Skeletal Muscle Contraction
What is the thin and thick filament composed of?
Thin: actin, tropomyosin, troponin
Thick: myosin, cross-bridges
Order of motor unit size
SO<FOG<FG
Major functions of hormones
1. Maintain Homeostasis
2. Coordinate growth and development
3. Assure reproduction
Order of Cortisol hormone development (ACTH, CRH, Cortisol)
CRH, ACTH, Cortisol
Order of skeletal muscle contraction events?
1. Events at the neuromuscular junction
2. Excitation/Contraction coupling
3. Cross-bridge cycling
Eye: SO. Smaller contractions allows for more control
Leg: FG. Larger contraction allows for less control
Difference between endocrine and exocrine glands
Endocrine: excreted and carried in the blood to target cells
Exocrine: release things to the outside of the cell or lumen space (sweat glands)
1. TRH, TSH, TH
Simulates oxidative metabolism, metabolic rate, glucose breakdown, promotes growth, and increases protein synthesis
Muscle stiffening after death
Rigor Mortis
Smooth muscle examples
Uterus, eyes, bladder, blood vessels, GI tract
ADH and Oxytocin
Effects of cortisol with too much and not enough
Too much: Cushing's, moon face, loss of protein, weakness, decreased healing, immunocompromised
Too little: Addison's, hypoglycemia, weakness, weight loss
Which statement is false about skeletal muscle structure?
A. a myofibril is composed of multiple muscle fibers.
B. Each end of a thick filament is surrounded by 6 thin filaments.
C. A cross-bridge is a portion of the myosin molecule.
D. Thick filaments contain the protein myosin.
A. a single skeletal muscle fiber, or cell, is composed of many myofibrils.
Explain smooth muscle contraction
1. Ca rises in the cells
2. Ca binds to calmodulin--> Active
3. Active calmodulin activate MLCK
4. Active MLCK uses ATP to phosphorylate myosin
5. Cross-bridge can bind to actin
6. Repeated cross-bridge cycling
7. Dephosphorylation my MLCP relaxation occurs due to decrease in Ca in the cell
Oxytocin and ADH action in the body
Oxytocin: Baby hormone. stimulates uterine contraction during labor and mammary glands during lactation
ADH: Vasopressin. Increases water permeability and reabsorbs water causing an increase in blood pressure
Which thyroid condition is associated with Grave's disease and which can cause a goiter
Hyperthyroidism
Hypothyroidism--> proptosis and cretinsim
Describe the four steps in one cross-bridge cycle. At what steps does ATP act?
1. an energized cross-bridge of myosin with its bound ADP and P binds to actin
2. The cross-bridge moves, shortening the sarcomere
3. ATP binds to the cross-bridge causing it to detach from actin
4. ATP is hydrolyzed to ADP and P which energizes the cross-bridge.
Contraction of the cell can not occur without the cell first being electrically excited. Depolarizations of the cell is responsible for elevation in cytosolic Ca2+ that is required for releasing troponin/tropomyosin from covering the binding sites.
Differences in Smooth and Skeletal muscle
Smooth: spiraled shape, single nucleus, no t-tubules, no troponin, underdeveloped SR, dense bodies, unstriated, interconnected
Skeletal: large, multi-nucleated, t-tubules, troponin, developed SR, round
Explain the order of how a hormone is transformed from hormone 1 to hormone 3
1. Stimulus
2. Hypothalamus begins secreting Hormone 1
3. Hormone 1 released in portal vessels
4. Hormone 1 stimulates Hormone 2 production in anterior pituitary gland
5. Hormone 2 release into circulating blood
6. Hormone 2 reaches endocrine gland and stimulates hormone 3 secretion
7. Hormone 3 released into circulating blood
8. Response from target cells from Hormone 3
What happens to the body when epinephrine and norepinephrine released
HR increases, RR increases, blood clotting decreased, dilated pupils, promotes lipolysis, decreased blood flow to GI and slows GI function, increases glucose production