Animal responses Flashcards
what is a sarcomere?
short units that make up myofibrils
what are the 2 myofilament proteins and what sizes are they (thick + thin)?
actin (thin)
myosin (thick)
what is the H zone?
only myosin
what changes from a relaxed sarcomere to a contracted sarcomere?
the A band remains the same length but the H-zone and I band shorten
what marks the end of each sarcomere?
a z-line
what are dark bands?
myosin + actin filaments overlapping
what are light bands?
only actin filaments
describe the structure of skeletal muscle
skeletal muscle is made up of muscle fibres (large bundles of long cells) which consists of many myofibrils
what is the cytoplasm of a muscle cell called?
the sarcoplasm
what is the cell membrane of muscle cell fibres called?
the sarcolemma
what are the folds of the sarcolemma called?
t-tubules (transerve tubules)
what do t-tubules do?
help spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre
what is the sarcoplasmic reticulum?
a network of internal membranes that runs through the sarcoplasm
what does the sarcoplasmic reticulum store and release?
calcium ions
needed for muscle contraction
give 2 structural points of muscle fibres
they are multinucleate
they have many mictochondria
how do sarcomeres contract?
myosin and actin filaments slide over one another
describe the structure of myosin and actin filaments
myosin filaments have globular heads
actin filaments contain the proteins troponin and tropomyosin and have binding sites for myosin heads
in resting muscle, what is the state of the myosin binding sites on actin
they are blocked by tropomyosin
in muscle contraction, what do calcium ions bind to and what does this cause to happen?
Ca2+ ions bind to troponin which causes tropomyosin to move away from the actin-myosin binding site and expose it
what causes the cross bridge to break?
ATP binding to the myosin head
what are neuromuscular junctions?
synapses between neurones and muscles
what does the somatic nervous system control?
conscious activity
what does the autonomic nervous system control?
unconcious activity
what are the 2 subdivisions of the autonomic nervous system?
parasympathetic = calms body down (rest + digest)
sympathetic = gets body ready for action (fight + flight)
what neurotransmitter does the parasympathetic system release?
acetylcholine
what neurotransmitter does the sympathetic system release?
noradrenaline
cerebrum role
involved in vision, hearing, learning, thinking
cerebellum role
involved in muscle coordination, posture, balance
medulla oblongata role
controls breathing rate and heart rate
what is the pituitary gland controlled by?
the hypothalamus
the 2 reflex arcs we need to know
blinking reflex
knee-jerk reflex
what are baroreceptors and where are they located?
pressure receptors found in the aorta and the vena cava
what are chemoreceptors and where are they located?
chemical receptors found in the aorta, carotid artery and medulla
which muscles are voluntary/involuntary
skeletal muscle = voluntary
smooth muscle + cardiac muscle = involuntary
role of dendrites
to carry nerve impulses to the cell body
role of dendrons
to carry nerve impulses away from the cell body
what are the 2 types of synapse?
excitatory and inhibitory
what happens at an excitatory synapse?
neurotransmitters depolarise the post-synaptic membrane so an action potential is fired
what happens at an inhibitory synapse?
neurotransmitters hyper polarise the post-synaptic membrane so an action potential is prevented from being fired
