Lecture 14

Question 1

-What do we have to add to the ADP molecule to ‘convert’ it into ATP? _______

-Muscle contraction depends on ATP—> ATP supply depends on the availability of ________ and ____________

-3 pathways of ATP Synthesis:
1.
2.
3.

Answer 1

-inorganic phosphate
-oxygen; organic energy sources (glucose, fatty acids)
1. Glycolysis (glycogen storage)
2. Anaerobic glycolysis (glycogen-lactate system)
3. Aerobic glycolysis (Krebs cycle & phosphorylation)

Question 2

Phosphagens
-Energy storing compounds:
-they provide an ___________ supply of ATP
-Not dependent upon presence of oxygen (________)

Answer 2

-contain high energy phosphates that can be used to make ATP
-immediate supply
-anaerobic

Question 3

Phosphagen System: The CrP-ATP system
-_______________ transfers 1 phosphate from phosphocreatine to ADP to yield creatine and ATP

Answer 3

creatine kinase

Question 4

Summary of Energy Systems
-Phosphagens (CrP-ATP system) used for _____________
examples:

-Anaerobic glycolysis used for ______________
examples:

-Aerobic glycolysis used for ___________
examples:

Answer 4

-powerful bursts of exercise
examples: 100m sprint, weight lighting (one single lift)

-medium length exercise that causes that burning feeling! (due to buildup of lactic acid)
examples: circuit training (exercise to exercise with little rest between), 400m race

-long distance exercise
examples: marathon, swimming

Question 5

After 2 min of exercise, _______ respiration plays a major role in ATP synthesis. In exercises lasting more than 10 minutes, over ____% of the ATP is produced like this

Answer 5

aerobic; 90%

Question 6

Anaerobic exercises= __________ training

-contraction of muscles against a load that resists movement
-You exercise till you gas out (you can’t sustain this kind of activity for extended time). _________ build up, and you start to feel the burn
-A few minutes a few times week is enough to __________ muscle growth from cellular enlargement (_______= increase in muscle size, which is NOT cell division)
-increase in muscle size is mostly because of the _________ ____ _______ that have existed since puberty

Answer 6

RESISTANCE
-lactic acid
-stimulate; hypertrophy
-enlargement of fibers

Question 7

Aerobic exercises= _________ training

-sustain for an extended period of time
-improves _______ -resistant muscles
-_____ twitch fibers: increased ________, _______, and __________
-improves skeletal strength
- raises______ count and oxygen transport capacity of the blood
- improves function of the ____,______ and _____

Answer 7

ENDURANCE
-fatigue
-slow; mitochondria, glycogen, and density of blood capillaries
-RBC
-CV, respiratory, NS

Question 8

Endurance training doesn’t significantly increase muscular strength, and resistance training doesn’t improve endurance. SO optimal performance and musculoskeletal health require ____________ (both)

Answer 8

Cross-training

Question 9

Age-related muscle loss, called _________, is a natural part of aging. After age 30, you begin to lose as much as ___% to ___% per decade

Answer 9

sarcopenia; 3%-5%

Question 10

Muscle fatigue

Answer 10

progressive weakness and loss of contractility from prolonged use of muscles

Question 11

Muscle Fatigue in
High-Intensity (SHORT duration):
-_____________: decreased release of Ca2+ from SR
-_____________: slow cross-bridge cycling mechanism of contraction, inhibits calcium release form SR, and lowers force production in myofibrils

Answer 11

K+ accumulation
ADP and Pi accumulation

Question 12

Muscle Fatigue in low-intensity (LONG duration):
-___________ as glycogen and glucose levels lower
-___________ through sweat can lower muscle excitability
-___________: less signals output to the skeletal muscles
-brain motor neurons inhibited by exercising muscle’s release of ________

Answer 12

-Fuel depletion
-Electrolyte loss
-Central fatigue
-amonia

Question 13

Maximum oxygen uptake (maximal aerobic capacity, VO2 max):

Answer 13

the maximum amount of oxygen that an individual can utilize during intense or maximal exercise

Question 14

VO2max peaks at around age ____/ males__females (usually)/ can be __x in trained endurance athletes

Answer 14

20; >; 2

Question 15

Skeletal Muscle Fiber Types:
1.
2.
-every muscle contains a mix of fiber types, but 1 type may predominate depending on muscle function
-fiber types within a muscle DIFFERS across individuals

Answer 15

1. slow twitch (slow oxidative fibers)
2. fast twitch (fast glycolytic or oxidative fibers)

Question 16

Slow oxidative fibers
-ATPases hydrolyze ATP ________
-__________ respiration pathway
-________ blood vessels and myoglobin= slow RED muscle fibers
-________ mitochondria
-________ sarcomeres
-_______ glycogen storage
- able to produce 32 ATP per glucose

-These muscle fibers are well adapted for ________ and _______ resistance
-found in muscles that support the body and maintain _________
-__________ units are composed of relatively small SO muscle fibers that produce more precise movements

Answer 16

-slowly
-aerobic
-increased
-increased
-decreased
-low
-endurance; fatigue
-posture
-small motor units

Question 17

Fast Glycolytic Fibers
-ATPases hydrolyze ATP ________
-_________ pathway
-largest & strongest
-_________ myoglobin and blood vessels= white muscle fibers
-__________ mitochondria
-__________ sarcomeres
-__________ glycogen reserves
-fatigues the fastest
-_____________ are composed of larger FG fibers and produce more power but less fine control

Answer 17

-QUICKLY
-anaerobic
-decreased
-decreased
-increased
-increased
-large motor units

Question 18

Fast Oxidative fibers
-ATPases hydrolyze ATP _______
-________ respiration pathway
-_______ blood vessels and myoglobin= fast red muscle fibers
-relatively rare in humans, except in some _________- trained athletes

