Human anatomy:Muscular System

Sarcoplasm

The cytoplasm of muscle cells

Skeletal muscle

-attach to the body skeleton

-they help form the much smooth contours of the body

-the fibers are cigar-shaped, large, and multicleated cells

Skeletal muscle pt2

• activated by reflexes, can contract with great force
• fibers appears to be striated --striated
• several muscle fibers are wrapped by a fibrous membrane called perimysium to form a bundle of fibers called a fascicle

Endomysim

Each skeletal muscle fiber is enclosed in a delicate connective tissue called an…..

Smooth muscle

• involuntary
• found mainly in hollow organs
• cells are spindled shaped and have one nucleus
• muscle contractions are slow and sustained
• to move food and emptying their bowels

Cardiac muscle

• only found in the heart
• started and involuntary
• fibers are cushioned by small amounts of connective tissue and arranged in spiral bundles
• contractions are steady, but with help of the nervous system it can be stimulated to a higher gear

muscle functions

• produces movement
• maintains posture
• stabilizes joints
• generates heat

Sarcolemma

oval nuclei that can be seen beneath the plasma membrane in the muscle cells

Myofibrils

chains of tiny contractile units called sarcomeres which are aligned end to end like boxcars in a train along the length of myofibrils

Actin (thin) and myosin (thick)

the myofilament two different proteins:

sarcomere reticulum

a specialized endoplasmic reticulum, the role is to store calcium and release it on demand when a muscle fiber contracts

dendrite

receive a neurotransmitter (axon) = chemical messenger

Neurotransmitter--acetylcholine (ACh)

when the nerve impulses reaches the axon terminals, a chemical referred to neurotransmitter is released, the specific transmitter that is stimulated skeletal muscles is….

Action potential

• ACH diffuses across the synaptic cleft and attaches to receptors of the sarcolemma
• 3 sodium atoms move to the muscle and 2 potassium move out of the cell
• ACH begins the process is broken down to acetic acid and choline by enzymes

Neuromuscular junction

area/space between axon terminal and muscle

pathways for ATP regeneration

• direct phosphorylation of ADP by creatine phosphate CP
• aerobic respiration occurs in the mitochondria-oxidative phosphorylation- the breakdown of glucose to water and CO2

Muscle fatigue

• when a muscle is unable to contract even though it is being stimulated bc a result of oxygen debt that occurred during muscle activity

Oxygen debt

• not able to take in oxygen fast enough to keep the muscle supplied
• blood supply is important bc the blood supplying the muscle with oxygen

muscle tone

• this state of continuous partial contractions

• result of different motor units, which are scattered through the muscle, being stimulated by the nervous system in a systematic way

Naming skeletal muscle

• direction of muscle fibers
• relative size of fibers
• location of the muscle
• number of orgins
• location of muscle origin and insertion
• shape of muscle
• action of muscle

3 thing to be present for muscles to contract

• 1. calcium-tropopnin/tropomyosin complex
• 2. ATP
• 3.ACh- actylcholine

Isotonic contractions

the mylofilaments are successful in their sliding movements, the muscle shortens and movement occurs

ex. going to the gym living weights

isometric contractions

when muscle do not shorten, the tension in the muscles keeps increasing, they are trying trying to slide, but the muscle is pitted against some more

ex. yoga-maintains length of that muscle

study images also *

study images also