- Endomysium: surrounds muscle fibers

All 3 extend beyond muscle to form a tendon

Nerve and Blood Supply

- Need A LOT of nutrients and oxygen

- Need to get rid of waste

- Each muscle fiber is in close contact with capillaries and neurons

Skeletal Muscle Histology

- Sarcolemma: plasma membrane

- Sarcoplasm: inner material of fibers (like cytoplasm)- Contains A LOT of mitochondria

- Sarcoplsmic reticulum: fluid-filled tubules that store calcium (like SER)

- Myofibrils: made of protein filaments that extend along length of fiber

The Muscle Fiber (Cell)

Skeletal Muscle Histology

Myofibrils

- Two types of Myofilaments (proteins):1) Actin → Thin filaments2) Myosin → Thick filaments

- Overlap to form light and dark bands

Sarcomere

- The basic functional unit of contraction

- Thin filaments (actin) anchored to Z disc

- Thick filaments (myosin) bind to thin filaments at myosin-binding site

Z disc Z disc

Sarcomere

Z discZ disc

Sarcomere

(b) Myofibril

Thin filament

Thick filament

Thin filamentThick filament

Actin and Myosin

Myosin tail

Myosin

Myosin heads

Myosin-binding site (covered by tropomyosin)

Actin Troponin Tropomyosin

Fasicles

Fibers

Myofibrils

Actin Myosin