Gross Q1 Flashcards
What is myology
branch of anatomy that deals with skeletal muscular system
how much of body weight is skeletal muscle
40-50 percent
Functions of skeletal muscle
Movement, stability, communication, control of body openings and passages, and heat production
what other systems is skeletal muscle closely interrelated with?
bones and joints, respiratory and digestive systems, the integumentary system, and the nervous system
what is a muscle cell called?
a muscle fiber
muscle fibers are grouped into bundles known as…
fasciculi
what are muscles fibers and fasciculi bound together by?
connective tissue
Functions of connective tissue in muscle
- connect muscle to bone or other structures
- provide route for nerves and blood vessels to supply muscle
- Provide non-contractile framework to transmit contraction to a bone
Three layers of connective tissue in skeletal muscle
- Epimysium
- Perimysium
- Endomysium
Function of Epimysium
wraps around the muscle fiber
Function of perimysium
wraps around the fascicle
Function of endomysium
wraps the muscle—> becomes tendon
T/F? There are multiple nuclei in a muscle fiber
True
what is a myofilament?
contractile unit of muscle, every muscle cell will contain dozens to hundreds of these.
What is a muscle fiber’s membrane called?
a sarcolemma
how much larger are adult muscles than neonate muscles?
10x larger
Hypertrophy
Increase in the size of each individual muscle fiber
Hyperplasia
Increase in the number of muscle fibers
what is the cytoplasm of a muscle cell called?
sarcoplasm
type I muscle fibers
Long, sustained muscle contraction is required. Associated with endurance. Specialize in aerobic metabolism
Type II muscle fibers
used in quick powerful activities- speed and strength. Associated with anaerobic metabolism.
called a fast twitch muscle fiber
Type II fibers
fatigue resistent fibers
Type I
Muscle fiber with Extensive capillary beds
Type I
muscle cell that uses more glycogen, less fatty acids
Type II
fiber that atrophies with aging
Type II
fiber type with more mitochondria
Type I
intermediate fibers
b/w type I and type II. They contract faster than type I but slower than type II. greater fatigue resistance but resemble type II fibers.
sarcoplasmic reticulum
an elaborate, tubular network that stores and transports Ca++ to myofibrils
transverse tubules
invaginations in the sarcolemma, allow action potentials to make their way into the muscle fibers and to the myofibrils
myoglobin
red protein pigment found in sarcolemma. almost indistinguishable from hemoglobin. stores O2 needed for aerobic respiration. greater affinity for O2 than hemoglobin
myofibril
contractile apparatus of the muscle fiber
I-Bands
light areas at the ends of sarcomeres
A-bands
the entire dark part of the contractile unit
H-bands
light areas in the middle of the A-bands
M-line
Dark band in the middle of the the A-band
Z-line
Dark line in the middle of the I-band
sarcomere
smallest functional unit of muscle, runs Z-line to Z-line
Actin
contractile protein mainly found in the I bands
Myosin
contractile protein mainly found in the A-bands
process of muscle contraction
nerve sends action potential, acytlcholine diffused across neuromuscular junction, binds to receptors. action potential travels down t-tubules, stimulates release of Ca++ from sarcoplasmic reticulum. Ca++ binds to troponin on actin filaments, changes the shape of tropomyosin and exposes myosin binding site. ATP allows myosin to interact with actin and cause a muscle contraction.
T/F? 1 ATP is required for myosin to bind to actin, but 1 ATP is not required to release actin.
false
preferred fuel source for aerobic metabolism
fatty acids
how are fatty acids stored in fat cells?
triglycerides
Phase One of cardiovascular exercise
lasts for a couple minutes. Creatine phosphate and glycogen are primary fuel. 20% of glycogen will be depleted
Phase two
shift to aerobic metabolism to utilize fatty acids and make ATP
Phase three
As fatigue sets in, shift back to anaerobic cycle to make ATP. Remaining glycogen is utilized. Lactic acid accumulates.
Ergogenic aid
a technique or substance used for the purpose of enhancing performance
Glycogen/Carb loading
Aims to increase intramuscular glycogen
day 1: work to exhaustion, deplete glycogen
days 2-4: continue to exercise. eat diet low in carbs
days 5-7: no exercise, high carb diet.
