TPR 11 - Muscular and Skeletal Systems Flashcards
1
Q
Skeletal muscle vs. cardiac muscle vs. smooth muscle.
A
1) Skeletal = voluntary muscle; role is to contract in response to conscious intent; STRIATED
2) Cardiac = found only in the wall of the heart; STRIATED; no control; innervated only by ANS
3) Smooth = found in the walls of all hollow organs such as the GI tract, urinary tract, etc.; no conscious control - innervated only by ANS
2
Q
Skeletal muscles provide voluntary movement of the body stimulated by ___.
A
somatic motor neurons
3
Q
Muscles are often attached to the bone by___.
A
Tendons, which are strong connective tissue formed primarly from collegen.
4
Q
Flexing versus extending.
A
Skeletal muscles can move a joint by flexing (reducing the angle of the joint) and extending (increasing the angle of the joint).
5
Q
Abducting versus adducting.
A
Abducting is moving away from the body’s midline.
Adducting is moving toward the body’s midline.
6
Q
Origin versus insertion.
A
The point on the bone where the muscle attaches is called the ORIGIN and the point where the muscle attaches on the bone more distant from the center of the body is the INSERTION.
7
Q
Which of these movements require contraction: abducting, adducting, origin, insertion…
A
They ALL require contraction. Muscles cannot expand with force. Muscles can only CONTRACT (get shorter) to cause force on bones and movement.
8
Q
Contraction of the triceps have the (same/opp) effect on the lower arm as the contraction of the bicep.
A
The opposite effect.
9
Q
Muscles that are responsible for movement in opp directions are termed _____, while muscles that move a joint in the same direction are ___.
A
Antagonistic and synergistic. Example of antagonistic: biceps and triceps. Bicep curl: biceps = flexor; triceps = extensor.
10
Q
Do antagonistic muscles receive stimulation by neurons that release diferent neurotransmitters?
A
No. All skeletal muscles are innervated by somatic motor neurons which release ACh at the neuromuscular junction. The difference in regulation is not the type of signal but rather the timing of the signal (frequency of stimulation, and thus amount of NT release)
11
Q
Muscle is composed of connective tissue that holds the muscle fibers (myofibers) together called:
A
fascicles.
12
Q
Skeletal muscle cells are mutinucleate ___, formed by the fusion of individual cells during development. They are innervated by a single nerve ending, and stretch the entire length of the muscle.
A
Mutinuclate syncyitia.
13
Q
The myofiber has a cell membrane called the ___ that is made of plasma MB and an additional layer of polysacharride and collagen.
A
Sarcolemma
14
Q
Fascicles versus myofiber versus myofibrils.
A
Fascicles are bundles of muscle cells. Myofiber are muscle cells and are multinucleate. Myofibrils are smaller units in a myofiber responsible for generating contractile force of skeletal muscle.
15
Q
The proteins in the myofibrils of myofiber that generate contraction are…
A
Actin and myosin.
16
Q
Actin polymers form?
A
Thin filaments.
17
Q
Myosin polymers form?
A
Thick filaments.
18
Q
Sarcomeres.
A
Overlapping arrenangement of bands of thick and thin filaments, bound by two Z lines.
19
Q
Z lines, I bands, A bands, H zone.
A
Z lines - line that seperates one sarcomere from next
I Band - The regions of sarcomere composed of only thin filaments
A Band - The full length of thick filaments; includes both the overlapping regions of thick/thin and the region with only thick filaments.
H zone - sarcomere region consisting of only thick filaments
20
Q
I Band
A
The regions of sarcomere composed of only thin filaments
21
Q
H Zone
A
Sarcomere region consisting of only thick filaments
Hefty zone.
22
Q
A band
A
The full length of thick filaments; includes both the overlapping regions of thick/thin and the region with only thick filaments.
23
Q
Go through the steps of the contractile cycle. Note which parts require ATP.
A
1) The myosin head is bound to ATP and is in its low energy configuration.
2) The myosin head hydrolyzes ATP to ADP and Pi, and is in its high energy configuration. ADP + TroPi are bound. Note myosin has ATPase activity.
3) The myosin head binds to actin, foming a CROSS BRIDGE
4) relreasing ADP and Pi, myosin returns to low energy configuration, sliding the actin chain toward the center of the sarcomere. This is the POWER STROKE.
5) Binding of a new ATP is necessary for the release of actin by the myosin head.
24
Q
Troponin-tropomyosin complex.
