UNIT 2 - Muscular System Flashcards
1
Q
Types of muscle
A
Skeletal, Cardiac and Smooth
2
Q
Terminology
Myo =
Sarco =
A
Terminology
Myo = Muscle
Sarco = Muscle cells
3
Q
Do muscle cells = muscle fibers
A
Yes
4
Q
What two things make up microfilaments
A
Actin + Myosin
5
Q
Can muscle cells divide?
A
No
6
Q
Can you replace destroyed muscle cells?
A
No
7
Q
Describe the muscle tissue - Skeletal
Voluntary control or Involuntary control?
A
Animal’s ‘muscles’ or meat.
Voluntary control
8
Q
Describe the muscle tissue - Smooth
Voluntary control or Involuntary control?
A
Found in eyes, air passages in lungs, stomach/intestines, urinary bladder, blood vessels, reproductive tract
Involuntary control
9
Q
Name 3 places you can find smooth muscle tissue
A
Found in eyes, air passages in lungs, stomach/intestines, urinary bladder, blood vessels, reproductive tract
(Any three work)
10
Q
Describe the muscle tissue - Cardiac
Voluntary control or Involuntary control?
A
Found in the heart ONLY
Involuntary control
11
Q
How is muscle tissue classified? (3)
A
Microscopic appearance - Striated or non-striated
Location in body - in organ, attached to skeleton
Method of nervous & endocrine control - Voluntary/involuntary
12
Q
List the 4 functions of muscle tissue
A
- Provide motion
- Maintain posture
- Regular organ volume
- Produce heat
13
Q
What caused contraction of the muscle cell?
A
Occurs by interaction of special protein fibers
Bonus: Actin & Myosin
14
Q
What 2 things are produced by muscle cell contraction?
A
Movement + Heat
15
Q
What is the 4 principal characteristics of muscle tissue?
A
- Excitability
- Contractility
- Extensibility
- Elasticity
16
Q
Describe the 4 principal characteristics of Muscle Tissue. What do they do?
A
- Excitability - Ability of muscle cell to respond to neurotransmitters or hormones by producing signals called action potentials (impulses)
- Contractility - Ability of muscle cell to shorten
- Extensibility - Ability of muscle cell to stretch w/o damage
- Elasticity - Muscle tissue to return to normal shape after shortening/stretching
17
Q
What four components make up skeletal muscles?
A
- Consists of cylindrical fibres (cells) that contain peripheral nuclei
- Appear striated under microscope due to light and dark bands present
- Usually voluntary control by the somatic nervous system
- Contraction enables movement of head, trunk, and extremities
18
Q
What is the location and function of skeletal muscles?
A
Location: usually attached to bones
Function: motion, posture, heat production
19
Q
Does each skeletal muscle cell have its own nerve supply?
A
Yes
20
Q
Can skeletal muscle cells divide? Can they regrow if badly damaged?
A
They cannot divide
They cannot regrow if badly damaged
21
Q
What is the belly of a muscle?
A
Main muscle mass and the contractile portion of the muscle
22
Q
What are the 3 muscle attachments?
A
Tendons, Aponeuroses, Direct
23
Q
What is a tendon?
A
A bundle of CT that attach muscle to bone
24
Q
What is aponeuroses?
A
A broad sheet of CT located b/w BROAD, FLAT muscles.
EX. Linea Alba
25
What is a direct or fleshy attachment?
Connection of muscle to bone w/ little visible CT involved
EX. Intercostal muscles
26
What are the names of the two attachment sites?
