Muscles Flashcards
How do horses generate movement?
-muscles contract and pull on a tendon
-the tendon is attached to a bone
-the muscle-tendon unit causes the bones to move
Adduction
moving in towards the body
Abduction
moving out away from the body
Flexion
closing the angle of the joint
Extension
opening the angle of the joint
How are muscles and tendons named?
for their type of movement, their location, and/or the structures they move
Extensor carpi radialis
extends the knee (carpus), located along the radius (on the dorsal side)
Flexor carpi radialis
flexes the knee, located along the radius (on the palmar side)
A muscle is a…
bundle of fasicles
A fasicle is a…
bundle of muscle fibers
Muscle fibers are…
bundles of myofibrils
Where does muscle contraction occur?
in the sarcomere
What is the thick filament made of?
myosin
What is the thin filament made of?
actin
What is the sarcomere made up of?
the thick and thin filaments
The thin filament is anchored to…
the Z line
The thick filament is anchored to…
the M line
When the muscle relaxes what is occuring?
tropomyosin is blocking the binding sites on Actin
When the muscle is contracting what is occuring?
tropanin releases tropomyosin so myosin can bind to actin and the muscle can contract
Steps to muscle contraction:
-a neural impulse occurs, signaling a need to contract
-the neural signal causes a chain of reactions resulting in the release of calcium within the muscle cell
-the calcium causes a change that allows the thin and thick filaments of the sarcomere to interact
-ATP is used as the thick and thin filaments associate and disassociate-causing the sarcomere to shorten (contraction)
How many phosphates are in ATP
3
How many phosphates are in ADP
2
Where do muscles get ATP
-stored ATP
-creatine phosphate
-aerobic (oxidative) metabolism
-anaerobic (glycolytic) metabolism
What is stored ATP good for?
brief activities, very limited amounts
What is creatine phosphate good for?
short activities, very limited amounts
Aerobic (oxidative) metabolism
-uses carbohydrates or fat
-efficient
-sustainable
-not always fast and needs oxygen
Primary sources of fuel for aerobic ATP production:
-fat
-carbohydrates
What is not a primary energy source for contracting muscle?
protein
Which is the more efficient fuel source for aerobic ATP production?
fat
Fat is…
-the most efficient source
-the most abundant source
Where is fat stored?
-some in muscle cells
-some in adipose tissue
What are fats stored as?
triglycerides
What is broken down in fats to produce ATP?
fatty acids
The process of aerobic ATP production with fat is relatively…
slow
What is the storage form of carbohydrates in the body?
gycogen
Where is glycogen stored?
-in the muscle cells
-in the liver
What is glycogen broken down to?
glucose
Glycogen stores are ______ ______ compared to fat stores
very small
Blood glucose fuel source for aerobic ATP production
muscle cells can take up glucose from the bloodstream for ATP
Sources of blood glucose
-food (primarily starches and sugars)
-liver glycogen
-gluconeogenesis in the liver
Anerobic (glycolytic) metabolism can only use _______ in ATP production
carbohydrates
Anaerobic (glycolytic) metabolism:
-not as efficient
-fast
-oxygen not needed (muscles don’t need to be warmed up yet)
-accumulation of H+ can lead to fatigue
Anaerobic (glycolytic) metabolism produces what with ATP from glucose?
lactic acid
What determines which energy system is used?
-oxygen availability
-activity
-fiber type
-training
Draft horses pulling heavy loads would use which ATP production system?
stored ATP and creatine-P
Endurance horses would use which ATP production system?
most aerobic metabolism
Racehorses would use which ATP production system?
aerobic and anaerobic metabolism (anaerobic allows the extra speed past what aerobic provides)
Muscle fiber types:
Type I, Type IIA, and Type IIX
Postural muscles are more of which fiber type?
more type I (don’t have to contract fast)
Driving muscles are more of which fiber type?
more type II (more exercise associated)
Fiber type distribution in breeds
it involves some genetics:
-arabians have more type I and type IIA
-quarter horses have more type IIA and type IIX
Type I muscle fibers
Fatigue resistant because:
-slow contraction (“slow-twitch”)
-red fibers (high in myoglobin)
-narrow diameter (better nutrients in/out)
-high blood flow
-many mitochondria (where a lot of ATP is produced)
-relatively high in fat (very aerobic, can utilize the fat)
-relatively low in glycogen
Type IIA muscle fibers
Moderately fatigue resistant because:
-fast contraction speed (“fast-twitch”)
-red fibers (moderate in myoglobin)
-medium diameter
-good blood flow
-moderate mitochondria
-medium in fat
-medium in glycogen
-function mostly aerobic
-can produce ATP anaerobically
Type IIX muscle fibers
NOT fatigue resistant because:
-fast contraction speed (“fast-twitch”)
-white fibers (low in myoglobin)
-largest in diameter (nutrients harder to get in/out)
-less blood flow
-fewer mitochondria
-low in fat
-high in glycogen
-mostly anaerobic
-have high buffering capacity (better able to deal with lactic acid)
What muscle fiber is mostly recruited for low intensity exercise?
type I
What muscle fiber is mostly recruited for high intensity exercise?
type IIX
Muscle fiber type recruitment:
1.) type I - will still be used as exercise intensity increases
2.) type IIA - continues to be recruited
3.) type IIX - all the muscle fibers are recruited now
Effects of training on the respiratory system
minimal effects
Effects of training on the cardiovascular system
-max HR is not changed
-stroke volume may increase
-increased capillary density in muscles (increases blood flow-increases O2)
With training, VO2 max _______
increases
-horses can exercise for a longer period of time
With training, horses use _______ more efficiently
O2
-do the same work but use less oxygen
Effects of training on muscle:
-increase in aerobic metabolism (use more fat and spare carbs, produce less lactic acid)
-increase in muscle glycogen concentrations (more substrate available for ATP synthesis)
-increase in intracellular buffering (can tolerate more lactic acid production)
With training less _______ is produced at any given intensity
lactate
With training horses use less _______ because…
glycogen because they’ll be using more fat