A
Complex that prevents contraction when Ca2+ is not present.
When troponin binds Ca2+, troponin undergoes a conformational change that moves tropomyosin out of the way, so that myosin heads can attach to actin and filament sliding can occur.
25
Tropomyosin.
A long fibrous protein that winds around the actin polymer blocking all the myosin binding sites.
26
Troponin.
A globular protein bound to the tropomyosin that can bind Ca2+. When troponin binds Ca2+, troponin undergoes a conformational change that moves tropomyosin out of the way, so that myosin heads can attach to actin and filament sliding can occur.
27
Which has ATPase activity? Myosin or actin?
Myosin.
28
The ___ is the synapses between an ___(synaptic knob) and a ____.
Neuromuscular junction is the synapse between a axon terminus and a myofiber. NMJ is not a single point, but rather a long trough of the cell membrane so the neuron can depolarize a large region of the postsynaptic membrane.
29
The postsynaptic membrane of a myofiber cell membrane is known as.
The motor end plate.
30
Impulse transmission at the NMJ is typical of chemical synaptic transmission. An AP arrives at the axon term, triggering opening of ___ channels; the resulting increase in ___ triggers the ___ of acteylcholine. Binding of ACh results in a postsynaptic ___ influx, which depolarizes the postsynaptic membrane.
An AP arrives at the axon term, triggering opening of Ca2+ channels; the resulting Ca2+ increase triggers the release of Ach. The postsynaptic MB contains ACh receptors, which are ligand gated Na+ channels.
Binding of ACh results in a postsynaptic Na influx, which depolarizes the postsynaptic membrane, depolarizaton is known as the end plate potential.
31
End Plate Potential (EPP)
The depolarization of the postsynaptic membrane of a myofiber.
32
ACh will continue to stimulate the post-synaptic receptors until its destroyed by ___.
Acetylcholinesterase, which hydrolyzes ACh to choline plus acetyl unit.
33
When a sufficient end plate potential occurs, the threshold is reached, and __ channels open in the postsynaptic membrane, initiating an action potential in the muscle cell. The AP here is propagated as in neurons
Na+ channels open.
34
How are teh APs in neurons and muscle cells (myofibers) similar/different?
They are pretty much the same. Neurons EPSP + IPSP add up, and if a threshold is reach Na+ channels open. For muscles, a sufficient end plate potential is required before Na+ channels open.
35
APs only occur at the cell surface. Myofibers are thick. How do we get to all the fibers?
We have deep invaginations in the cell membrane called TRANSVERSE TUBULES, which allow the AP to travel into the thick cell.
36
Sarcoplasmic reticulum.
A specialized endoplasmic reticulum. As the AP spreads along the T tubules, it triggers changesin the SR, opening Ca2+ channels. Ca2+ ions stored in the interior of the SR flow through open channels in the SR into the cytosol and bind to the tropoinin complex, initiating contraction of the muscle fiber.
37
The smallest measurable muscle contraction is known as:
Muscle twitch. A twitch results from the activation of one motor neuron
38
Motor unit and recruitment.
A motor unit is a group of myofibers innervated by the branches of a single motor neuron. A
39
The nervous system can increase the force of contraction in two ways:
1) motor unit recruitment (activating more motor neurons)
| 2) frequency summation - a second contraction that occurs immediately after the first and builds on it
40
Frequency summation.
Each contraction ends with SR returning the Ca2+ to low resting levels. If a 2nd contraction occurs fast enough, there is insufficient time for the Ca2+ to be sequestered, and the 2nd contraction builds on the first. This may happen just right after the refractory period.
41
A rapidly repeating series of stimulations results in the strongest possible contraction, known as ___.
Tetanus.
42
Length-tension relationship.
A muscle contracts most forcefully at an optimum length. This corresponds to the sarcomere length of 2.2 microns, where a max degree of overlapp occurs between actin and myosin thinn/thick filaments.
43
Why is creatine phosphate important for extended muscle contraction?
ATP supplies the E for contraction. However, glycolysis and the TCA cycle are not fast enough to keep pace with rapid ATP utilization during extended contraction. For immediate term energy storage molecule, you have creatine phosphate. During contraction, its hydrolysis drives the regeneration of ATP from ADP and Pi.
44
Function of myoglobin.
A globular protein similar to a hgb subunit. The role is to provide a O2 source reserve by taking O2 from hgb and then releasing it as needed.
45
Rigor Mortis.