Origin + Insertion
27
Describe the origin attachment site
- The stationary end of muscle
- Usually proximal on limbs
- Some divided into several parts (bellies) w/ different heads and points of origin (ex. triceps brachii)
28
Describe the insertion attachment site
- Attachment at the movable end of muscle
- Usually distal on limb
29
Describe the muscle action of a prime mover (agonist)
- A muscle that directly produces the desired movement
30
Describe the muscle action of an antagonist
- A muscle or group of muscles that opposes the action of a prime mover
- Helps smooths out the movement or prevent it from happening
31
Describe the muscle action of a synergist
- A muscle or group of muscles that contract with the prime mover
- Assists the prime mover in carrying out its action
32
Describe the muscle action of a fixator
- Muscles that stabalise the joints to allow other movements to take place
EX. Digit flexors and carpal extensors
33
What 6 things make up muscle-naming conventions
Action - Relates to its function
Shape - Denotes distinctive shape
Location - Relates to bodily location
Direction of fibers
Numbers of heads or divisions
Attachment Sites
34
Give an example of each of the 6 muscle-naming conventions listed below;
Action, shape, location, direction of fibers, # of heads or divisions, attachment sites
Action - Flexor + Extensor muscles
Shape - Deltoid = triangle shape, deltoid muscle
Location - Biceps Brachii in brachium, Biceps Femoris in hind limb, femur
Direction of Fibers - Rectus = straight, Rectus Abdominus are 2 straight muscles on linea alba
Number of Heads - Cephal = heads. Bi = 2. Biceps = 2 heads
Attachment Sites - Brachiocephalicus attaches at brachium and the head
35
What are the two functional groupings of muscle and what do they do?
Extrinsic Muscles - Limb to Axial skeleton
Intrinsic Muscles - Extend b/w bones of limb itself
36
Describe flexor muscles location + function
- Muscles on the side of the limb towards which the join bends
- Contraction of a flexor decreased the angle of the joint, bends it
37
Describe extensor muscles location + function
- Located on the opposite side of flexors
- Contraction of extensor increases the angle of the joint, or straightens it
38
Describe adductors and abductor muscles
Adductors pull TOWARDS the medial plane
Abductors pull AWAY from the median plane
39
Describe sphincter muscles with an example
- Muscles that surround an opening
EX. Pyloric sphincter opening into the small intestine from the stomach
40
Describe the cutaneous muscles
- In the superficial layer b/w the skin and deep fascia which covers skeletal muscles
- Responsible for skin movement
EX. Cutaneous trunci
41
List the 3 CT layers of muscle
Endomysium, Perimysium, Epimysium
42
Describe the 3 CT layers of muscle
Endomysium: CT layer of fine reticular fibers surrounding each muscle
Perimysium: Tough CT binding together fascicles, or bundles, of muscle fibers
Epimysium: Tought collagenous CT that binds[ get from slides]
43
Describe the microscopic anatomy of skeletal muscles
1. Very long, thin fibers (cells)
2. Can go up to ~25 MM long, up to 80MM wide
3. Multinuclear - up to or >100 nuclei on periphery of cell
4. Filled with myofibrils
44
What are myofibrils? What are they made of?
Myofibrils - Long thin structures of tightly packed myofilaments
Made of thin actin + thick myosin filaments
Arranged in groups called sarcomeres in which the actin + myosin give it its striated appearance
45
Describe the sliding filament mechanism.
- Thin actin ratchet themselves along myosin filaments and slide to shorten sarcomere which shorten overall muscle fiber (contraction)
46
Something related to microanatomy + sliding mechanism (incomplete Q)
- Contains mitochondria for energy production
- They have endoplasmic reticulum called SARCOplasmic reticulum
- System of tubules called transverse or T tubules extend into cell from sarcolemma and assist in transmission of nerve impulses
47
How is the sliding filament mechanism activated? What causes it?
The movement or "pumping" of Ca ions from SR to sarcoplasm to initiate contraction process
- Relaxation of muscle fiber involves movement of CA ions in reverse directions
- both require ATP - made in mitochondria
48
What is a neuromuscular junction?
- A junction in which a motor nerve links to the muscle fiber
- Not a direct contact but a close association through a gap, or synaptic space
49
What are motor units? Describe them
Refers to the bundle of muscle fibers innervated by a particular nerve cell.
- Fewer fibers per unit allow precision of movement.
EX. eyes will have very few fibers per motor unit for fine movement
EX. Muscles in legs have 2000+ for powerful contractions w/ fewer nerves
50
How does the neuromuscular junction work?
