Muscles (general)

Question 1

What are the three types of muscles. Describe if they are multi or uninucleated.

Answer 1

1) Smooth: involuntary, non-striated, uninucleated fibers. Found in hollows.
2) Skeletal: voluntary, striated, multinucleated. The cells are longer than their width, hence called muscle fibres.
3) Cardiac: involuntary, striated, uninucleated. Don’t look like fibres but have extension or branches

Question 2

What is a sarcolemma?

Answer 2

Is the electronically polarized cell membrane of a skeletal muscle fibre/cell.

Question 3

What is the difference between a fasciculi and a fascicle?

Answer 3

Fasciculi: number of muscle bundles. (Composed of multiple fascicle)
Fascicle: number of muscle fibres

Question 4

What kind of connective tissue is a fascicle surrounded by?

Answer 4

Fascicle (number of muscle fibres) is surrounded by delicate connective tissue called Endomyosin

Question 5

What else besides the endomysium covers the facile (each bundle)

Answer 5

It is also surrounded by Perimysium

Question 6

What is the top layer of connective tissue on a fascicles (bundle)

Answer 6

Epimysium

Question 7

What layer is on top of the Epimysium?

Answer 7

Areolar connective tissue called fascia

Question 8

What is the two adjacent Z lines called

Answer 8

A Sacromere.

Question 9

What is the function of T tubules

Answer 9

T Tubules is part of the sacrotubular system and participates in the rapid transmission of a nerve impulse to all the fibrils.

(Sacroplasmic reticulum also part of the sacrotubular stores Ca+)

Question 10

What is a motor unit?

Answer 10

A motor unit is what innervtes multiple muscle cells/fibres.

Question 11

What are the 4 properties of a muscle cell:

Answer 11

1) Excitability (by a stimulus)
2) Conductivity (of a stimulus through cytoplasm)
3) Contractility(rxn to stimulus)
4) Elasticity (allows cell to retake original shape after the contraction is finished.)

Question 12

How is a muscle cell electrically charged?

Answer 12

The outside of a muscle cell is positively charged and negatively charged inside. This electrical distribution is known as resting potential of the cell membrane.

Question 13

What happens when a motor neuron innervates the muscle cell?

Answer 13

Acteylcholine (neurotransmitter) is released by axon terminals into the neuromuscular junction. This causes Na ions to rush inside the cell membrane creating n electrical potential. (Changing the inside of the cell from negative to positive)
K attempts to move outside the cell in order to restore the resting potential but can’t do so due to the influx of Na rushing in.
This influx of Na causes T tubules to try it the stimulus deep into the muscle creating an action potential.
The action potential causes sarcroplasmic reticulum to release Ca into the fluid that surrounds the myofibrils of actin and myosin,
The Ca interacts with the Troponin and Tropomyosin which were previous inhabiting actin and myosin from reacting with each other. (Inhibitor substance)
The activated myosin is able to link up to the actin and contraction can occur

Question 14

What are the 4 sources of energy for muscle cells?

Answer 14

1) anaerobic-> by product Latin acid
2) aerobic (Krebs)
3) Fatty acids
4) Phosphocreatine

Question 15

What does the speed of a contraction depend on?

Answer 15

1) Strength
2) Speed
3)Duration of stimulus
(Also dependent on the weight of the load and the temperature)

Question 16

What is muscle tone?

Answer 16

Muscle tone is the state of partial contraction maintained throughout a whole muscle.

Question 17

What is muscle tone do?

Answer 17

Tone maintains pressure on the abdominal contents, helps maintain blood pressure in blood vessels and aids in digestion. (Also makes firm appearance to skeletal muscles.)

Question 18

What is the difference between isotonic and isometric contractions?

Answer 18

Isotonic: muscles become shorter and thicker as when lifting a weight and tension remains the same
Isometric: contracts occurs when tension increases but the muscle remains at a constant length as when we push against a wall.

Question 19

Where is smooth muscle found? Structured?

Answer 19

Smooth muscle is found in hollow structures such as intestines, arteries and bladder.
It is arranged in two layers:an outer longitudinal layer and an inner circular layer. The result is that material is pushed forward in the tube by simultaneous contraction of both layers

Question 20

What is an intercalated disk and where is it found?

Answer 20

An intercalated disk is for coordinating contraction. It is found in the cardiac cells.

Question 21

What is the difference between origin and insertion?

Answer 21

Origin: Proximal, is the place of fixed attachment.
Insertion: Distal, is the movable attachment of muscle (where the contraction can be seen)

Question 22

What is the main muscle that moves the head?

Answer 22

Sternocleidomstoid

Question 23

What is the upper arm main moved by?

Answer 23

Deltoid, pectorals and rotator cuff muscles