The rigidity of skeltal muscles which occurs soon after death. It results from ATP exhaustion; without ATP myosin heads cannot release actin; muscles can't contract or relax.
46
During prolonged contraction, the supply of O2 runs low, and meetabolism becomes____. ___ is produced and mvoes into the bloodsstream, causing a drop in pH. The liver picks it up and converts it to ____, which can be used in various pathways.
During prolonged contraction, the supply of O2 runs low, and meetabolism become anaerobic. LACTIC ACID is produced and mvoes into the bloodsstream, causing a drop in pH. The liver picks it up and converts it to PYRUVATE, which can be used in various pathways.
47
What are some unique properties of slow twitch muscles.
These fibers are also red slow twitch or red oxidative fibers bc of their high myoglobin content. They have much better blood supply than fast, so they can maintain contraction for a longer period of time. Ex. Distance runners
48
Type IIA versus type IIB fast twitch fibers
2A: AKA oxidative fibers; somewhat resistant to fatigue but cannot maintain activity for as long as slow; only around 30 minutes
2B: White fast twitch; these contract very quickly with great force; but, they fatigue just as quickly; maximizing around one minute of use; provide explosive force needed for jump shots.
49
Slow twitch vs. T2A vs T2B in terms of speed of contraction, force generated, mitochondria, capillaries, and fatigue resistance
Slow: slow; low force; many mito; dense capillaries; high hours of use
T2A: intermediate speed of contraction; medium force; some mito; medium capillaries; medium 30 minutes
T2B: very fast speed of contraction; high force; very few mito; very few capillaries.
50
Cardiac muscle is similar to skeletal muscles in the following ways (name 4):
1) thick and thin filaments are organized into sarcomeres
2) T-tubules are present and serve the same function (transmission of APs into the interior of the thick cell.
3) Troponin-tropomyosin regulates contractions in the same way
4) the length-tension relationship works the same and is more significant in cardiac muscle, since it's not connected to a bone; this relationship is important to maximize cardiac output and keep a steady EJ fraction. Too much stretch could lead to reduced EJ and death.
51
Cardiac muscle is different from skeletal in the following ways (name 5):
1) Cardiac muscle is a FUNCTIONAL syncytium but not an actual one. Cardiac muscle cells each only have one nucleus. Skeletal muscles cells are formed by fusion of cells.
2) Cardiac muscles act like a syncytium because they have GJ known as intercacalted disks.
3) Some of the Ca2+ required for cardiac muscle contraction comes from EC environment, through voltage gated Ca2+ channels. In skeletal, all the Ca2+ for contractions from from the SR.
4) Cardiac muscle contractions don't depend on stimulation by motor neurons; the vagus nerve releases ACh to inhibit spontaneous depolarization of the SA node, decreasing HR.
5) The AP in cardia muscle depends not only on Na+ gated channels, but also voltage gated Ca+ chennels, because they respond more slowly to threshold depolarization, they cause a notable plateau phase.
52
_____ and ____ have the same steeply spikingn AP, while _____ muscle cells have a spike and a plateau.
Skeletal muscles and neurons have the same steeply spikingn AP, while cardiac muscle cells have a spike and a plateau.
53
Explain the significance of the plateau phase of an AP in cardiac muscle cell.
1) Longer duration of contraction facilitates ventricular emptying (better EJ fraction)
2) A longer refractory period prevents disorganized transmission of impulses throughout the heart, and makes summation and tetanus impossible.
54
Give the similaries between skeletal muscle and smooth muscle. There are two.
1) The sliding of actin and myosin filaments, the four-step contractile cycle is the same.
2) Contraction is triggered by an increase in cytoplasmic [Ca2+].
55
Describe the external and internal anatomy of the smooth cell.
Smooth cells are much narrower and shorter then a skeletal muscle cell. T- tubules are not present, smooth cells are small and depolarization can affect the entire cell; each cell has only one nucleus and is connected to its neighbors by GJ, like cardiac muscle cells, which allows impulses to spread from cell to cell.
56
Do smooth muscles have thick and thin filaments?
Yes. But, they are not organized into sarcomeres. Instead, they are dispersed in the cytoplasm. No regular A band, Hzone, etc.
57
Do smooth muscles have the troponin-tropomyosin complex?
No. Contraction is regulated by calmodulin and myosin and light-chain kinase. Calmodulin binds Ca2+ and then activates MLCK. MLCK phosphorylates a portion of myosin, thus activating it.
58
How does smooth muscle get its Ca2+ compared to skeletal muscles?