(incomplete)
- When a nerve impulse travels down the nerve, there is a massive exocytosis of nerve cell vesicles called synaptic vesicles
- Synaptic vesicles contain the neurotransmitter, acetylcholine
51
Summarize a nerve pulse for neuromuscular junction
- Acetylcholine diffuses across synaptic space and binds receptors on motor end plate of sarcolema, initiates muscle contraction
- ACH-erase destroys acetylcholine in synaptic space
- Nerve pulse ends
51
Describe initiation of muscle contraction and relaxation
- Motor nerve fiber stimulated
- Impulse reaches neuromuscular junction
- Depolarizes nerve cell membrance and opens voltage-sensitive Ca channels to allow Ca to enter axon terminal and release acetylcholine
- ACH released into synaptic space by exocytosis
- Initiates opening of Na channels to move Na into muscle fiber to depolarize impulse transmitted along sarcolemma through T tubules (end place potential)
- ACH-erase splitting ACH into acetate and choline same time
Ends stimulation
51
Describe what happens when a muscle relaxes
- SR pumps Ca back in
- Removing Ca halts contraction (requires ATP)
- Ca lvls in SR relate to the amount in blood
52
What is rigor mortis?
- At death, Ca leaks into sarcoplasm and initiates contraction
- ATP used to start contraction but becomes exhausted with no working mitochondria
- Contraction maintained because actin and myosin are bonded
- wears off as tissues autolyze
53
What can go wrong with neuromuscular junction with curare?
- A SA indian arrowhead poison. Binds to acetylcholine receptor sites on motor end plate and blocks attachment of acetylcholine.
Causes paralysis
54
What can go wrong with neuromuscular junction with botulinus toxin?
- Produced by clostridium botulinum, blocks release of acetylcholine and prevents stimulation of motor end plate
55
What can go wrong with neuromuscular junction with tetanus toxin
Produced by clostridium tetani, causes continuous stimulation of motor neurons and results in tetanic contractions of muscles. Ex. Lockjaw
56
What can go wrong with neuromuscular junction with organophosphates?
Internal and external parasites used to be treated with organophosphates. Inhibit ACH-esterase, which breaks down ACCH.
Signs include hypersalivation, miosis, ataxia, increased bronchial secretions
57
What can go wrong with neuromuscular junction with myasthenia gravis?
Autoimmuno disorder caused by antibodies against ACCH receptors. Blocks attachment of ACCH causing skeletal muscle weakness and eventually loss of function.
Treat with immunosuppressive drugs.
58
Describe what spasms are and give an example
A sudden involuntary contraction of muscle that can be accompanied by pain - can be as severe as convulsions. Ie. Hiccup
59
Describe what cramps are
Like spasms, but contraction is painful and sustained (tetanic). May result from accumulation of lactic acid, ca deficiencies, or a blow to the muscle
60
What is the all-or-nothing principle?
- An individual muscle fiber will contract completely or not at all in response to a nerve impulse
- We can control strength of contraction by controlling the number of muscle fibers stimulated
61
Describe fine movements. Do they have a lot or very few muscle fibers stimulated?
Fine movements will only have a few muscle fibers stimulated
62
Describe strong movements. Do they have a lot or very few muscle fibers stimulated?
Will have many muscle fibers stimulated
63
What is a twitch contraction? Describe it's 3 phases and how long it takes
A single muscle fiber contraction
1. Latent phase: Nerve impulse reaches muscle fiber, contraction not started
2. Contracting phase
3. Relaxation phase
Takes ~0.1 seconds
64
What does it take 0.1 seconds for a twitch?
The nervous system coordinates signals so that the muscle fibers twitch out of sync with each other and allow an overall sustained contraction of the whole muscle
65
What is creatine phosphate? What does it help with?
It is a compound in muscle fiber that regenerates ATP
- CP splits and releases energy to attach a phosphate group back to ADP molecule
- Energy for regen of CP and ATP comes from catabolism of glucose or free fatty acids (usually w/ oxygen)
66
What are myoglobin?
A large protein molecule like hemoglobin
67
Describe the oxygen debt
As long as oxygen is present in tissue, energy is supplies through aerobic metabolism
If oxygen is used up, muscles may switch to anaerobic metabolism.
- Less efficient
- Produces lactic acid that can burn and cause muscle discomfort
- Lactic acid transported to blood to liver and converted back to glucose - requires oxygen so may breath heavily after exercise
68
What are the three energy stores in muscles? What is the oxygen store in muscles?
3 - ATP, creatine phosphate, glycogen
1 - Myoglobin
69
How can you improve muscle metabolism?
