Muscular System

Question 1

What are the functions of the muscular system?

Answer 1

• movement
• maintenance of posture
• respiration ( diaphragm)
• heat production
• communication ( verbally talking, writing, throughout the body )
• construction of organs and vessels ( blood vessels, smooth muscles etc )
• contraction of heart

Question 2

What are the general properties of muscle?

Answer 2

• contractility: ability of muscle to shorten with force
• excitability: capacity of muscle to respond to a stimulus ( from our nerves )
• extendability: muscle can be stretched to its normal resting length and beyond to a limited degree
• elasticity: ability of muscle to recoil to original resting length after stretched

Question 3

What are the types of muscle tissue??

Answer 3

• skeletal : attached to bone, responsible for facial expressions, posture, other types of body movement
• voluntary
• smooth : most muscles, walls of hallow organ, blood vessels, eyes glands and skin
• propel urine, mix good in digestive tract, regulating blood flow
• controlled, involuntary by endocrine and autonomic nervous system
• Cardiac : heart: major source of movement of blood
• autorhythmic
• controlled involuntary by endocrine and autonomic nervous system

Question 4

Explain the skeletal muscle structure

Answer 4

• composed of muscle cells , connective tissue, blood vessels and nerves
• tend to be smaller diameter in small muscles and larger in large muscles
• develop from myoblasts
• striated appearance due to light and dark banding

Question 5

Explain muscle twitch

Answer 5

• muscle contraction in response to a stimulus that causes action potential in one or more muscle fibers

Question 6

Phases of muscle twitch

Answer 6

• lag or latent
• contraction
• relaxation

Question 7

Explain muscle fatigue

Answer 7

• decreased ability to work and reduced efficiency of performance

Question 8

What are the types of muscle fatigues

Answer 8

• psychological: depends on emotional state of individual
• muscular: results from ATP depletion
• synaptic: occurs in NMJ due to lack of acetylcholine

Question 9

What are the 3 sources that comes from ATP

Answer 9

-Creatine phosphate: during resting conditions stored energy to synthesize ATP

• anaerobic respiration
• occurs in a sense of oxygen and results in breakdown of glucose to yield ATP and lactic acid
• aerobic respiration
• requires oxygen and breaks down glucose to produce ATP, CO2 and water
• more efficient than anaerobic

Question 10

What is oxygen debt?

Answer 10

• oxygen taken in by the body, above that required for resting metabolism after exercise

Question 11

What is hypertrophy?

Answer 11

Increase in muscle size

Question 12

What is atrophy?

Answer 12

Decrease in muscle size

Question 13

Cardiac muscle

Answer 13

• only found in heart
• striated
• each cell usually only has one nucleus
• autorhythmic cells

Question 14

What are the effects of aging on skeletal Muscle

Answer 14

• reduced muscle mass
• increased time for muscle to contract in response to nervous stimuli
• reduced stamina
• increased recovery time
• loss of muscle fibers
• decreased density of capillaries in muscles

Question 15

Physiology of the skeletal muscle fibers

Answer 15

• nervous system controls muscle contractions through action potentials
• resting membrane potentials
  * inside cell more negative accumulation of large protein molecules
  * more K on inside than outside. K leaks out but not completely because negative proteins hold some back
  * outside cell more positive and more Na on outside than inside
  
  • Na / K pump maintains this situation

Question 16

Muscle length vs tension

Answer 16

• active tension : force applied to an object to be lifted when a muscle contracts
• stretched muscle : not enough cross bridging
• crumpled muscle: myofilaments crumpled, cross bridges can’t contract
• passive tension: tension applied to load when a muscle is stretched but not stimulated
• total tension: active plus passive

Question 17

Explain smooth muscle

Answer 17

• not striated, fibers smaller than those in skeletal muscle
• spindle- shaped; single, central nucleus
• more actin than my myosin

Question 18

How are muscles named

Answer 18

1. Location: pectoralis gluteus, brachial
2. Size: Maximus , minimum, longis, brevis
3. Shape : deltoid, quadratus, teres
4. Orientation : rectus
5. Origin and insertion: sternocleidomastoid, brachioradialis
6. Number of heads: biceps, triceps
7. Function: abductor, adductor, masseter

Question 19

Movements accomplished by muscles

Answer 19

• muscles and their tendons and bones act together as lever systems to move either parts of the body or the whole body
• Lever: rigid shaft or bone
• Fulcrum: pivot point or joint
• weight or resistance: force of gravity either in the form of the weight of the body party or the weight of an object being lifted, pulled or pushed