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Anatomy and Physiology 1 > Chapter 9 > Flashcards

Chapter 9 Flashcards

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1
Q

What are the types of muscle tissue?

A
  • Smooth
  • Cardiac
  • Skeletal

Each type has distinct locations and functions in the body.

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2
Q

Where is smooth muscle tissue found?

A
  • Walls of hollow organs
  • Blood vessels
  • Eye
  • Glands
  • Skin

Smooth muscle is involved in involuntary functions such as propelling urine and regulating blood flow.

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3
Q

What are some functions of smooth muscle?

A
  • Propel urine
  • Mix food in digestive tract
  • Dilate/constrict pupils
  • Regulate blood flow

Smooth muscle operates involuntarily and is autorhythmic in some locations.

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4
Q

How is smooth muscle controlled?

A

Involuntarily by endocrine and autonomic nervous systems

This means it operates without conscious control.

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5
Q

What is the definition of contractility in muscle tissue?

A

Ability of a muscle to shorten with force

This property is essential for muscle function and movement.

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6
Q

What are the general functions of the muscular system?

A
  • Movement of the body
  • Maintenance of posture
  • Respiration
  • Production of body heat
  • Communication
  • Constriction of organs and vessels
  • Contraction of the heart

These functions highlight the role of muscles in various physiological processes.

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7
Q

What type of muscle tissue is responsible for locomotion and facial expressions?

A

Skeletal muscle

Skeletal muscle is voluntary and allows for conscious movements.

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8
Q

What is the primary function of cardiac muscle?

A

Movement of blood

Cardiac muscle is autorhythmic and controlled involuntarily.

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9
Q

How is cardiac muscle controlled?

A

Involuntarily by endocrine and autonomic nervous systems

This ensures the heart functions continuously without conscious thought.

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10
Q

What is the primary function of skeletal muscle?

A
  • Responsible for locomotion
  • Facial expressions
  • Posture
  • Respiratory movements
  • Other types of body movement

Skeletal muscles are under voluntary control, allowing for intentional movements.

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11
Q

What is the endomysium?

A

Loose C.T. separating individual muscle fibers within each fascicle.

Endomysium is crucial for the structural integrity of muscle fibers.

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12
Q

What do collagen from connective tissue layers form?

A

Tendons or aponeuroses, which attach muscle to bone.

Tendons connect muscles to bones, allowing for movement.

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13
Q

What is elasticity in muscle tissue?

A

Ability of muscle to recoil to original resting length after stretched.

Elasticity is important for muscle function and recovery.

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14
Q

What does excitability refer to in muscle tissue?

A

Capacity of muscle to respond to a stimulus (usually from nerves).

This property is essential for muscle contraction and movement.

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15
Q

What stimulates skeletal muscle contraction?

A

Motor neurons.

Motor neurons play a key role in initiating muscle movements.

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16
Q

How many muscle fibers does each motor neuron control?

A

Several muscle fibers.

This allows for coordinated muscle contractions.

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17
Q

What surrounds muscle fibers?

A

Extensive capillary beds.

Capillaries provide necessary nutrients and oxygen to muscle fibers.

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18
Q

How do skeletal muscle fibers develop?

A

From fusion of myoblasts, resulting in large, multinucleated muscle cells.

This process is critical for muscle fiber formation.

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19
Q

What is the average length of skeletal muscle fibers?

A

1-4 mm (can get up to 1 foot).

The length varies, affecting muscle function.

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20
Q

What is the average diameter of skeletal muscle fibers?

A

10-100 microns.

Diameter influences the strength and capability of muscle contractions.

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21
Q

What appearance do skeletal muscle fibers have?

A

Striated.

The striated appearance is due to the organization of myofilaments.

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22
Q

What happens to the number of muscle fibers after birth?

A

Remains relatively constant; muscles get larger due to hypertrophy.

Hypertrophy increases muscle size through fiber growth.

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23
Q

What is the epimysium?

A

C.T. that surrounds a whole muscle (many fascicles).

Epimysium provides structural support to entire muscles.

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24
Q

What merges with muscular fascia?

A

Epimysium.

Muscular fascia separates adjacent muscles and provides additional support.

