animal responses Flashcards
what is a reflex?
what does the reflect travel to?
what are the two reflexes?
-where the body responds to a stimulus without making a conscious decision to respond because the pathway of communication does involve conscious parts of the brain
-from receptors to effects and is rapid to avoid damage
-blinking reflex and knee-jerk reflex
describe the blinking reflex-
-sensory nerve ending in the cornea (front of eye) are stimulated by touch
-a nerve impulse is sent along the sensory neurone to a relay neurone in the CNS
-the impulse is then passes from the relay neurone to motor neurones
-the motor neurones send impulses to the effectors = the Orbicularis Oculi muscles that move your eyelids
-these muscles contract causing your eyelids to close quickly and prevent your eye from being damaged
describe the knee-jerk reflex-
-stretch receptors in the quadriceps muscle detect that the muscle is being stretched
-a nerve impulse is passed along a sensory neurone in the spinal cord (there is no relay neurone involved)
-the motor neurone carries the nerve impulse to the effector (the quadriceps muscle) causing it to contract so the lower leg moves forward quicker
what do both synapses respond to?
-danger in order for survival
describe the fight or flight response-
-the autonomic nervous system detects the potential threat, sending an impulse to the hypothalamus
-resulting in more impulses being transmitted along the sympathetic nervous system and the adrenal-cortical system
-the effectors are the adrenal glands, which will release more adrenaline and noradrenaline
-the release of these hormones triggers the hypothalamus to stimulate the release of adrenocorticotropin hormone (ACTH) from the pituitary gland
describe the action of the endocrine system if glucose is low-
-adrenaline, the first messenger, attaches to receptors on the surfaces or target cells (liver)
-this causes the enzyme adenylyl cyclase to change shape and become activated
-activated adenylyl cyclase catalyses the conversion of ATP to the second messenger molecule cyclic AMP (cAMP)
-cAMP binds to protein kinase A enzymes, activating them
-active protein kinase A enzymes initiate a series of enzymes activations that result in the breakdown of glycogen to glucose = this process is known as glycogenolysis
EFFECTS OF HEART RATE-
what is the cardioregulatory centre in the brain?
what two distinct parts is the medulla made up of?
what are both centres connected to?
-the medulla
-the acceleratory centre, which causes the heart to speed up
-the inhibitory centre, which causes the heart to slow down
-the sinoatrial node (SAN) by nerves that are part of the autonomic nervous system.
what causes acceleratory and inhibitory centres to be activated?
what can the internal stimuli be detected by?
what do these receptors do?
what do lower frequency impulses activate?
what do higher frequency impulses activate?
-exercise causes several internal conditions to change, creating internal stimuli:
•carbon dioxide concentration in the blood increases
•there is an initial fall in blood pressure caused by the dilation of muscle arterioles
-chemoreceptors and pressure receptors located in the aorta and the carotid arteries
-release nerve impulses that are sent to the acceleratory and inhibitory centres
-the inhibitory centre to slow down the heart rate
-the acceleratory centre to speed up the heart rate
once the acceleratory area has been activated, what are impulses sent along?
what is secreted at the synapse with the SAN?
what does it cause?
resulting in?
-the sympathetic neurones to the SAN
-noradrenaline is secreted at the synapse with the SAN
-noradrenaline causes the SAN to increase the frequency of the electrical waves that it produces
-increased heart rate
once the inhibitory centre has been activated, impulses are sent along?
what is secreted at the synapse with the SAN?
what does this neurotransmitter cause?
resulting in?
-the parasympathetic neurones to the SAN
-Acetylcholine is secreted at the synapse with the SAN
-acetylcholine neurotransmitter causes the SAN to reduce the frequency of the electrical waves that it produces
-reduces the elevated heart rate towards the resting state
endocrine system controlling heart rate-
what is a gland?
what two hormones are secreted by the adrenal glands and what do they do?
what hormone secreted by the thyroid gland? what does it do?
-a group of cells that produces and secrets one or more substances
-noradrenaline and adrenaline both cause an increase in heart rate
-thyroxine causes and increase in heart rate
how to test heart rate?
-use a heart rate monitor to record the heart rates of each individual at rest
-run on the spot for 30 seconds
-measure heart rate while running
-then measure the heart rate after running
what are the 3 types of muscle found within mammals?
-skeletal
-smooth
-cardiac
skeletal muscle-
what is it also called and what does it allow?
structure?
what is the cell membrane of the muscle fibre called?
what does this have?
what are these folds called? and what do they do?
what is the sarcoplasmic reticulum?
what do muscle fibres have?
contract?
-also called striated muscle (stripy)
-allows movement of the skeleton
-cylindrical, multinucleate, full of mitochondria to provide ATP needed for muscle contraction
-sarcolemma
-the sarcolemma has bits of it that are folded inwards across the muscle fibre and stick into the sarcoplasm
-Transverse tubules (T-tubules), they help to spread electrical impulses throughout the sarcoplasm so they reach all parts of the muscle fibre
-a network of internal membranes that runs through the sarcoplasm, it stores and releases calcium ions that are needed for muscle contraction
-lots of long, cylindrical organelles called myofibrils made up of proteins
-fast = used for speed and strength = fatigue quickly
-slow = used for endurance and posture = fatigue slowly
myofibrils-
where are they located?
what does each myofibril contain?
what are thick filaments made of?
what are thin filaments made of?
looking at a myofibril under the microscope, what are the dark and light bands?
what are the many short units called that make up a myofibril?
