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63 Cards in this Set

  • Front
  • Back
3 types of muscle
1. skeletal muscle: voluntary muscle
2. cardiac muscle: only found in the heart
3. smooth muscle: found in the walls of all hollow organs ie: GI tract, urinary system, uterus, etc.
strong connective tissue made of collagen that attaches muscle to bone

skeletal muscle is attached @ each end to 2 different bones
how does the muscle move?
contracting to bring points of attachment on the 2 bones together.

reducing the angle of the joint
increasing angle of the joint
moving away from body's midline
moving toward body's midline
point on bone where muscle attaches that's closest to center of the body
point on bone where muscle attaches that's farther from center of body.

muscle contracts, insertion point is brought closer to its origin
muscles that move in opposite directions
muscles that move a joint in the same direction
what neurotransmitter causes movement of muscle cells?
heirarchy of the muscle
polymerized actin (thin) & myosin (thick) filaments--> sarcomere: unit of contraction--> myofibril: string of sarcomeres + plasma membrane--> muscle cells: muscle fibers/myofibers--> fascicle: group of cells--> whole muscle: group of fasciles
Sliding filament theory of muscle contraction cycle
1. cross-bridge formation: myosin head binds to myosin binding site on actin. requires Ca2+

2. powerstroke: myosing head pulls actin chain towrds the center of the sarcomere, releasing ADP.

3. myosin head releases actin in the presence of ATP.

4. myosin resets to high-energy conformation using ATP hydrolysis.
why can't the muscle contract w/out Ca2+ present?
b/c thin filament contains troponin-tropomyosin complex, which prevents contraction in absence of Ca2+.

tropomyosin is a long fibrous protein that winds arounda ctin polymer, blocking all the myosin binding sites. troponin is a globular protein bound to tropomyosin that can bind to Ca2+. when troponin binds to Ca2+, troponin changes conformation and moves tropomyosin out of the way, allowing myosin head to attach to actin and begin filament sliding.
neuromuscular junction (NMJ)

what is the neurotransmitter?
synapse b/w synaptic knob (axon terminus) and myofiber. a long invagination of the cell membrane. the axon terminus is elongated to fill the song synaptic cleft. this allows the neuron to depolarize a large region of the postsynaptic membrane (motor end plate) at once.

Acetylcholine (ACh)
muscle twitch

what causes it?
smallest measurable muscle contraction

activation of one motor neuron
2 ways that the nervous system increases the force of muscle contraction
1. Motor unit recruitment:
motor unit--group of myofibers innervated by branches of a single motor neuron's axon. the larger the muscle twitch, the more motor neurons activating/recruited.

2. frequency summation: each contraction ends when SR returns [Ca2+] to low resting levels. when a 2nd contraction occurs rapidly enough, the SR doesn't have enough time to lower [Ca2+] levels, so 2nd contraction builds on the first.
strongest possible contraction caused by a rapidly repeating series of stimulations
creatine phosphate
intermediate-term energy storage molecule. During contraction, it is hydrolyzed to drive the regeneration of ATP from ADP + Pi
globular protein similar to hemoglobin subunits.

provides an oxygen reserve by taking O2 from hemoglobin and releasing it as needed.
what happens to the muscles during prolonged contraction?
supply of O2 runs low, metabolism becomes anaerobic, producing lactic acid.
lactic acid moves into bloodstream, lowering pH. liver picks up lactate and converts it to pyruvate.
rigor mortis
rigidity of skeletal muscles after death. results from complete ATP exhaustion, which inhibits myosin heads releasing actin so that the muscle cannot contract or relax.
cardiac muscle cells
1. appearance
2. upstroke of AP
3. Plateau
4. duration of AP
5. Calcium from
6. molecular basis for contraction
7. functional syncytium
8. contraction dependent of Ca2+
2. Inward Ca2+ (SA node) and inward Na+ (atria, ventricles, Purkinje)
3. Yes, except for SA node
4. 300msec (long)
5. AP opens VG Ca2+ channels; Ca2+ current inward during plateau; Ca2+ induced Ca2+ release from SR
6. Ca2+ troponin binding
7. functional syncytium
8. Partially dependant on extracellular Ca2+
skeletal muscle cells
1. appearance
2. upstroke of AP
3. Plateau
4. duration of AP
5. Calcium from
6. molecular basis for contraction
7. functional syncytium
8. contraction dependent of Ca2+
1. striated
2. Inward Na+ current
3. No
4. 2-msec (short)
5. AP opens VG Ca2+ channels in SR; Ca2+ released from SR
6. Ca2+ troponin binding
7. No. regular syncytium
8. No
smooth muscle cells
1. appearance
2. upstroke of AP
3. Plateau
4. duration of AP
5. Calcium from
6. molecular basis for contraction
7. functional syncytium
8. contraction dependent of Ca2+
1. smooth
2. Inward Na+
3. No
4. 20msec, long, but shorter than cardiac
5. AP opens Ca2+ channels in cell membrane; inward Ca2+ current
6. Ca2+ calmodulin binding; myosin light chain kinase activation
7. Yes
8. Yes
what is a syncytium?

what has this?
when cells have more than 1 nucleus, allowing AP to propagate throughout entire muscle.

skeletal muscle cells
what is a functional syncytium?

what has this?
cells w/ 1 nucleus, but connected to neighboring cells through intercalated disks. this allows APs to propagate throughout the entire muscle w/o nuclei and cytoplasmic contents shared.

cardiac muscle cells (intercalated disks)
smooth muscle (gap junctions)
calmodulin and myosin light chain kinase (MLCK)
calmodulin binds Ca2+ and activates MLCK. MLCK phosphorylates a portion of the myosin molecule, activating its enzymatic/mechanical activity.
occurs in smooth muscle cells
Troponin-tropomyosin complex
prevents contraction when Ca2+ is not present.

