Ch 10

3 types of muscle tissue

Skeletal, cardiac, smooth

Muscular system

ONLY skeletal muscles; each muscle is considered an organ

Funtions of muscle

Movement, Stability, Control of body openings and passages, heat production

Movement for Muscles

to move body parts, body contents, and to communicate

Stability in Muscles

Maintain posture and resist pull of gravity

Excitability (Responsivenes)

react to stimuli

What is another name for excitability?

Responsiveness

Condutivity

Spread electriacal impulse through muscle cell

Contractility

Shorten when stimulated

Extensibility

Can stretch without harm

(Lengthen beyond normal position without being harmed)

Elacticity

Can recoil from stretch

Skeletal

Voluntary, striated, attached to bone, contains muscle cell (muscle fiber/myofiber)

Skeletal muscle cell

Muscle fiber / Myofiber

Cardiac

Involuntary, striated, cardiomyocyte cell

Cardiac Cell is called

Cardiomyocyte

Smooth

Involuntary, non-striated, fusiform shaped

Fusiform cell shape

(diamond shape) tapered at ends

Structures of a muscle fiber

Sarcolemma

Sarcoplasm

Sarcoplasmic reticulum

Sarcolemma

Have Transverse (T) Tubules (invaginations of the sarcolemma)

Sarcoplasm

Contain myofibrils, glycogen, and myoglobin

Sarcoplasmic reticulum

A modified ER located with calcium + contains terminal cisterns

T/F : Calcium is not important

FALSE; Calcium is important as it aids muscle contractions.

Myofilaments

Contractile proteins and regulatory proteins

What are the types of myofilaments?

thick and thin filaments

Thick myofilament

Are Myosin

Thin myofilament

Are actin

Fibrous (F) actin

The part that resembles a necklace

Globular (G) actin

The bead in the necklace

Active Site

Myosin binding area on G actin

(Blocked by tropomyosin)

Regulatory proteins

Regulate when contraction occurs; consist of tropomyosin and troponin

Tropomyosin

Blocks active sites when the muscle relaxes

Troponin

Attaches to tropomyosin and binds to calcium when excited

Striations

narrows stripes that run perpendicular to the length of the cell

What are striations composed of?

Z lines, I band, A band, M line, H band

Sarcomeres

Goes from one Z-disc to another Z-disc, which consist of:

- A Band

- H Band

- M-Line within

A band

DARK stripe of thick myofilaments that partly overlap thin myofilaments

(Memory Trigger: Dark has an A in it)

H Band

Central region of A band that is a little lighter due to lack of thin myofilaments

M Line

Midline of A band (and H) that anchors thick myofilaments together

I Band

Light strip of thin myofilaments only

(Memory Trigger: i in light)

Z Disc (Z-Line)

- Midline of I band

- defines boundaries of sarcomere

- anchors actin and titin

During heavy exercise, the muscular system receives more than _________ of the heart's output.

3/4

Myasthenia gravis (MG)

autoimmune disease, destruction of neurotransmitter receptors

Muscular dystrophy

- Defective gene for dystrophin (a muscle protein)

- Skeletal muscle degeneration

Myopathies

diseases of muscle

Multiunit

independent control of smooth muscle cells

Unitary

Several cells excited at once; widespread in viscera

Synaptic Knob

Contains neurotransmitters

Synaptic cleft

The space where neurotransmitters are released

Postsynaptic membrane folds

Contains receptors to receive neurotransmitters