Side effects of carb-loading
dizziness, light-headedness, lethargy, lower mental acuity, increase in weight due to increased glycogen and water in muscles
Caffeine benefits
2 cups of coffee used 1:30 before a race can allow fatty acids to be broken down more efficiently. delays phase 3
caffeine cons
it is a diuretic and can cause nervousness
Blood doping process
blood cells are drawn from the athlete and stored several months before. on the day of the race, cells are reintroduced into the blood to allow greater O2 carrying capacity
Doping risks
can cause rashes and fevers, acute hemolysis, transmission of viruses and can cause fluid buildup leading to kidney damage or clotting
Erythropoetin (EPO)
hormone that causes production of red blood cells in bone marrow. can thicken blood to dangerously high levels
Anabolic steroids
synthetic forms of testosterone that cause anabolic effects but less androgenic effects. less rapidly broken down than regular testosterone.
oil-based steroids
injected with fewer side-effects but can be tested months after stopping
water-based steroids
taken in pill form with more side-effects. cleared from system in 3-4 weeks.
patches/gels
another way to administer steroids. more androgenic effects
pyramiding
user starts at a low dosage, raises to a peak and then tapers down the amount being taken
stacking
user takes several forms of the drug. Both oil and water based
short term side effects of steroids
headaches, dizziness and nausea, acne, shrinkage of testes, gynecomastia, tendon damage
long term side effects of steroids
issues with cardiovascular system, digestive system, prostrate cancer, endocrine system
steroid side-effects in females
increase clitoral size, decrease mammary gland size, develop facial hair, voice deepen, tendon damage
steroid side-effects in adolescents
premature closing of growth plates –> shortened stature.
anabolic steroids work by…
increasing growth hormone production,
increasing protein synthesis and decreasing protein breakdown.
Chemical composition of muscle
75% water
20% protein (mainly myosin)
5% other
What nerves are supplied to every muscle cell?
motor nerve (efferent) fiber and a sensory (afferent fiber)
Nerve fibers enter and leave a muscle via the ______ _______ components of the muscle
connective tissue
What is the motor unit?
a single neuron and all the muscle fibers it innervates. It is the smallest part of a muscle that can contract independently
What determines the precision of muscle?
the smaller the motor unit the more precise its movements will be
Where does the motor unit originate and terminate?
Originates: in the ventral horn of the gray matter in the CNS.
CNS–>PNS–>muscle fiber sarcolemma
Terminates: in the sarcolemma of the muscle fiber (terminal end)
What is the PRE-synaptic portion of the neuromusclular junction (NMJ)?
The nerve ending
What is the POST-synaptic portion of the NMJ?
sarcolemma of the muscle fiber
What is the SYNAPTIC CLEFT ?
space b/w pre and postsynaptic portions where ACH is released.
__________ is released at the presynaptic portion of the NMJ via a __________ potential.
Acetylcholine (ACH) ; action potential
Once ACH completes its binding, __________ is the enzyme that breaks down ACH.
Acetylcholinesterase (ACHe)
ACHe degrades ACH into _______ & _______.
acetate ; choline
What is Myasthenia Gravis?
most common NMJ autoimmune disorder. Rogue antibodies damage ACH receptor sites on the sarcolemma. Begins affecting muscles supplied by cranial nerves (e.g. eye/face muscles). May progress to extremities.
Patients may suffer tumor to the thymus gland (removal may = remission)
A pregnant women suffering from Myasthenia Gravis has a ____% chance that her infant develops ________ neonatal myasthenia gravis
25% ; Transitional Neonatal Myasthenia Gravis
How does Nicotine affect the NMJ?
Nicotine competes with ACH in receptor sites binding. Its actions are more prolonged than ACH
How does Snake Venom affect the NMJ?
prevents ACH from binding to receptor sites. Unlike nicotine…snake venom doesn’t cause action potential to occur.
How does Organophosphates affect the NMJ?
inactivates ACHe. ACH cannot be broken down and accumulates in postsynaptic NMJ. Examples include parathion & malathion found in insecticides.
How does Botulin Toxin affect NMJ?
released from bacteria: clostridium botulinum . causes food poisoning…botulism.
Blocks release release of ACH from presynaptic portion of NMJ. First affects cranial nerves and can be fatal.