Tropomyosin: long fibrous protein that winds around actin polymer, blocking all myosin binding sites.
Troponin: globular protein bound to tropomyosin that can bind to Ca2+.

when tropomyosin binds Ca2+, troponin undergoes conformational change that moves tropomyosin out of the way so that myosin heads acan attach to actin and filament sliding can occur.

regulates muscle contraction in Cardiac and skeletal muscle cells.
roles of the vertebrate skeleton
1. support the body
2. provide framework of movement
3. protect vital organs
4. store calcium
5. synthesize the formed elements of the blood: RBCs, WBCs, platelets.
production of blood elements. occurs in the marrow of flat bones.
connective tissue
cells and materials they secrete.
ex: bone
derived from the fibroblast, which is named for its ability to secrete fibrous material
ex: collagen, elastin,
cells derived from fibroblast:
adipocytes, chondrocytes, osteocytes
important extracellular protein that give tissue the ability to stretch and regain its shape.
cartilege cells
bone cells
2 types of connective tissue
1. loose connective tissue: adipose tissue: fat cells
extracellular matrix: material located b/w cells throughout body. made of proteoglycans (large macropolymers made of protein core w/ many attached carb chains called glycosaminoglycans (GAGs) which are very hydrophillic)

2. dense connective tissue: tissues that contain large amounts of collagen
ex: bones, cartilage, tendons, ligaments
2 primary bone structures
1. flat: location of hematopoiesis and used to protect organs.
ex: scapula, ribs, skull

2. long: important for support and movement.
ex: bones of the limbs.
parts of long bones
1. diaphysis: main shaft. it's a tube composed of compact bone
2. flared end
2 general structures of bone
1. spongy: porous bone, always surrounded by a layer of compact bone.
2. compact: hard and dense
bone marrow
non-bony material found in shafts of long bones and in pores of spongy bones.
1. red marrow: found in spongy bone w/in flat bones. site of hematopoiesis. activity increases in response to erythropoietin (kidney hormone)

2. yellow marrow: found in shafts of long bones. filled w/ fat. inactive
2 main ingredients of bone
1. collagen
2. hydoxyapatite: solid material composed of calcium phosphate crystals.
bone synthesis
collagen is laid down in a highly ordered structure, then hydroxyapatite crystals form around collagen framework
spikes of bone in spongy bone
basic unit of compact bone
haversian system

in the center of the osteon is the central canal (haversian), which contains blood, lymph vessels and nerves.

canal is surrounded by concentric rings of bone called lamallae.

canaliculi (small channels) branch out of central canal into lacunae (spaces). in each lacuna is an osteocyte (mature bone cell).
how do osteocytes contact each other?
gap junctions!

Perforating/Volkmann's canals: channels that run perpendicular to central canals to connect osteons.
3 types of cartilage
1. hyaline: strong and somewhat flexible.
trachea and larynx are reinforced by this.
articular cartilage: hyaline cartilage that lines joints

2. elastic cartilage: found in areas that require support and more flexibility. contains elastin.
ex: ear and epiglottis

3. fibrous: rigid; found in places that require strong support.
ex: pubic symphysis, invertebral disks of the spinal column
is cartilage innervated?

how does cartilage receive nutrients and immune protection?

why does cartilage take a long time to heal?
no! it's avascular!

from surrounding fluid.

b/c it isn't directly supplied by blood and has a low rate of metabolism.
strong tissues composed of dense connective tissue. connects bones to bones!
strong tissues composed of dense connective tissue.
connects bones to muscles!
where bone meets bone
immovable joints
points where 2 bones are fused together.
ex: skull
slightly movable joints
provide mobility and support.
ex: vertebral joints
freely movable joints
supported by ligaments
ex: ball & socket--> hip, shoulder
ex: hinge--> elbow
synovial capsule
keeps synovial fluid w/in the joint

synovial fluid keeps movable joints lubricated.
endochondral ossification
bone growth that occurs when hyaline cartilage is produced, then replaced by bone.
intramembrous ossification
synthesis of bone from mesenchyme (embryonic tissue)

happens in flat bones
process of continually degrading and remaking bone
BUILD BONE by laying down collagen and hydoxyapatite
CRUSH BONE by dissolving the hydroxyapatite crystals.

basically a phagocytic cousin of the machrophage.
parathyroid hormone

what does it stimulate?

how does it effect the kidney?

how does it effect the intestines?
stimulates osteoclast activity

increases reabsorption of Ca2+ and stimulates Vitamin D into calcitriol

indirectly increases intestinal Ca2+ absorption (through calcitriol)
what does it stimulate?

how does it effect the kidney?

how does it effect the intestines?
may stimulate osteoclast activity (minor effect)

increases reabsorption of phosphorus

increases intestinal absorption of Ca2+

how is it made?

what does it stimulate?

how does it effect the kidney?
derived from Vitamin D by the kidney

inhibits osteoclast activity

decreases reabsorption of Ca2+