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25
What is the perimysium?
Loose C.T. surrounding a group of muscle fibers; passage for blood vessels and nerves. ## Footnote It helps organize muscle fibers into functional units.
26
What are bundles of muscle cells called?
Fascicles. ## Footnote Fascicles are important for the functional arrangement of muscle fibers.
27
What does extensibility refer to in muscle tissue?
Muscle can be stretched beyond its normal resting length and still be able to contract. ## Footnote This property allows muscles to accommodate various movements.
28
What is Motor Neuron Disease commonly known as?
ALS (Amyotrophic Lateral Sclerosis) or Lou Gehrig’s Disease. ## Footnote This disease affects motor neurons and can lead to muscle weakness and atrophy.
29
What happens to the sarcomere during muscle contraction?
The actin myofilaments slide past the myosin myofilaments, bringing the z disks closer together and shortening the sarcomere.
30
What remains unchanged in length during muscle contraction?
The myosin myofilaments do not change in length.
31
What happens to the H zone during muscle contraction?
The H zone disappears as actin overlaps in the center of the sarcomere.
32
What are the two main types of myofilaments in muscle fibers?
Actin (thin) and myosin (thick) myofilaments.
33
What is the structure of actin myofilaments?
Two strands of fibrous (F) actin form a double helix composed of G actin monomers.
34
What role does tropomyosin play in muscle contraction?
Tropomyosin winds along the groove of the F actin double helix, regulating the interaction between G actin and myosin.
35
What is the function of troponin?
Troponin regulates muscle contraction by binding to actin, tropomyosin, and calcium ions.
36
What is an action potential?
An electrical signal carried by motor neurons that stimulates muscle fiber action potentials.
37
What is the role of the Na+/K+ pump in muscle physiology?
Maintains resting membrane potential by moving sodium and potassium ions across the membrane.
38
Fill in the blank: The model describing how actin myofilaments slide over myosin is called the _______.
Sliding Filament Model
39
What is the primary function of the neuromuscular junction?
It is the point of contact between a motor neuron and a muscle fiber.
40
What neurotransmitter is released at the neuromuscular junction?
Acetylcholine (ACh)
41
What is the presynaptic terminal in the neuromuscular junction?
The axon terminal with synaptic vesicles containing neurotransmitters.
42
What is the function of myosin heads during muscle contraction?
They bind to active sites on actin to form cross-bridges.
43
What type of enzymes are myosin heads classified as?
ATPase enzymes.
44
What happens to sarcomeres during muscle relaxation?
Sarcomeres lengthen due to external forces, like the contraction of antagonistic muscles.
45
True or False: The sliding filament model states that actin and myosin change in length during contraction.
False
46
What happens during depolarization?
Inside of plasma membrane becomes less negative. If change reaches threshold, depolarization occurs. ## Footnote Depolarization leads to the opening of Na+ channels.
47
What occurs during repolarization?
Return of resting membrane potential; membrane potential drops lower than resting potential before rebounding. ## Footnote This is due to Na+ and K+ concentrations; Na/K pump restores resting potential.
48
What is the all-or-none principle?
Like a camera flash system; action potentials either occur fully or not at all. ## Footnote This principle ensures consistent action potential strength.
49
How does an action potential propagate?
It causes another action potential in the adjacent plasma membrane, spreading along the membrane. ## Footnote The orange band indicates the local area of action potential.
50
What are voltage-gated ion channels?
Channels that open and close in response to small voltage changes across plasma membrane, specific for certain ions. ## Footnote These channels are crucial for action potential generation.
51
What happens during the depolarization phase of an action potential?
Na+ channels open, Na+ diffuses into the cell, making the inside positively charged. ## Footnote This is the initial step in generating an action potential.
52
What does it mean for action potentials to propagate?
They spread from one location to another; new action potential forms at each successive location. ## Footnote This ensures rapid signal transmission along the membrane.
53
What occurs during the repolarization phase?
Na+ channels close, K+ channels open, increasing K+ movement out of the cell, making the inside negatively charged again. ## Footnote This restores the negative charge inside the cell.
54
What is the resting membrane potential?
Na+ channels are closed, some K+ channels are open; K+ diffuses out, making the inside negatively charged compared to the outside. ## Footnote This is the baseline state of a neuron before action potentials occur.
55
What are ligand-gated ion channels?
Channels that open when ligands bind to receptors, specific for certain ions. ## Footnote Neurotransmitters are common examples of ligands that activate these channels.
56
Fill in the blank: The action potential is a stimulus that causes another action potential to be produced in the _______.
adjacent plasma membrane.
57
True or False: Action potentials move along the membrane continuously.
False.
58
Fill in the blank: During depolarization, Na+ channels are ______.
open.
59
What happens to K+ channels during repolarization?
More K+ channels open, allowing K+ to move out of the cell. ## Footnote This process contributes to the negative charge inside the cell.
60
What is excitation-contraction coupling?
Links electrical and mechanical components of contraction.
61
What initiates muscle contraction during excitation-contraction coupling?
Calcium enters sarcoplasm, binds troponin.
62
What is produced on the sarcolemma during excitation-contraction coupling?
Action potential (AP).
63
What role do T tubules play in excitation-contraction coupling?
AP propagated into T tubules.
64
What is the function of the neuromuscular junction?
Facilitates communication between nerve and muscle.
65
What are synaptic vesicles?
Structures that store neurotransmitters.
66
What neurotransmitter is released at the neuromuscular junction?
Acetylcholine (ACh).
67
What is acetylcholinesterase?
A degrading enzyme in synaptic cleft that prevents accumulation of ACh.
68
What happens to ACh after it binds to ligand-gated Na+ channels?
ACh unbinds from the channels, which then close.
69
How is acetylcholine removed from the synaptic cleft?
Broken down into acetic acid and choline by acetylcholinesterase.
70
What occurs during depolarization of the T tubule?
Gated Ca2+ channels in the sarcoplasmic reticulum open.
71
What initiates the release of acetylcholine from synaptic vesicles?
Calcium ions enter the presynaptic terminal.
72
How is ACh released into the synaptic cleft?
By exocytosis.
73
What happens to choline after ACh is broken down?
Choline is symported with Na+ into the presynaptic terminal.
74
What is formed within the presynaptic terminal after ACh breakdown?
ACh is reformed using acetic acid and recycled choline.
75
What is the role of ligand-gated Na+ channels in the postsynaptic membrane?
Open and allow Na+ to enter, causing depolarization.
76
What happens if depolarization of the postsynaptic membrane passes threshold?
An action potential is generated along the postsynaptic membrane.
77
What role do calcium ions play in muscle contraction?
Bind to troponin molecules.
78
What happens to tropomyosin when troponin binds calcium?
Tropomyosin moves, exposing active sites on G actin.
79
What forms when myosin heads bind to active sites on G actin?
Cross-bridges are formed.

Anatomy and Physiology 1 (1 decks)

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