Skeletal muscles rely heavily on Ca2+ from SR; the SR in smooth muscles is poorly developed. Instead, SM relies heavily on EC stores of Ca2+ for contraction.
59
Describe the AP of smooth muscles.
The SM AP varies depending on location of the SM. Most SM cells elicit SPIKE POTENTIALS similar to skeltal muscle AP, but since SM have few voltaged gated Na+, their AP is determined by slow channels only, so it takes a long time to fire an AP relative to skeletal muscle.
60
Vascular smooth muscle and the uterus is smooth muscle. How does it sustain prolonged contractions?
Smooth muscles in these areas has APs similar to those of cardiac muscle, although witha less sharp spike.
61
Slow waves.
Slow waves are necessary to coordinate APs; they do NOT elicit action potentials. Action potentials occur "on top of" slow wave if membrane potential is being depolarized to threshold by a nearby neuron.
62
What types of neurons innervate smooth muscle? Skeletal?
Autonomic motor neurons innervate smooth muscle.
Somatic motor neurons innvervate smooth muscle.
SNS or voluntary nervous sys. is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles.
63
How is smooth muscle activation similar to both skeletal and cardiac muscle cells?
INDIVIDUAL neurons activate smooth muscle cells, like in skeletal muscles. However, the AP then spreads from cell to cell. In skeletal muscle, AP is limited to one large myofiber composed of myofibrils. Therefore, the SM is also like the cardiac muscle in that it's a functional syncytium.
64
We have an ___ made of bone.
Endoskeleton.
65
The vertebral skeletal system serves 5 roles.
1) support body
2) provide framework for movement
3) protect vital organs (brain, heart, etc.)
4) store Ca2+
5) Synthesized formed elements of the blood (RBCs, WBCs, platelets).
66
The formation of formed elements is known as:
Hematopoiesis.
67
The vertebrate is divided into axial and appendicular components. Which bones are constituted as axial bones?
The axial skeleton consists of the skull, vertebral column, and ribcage. All other bones are part of the appendicular skeleton.
68
Connective tissue and where they are derived from.
Connective tissue consists of cells and the materials they secrete. All connective are derived from FIBROBLAST. Connective tissues are different from other tissue types in that it's primarily extracellular material
69
Which cells secrete collagen?
Fibroblasts.
70
Elastin.
An extracellular protein which gives tissues the ablity to stretch and regain its shape.
71
Which cell(s) is the progenitor of adipocytes, chondrocyte (cartilage cells) and osteocytes (bone cells).
Fibroblasts!
72
Componenets of the EC matrix:
collagen, elastin, ground substance (thick viscous material) - composed of proteoglycans and carbohydrate chains called glycoasminoglycans that are attached to these core proteins. This gives tissue its characteristic thick firmness.
73
There are two types of conneecive tissue. Distinguish betweent the two.
Loose: packing tissues, and include areolar tissue (soft tissue located b/t most cells throughout the body) and adipose tissue. Think packing peanuts.
Dense: Tissues that ocntain large amounts of fibers (espeically collagen), suc as tendons, ligaments, cartilage, and bone.
74
Dense connective tissue.
Dense: Tissues that ocntain large amounts of fibers (espeically collagen), suc as tendons, ligaments, cartilage, and bone.
75
Two primary bone shapes.
Flat and long.
76
Function of flat bone.
Flat bones such as the scapula, ribs, and skull bones are the location of hematopoisis and are important for proteinction of organs.
77
The function of long bone.
Long bones are important for support and movement.
78
Diaphysis versus epiphysis/
The main shaft of the long bone is called the diaphysis. The flared end is called the epiphysis.
79
Compact versus spongy bone.
Compact bone is hard and dense while spongy bone is porous. Spongy bone is always surrounded by a layer of compact bone.
80
The diaphysis of long bones is a tube is composed only of ___ bone.
Compact bone.
81
Where is bone marrow found? Red bone marrow? Yellow marrow?
Bone marrow is non-bony material found in the shafts of long bones and the pores of spongy bone.
Red marrow is found in spongy bone within flat ones; site of hematopoisis.
Yellow marrow is found in the shafts of long bones; it's filled with fat and is inactive.
82
The site of hematopoisis.
Flat bones such as scapula, ribs, and the bones of the skull are the location of hematopoiesis. Specifically, this occurs in the red marrow. Red marrow is responsive to erthropoetin.
83
Bone is composed of two principle ingredients:
Collagen and hydroxyapatite.
