Animal Responses Flashcards
Outline the process of muscle contraction
Action potential from motor neurone arrives @ muscle cell
AP propagated along sarcolemma & down t-tubules - triggers voltage gated receptors in sarcoplasmic reticulum ; Ca2+ ions released into sarcoplasm
Ca2+ binds to troponin causing it to change shape; moving tropomyosin out of the actin-myosin binding site
Globular myosin head binds to actin-myosin binding site so form actin-myosin cross bridge, sliding the actin filament along to the centre of the sarcomere
what is Central Nervous System composed of?
brain & spinal cord; relay neurones & cell bodies of motor neurones
what is the peripheral nervous system composed of?
sensory neurones & axons of motor neurones
(sensory system & motor system)
tip: peripheral means edge
what 2 categories are the PNS motor neurones divided into?
somatic; conscious control (voluntary)
&
autonomic; unconscious control (involuntary) eg intestinal smooth muscle contractions
where do autonomic motor neurones carry nerve impulse from and to?
CNS to the:
cardiac muscle / smooth muscle in gut / blood vessels / glands / bladder
difference between somatic and autonomic motor neurones
somatic are myelinated
what 2 categories can the autonomic nervous system be split into?
sympathetic; involves noradrenaline- fight or flight response to threatening conditions
&
parasympathetic; involves acetylcholine; relaxed response maintaining suitable state for non-threatening conditions
where is the cerebrum located in the brain & what does it control?
involved in 'higher' brain activities - conscious thoughts - emotional responses - intelligence decision-making, judgement - factual memory -overriding reflexes
where is the medulla oblongata located in the brain & what does it control?
in brainstem @ top of spinal cord
- controls involuntary responses (autonomic); various centres for: heart rate, breathing rate, digestive system(smooth muscle movements in gut), blood pressure
where is the hypothalamus located in the brain & what does it control?
controls autonomic nervous system & endocrine glands (eg. releases hormones that control pituitary gland)
- homeostatic control (eg. temp, osmoreg)
where is the pituitary gland located in the brain & what does it control?
endocrine gland under the hypothalamus; controls endocrine system
outline the corneal blink reflex pathway
- 5.
outline the corneal blink reflex pathway
- sensory neurone in cornea stimulated, which enters the pons (area of brainstem)
- relay neurone
- motor neurone
- effector = eyelid muscle; contracts
where is the cerebellum located in the brain & what does it control?
underneath cerebrum (tip; belly)
- muscle coordination (memory)
- balance
- posture control
what stimulates the blink reflex ?
sudden movements close to eye
foreign object touching eye
loud sounds
what is a reflex arc
the nerve pathway involved in a reflex action
why is the knee jerk reflex described as a spinal reflex?
nervous pathway passes through spinal cord rather than brain
outline the knee jerk reflex pathway
only involves 2 neurones: sensory neurone –> motor neurone
- tapping patella kneecap stretches the quadriceps muscles
- 4.
what is the role of ATP in muscle contraction
part of the myosin head acts as an ATPase; converts ATP–>ADP + Pi, releasing energy
- myosin head binds to actin filament; actin-myosin cross bridge forms
- myosin head moves (tilts backwards), causing the actin filament to slide past the myosin filament
- after the power stroke, another ATP binds to myosin head; BREAKS the cross-bridge
- myosin head returns to original position (slides forward), as ATP is hydrolysed, energy is released for this movement to occur
- same process used for the myosin head to make a new cross-bridge further along the actin filament; sliding the actin further along the myosin
there is only enough ATP readily available in muscle tissue to support 1-2 secs of muscle contraction, how is the ATP regenerated to allow contraction to continue?
- Bohr effect draws more O2 from Hb into the blood, diffusing into the cell.AEROBIC RESP produces more ATP
- Anaerobic Resp generates ATP: but leads to lactic acid which is toxic if built up
- Creatine Phosphate in sarcoplasm = reserve of phosphate groups; which can be transferred to ADP quickly by creatine phosphotransferase to generate more ATP.
outline what happens at the neuromuscular junction
- AP arrives @ end of axon- opens Ca2+ channels in membrane so Ca2+ floods into the end of axon
- Ca2+ binds to Vesicles of acetylcholine; causes them to move towards & bind with fuse with plasma membrane
- Acetylcholine diffuses across gap & fuses with receptors on sarcolemma- opens Na+ channels , causing Na+ influx into muscle fibre- depolarises sarcolemma.
- wave of depolarisation spreads along sarcolemma & down transverse(t)tubules into the muscle fibre
Outline the basic reflex arc
- Receptor detects stimulus and creates an action potential in the sensory neurone.
- Sensory neurone carries impulse to spinal cord.
- Relay neurone connects sensory neurone to motor neurone in the brain or spinal cord.
- Motor neurone carries an impulse to the effector to carry out the appropriate response.
- Effector organ changes in response to stimulus to avoid harm.
