Muscle and Skeletal System Flashcards Preview

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Flashcards in Muscle and Skeletal System Deck (38):
1

Cartilage

-Connective tissue

2

What synthesizes cartilage?

Chondrocytes

3

Bone

-Specialized mineralized connective tissue
-Elastic, lightweight

4

Compact bone

-Dense bone deposited in units called osteons
-Channels called Haversian canals surrounded by bony matrix (lamellae)

5

Spongy bone

-Much less dense
-Interconnecting spicules with yellow marrow (adipose) or red marrow (blood formation)

6

Osteoblasts

-Synthesize/secrete organic components of bone matrix - collagen
-Mature into osteocytes

7

Osteoclasts

-Lg, multinucleated cells
-Bone reabsorption

8

What are the methods of bone formation?

-Endochronal Ossification (cartilage)
-Intramembranous ossification (mesenchymal tissue)

9

Pyramidal system

Axons of pyramidal cells of motor cortex synapse on lower motor neurons

10

What is the extrapyramidal system?

-Somatic motor commands at the involuntary level
-Skeletal muscle tone primarily controlled by red nucleus in midbrain

11

Skeletal muscle

-Mulitnucleated, striated
-Controlled by SNS, voluntary movements
-Myofibrils (divided into sacromeres) enveloped in sarcoplasmic reticulum
-High energy requirements --> mitochondria rich

12

T system

-Transverse tubules perpendicular to myofibrils
-Ion channels --> propagate action potentials

13

Which bands reduce in size during muscle contraction?

-I and H band

14

What is the neuromuscular junction?

-Link between nerve terminal and sarcolemma of muscle fiber

15

How is an action potential generated in muscle contraction?

-Enough neurotransmitters diffuse across cleft and stimulate receptors on sarcolemma, changing permeability

16

What occurs once an action potential is generated?

-Potential is conducted along sarcolemma and T system into interior of muscle fiber
-SR release Ca++ into sarcoplasm --> bind troponin C on actin --> actin/myosin slide --> sarcomere contracts

17

What is rigor mortis?

-Muscle contract w/o potentials due to lack of ATP which is needed to release myosin heads from actin filaments

18

Isotonic contraction

-Muscle shortens against fixed load
-Constant tension

19

Dynamic contraction

-Concentric and eccentric contractions
-Change length of muscle and tension

20

Concentric contraction

-Muscle fibers shorten, tension increases

21

Eccentric contraction

-Muscle fibers lengthen, tension increases

22

Isometric contraction

-Both ends of muscles are fixed, no change in length
-Tension increases

23

How can strength of muscle contraction be increased?

-All or nothing response
-Increase by recruiting more muscle fibers

24

Simple twitch

-Single muscle fiber to brief stimulus
-Latent, contraction, relaxation

25

Temporal summation

-Contractions combine --> stronger/prolonged

26

Tetanus

-Muscle fibers continuously stimulated and can't relax
-Muscle will fatigue and contraction weakens

27

Tonus

-Partial contraction
-Muscles are never completely relaxed

28

Cori cycle

-Converts lactic acid in liver to glucose --> bloodstream
-Muscle uses glucose or stores as glycogen
-NOT include breaking down glycogen/production of lactic acid

29

Smooth muscle

-Digestive tract, bladder, uterus, blood vessel walls
-One central nucleus
-No striations
-Smooth, continuous contractions

30

Cardiac muscle

-Actin/myosin arranged in sarcomeres (striated)
-Only 1-2 nuclei

31

What are forms of energy reserves for muscles?

-Creatine phosphate
-Myoglobin (store oxygen)

32

What do the inorganic components of bone form?

-Hydroxyapatite crystals (phosphate, calcium, hydroxide)

33

Which bones are typically formed from endochondral ossification?

-Long bones

34

Which bones are typically formed by intramembranous ossification?

-Skull

35

What makes up the diaphysis?

-Bone marrow surrounded by compact bone

36

What makes up the epiphysis?

-Spongy bone coated with thin layer of compact bone

37

What is the epiphyseal plate?

-Separate the diaphysis and epiphsis
-Cartilage in growing bones
-Source of longitudinal growth

38

Why are muscles found in antagonistic pairs?

-Because extension can only occur passively
-E.g. triceps and biceps