lec 8- Muscle and bones Flashcards
what are the two types of movement?
-Movement of entire animal relative to environment
-Movement of one part of the animals body relative to entire body
what does movement allow an animal to do?
seek food, water, shelter, mates, and avoid predators
what are voluntary muscles?
muscles that can respond to conscious thought and are stimulated by neurons in somatic division
what are involuntary muscles?
muscles that contract in response to unconscious electrical activity and are stimulated by neurons in the autonomic division
what are smooth muscle characteristics and what does it do?
are unbranched, tapered at each end, and often organized in thin sheets, lack sarcomeres, unstriated and involuntary. Essential to lungs, blood vessels, digestive system, urinary bladder, and reproductive system
what neurotransmitter stimulates stomach contractions?
Acetylcholine
which neurotransmitters inhibit stomach contractions?
Sympathetic neurons release norepinephrine and glands release epinephrine which inhibit contractions
what are cardiac muscle characteristics and what does it do?
Contain sarcomeres and are striated, have branched structure and are directly connected end to end by intercalated discs which are important for heartbeat coordination and it is involuntary. Make up the walls of the heart and is responsible for pumping blood throughout the body
what acts as glue to stick intercalated discs together?
Desmosomes
what lets electrical signals to pass through the intercalated discs
Gap junctions
what do parasympathetic neurons secrete to slow down the heartbeat?
acetylcholine
what do sympathetic neurons secrete to speed up the heartbeat?
norepinepherine and epinephrine
what is a cardiomyocyte?
a contractible heart cell
what happens during the plateau phase in a cardiomyocyte?
calcium influx, calcium channel opens allowing complete contraction
what are skeletal muscle characteristics and what does it do?
Exceptionally long, unbranched, multinucleate muscle fibres, voluntary, striated, result from the fusion of multiple cells. Allows movement of an organism
what are myofibrils made of?
many sarcomeres
do skeletal muscles exert a force?
yes, that is how we move
what are skeletal muscles stimulated by?
somatic motor neurons, damage to them results in paralysis
what are the three types of skeletal fibres?
Slow muscle fibres, fast muscle fibres, and intermediate muscle fibres
explain slow, fast, and intermediate muscle fibres
-Slow muscle fibres-
Appear red due to presence of iron bound with oxygen in myoglobin which stores oxygen, contract slowly due to myosin hydrolyzing ATP at a slow rate and fatigue slowly due to big stream of ATP from mitochondria via aerobic respiration
-Fast muscle fibres-
Appear white due to low myoglobin, contract rapidly due to myosin hydrolyzes ATP at a fast rate, fatigue fast because main source of ATP is glycolysis
-Intermediate muscle fibres-
Appear pink or red, contractile properties vary but intermediate between slow and fast fibres, obtain ATP from glycolysis and aerobic respiration
can humans increase density of mitochondria and myoglobin enabling increased performance?
yes, but not slow or fast muscle fibres
what are the two types of muscle arrangements and what do they do?
Parallel- small force, large length change
Pennate- large force, small length change
what are the three types of skeletal systems and what do they do?
Hydrostatic system- use hydrostatic pressure of enclosed body fluids to support body
Exoskeletons- have rigid structures on the outside of body, apodemes are the ingrowth where muscles attach
Endoskeletons- have rigid structures inside the body, change shape by changing joint angles
what is cartilage?
cells scattered in a gelatinous matrix
what is a ligament?
bands of fibrous tissue that connect bones to bones
what is a tendon?
fibrous connective tissue that connects bone to skeletal muscle
what are osteoblasts and osteoclasts and what they do?
Osteoblasts- secrete extracellular matrix that builds bone
Osteoclasts- reabsorb bone by secreting acid
what are osteogenic cells and osteocytes and what do they do?
Osteogenic cells- develop into osteoblasts
Osteocytes- secreted matrix of osteoblast calcifies and becomes osteocytes after conformational change, most common bone cell
what is osteoporosis?
Osteoporosis is a disease that makes bones brittle
