Topic G - Coordination & Response Flashcards
how do organisms respond to changes in their surroundings
Tropisms
what tropism detects light
phototropism
what tropism detects moisture ( water)
hydrotropism
what tropism detects gravity
geotropism
in what direction of growth do shoots grow ( 2 things )
- towards light = +ve phototropism
2. away from gravity = -ve geotropism
in what direction of growth do roots grow ( 2 things )
- towards moisture = +ve hydrotropism
2. towards gravity = +ve geotropism
what are the 5 steps to co-ordinated/ reflex arc response
- stimulus =change in enviroment
- Receptor= sensor organs (nerve ending)
- Co-ordinating centre = brain + spinal chord
- Effector = muscle
- Response = movement
what is homeostasis
maintenance of constant internal enviroment
what are examples of homeostasis
body water content
body temperature
what do plants respond to
stimuli = light, heat, moisture
what is auxin
plant hormone that controls growth
where is auxin produced
in the shoot tips
what does auxin increase and decrease
increases growth in shoots
decreases growth in roots
how does auxin work in response to light
auxin accumulates on the dark side= growth on that side= bend towards light
what are 2 parts of the central nervous system and what are they linked to and how
brain + spinal chord
link to sense organs by nerves
what does stimulation of receptors in sense organs do
sends electrical impulse along nerves into and out of central nervous system= rapid responses ( reflex)
- what do synapses do
2. what do neurotransmitters (chemicals ) do at the synapse
1.connect neurons (connection between 2 neurons =synapse)
- transfers nerve signals by diffusing across the gap
+ set of new a new electrical signal in the next neurone
describe process of reflex arc - removal of finger from a hot object
(CNS= central nervous system)
- stimulus = hot object
- receptors (skin) detect stimulus
- impulse sent along sensory neurone to the CNS
- in CNS impulses are passed along relay neurone (via a synapse)
- relay neurones relay impulse to a motor neurone
- impulse travels along motor neurone to the effector (muscle)
- muscle contracts + moves finger away from hot object
what is the eye and what does it do
receptor = major sense organ = detects light
how does the eye focus on distant objects
cilary muscles relax= suspensory ligament pulled tight= lens = less convex (flat) = refracts light by smaller amount
how does the eye focus on nearer objects
cilary muscles contract = smaller amount of space = suspensory ligament relax = lens = more convex (rounded) = refracts light by larger amount
function of iris
muscle which contracts or relax to change pupil size
how does eye react to bright light
circular muscles contract= radial muscles relax= pupil constricts( smaller )= lets less light in
how does eye react to dim/ no light
circular muscles relax = radial muscles contract = pupil dilates = lets more light in
What process can help us cool down when we are to hot
Vasodilation
sweating- when it evaporates it transfers energy from skin to the environment= cooler
How does vasodilation work
- Muscles relax widening entrance to capillaries.
- More blood flows through capillaries towards surface of skin
- Increased heat loss by radiation and reduction
What process helps to warm us up when to cold
Vasoconstriction
shiver + exercise = increase rate of respiration= transfers more energy to warm body
How does vasoconstriction work
- Muscles contract constricting entrance to capillaries.
- Very little blood flows through capillaries
- Reduced heat loss
How does hair on our body react when cold
- Hair muscles pull hairs on end.
- Erect hairs trap air.
- Blood flow in capillaries decreases.
How does sweating occur when hot
- Hair muscles relax. Hairs lie flat so heat can escape.
- Sweat secreted by sweat glands. Cools skin by evaporation.
- Blood flow in capillaries increases.
Describe differences in type of signal of nervous system ( N ) and hormonal system ( H )
- N = electrical
H = chemical
Describe differences in transmitting of signal ( how message sent ) of nervous system ( N ) and hormonal system ( H )
N = nerve cells. ( exocrine ) H= nerve cells in blood stream ( endocrine )
Describe differences in effectors of nervous system ( N ) and hormonal system ( H )
N = muscle or glands H = target cells in particular tissues
Describe differences in type of response of nervous system ( N ) and hormonal system ( H )
N= muscle contraction or secretion
H = chemical change
Describe differences in speed of response of nervous system ( N ) and hormonal system ( H )
N= very rapid
H= slower
Describe differences in duration of response of nervous system ( N ) and hormonal system ( H )
N= short ( until nerve impulses stops
H = long ( until hormone is broken down
Where is adrenaline found and what does it do
- Found in Adrenal gland
2. Prepares body for physical activity
Where is insulin found and what does it do
- Found in Pancreas gland
2. Lowers blood glucose
Where is testosterone found and what does it do
- In Testes gland
2. Controls development of male secondary characteristics
Where is progesterone found and what does it do
- In Ovaries
2. Regulates menstrual cycle
Where is oestrogen found and what does it do
- In Ovaries
2. Controls the development of female secondary sexual characteristics
PAPER 2
What 4 hormones are found in the Pituitary
- Follicle stimulating hormone ( FSH )
- Luteinising hormone ( LH )
- Anti - diuretic hormone ( ADH )
- Growth hormone ( GH )
PAPER 2
What is the role of the follicle stimulating hormone ( FSH )
Stimulates egg development and oestrogen secretion in females and sperm production in males
PAPER 2
What is the role of the luteinising hormone ( LH )
Stimulates egg release ( ovulation ) in females and testosterone in males
PAPER 2
What is the role of the anti - diuretic hormone ( ADH )
Controls water content of the blood
PAPER 2
What is the role of the growth hormone ( GH )
Speeds up rate of growth and development in children
what 3 things does a co-ordinated response require
stimulus
receptor
effector