Answer 18

-quickly
-aerobic
-increased
-endurance

Question 19

Cardiac Muscle:
-____________: able to contract rhythmically and independently of NS
-___________ cells in the heart stimulate electrical contraction, if these cells fail, an artificial ‘________’ can be used
-__________ NS can increase or decrease heart rate & contraction strength
- muscle cells of a given chamber must contract in ________
- contraction must last long enough to expel _____ (very SLOW twitches)

Answer 19

-auto-rhythmic
-pacemaker; ‘pacemaker’
-autonomic
-unison
-blood

Question 20

Cardiac muscle:
-cardiomyocytes are _______ and ______ (vs skeletal muscle fibers) and slightly _______
-_____ nuclei near the middle of the cell
-striated
-no perimysium or epimysium (endomysium ONLY)
-limited capacity for ___________: after a heart attack, lost cardiac muscle is replaced by scar tissue

Answer 20

-shorter and thicker; branched
-1 or 2 (uninucleated)
-regeneration

Question 21

Cardiac muscle

-cardiomyocytes are joined together by ___________

-part of sarcolemma. they contain ________ & _________

-SR less developed, but T tubules are _____

Answer 21

-intercalated discs
-gap junctions; desmosomes
-larger

Question 22

Smooth Muscle
-smooth muscle forms layers within walls of _______ organs
-it can propel contents of an organ (e.g. food in GI tract)
-it can modify pressure and flow of ______ in the circulatory system and _____ in the respiratory system (by dilating or constricting)
-can provide _____ control in some locations:
-_________ muscles raise hairs in skin
-smooth muscles of _____ controls pupil size

Answer 22

-hollow
-blood; air
-fine
-pilorector (arrector pili)
-iris

Question 23

Smooth muscle
-myocytes have a ______ shape
-there is __ nucleus, located near the middle of the cell
-capable of _________, mitosis and __________( cell division)
-injured smooth muscle _________ well by mitosis
-thick and thin filaments are ________, but different organization
-NOT STRIATED
-z discs are absent!
-__________: attach to the sarcolemma, they work like z-disc in a sarcomere

-some smooth muscles lack nerve supply; others receive input from _______ fibers with many varicosities containing synaptic vesicles

Answer 23

-fusiform
-1
-hypertrophy; hyperplasia
-regenerates
-present
-dense bodies
-autonomic

Question 24

Types of Smooth Muscle
1.
2.

Answer 24

1. unitary (single unit) (visceral muscle)
2. multiunit

Question 25

Unitary smooth muscle
-requires only __ or ___ nerve fibers to activate an entire sheet of smooth muscle
-contains ________: allow for unison contraction of the entire sheet
-NOT associated with a single ________
-found in most……

Answer 25

-1 or 2
-gap junctions
-myocyte
-blood vessels; respiratory, urinary, and reproductive tracts

Question 26

Multiunit smooth muscle
-requires ______ nerve fibers
-contains no (or few) ________: cells are not electrically connected
-each associated with a particular myocyte (contracts __________)
-found in most….

Answer 26

-multiple
-gap junctions
-independently
-largest arteries, air passages, piloerector muscles, iris of the eye

Question 27

In smooth muscle….
-contraction & relaxation very _____ (vs. skeletal muscle): slow myosin ATPase enzyme and pumps that remove ______ but can remain contracted for a long time without ________
-______________: some in GI tract depolarize at regular intervals
-makes most of its ATP __________
-does NOT contain myofibrils or sarcomeres
-contract via a ____________

Answer 27

-slow; Ca2+; fatigue
-autorythmicity
-aerobically
-sliding filament mechanism

Question 28

Sliding filament mechanism
-myosin filament heads slide the actin filaments forward–> they also pull on the _________ –> which then pulls on the network of intermediate filaments-> _________ of the cell

Answer 28

dense bodies; shortening

Question 29

Smooth Muscle Contraction:
-Most Ca2+ needed for muscle contraction comes from ________ by a way of Ca2+ channels in sarcolemma
-Ca2+ bind to __________ protein
-this protein complex activates myosin light-chain kinase (MLCK)
-MLCK adds a phosphate group to small regulatory protein on the myosin head: activation of myosin ___________
-Hydrolysis of ATP, binding of myosin heads to _____, generation of repetitive power and recovery strokes

Answer 29

-ECF
-calmodulin
-ATPase
-actin

Question 30

Smooth Muscle Relaxation:
-_____ is pumped out of the cell or back into the SR
-Ca2+ dissociates from calmodulin (CaM)
-Myosin phosphatase removes phosphate from myosin
-decreases myosin ________ activity
-_______________: enables myosin to remain attached to actin for a prolonged time without consuming more ATP
-this mechanism and increased fatigue resistance enable maintenance of a tetanus tonic contraction (___________)

Answer 30

-Ca2+
-ATPase
-latch-bridge mechanism
-smooth muscle tone

Question 31

Stress-relaxation response:

Answer 31

smooth muscle responds to stretch only briefly, and then adapts to its new length. New length retains ability to contract (especially visceral urinary type)

Question 32

Stress-relaxation response reasons:
1. there are no _______ so thick filaments cannot butt against them and stop contraction
2. Since the thick and thin filaments are not arranged in orderly _________, stretching does not cause a situation where there is too little overlap for cross-bridges to form
3. The thick filaments of smooth muscle have myosin heads along their _______ _______, so cross bridges can form anywhere

Answer 32

1. Z discs
2. sarcomeres
3. entire length

Question 33

Plasticity

Answer 33

ability to adjust its tension to the degree of stretch
-allows hallow organs to gradually fill, temporarily store, and then expel their contents efficiently (e.g. stomach, bladder)