Coordination and response Flashcards
What does responding to the environment help organisms do?
Survive
What’s a stimulus?
Change in environment
What do receptors do?
Detect stimuli
What’s an effector?
cells which bring a response to stimuli
How do receptors and effectors communicate?
Via the central nervous system or hormonal system
What’s in the CNS?
Brain and spine
What does the CNS do?
Coordinates electrical impulses to the effectors, very fast responses
What’s a reflex?
An automatic response to prevent injury
What’s the reflex arc?
Stimulus occurs
receptor creates impulses down the sensory neuron
Impulses are passed along a relay neurone, via a synapse
Impulses travel along a motor neurone, via a synapse
When impulses reach effector the change occurs
Structure of the eye?
P45
Function of the conjunctiva?
lubricates and protects surface of the eye
Function of the cornea?
Refracts light into the eye, transparent and no blood vessels so oxygen diffuses in
Function of the iris?
Controls how much light enters the eye
Function of the lens?
Focuses the light on the retina
Function of the optic nerve?
carries impulses from receptor to the brain
What’s the iris reflex?
Bright light= pupil smaller so less light in to damage the retina
Dim light= pupil increases to let more light in to see
What happens when the eye focuses on a distant object?
Ciliary muscles relax, suspensory ligaments tighten
Making eyeball thinner, so light reflects onto retina
What happens when the eye focuses on a close object?
Ciliary muscles contract, suspensory ligaments slacken
Making eyeball fatter, so light reflects onto retina
What does it mean if your long sighted?
Can’t focus on near objects, due to light not being bent enough
What does it mean if yourshort sited?
Can’t focus on far objects, since light is bent too much
What are hormones?
Chemical messages sent in the blood
ADH source Role and effect?
Pituitary gland
Controls water content
Increases the permeability of the kidney
Adrenaline source Role and effect?
Adrenal glands
Readies body for fight or flight
Increases blood flow to muscles
Insulin source Role and effect?
Pancreas
Helps control blood sugar level
Stimulates the liver to turn glucose into the glycogen for storage
Testosterone source Role and effect?
Testes
Main male sex hormone
Promotes male secondary sexual characteristics
Progesterone source Role and effect?
Ovaries
Support pregnancy
Maintains the lining of the uterus
Oestrogen source role and effect?
Ovaries
Main female sex hormone
Controls menstrual cycle and promotes female secondary characteristics
Characteristics of nerves?
Very fast message
Act for a short time
Act on a precise area
Characteristics of hormones?
Slower message
Act for a long time
Act in a general way
What’s homeostasis
The maintenance of a constant internal environment
How is water lost in the body?
The skin as sweat
Lungs as breath
Kidneys as urine
Why is the body temp 37 degrees?
Optimal for enzymes, CNS triggers effectors to maintain this
What happens to the skin when your too hot?
Lots of sweat produced to evaporate and remove heat from the body
Vasodilation- blood vessels go closer to skin, so more heat is radiated away
Hairs lay flat
What happens to the skin you too cold?
Little sweat produced
Vasoconstriction, blood vessels move away from skin surface
Shiver to create heat
Hairs stand up
Why do smaller organisms cool down quicker?
Bigger surface area to volume ratio
How do plants respond o changes in environment?
Grow towards light to maximise photosynthesis
Sense gravity, so their roots grow in the right direction
Climbing plants have a sense of touch
How do plants respond to predators?
Produce toxins
How do plants respond the abiotic stress?
Produce antifreeze
What does auxin do?
Plant growth hormone which prevents growth in shoots, but causes growth in roots
How are shoots positively phototropic?
Auxin goes to the side of shoot in shade, causing it to grow towards the light, they also grow away from gravity
How are roots positively geotropic?
More auxin in lower side, causing it to grow downwards
