chapter 9 part 1

Question 1

functions of the muscular system tissues

Answer 1

Skeletal.
* Responsible locomotion, facial expressions, posture, respiratory movements, other types of body movement.
* Voluntary and controlled by the nervous system.
attached to bones
Smooth.
* Walls of hollow organs, blood vessels, eye, glands, skin.
* Some functions: propel urine, mix food in digestive tract, dilating/constricting pupils, regulating blood flow.
* In some locations, autorhythmic.
* Controlled involuntarily by endocrine and autonomic nervous systems.
Cardiac.
* Heart: major source of movement of blood.
* Autorhythmic.
* Controlled involuntarily by endocrine and autonomic nervous systems.

Question 2

types of muscle tissue

Answer 2

skeletal muscle
smooth muscle
cardiac muscle

Question 3

functions of the muscular system

Answer 3

1. Movement of the body.
2. Maintenance of posture.
3. Respiration.
4. Production of body heat.
5. Communication.
6. Constriction of organs and vessels.
7. Contraction of the heart

Question 4

Contractility:

Answer 4

ability of a muscle to shorten with force.

Question 5

Extensibility:

Answer 5

muscle can be stretched beyond it normal resting length and still be able to contract.

Question 6

Elasticity:

Answer 6

ability of muscle to recoil to original resting length
after stretched

Question 7

Excitability:

Answer 7

capacity of muscle to respond to a stimulus (usually from nerves).

Question 8

Perimysium

Answer 8

Loose C.T. surrounding a group of muscle fibers; passage for blood vessels and nerves.
* Bundles of muscle cells are called fascicles.

Question 9

Epimysium

Answer 9

C.T. that surrounds a whole muscle (many fascicles).
* Merges with muscular fascia, the layer of C.T. between adjacent muscles and between muscles and skin.

Question 10

Endomysium.

Answer 10

Loose C.T. separating individual muscle fibers within each fascicle.
* Collagen from CT layers merge to form tendons or aponeuroses, which attach muscle to bone.

Question 11

Motor neurons

Answer 11

stimulate skeletal muscle contraction.
* Each motor neuron controls several muscle fibers.
* Each muscle fiber is supplied by a branch of the motor neuron.
* An artery and 1 to 2 veins extend with a nerve through the C T layers.
* Extensive capillary beds surround muscle fibers

Question 12

myoblasts

Answer 12

resulting in large, multinucleated muscle cells.
* 1 to 4 mm avg length (can get up to 1 foot).
* 10 to 100 microns avg diameter.
* Have a striated appearance.
* Number of fibers remains relatively constant after birth;
muscles get larger due to hypertrophy of muscle fibers.

Question 13

Sarcolemma –

Answer 13

plasma membrane; surrounds sarcoplasm (cytoplasm) and other contents of cell.

Question 14

Transverse tubules (T tubules)

Answer 14

– inward folds of sarcolemma; project into the interior of muscle cell.

Question 15

Sarcoplasmic reticulum (SR) –

Answer 15

specialized smooth endoplasmic reticulum; stores calcium.
* Enlarged portions called terminal cisternae lie adjacent to T tubules.
* Two terminal cisternae and their associated T tubule form a triad.

Question 16

Myofibrils

Answer 16

– bundles of protein filaments; contain the protein filaments (myofilaments) that cause contraction.

Question 17

Titin filaments:

Answer 17

elastic chains of amino acids; make muscles extensible and elastic.

Question 18

types of muscle contractions

Answer 18

isometric and isotonic

Question 19

Isometric:

Answer 19

no change in length but tension increases.
* Postural muscles of body.

Question 20

isotonic:

Answer 20

change in length but tension constant.