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Anatomy And Physiology > Chapter 9 > Flashcards

Chapter 9 Flashcards

1
Q

Muscle tissue function

A

Body movement
Stabilize body position
Organ volume regulation
Move substances in body
Heat production

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2
Q

Skeletal muscle structure/function/location

A

Attached to skeleton
Movement
Voluntary control: nervous system, some subconscious control (breathing)
Cells: large, slender, multinucleated, striated

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3
Q

Cardiac muscle structure/function/location

A

Heart walls
Circulate blood
Involuntary: autorythmic
Regulated by nervous and endocrine system
Cells: short, striated, branches, single nucleus, connected by intercalated discs

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4
Q

Smooth muscle structure/function/location

A

Walls of blood vessels, airways, internal organs of abdominal pelvic cavity
Movement of food/using/reproductive tract secretion
Controls diameter of blood vessels, respiratory tract
Involuntary: nervous and endocrine
Cells: small spindle shaped, tapered oval nucleus, no striations

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5
Q

Properties of muscular tissue

A

Electrical excitability: respond to stimuli by producing action potentials (pacemaker, neurotransmitters/hormones)
Contractility: contraction develops with or without shortening
Extensibility and elasticity: stretch without damage, return to original shape and length

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6
Q

Skeletal muscle composition

A

Connective tissue
Nerves
Blood vessels
Skeletal muscle tissue

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7
Q

What does the hypodermis do?

A

Separates skin from muscles
Protects muscle
Insulation
Energy source

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8
Q

What is fascia?

A

Irregular connective tissue
Sheet wrapping muscles and organs
Hold groups of muscles of similar functions

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9
Q

3 parts of a tendon

A

Epimysium: entire muscle organ
Perimysium: bundles of fibers (fascicle), blood/nerve supply
Endomysium: individual muscle fibers, contain myosatellite cells, capillaries and nerve fibers

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10
Q

Somatic motor neurons

A

From brain and spinal cord
Nerve cells stimulate group of skeletal muscle fibers

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11
Q

Muscle cell components

A

Transverse tubule: distribute action potential for synchronous muscle fiber contraction
Terminal cisternae: dilated ends
Sarcomere: contractile unit
Thin filament: actin
Thick filament: myosin
Sarcolemma: plasma membrane
Sarcoplasm: ATP, glycogen, cytoplasm, myoglobin
Myofibril: protein fibers, parallel surrounded by SR, banded
Sarcoplasmic reticulum: like SER, store Ca2+

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12
Q

Sarcomere architecture

A

Sarcomere: repeating unit of striating myofibrils
Z disc: separate one Sarcomere from the next
Zone of overlap: actin and myosin
M line: center of H zone, hold thick filaments together
H zone: center of A band, thick filaments
A band: along entire thick filament, dark, overlapping parts of thin filaments
I band: z disc, actin filaments, no myosin

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13
Q

Actin

A

Thin filament
Contractile protein
Attached to z discs
2 strands of actin: actin molecules in strand have myosin binding site

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14
Q

Tropomyosin

A

Regulatory
In resting muscle, covers myosin binding sites on actin

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15
Q

Troponin

A

Regulatory
3 parts for binding: tropomyosin, actin, Ca2+

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16
Q

Myosin

A

Motor protein
Composed of 2 twisted myosin molecules
Tail: interacts with other myosin molecules
Neck: hinge
Head: two globular subunits, interacts with actin by forming cross-bridges during contraction

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17
Q

Titan

A

Attaches myosin to z line (elastic)
prevents overstretching

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18
Q

Actinin

A

Z disc
Attaches to titan and actin

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19
Q

Dystrophin

A

Link thin filaments of Sarcomere to integral membrane proteins of sarcolemma

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20
Q

Myomesin

A

M line (center)

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21
Q

Sliding filament model

A

During contraction myosin heads pull on actin filaments
Thin filaments slide past thick ones toward M line
Thin and thick filaments do not change length
H and I bands become smaller/disappear
Zones of overlap enlarge
Z lines get closer
A band width stays the same
Shorter sarcomeres = shorter myofibrils = shorter muscle fibers = contraction

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22
Q

Where does communication between the nervous system and muscle occur?

A

Neuromuscular junction

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23
Q

Excitation-contraction coupling

A

Action potential generated in Sarcolemma linked to muscle contraction
Action potential enters t-tubule
SR permeability changes: terminal cisternae calcium channel opens
Calcium release affects thin and thick filaments interaction in zones of overlap

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24
Q

Neural control of skeletal muscle contraction

A

Motor neuron relays signals from brain or spinal cord
Axons from motor neurons travel to skeletal muscle fiber
Electrical signal (action potential) travels along axon of neuron
Action potential gets converted to chemical signal to affect muscle fiber
Chemical signal produces electrical signal and contraction in muscle fiber

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25
Q

Neuromuscular junction

A

One per muscle fiber
Presynaptic terminal: synaptic vesicles contain chemical neurotransmitter acetylcholine
Synaptic cleft: between neuron and muscle fiber
Motor end plate: muscle fiber Sarcolemma

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26
Q

Step 1 of neuromuscular excitation

A

Neuronal action potential arrives at synaptic terminal
Sudden change in transmembrane potential
Voltage gated Ca2+ channels open
Ca2+ rushes into the presynaptic terminal

27
Q

Step 2 of neuromuscular excitation

A

Ca2+ rushes into the presynaptic terminal, stimulates synaptic vesicles exocytosis
Ach released via exocytosis
Diffuses across synaptic cleft

28
Q

Step 3 of neuromuscular excitation

A

Ach binds to Ach receptors on Na+ channel in Sarcolemma of motor end plate
Increase membrane permeability to Na+
Extracellular Na+ greater than Intracellular Na+
Na+ rushes into sarcoplasm

29
Q

Step 4 of neuromuscular excitation

A

Change of sodium distribution causes action potential (electrical signal)
Spreads across entire Sarcolemma
Triggers muscle cell contraction (excitation-contraction coupling)
Return to rest

30
Q

Botulism

A

Bacteria prevents Ach release

31
Q

Myasthenia

A

Autoimmune disorder, abs bind/block Ach receptor

32
Q

Where is calcium stored?