-in the sarcoplasm
-two types of protein filament that move past each other to make the muscle contract:
•thick filaments made of myosin
•thin filaments made of actin
-myosin
-actin
-dark bands contain thick myosin filaments and some overlapping thin actin filaments = called A bands
-light bands contain thin actin filaments only = called I bands
-sarcomeres
myofibril-
what are the ends of each sarcomere marked with?
what is in the middle of each sarcomere?
what is around the M line?
draw the pic and table-
-a Z line
-an M line and it is the middle of the myosin filaments
-the H zone
smooth (involuntary) muscle-
what control is it?
what does it have?
does not have?
what does each muscle fibre have?
what shape are the muscle fibres?
do they fatigue?
-unconscious control of body parts eg. gut and airway movements
-contains both actin and myosin
-does not have any banding or striation
-one nucleus = mono nucleate
-spindle shaped with pointed ends and only about 0.2mm long
-they contract slowly and fatigue
cardiac muscle-
where?
what is the heart’s electrical impulse?
does it fatigue?
what is it made of?
what are the the muscle fibres?
how many nucleus’s does each muscle fibre have?
what can you also see some of?
fatigue?
ATP?
-in the walls of the heart
-it is myogenic so can contract without external stimulation through the autonomic nervous system
-it doesn’t tire or fatigue so can contract continuously
-large number of mitochondria for continuous contraction
-muscle fibres connected by intercalated discs which have low electrical resistance so nerve impulses pass easily between cells
-branched to allow nerve impulses to spread quickly through the whole muscle
-one nucleus and the muscles fibres are cylindrical
-some cross-striations
-muscle fibres contract rhythmically and don’t fatigue
look at book to see microscope
transmission across a neuromuscular junction-
4 important things?
describe-
- striated muscle contracts when it receives an impulse from a motor neurone via the neuromuscular junction
- neuromuscular junctions work in similar ways to synapses
3.located between a neurone and a muscle cell - CAN ONLY BE EXCITATORY
-when an impulse travelling along the axon of a motor neurone arrives at the pre-synaptic membrane, the action potential causes an influx of calcium ions to diffuse into the neurone
-this stimulates vesicles containing acetylcholine to fuse with the presynaptic membrane
-acetylcholine is released and diffuses across the neuromuscular junction and binds to cholinergic receptors on post-synaptic membrane (sarcolemma).
-this stimulates ion channels in the sarcolemma to open allowing sodium ions to diffuse in
-this depolarises the sarcolemma, generating an action potential that passes down the T-tubules towards the centre of the muscle fibre
-action potential causes voltage-gated calcium ion channels in the membranes of the sarcoplasmic reticulum to open
-calcium ions diffuse out of the sarcoplasm reticulum and into the sarcoplasm surrounding the myofibrils
-calcium ions bind to troponin molecules stimulating them to change shape
-causing the troponin and tropomyosin proteins to change position on the actin filaments
-the myosin binding sites are exposed to the actin molecules
-the process known as the sliding filament model can now start
structure of thick filaments/myosin in a myofibril-
structure?
binding sites?
-fibrous proteins with globular heads that are hinged so they can move back and forth
-each myosin head has a binding site for actin and a binding site for ATP
-their globular heads all point away from the M line
structure of thin filaments (actin) within a myofibril-
structure?
binding sites?
what is also found?
what do they form?
-globular protein molecules
-actin filaments have binding sites for myosin heads, called actin-myosin binding sites
-two other proteins called tropomyosin and troponin are found between actin filaments. these proteins are attached to each other and they help myofilaments move past each other
-two actin chains that twist together to form one thin filament
what happens to binding sites in treating muscle?
so?
-in resting/unstimulated muscle, the actin-myosin binding site is blocked by tropomyosin, which is held in place my troponin
-so myofilaments can’t slide past each other because the myosin heads can’t bind to the actin-myosin binding site on the actin filaments.
describe the sliding filament theory-
-nerve impulse arrives at the neuromuscular junction
-calcium ions are released from the sarcoplasmic reticulum into the sarcoplasm by diffusion
-calcium ions bind to troponin molecules stimulating them to change shape and shift their position of the troponin and tropomyosin
-this exposes the myosin binding sites in the actin filaments
-myosin heads bind with myosin binding sites on the actin filament, forming cross-bridges
-when the myosin heads bind to the actin, known as a power-stroke, a molecule of ADP and Pi are released
-the myosin changes shape
-the myosin head nods forward
-the actin moves over the myosin
-an ATP molecule binds to the myosin allowing it to detach from the actin
-an ATPase on the myosin head hydrolyses the ATP, forming ADP and Pi
-the energy released from this allows the myosin head to return to it’s original position
-the myosin head can now bind to a new binding site on the actin filaments