Carbohydrate loading - increased muscle glycogen stores and useful for short term strenuous exercise
High fat diets - Acclimate muscle to using fat as fuel and useful for long distance (endurance) races
70
Describe heat production in muscles contracting
Heat is a by-product of muscle contraction
This may be exploited by shivering when cold
We must cope with excessive heat by panting/sweating during exertion. If this failed, hyperthermia may occur and cause convulsions
71
What are the two muscle fiber types?
Type 1 - Slow twitch
Type 2 - Fast twitch
72
Describe the two types of muscle fibers and what are their differences?
Type 1 - slow to contract, sustain contractions longer, more mitochondria + myoglobin than fast twitch.
Type 2 - Fast contraction, fatigue more easily, designed for short bursts of use
73
Which muscles are more likely to be type 1? Type 2?
Type 1 - postural muscles
Type 2 - Action muscles
74
Compare and list the differences between twitch vs. whole muscle contraction
Twitch: brief contraction of muscle fibers in motor unit when a single motor neuron is stimulated
Whole muscle: longer contraction of many muscle fibers in many units when many motor neurons are stimulated
75
Describe isometric vs. isotonic contractions
Isometric: muscles develops tension but does not change length
Isotonic: muscles shortens during contraction
76
What are contracted flexor tendons?
Congenital- pasterns/fetlocks/carpal joints flexed due to shortened flexor tendons and associated muscles
77
Describe cardiac muscle and it's function
Involuntary, striated muscle. Pumps blood to all parts of the body.
78
What are the cells of the cardiac muscle? Describe them and how they work
branches, cylindrical, striated, contain 1 centrally located nuclei
Securely attached to each other end to end by intercalated disk that contains desmosomes, gap junctions, and allows coordinated contraction and synchronous movement
Cannot regenerate or divide if damaged
79
What are pacemaker cells? How do they work?
Pacemaker cells initiate contractions.
Modified muscle cells called Purkinje fibers conduct impulses within the heart(like nerve fibers) and results in coordinated cardiac activity
80
Describe the physiology of cardiac muscle contractions
2 important characteristics
1 - they contract rhythmically w/o external stimulation (may be at different rates for different cells)
2 - if two cells are in contact, they synchronize their contraction rate at the rate of the fastest cell
81
Where does contraction start in the heart? Where is it located?
It starts in the sinoatrial node (SA node), in the R atrium
82
Describe the SA node and what it does
Called the pacemaker of the heart. Cells contract at a faster rate than surrounding cells which gives them control over the rest of the cardiac muscle fibres
- once the SA node initiates contraction it spreads along specific paths
These structures can assist, delay, or redirect transmission of impulse for smooth, efficient contraction
83
What are the two parts of the autonomic nervous system (ANS)? Describe them
Sympathetic - Fight or flight response, heart beats fast during stress
Parasympathetic NS - counters this stimulation and slows HR during resting and relaxed states
84
Describe smooth muscle
Nonstriated involuntary muscle controled by the autonomic nervous system and hormones
-Contractions tend to be slow
- 2 kinds - visceral(single-unit) and multiunit
85
What is the microscopic appearance of smooth muscle
No t-tubules
filaments are arranged in crisscross pattern
contraction causes 'balling up' of cell
The action results in greater shortening than skeletal or cardiac muscle
86
What is the function and location of smooth muscle
Func.: Constriction of blood vessels and airways, contraction of urinary bladder and gallbladder
-maintains a constant tone or constant state of partial contraction
- tends to contract in response to stretching and relaxes after awhile
Loc.: Visceral found in veins, hollow organs (stomach, intestines, uterus)
Multiunit in walls of LG arteries, airways to lungs, arrector pili muscles of hair follicles
87
Decribe the physiology of visceral smooth muscle
- cells are organized into LG sheets
- Fibers connected by gap junctions to form lg networks
- Contractions are lg, slow, rhythmic waves
- Has a nerve supply but that doesn't initiate contraction but modifies it
ANS - Sympathetic stim decreases activity
Parasympathetic stim increases activity
88
Describe the physiology of multiunit smooth muscle
-Cells are innervated individually or in sm groups
- require ANS stim for contraction - no automatic contractile activity. Maintains a resting tone
-results in sm, delicate movements like the iris, walls of lg arteries and veins
- Action is specific and carefully controlled
