kinesiology unit test 4a

Question 1

What is the muscular system composed of?

Answer 1

made up of the body’s bones, muscles, joints, and connective tissue that binds bones and muscles together

Question 2

What are the functions of the muscular system?

Answer 2

1. movement (includes; breathing, eating, heart beating)
2. provide form and support (maintain posture)
3. posture energy
4. heat production - produce heat and maintain normal body temperature
5. protects the body’s vital organs

Question 3

what are the three types of muscle in the human body?

Answer 3

(a) smooth muscle
(b) cardiac muscle
(c) skeletal muscle

Question 4

What are the characteristics of smooth muscle?

Answer 4

Where? hollow organs, blood vessels, walls
Control? involuntary, slow
Look? Spindle-shaped, 1 nuclei (middle)

Question 5

What are the characteristics of cardiac muscle?

Answer 5

Where? heart
Control? involuntary, middle
Look? branched, 1 or 2 nuclei (middle)

Question 6

What are the characteristics of skeletal muscle?

Answer 6

Where? attached to tendon/bone, attach to aponeurosis
Control? voluntary, fast
look? Striated, many nuclei

Question 7

Definition - agonist

Answer 7

Agonist muscle (primary mover)
- the muscle primarily responsible for movement of a body part, e.g. the tricep is the prime mover in elbow extension (the biceps relax)

Question 8

Definition - antagonistic muscle

Answer 8

• the muscle that counteracts (opposes) the agonist, lengthening when the agonist muscle contracts, e.g. elbow in flexion, triceps must relax to allow movement to take place (while the biceps contracts)
  -complex movements such as running involve many muscles acting as agonist and antagonist muscle pairs as well as muscle that acts as “Stabilizers” or “fixators”

Question 9

definition of a stabilizer?

Answer 9

(fixator) muscle - muscles that provide support and hold a joint in place so that desired movement can occur at another joint

Question 10

how does skeletal muscle attach to bone?

Answer 10

Indirect (most common);
- muscle-> tendon-> periosteum
- the epimysium (a health of connective tissue that surrounds the exterior of the muscle fibre) extends past muscle as a tendon
direct attachment
-muscle -> periosteum
-epimysium adheres to fuses with the periosteum

Question 11

Definition of origin?

Answer 11

proximal attachment - where muscle attaches to the least moveable area of the bones of the axial skeleton

Question 12

Definition of insertion?

Answer 12

distal attachment - where muscle attaches to the bone that is moved the most

Question 13

definition of function?

Answer 13

Action/motion - what the muscle does when activated

Question 14

What is DOMS (delayed onset muscle soreness)

Answer 14

believed to be a result of microscopic tearing deep within the muscle fibres. it is most frequently felt when you begin a new exercise program, change your exercise routine, or dramatically increase the duration or intensity of your exercise routine. It may last from several hours to several days after the exercise session

Question 15

Types of muscle contraction

Answer 15

concentric: muscle fibers shorten
- the origin and insertion of the muscle move closer together (length of muscle shortens and develops tension)

Eccentric: muscle fibres lengthen
-origin and insertion of the muscle move apart (the muscle develops tension, but rather than shorten, it lengthens during contraction to resist some force that causes motion
-any controlled lowering where gravity would otherwise accelerate the movement involves eccentric contraction

Isometric: muscle fibres do not change in length
- considerable tension may be developed int he muscle but no movement is produced by the contraction (length of muscle does not change)

Question 16

The all or none principle

Answer 16

• when a motor unit is stimulated to contract, it will do so to its fullest potential.
• when a motor unit/ fibres they are turned on (stimulated), either all fibres will contract or none will contract, there is no partial contraction

Question 17

Connective tissue of muscles

Answer 17

• hold muscle together
• provide a passageway for blood vessels and nerves to reach individual muscle cells
• attach muscle to bone

Muscle fibre looking outward:
- epimysium
- sheath enveloping entire muscle
-perimysium
-binds muscle fibers together

Muscle fiber looking inward:
- endomysium
- sheath of connective tissue surrounding muscle fibre
- sarcolemma
- plasma membrane that lies under the endomysium
- sarcoplasm - contains the cytoplasm
- myofibrils
- contain actin and myosin
- sarcomeres
- tiny compartments containing myosin and actin

Question 18

muscle fiber

Answer 18

• sarcoplasm. a muscle cell’s cytoplasm, which is contained by the sarcolemma
• sarcoplasmic reticulum. A network of channels in each muscle fibre that transport the electrochemical substances involved in muscle activation

Question 19

Neuromuscular junction

Answer 19

• neuromuscular system, the link between the muscular system and the nervous system (the system of nerve impulses originating in the brain and spinal cord)

Question 20

The motor unit

Answer 20

• nerves transmit impulses (action potential) in “waves” that ensure smooth movements
• a muscle twitch is a single nerve impulse and the resulting contraction
• one neutron or nerve (called the motor neuron) may be responsible for stimulating a number of muscle fibers
• the motor unit consists of a motor neuron, its axon (pathway) and all the muscle fibers it stimulates

Question 21

Motor units can be categorized into small or large units:

Answer 21

1. a small motor unit can have a few muscle fibers that it stimulates, which produce fine motor (muscle) movements (such as the motor units of the eye)
2. large motor units are larger and produce gross motor movements. A single motor unit within the quads may stimulate 300 to 800 muscle fibers. For maximal muscle force to be produced, all motor units within that muscle or muscle group be recruited

Question 22

the neuromuscular junction

Answer 22

• the point at which nerves (motor neurons), that transmit the message causing the muscle to move, come into contact with the muscles
• the electrical impulse travels along the nerve pathways to the contact point between the nerve and muscle (the junction)
• a chemical neurotransmitter (acetylcholine) is then released from the synaptic vesicles into the cleft and binds to the muscle terminal
• this is detected by receptors on the surface of the muscle fiber, resulting in contraction

Question 23

Sliding filament theory steps 1-5

Answer 23

1. message originates and is released from the CNS travelling down the spinal cord and the peripheral nervous system to the muscle
2. the message then travels from the axon branch through to the axon terminal via acetylcholine to the sarcolemma of each muscle fibre involved
3. message travels through transverse tubular muscle fibre. A chemical change occurs and Act causes the sarcoplasmic reticulum to release calcium ions from the terminal cisternae (lateral sac)
4. The Ca++ find their way to attachment sites on troponin (a protein), which are located on the actin’s tropomyosin (a protein). This binding removes the blocking action of tropomyosin

Question 24

Sliding filament theory steps 5-7

Answer 24

5. the tropomyosin swivels (position change) thus exposing binding sites for the myosin one the actin filament
6. the myosin heads (cross bridges) attach themselves to the binding sites on actin
7. The ATP is broken down into ATPase enzyme allowing the myosin cross-bridge to reattach to another site on the actin molecule causing the power stroke and the sliding of the actin along the myosin filament