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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
Neuromuscular junction
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
26
Step 1 of neuromuscular excitation
Neuronal action potential arrives at synaptic terminal Sudden change in transmembrane potential Voltage gated Ca2+ channels open Ca2+ rushes into the presynaptic terminal
27
Step 2 of neuromuscular excitation
Ca2+ rushes into the presynaptic terminal, stimulates synaptic vesicles exocytosis Ach released via exocytosis Diffuses across synaptic cleft
28
Step 3 of neuromuscular excitation
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
Step 4 of neuromuscular excitation
Change of sodium distribution causes action potential (electrical signal) Spreads across entire Sarcolemma Triggers muscle cell contraction (excitation-contraction coupling) Return to rest
30
Botulism
Bacteria prevents Ach release
31
Myasthenia
Autoimmune disorder, abs bind/block Ach receptor
32
Where is calcium stored?
Sarcoplasmic reticulum at rest Released by action potential for muscle contraction Pumped back to SR after contraction by Ca2+ pumps
33
T-tubules
Sarcolemma extension Extend into sarcoplasm 90º Relay changes in transmembrane potential to inside the cell
34
Terminal cisternae
Bulges of SR adjacent to t-tubules on both sides Ca2+ storage Connected to t-tubules with voltage sensitive calcium channels
35
Muscle contraction: resting Sarcomere
Myosin head energizes to power contraction Energy stored in head Start of contraction cycle
36
Step 1 in muscle contraction
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
Step 2 in muscle contraction
Cross bridge formation Myosin heads bind to exposed active sites on actin
38
Step 3 of muscle contraction
Power stroke Cocked myosin head uses stored energy to power stroke Actin filaments slide past myosin filaments ADP and phosphate released
39
Step 4 of muscle contraction
Another ATP binds Myosin and actin link broken Actin active site exposed: bind another myosin Myosin heads do not all detach at once
40
Step 5 of muscle contraction
Myosin reactivation ATPase in myosin head recocks head
41
Muscle relaxation
Neural stimulus ends ACh is broken down by AChE Calcium channels close SR reabsorbs calcium Troponin-tropomyosin reassociate
42
Motor unit
All muscle fibers controlled by single motor neuron More fibers = more sensitive
43
Twitch contraction
Contraction of all muscle fibers in response to single action potential Produce tension Myogram: record muscle contraction
44
Wave summation
Second action potential arrives before muscle fiber relaxed Larger contraction then the first
45
Incomplete tetanus
Increased frequency Partial relaxation Wave summation
46
Fused tetanus
Increased frequency No relaxation Rare
47
Length-tension relationship
Forced contraction depends on Sarcomere length in muscle before contraction begins Sarcomere shortening produces tension
48
Asynchronous motor unit recruitment
Activated on a rotating basis Some rest/recover while other contract: incomplete tetanus Prevents jerky movements Slightly less than maximal tension
49
Muscle tone
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
Isometric contraction
Same length Contraction without change in length Tendons stretch Ex. Holding a heavy book out in front of you
51
Isotonic contraction
Contraction with change in length Maintains constant tension Concentric: shorten Eccentric: lengthen
52
Muscle relaxation
Elastic forces: recoiling, pull tendons/ligaments return sarcomeres Opposing muscle contraction: antagonistic pairs Gravity
53
Muscle metabolism sources
Creatine phosphate Anaerobic respiration: glycolysis, lactic acid fermentation Aerobic metabolism: in mitochondria, best source of ATP
54
Creatine phosphate
15ish seconds High energy phosphate from surplus ATP Donates ATP back to ADP in quick contraction Pumps calcium back to SR
55
Anaerobic respiration
30-40 seconds Rapid ATP production Glycolysis: blood glucose, glycogen used Low O2: lactic acid production
56
Aerobic respiration
Long term Breathing rate increases O2 delivery increases Fatty acids used more as glycogen and glucose get used
57
Muscle fatigue causes
Depleted energy sources Reduction in calcium released from SR Insufficient O2 Lactic acid build up Psychological Reduced ACh release
58
Slow oxidative fibers
Type 1 Red Small diameter Slow contraction More mitochondria Large capillary supply Lots of myoglobin Slow to fatigue Ex. Long distance running
59
Fast glycolytic fibers
Type IIB White Anaerobic Large diameter Powerful/fast contractions Low myoglobin Few capillaries Few mitochondria Lots of glycogen Fatigue easily Ex. Weight lifting
60
Fast oxidative glycolytic fibers
Type IIA Intermediate Midsize More capillaries than fast glycolytic Ex. Walking
61
What do the colors of muscle mean
White: speed, fast Red: endurance, slow
62
Hypertrophy
Muscle growth More myofibrils Larger diameter More muscle proteins More glycogen reserves
63
Atrophy
Muscle degeneration Lack of activity Genetics Malnutrition Decreased size Decreased tone Decreased power

Anatomy And Physiology (19 decks)

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