Muscles Chapter 28

Question 1

Muscle major tissue types

Answer 1

a) Mucscle
b) Nervous
c) Connective
d) Epithelial

Question 2

Tendons and ligaments

Answer 2

Tendons attach muscle to bone.

Ligaments attach bone to bone.

Question 3

3 types of muscle tissue

Answer 3

a) Cardiac
b) Smooth
c) Skeletal
All derived from mesoderm.

Question 4

Cardiac Muscle

Answer 4

Intercalated disks unique to cardiac muscle. Membranous boundary between adjacent cells. Single nucleus, striated, involuntary muscle.

Question 5

Gap junctions also present in the cardiac tissue.

Answer 5

They allow direct transmission of the depolarizing current to go from cell to cell. Electrically coupled.

Question 6

Gap Junctions

Answer 6

Connect the cytoplasm from one cell to another.

Question 7

Cardiac muscle cells hormone

Answer 7

Artial atriuretic factor - acts on kidneys to help lower blood pressure by allowing Na and H2O loss.

Question 8

Heart non regeneration

Answer 8

Damage to the heart does not result in cell regeneration, instead dead muscles cells are replaced by fibrous connective tissue.

Question 9

Smooth Muscle

Answer 9

No striations, involuntary, and single nucleus.

Found in walls of blood vessels, GI tract, urinary, reproductive, urinary bladder, and internal organs.

Question 10

Smooth muscles are regulated by

Answer 10

Hormones, ANS, local physiological conditions.

Unlike cardiac muscle regeneration is possible, can do mitosis.

Question 11

Calmodulin

Answer 11

Ca2+ complex with calcium binding protein. It is involved in the contraction of smooth muscle.

Question 12

Skeletal muscle

Answer 12

Striated, voluntary, and multinucleated.

No mitosis though regen can occur. Satellite cells reside on the external surface.

Question 13

Epimysium

Answer 13

Dense connective tissue that surrounds muscle.

Question 14

Muscle fibers can be

Answer 14

a) Red: many mitochondria, rich in Mb, rich in oxidative enzymes, and blood supply.
b) White: few mitochondria, poor in oxidative enzymes, poor in Mb, poor in blood supply.
c) Intermediate

Question 15

Myofibrils are composed of

Answer 15

Thin and Thick filaments. Filament arrangement creates a pattern of light and dark bands.

Question 16

Sarcomere

Answer 16

Structural and functional unit of myofibril. Part of the myofibril between two Z lines.
Dark bands = A bands
Light bands = I bands
H zone = center of A bands, lighter/pale area inside

Question 17

Proteins contributing to Sarcomere

Answer 17

Titin: helps position of the thick filaments
Nebulin: Helps stabilize thin filaments.
Alpha - actinin: stabilize thin filaments

Question 18

Muscle contraction will:

Answer 18

a) I bands shorten
b) H zone shortens
c) A bands do not change
d) Z lines come closer together

Question 19

Bound to actin is

Answer 19

Tropomyosin: regulatory protein

Troponin complex: more proteins

Question 20

When actin and myosin cannot associate:

Answer 20

Ach from presynaptic nerve binds to muscle fiber receptor and depolarizes it via T tubules. The sarcoplasmic reticulum releases Ca2+ through voltage gated Ca2+ release channels and enters the cytosol to bind to troponin. Troponin changes shape and it exposes the binding site for myosin.
Myosin head binds to the actin filaments with help of ATP.
ATP now binds to myosin head causing it to release it’s grip on actin. Hydrolysis of ATP returns its head back to original positions.

Question 21

Actin, myosin, troponin 6 steps

Answer 21

1) Ach release to muscle fiber receptor, T tubules, depolarization of sarcoplasmic reticulum.
2) S.R. voltage gated releases Ca2+ into cytosol to bind troponin.
3) Change of shape of troponin, exposing binding site for myosin.
4) Myosin head binds to actin filament.
5) Myosin heads tilt towards center of sarcomere sliding the actin filament with them, ATP powered.
6) ATP binds to myosin head, to help release grip on actin.

Question 22

Rigor Mortis

Answer 22

Lack of ATP prevents dissociation of actin and myosin. State of muscle contraction. Rigidity of the corpse disappears because the muscle proteins decompose. Putrescine and cadaverine are produced when proteins decompose.

Question 23

Triad muscle

Answer 23

T tubule and two small cisternae of sarcoplasmic reticulum. When the membrane depolarizes Ca2+ is released, when depolarization ends, Ca2+ is transported back into the cisternae.

Question 24

Process of recruitment

Answer 24

You brain recruits motor neurons along with motor units. It depends on the number of muscle fibers and the number of motor units activated.

Question 25

Isotonic vs Isometric

Answer 25

Isotonic: muscle tension is constant; muscle shortens as it contracts.
isometric: muscle generates tension; muscles do not change length.

Question 26

GTO

Answer 26

Golgi Tendon Organ. Mechanoreceptors that are found at the junctions of muscles and tendons. Regulates and aids in amount of force of muscles contraction.