Human Musculoskeletal Anatomy Flashcards
What is the Epimysium?
protective sheath/layer, from friction against other muscles/bones
What is the Perimysium?
connective tissue
What is the Fascicle?
bundle of muscle fibres
WHat is the Endomysium?
fibrous connective layer of tissue, insulates each muscle fibre
What is a muscle fibre?
long, cylindrical, multi-nucleate muscle cell
What is a myofibril?
bundles of proteins (actin and myosin) important in muscle contraction
is long cylindrical organelle within muscle fibre
What is the sarcolemma?
muscle fibre cell membrane
What is the sarcoplasm?
fluid (cytoplasm) contains glycogen and fats for energy and mitochondria for production
What is a tendon?
connective tissue that attaches muscle to bone
What is a sarcomere?
repeating segments of a myofibril (smallest structure)
What are the 3 types of muscle?
cardiac, smooth, skeletal
What is cardiac muscle?
found in the heart, muscle is myogenic and is not under conscious voluntary control
What is smooth muscle?
found in gut and blood vessel lining. This muscle is neurogenic and is not under voluntary, conscious control
What is skeletal muscle?
attached to bone, is neurogenic and is under voluntary conscious control
What does neurogenic mean?
contraction initiated by a neurone
What does myogenic mean?
contraction initiated by the muscle itself
What 2 terms can muscle fibres be described as relating to abundance of nuclei?
Coenocytic and Syncytium
WHat does coencytic mean?
a cell that has lots of nuclei because he nucleus has divided by mitosis many times but the cell didn’t divide afterwards
What does syncytium mean?
the presence of many nuclei as a result of the fusion of many cells
What 4 proteins does the ultrastructure of myofibrils consist of?
actin, myosin, troponin, tropomyosin
What is actin?
thin, consists of 2 strands woven around each other. Form thin myofilaments
What is myosin?
thicker, consists of many rod-shaped filament tails with bulbous heads that project from the strand. Form thick myofilaments
What are small subsections of a myofibril called?
SARCOMERE
What does a sarcomere consist of?
z-line, I-band, H-zone, M-line, A-band, myosin, actin, zone of overlap
What is the z-line?
end points of a sarcomere, separating 2 sarcomeres
What is the H-zone?
zone consisting of only myosin
What is the I-band?
zone consisting of only actin
What is the M-line?
attachment site for the thick filaments (myosin)
What is the A-band?
centre of sarcomere contains both thick (myosin) and thin (actin) filaments, spans the H-zone
Where are the stores of glycogen in the body?
muscles and liver
Why do the muscles have a high glycogen store?
may need to respire rapidly during exercise
What stores can the muscles use for energy?
Glycogen - glucose store (large store)
Triglyceride - lipid store
Muscle tissue - protein store (causes some damage to muscles)
What happens in anaerobic respiration?
glycolysis only (without oxygen) produces lactate converted to lactic acid - provides a short release of energy
What is creatine phosphate?
made under aerobic conditions acts as a store of phosphate, as oxygen levels fall creatine phosphate enables the rapid conversion of ADP to ATP. only a very small amount can be stored
What does build up of lactic acid in the muscles cause?
fatigue and cramp
What are the 2 types of muscle fatigue?
neural and metabolic
What is muscle fatigue?
when muscle cannot contract/relax at correct time
decline of a muscle to generate force
WHat is neural fatigue?
nerves cannot generate an impulse
What is metabolic fatigue?
shortage of substances
accumulation of metabolites
lactate reduces the sensitivity of contractile proteins to Ca2+
What happens during sustained exercise (aerobic respiration)?
initially low ATP in muscles is used up quickly
creatine phosphate can then be used to phosphorylate ADP to replenish ATP (also short term)
Anaerobic respiration can produce limited ATP (net 2 ATP) but also produces lactate
Aerobic respiration must take over again due to lack of ATP and lactate build up
What is cramp?
severe involuntary contraction
How does the lactate production cause cramps?
lactate inhibits the Cl- ion effect - this means more likely to release Ca2+ and lactate allows K+ to enhance contraction
What are the features of Fast Twitch muscle?
fatigue rapidly
contract quickly, relax rapidly
store of glucose for glycolysis
anaerobic
low density of capillaries
high glycogen store
few mitochondria
high density of myofibrils
What are the features of Slow Twitch muscles?
Fatigue slower
contract slowly and for longer time
oxygen available even at low partial pressures
aerobic
good blood supply
have many mitochondria
low density of myofibrils
darker in colour
high concentration of myoglobin
What are the cells within the matrix of cartilage called?
chondrocytes
What do chondrocytes do?
responsible for cartilage formation, secrete an extracellular matrix containing elastic material and collagen
WHere are chondrocytes found?
in the matrix, within lacunae
WHat are lacunae?
spaces in the matrix
What is there none of in the matrix of cartilage?
no blood supply, so rely on diffusion from neighbouring blood vessels, metabolism really slow so repair takes a long time
What are the 3 types of cartilage?
Hyaline, Elastic, Fibro
Which cartilage is the weakest?
hyaline
Which cartilage is the strongest?
fibro
Where is hyaline cartilage located?
nose and ends of bones (to prevent friction)
Where is elastic cartilage located?
ear, epiglottis - elastic but maintains shape
WHere is fibro cartilage located?
intervertebral discs, ligaments - for loadbearing
Which cartilage has the highest proportion of collagen?
Hyaline
What does matrix of Elastic cartilage contain?
collagen, and also a network of elastic fibres
WHat does matrix of fibro cartilage contain?
collagen organised in dense fibres, organised in direction of stress, fewer chondrocytes
What is ossification?
process of bone formation by laying down of new bone
What happens to hyaline cartilage in the embryo?
it ossifies, osteoblasts secrete layers of bone matrix around the cartilage and blood vessels invade. In adults hyaline cartilage remains at ends of bones as articular cartilage.