Stimuli and Responses Flashcards
what are semi-lunar valves?
- one way valves
- open when pressure greater in ventricles than blood vessels
what are purkyne fibres?
electrical impulses that cause ventricles to contract from base up
what are atrioventricular valves?
- one way valves
- open when pressure higher in atria than ventricles
what does non-conducting tissue do?
stops electrical impulse from SAN reaching ventricles
define tropism?
response of plant to directional stimulus
how do plants repond to stimuli?
using growth factors/hormones
(INDOLEACETIC ACID)
where is IAA found and what does it promote?
- growing regions (shoot tips)
- cell ELONGATION
how do auxins move long and short distances?
- short distances - diffusion and AT
- long distances - via phloem
phototropism in shoots?
- IAA accumulates in shaded side of shoot
- IAA causes cell elongation in shaded side
- shoot grows towards light
phototropism in roots?
- IAA accumulates in shaded side
- IAA inhibits cell growth on shaded side
- root grows away from light
gravitropism in shoots?
- IAA moves to underside
- IAA causes cell elongation on lower side
- shoot moves away from gravity
gravitropism in roots?
- IAA moves to underside
- IAA inhibits cell growth on lower side
- root grows towards gravity
high blood o2, low CO2, high pH?
- chemoreceptors detect high blood pressure, low CO2, high pH
- receptors send nerve imp to medulla oblongata
- medulla sends imp along parasympathetic neurones
- parasympathetic neurones secrete ACh
- heart rate slows down
high blood pressure?
- baroreceptors detect high blood pressure
- receptors send imp to medulla
- medulla sends imp along parasympathetic neurones
- parasympathetic neurones secrete ACh
- heart rate slows down
low blood o2, high blood co2, low pH?
- chemoreceptors detect low blood o2, high blood CO2, low pH
- receptors send nerve imp to medulla
- medulla sends imp along sympathetic neurones
- sympathetic neurones secrete noradrenaline
- heart rate speeds up
low blood pressure?
- baroreceptors detect low blood pressure
- receptors send nerve imp to medulla
- medulla sends imp along sympathetic neurones
- sympathetic neurones secrete noradrenaline
- heart rate speeds up
what is the pascinian corpuscle?
a receptor that detects pressure, touch and vibrations in skin
stimulation of pascinian corpuscle?
- pressure causes lamellae to stretch and deform
- stretch mediated sodium ion channels open
- sodium ions diffuse into memb
- greater stimulus, more sodium ion channels open
- depolarisation
- if threshold reached - AP initiated
what is depolarisation of neurone?
generator potential
control of heart rate?
- SAN initiates heart beat
- sends electrical imp across atria
- atria contract
- non-conducting tissue prevent electrical imp reaching ventricles
- AVN delays electrical imp
- allows atria contract and empty before ventricles contract
- AVN sends imp along bundle of his and purkyne fibres
- ventricles contract from base up
left ventricle?
- highest blood pressure
- most cardiac muscle - contracts with greatest force
- pumps blood to whole body
atrial systole?
- atria contract
- ventricles relax
- AV valves open
- SL valves close
ventricular systole?
- atria relax
- ventricles contract
- AV valves close
- SL open
diastole?
- atria and ventricles relax
- AV valves open
- SL valves open