The muscular system

Question 1

What are the 3 functions of muscle?

Answer 1

Movement, maintaining posture and heat generation.

Question 2

What are the 3 types of muscles and indicate whether they are under voluntary or involuntary control?

Answer 2

Skeletal - voluntary
Cardiac - involuntary
Smooth - involuntary

Question 3

When referring to muscles what do voluntary and involuntary mean?

Answer 3

Voluntary means that the muscle is under conscious control
Involuntary means that the muscle is not under conscious control

Question 4

Describe the primary differences between skeletal, cardiac and smooth muscles

Answer 4

Skeletal muscles are under conscious control, are attached to the skeleton, serve to move the skeleton and generate heat.

Cardiac muscle is located in the heart, serves to pump blood and is not under conscious control.

Smooth muscle is located in multiple internal organs such as the stomach, intestines and blood vessels, serve to bring about movements in those organs and is not under conscious control.

Question 5

What is the name of the fibrous tissue sheath that surrounds an individual muscle fibre(cell)?

Answer 5

The endomysium

Question 6

What is the name of the fibrous tissue sheath that surrounds an entire muscle?

Answer 6

The epimysium

Question 7

What is the name of the fibrous tissue band that runs between the abdominal muscles? What is the scientific term for this structure?

Answer 7

The linea alba
It is an aponeurosis

Question 8

What is the difference between the origin of a muscle and its insertion?

Answer 8

The origin is the attachment of the muscle to the skeleton that is relatively stable that allows the contraction of that muscle to move the part of the skeleton that is attached at the site termed the insertion.

Question 9

What is the definition of an agonist muscle? Give and example and describe what part of the skeleton it moves.

Answer 9

An agonist is a muscle that directly produces a desired movement. The Biceps brachii is an agonist. It brings about upward movement of the forearm (radius and ulna). The triceps brachii is also an agonist and brings about the downward movement of the forearm.

Question 10

What is the definition of an antagonist? Give an example and describe part of the skeleton it controls.

Answer 10

An antagonist is a muscle that directly opposes the movement of an agonist. The triceps brachii is the antagonist to the biceps brachii. It opposes the upward movement of the forelinmb brough about by contraction of that muscle.

Question 11

Based on the naming conventions of muscles approximately where would the deep digital flexor muscle be located and what would be its function?

Answer 11

It would be located deep to other muscles in other words closer to the bone in the limbs and its function would be to flex the digits.

Question 12

What does the masseter muscle do?

Answer 12

It is the main muscle of chewing

Question 13

What are the names of the abdominal muscles listed in order from most superficial to deepest?

Answer 13

External abdominal oblique, internal abdominal oblique, rectus abdominis and transverse abdominis.

Question 14

What is the basic contractile unit of skeletal muscle called?

Answer 14

Sarcomere

Question 15

Define myofibril

Answer 15

It is a structure within a muscle cell that is made up of sarcomeres laid end to end

Question 16

What are the main components of muscle fibres (cells)?

Answer 16

Myofibrils, mitochondria, sarcoplasmic reticulum and Transverse tubules

Question 17

What substances give skeletal muscle a striated appearance?

Answer 17

Actin, myosin and Z-lines

Question 18

Define a motor unit

Answer 18

One nerve fiber and all the muscle fibers it innervates

Question 19

What is the neurotransmitter that works in the neuromuscular

Answer 19

Acetylcholine

Question 20

What ion, released from the sarcoplasmic reticulum by a nerve impulse, starts the contraction process in a muscle fiber?

Answer 20

Calcium

Question 21

What are the names of the 2 fibres in the sarcomere that contract against each other to bring about muscle contraction

Answer 21

Actin and myosin

Question 22

What molecule provides the power for the sliding of actin and myosin against each other?

Answer 22

ATP

Question 23

What does ATP convert to once it has released its power?

Answer 23

ADP

Question 24

In muscles, what molecule allows ADP to be recharged to ATP in preparation to power further muscle contractions?

Answer 24

Creatine Phosphate

Question 25

What is the name of the molecule that stores oxygen in the muscle?

Answer 25

Myoglobin

Question 26

Why does an animal breathe heavily for a while after heavy exercise?

Answer 26

Anaerobic exercise leads to the production of lactate that can be converted back to glucose in the liver but requires oxygen necessitating panting until this process is complete.

Question 27

How do muscles work?

Answer 27

When a muscle contracts every cell in that muscle shortens. When a muscle relaxes every cell in that muscle lengthens.

Question 28

How do muscles generate heat?

Answer 28

They undergo spasmodic contractions that generate heat. Also known as shivering. Not under voluntary control.

Question 29

What is the name of the group of muscles that is the main adductor of the forelimb?

Answer 29

The pectoral muscles

Question 30

Name the muscles that flex and extend the elbow joint.

Answer 30

Flex biceps brachii. Extend triceps brachii.

Question 31

What movements do contraction of the muscles on the cranial aspect of the distal forelimb (below the elbow) bring about?

Answer 31

Extension of the digits and the carpus

Question 32

What movements do contraction of the muscles on the caudal aspect of the distal forelimb (below the elbow) bring about?

Answer 32

Flexion of the carpus and digits

Question 33

What main muscle groups extend the hip?

Answer 33

The gluteals and the hamstrings

Question 34

What muscles do we use for intramuscular injections in dogs and cats?

Answer 34

Quadriceps, Lumbar,Triceps, Semimembranosus/semitendinosus

Question 35

What muscles do we use for intramuscular injections in horses?

Answer 35

Neck,Semimembranosus/semitendinosus, Pectoral muscles

Question 36

What are the unique characteristics of cardiac muscle?

Answer 36

Cells contract spontaneously with no external stimulation. Groups of cells contract at the rate of the most rapid cell in the group.

Question 37

What effect does stimulation by the sympathetic nervous system have on cardiac muscle?

Answer 37

It increases heart rate.

Question 38

What are the functions of intercalated discs in cardiac muscle?

Answer 38

The represent a physical attachment between cardiac muscle cells and they allow electrical impulses to pass between cardiac muscle cells.

Question 39

What structure generates the impulse that starts each heart beat?

Answer 39

The Sinoatrial node.

Question 40

List where visceral smooth muscle is located

Answer 40

Stomach, intestines, uterus, urinary bladder

Question 41

In the wall of the gastrointestinal tract (GIT) what triggers smooth muscle to contract?

Answer 41

Stretching of the walls of the GIT

Question 42

What effect does stimulation from the sympathetic nervous system (fight or flight) have on visceral smooth muscle?

Answer 42

It decreases activity

Question 43

List where multiunit smooth muscle is located

Answer 43

Iris and ciliary body of eye, walls of small blood vessels, and small air passageways in lungs