A

Sarcoplasmic reticulum at rest
Released by action potential for muscle contraction
Pumped back to SR after contraction by Ca2+ pumps

33
Q

T-tubules

A

Sarcolemma extension
Extend into sarcoplasm 90º
Relay changes in transmembrane potential to inside the cell

34
Q

Terminal cisternae

A

Bulges of SR adjacent to t-tubules on both sides
Ca2+ storage
Connected to t-tubules with voltage sensitive calcium channels

35
Q

Muscle contraction: resting Sarcomere

A

Myosin head energizes to power contraction
Energy stored in head
Start of contraction cycle

36
Q

Step 1 in muscle contraction

A

Calcium arrives to zone of overlap
Calcium binds to troponin
Tropomyosin moves away from myosin binding sites
Myosin binding sites on actin are ready to interact with myosin

37
Q

Step 2 in muscle contraction

A

Cross bridge formation
Myosin heads bind to exposed active sites on actin

38
Q

Step 3 of muscle contraction

A

Power stroke
Cocked myosin head uses stored energy to power stroke
Actin filaments slide past myosin filaments
ADP and phosphate released

39
Q

Step 4 of muscle contraction

A

Another ATP binds
Myosin and actin link broken
Actin active site exposed: bind another myosin
Myosin heads do not all detach at once

40
Q

Step 5 of muscle contraction

A

Myosin reactivation
ATPase in myosin head recocks head

41
Q

Muscle relaxation

A

Neural stimulus ends
ACh is broken down by AChE
Calcium channels close
SR reabsorbs calcium
Troponin-tropomyosin reassociate

42
Q

Motor unit

A

All muscle fibers controlled by single motor neuron
More fibers = more sensitive

43
Q

Twitch contraction

A

Contraction of all muscle fibers in response to single action potential
Produce tension
Myogram: record muscle contraction

44
Q

Wave summation

A

Second action potential arrives before muscle fiber relaxed
Larger contraction then the first

45
Q

Incomplete tetanus

A

Increased frequency
Partial relaxation
Wave summation

46
Q

Fused tetanus

A

Increased frequency
No relaxation
Rare

47
Q

Length-tension relationship

A

Forced contraction depends on Sarcomere length in muscle before contraction begins
Sarcomere shortening produces tension

48
Q

Asynchronous motor unit recruitment

A

Activated on a rotating basis
Some rest/recover while other contract: incomplete tetanus
Prevents jerky movements
Slightly less than maximal tension

49
Q

Muscle tone

A

At rest, small amount of tension but no movement
Result of weak, involuntary contractions of motor units
Alternate active and inactive motor units
Higher muscle tone = higher resting rate of metabolism

50
Q

Isometric contraction

A

Same length
Contraction without change in length
Tendons stretch
Ex. Holding a heavy book out in front of you

51
Q

Isotonic contraction

A

Contraction with change in length
Maintains constant tension
Concentric: shorten
Eccentric: lengthen

52
Q

Muscle relaxation

A

Elastic forces: recoiling, pull tendons/ligaments return sarcomeres
Opposing muscle contraction: antagonistic pairs
Gravity

53
Q

Muscle metabolism sources

A

Creatine phosphate
Anaerobic respiration: glycolysis, lactic acid fermentation
Aerobic metabolism: in mitochondria, best source of ATP

54
Q

Creatine phosphate

A

15ish seconds
High energy phosphate from surplus ATP
Donates ATP back to ADP in quick contraction
Pumps calcium back to SR

55
Q

Anaerobic respiration

A

30-40 seconds
Rapid ATP production
Glycolysis: blood glucose, glycogen used
Low O2: lactic acid production

56
Q

Aerobic respiration

A

Long term
Breathing rate increases
O2 delivery increases
Fatty acids used more as glycogen and glucose get used

57
Q

Muscle fatigue causes

A

Depleted energy sources
Reduction in calcium released from SR
Insufficient O2
Lactic acid build up
Psychological
Reduced ACh release

58
Q

Slow oxidative fibers

A

Type 1
Red
Small diameter
Slow contraction
More mitochondria
Large capillary supply
Lots of myoglobin
Slow to fatigue
Ex. Long distance running

59
Q

Fast glycolytic fibers

A

Type IIB
White
Anaerobic
Large diameter
Powerful/fast contractions
Low myoglobin
Few capillaries
Few mitochondria
Lots of glycogen
Fatigue easily
Ex. Weight lifting

60
Q

Fast oxidative glycolytic fibers

A

Type IIA
Intermediate
Midsize
More capillaries than fast glycolytic
Ex. Walking

61
Q

What do the colors of muscle mean

A

White: speed, fast
Red: endurance, slow

62
Q

Hypertrophy

A

Muscle growth
More myofibrils
Larger diameter
More muscle proteins
More glycogen reserves

63
Q

Atrophy

A

Muscle degeneration
Lack of activity
Genetics
Malnutrition
Decreased size
Decreased tone
Decreased power

Anatomy And Physiology (19 decks)

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