84
Describe the microscopic structure of compact bone using the following terms: osteon, central canal, lamellae, lacunae, canaliculi, osteocyte, and perforating volksman canals.
The basic unit of compact bone is the OSTEON. The center of the osteon is a hole called the CENTRAL CANAL, which contains blood + lymph vessels and nerves. Surrounding the canal are concentric rings called LAMELLAE. Tiny channels, or CANALICULI branch out from the central canal into spaces called LACUNAE, which houses a single OSTEOCYTE.
85
Cartilage.
Strong but very flexible EC tissue secreted by chondrocytes. Cartilage is NOT innervated and does NOT contain blood vessels. It receives nutrition and immune protection from the surrounding fluid.
86
Three types of cartilage.
Hyaline, elastic, firbrous.
87
Hyaline cartilage and examples in the body.
Strong and somewhat flexible. The larynx and trachea are reinforced by hyaline cartilage, and joints are lined by hyaline cartilage, known as an articular cartilage.
88
Elastic cartilage and where it's located in the body.
Elastin cartilage is found in structures such as the outer ear and epiglottis and require support and more flexibility than hyaline cartilage can provide. It contains elastin.
89
Fibrous cartilage and examples in the body.
Very rigid and found in places where strong support is needed, such as the pubic symphysis ad intervertebral disks of the SC.
90
The type of cartilage the intervertebral disks of the SC are made of.
Fibrous cartilage.
91
Ligaments.
Ligaments connect bones to other bones.
92
Tendons.
Tendons connect bones to muscles.
93
Synarthroses versus amphiarthosis and diarthroses.
1) Synarthroses: immovable joints; basically where bones are fused together, such as the skull.
2) Amphiarthroses: slightly moveable joints that provide mobility and a great deal of support; ex. vertebral joints.
3) Diarthroses: Freely movable joints: several types - ball and socket like hip and shoulder; hinge like elbow.
94
Use the following in a sentence: synovial fluid, synovial capsule, articular cartilage.
Movable joints are lubricated by synovial fluid, which is kept within the joint by the SYNOVIAL CAPSULE. The surfaces of the two bones that contact each other are perfectly smooth bc they are lined by ARTICULAR CARTILAGE.
95
Inflammation of the joints.
Arthritis - this can lead to the destruction of articular cartilage.
96
Most bone growth occurs by ___. In which ___ is produced and replaced by ___.
Most bone growth occurs by endochondral ossification, in which hyaline cartilage is replaced by bone.
97
The synthesis of bone from an embryonic tissue called mesenchyme.
Intramembranous ossification. This results in layers, thus intramembranous ossification results in flat bones.
98
The significance of the epiphyseal plate and how it disappears over development.
During childhoold, a structure called the epiphyseal plate is seen b/t the diaphysis and epiphysis. The plate is a disk of hyaline cartilage that is actively being produced by chondrolytes. As the chondrocytes divide, the epiphysis and diaphysis are forced apart. Then, the cartilage is replaed by bone (ossified), a process sstimulated by GH. Around 18, the diaphysis and epiphysis meet and fuse togeteher, lengthening can no longer occur.
99
True of false. During adulthood, bones do not elongate or remade.
Bones no longer elongate, but bone is continually degraded and remade in a proess termed remodeling.
100
The cells which make bone by laying down collagen and hydroxyapatite.
Osteoblasts.
101
The osteoblast synthesizes bone until it is surrounded by bone. It space left in is now called a ____, and the osteoblasat is now called an ___.
Lacuna, osteocyte.
102
Osteoclast.
Cells called osteoclasts continually destroy bone by dissolveing the osteoblast is now called an osteocyte. Bones destroyed by oseteoclasts must be replced by osteoblasts.
103
An increased ratio of osteoclast to osteoblast activity results in the liberation of ___ and ____ into the bloodstream.
Calcium and phosphate.
104
PTH.
Stimulates osteoclast activity, kidney effect - increases reabsorption of Ca 2+, stimulates conversion of Vit D into calcitriol; effect on intestine - indirectly increases intestinal Ca2+ absorption.
105
Calcitonin.
May stimulate osteoclast activity, but minor effect; kidney effect - increases reabsorption of phosphorus; intrestine effect - increases intestinal absorption of Ca2+
106
Calcitriol.
Inhibits osteoclast activity; kidney effect - decreases reabsorption of Ca; no effect on intestine.
107
Which hormones increase blood Ca?
PTH and calcitonin.
