Coordination And Response Flashcards
Reflex pathway
- stimulus
- receptor
- sensory neurone
- relay neurone
- motor neurone
- effector
- response
Sclera
Tough white overcoating of the eye
Cornea
Front part of the sclera which is transparent and let’s light into the eye
Iris
Coloured ring of tissue which controls/varies the amount of light entering the eye
Pupil
Hole in the iris, allows light into the eye
Lens
Transparent structure which has flexible shape and focuses light onto the retina
Ciliary muscle
Ring of muscle which controls the shape of the lens for light focusing
Suspensory ligaments
Fibres that hold the lens in place (attached to the ciliary muscle)
Vitreous humour
Clear liquid that supports the spherical shape of the eye
Retina
Light sensitive layer and contains millions of light sensitive cells:
Rods - sensitive in low light intensities, and only detect black and white.
Cones - distinguish colour
Fovea
Area of high concentration of densely packed cone cells. Responsible for colour vision in humans.
Optic nerve
Carries nerve impulses from the rods and cones to the brain.
Blind spot
Where optic nerve leaves the retina. It contains no rods or cones
Choroid
Layer underneath the sclera. It is dark because it contains many pigment cells this stops light from being reflected around the eye. It is also packed with blood vessels
Conjunctiva
Thin epithelium continuous with the cornea
Nervous vs hormonal coordination
Nervous:
- electrical impulses
- transported along neurones
- short acting/lasting
- travel quickly
- specific effects : single sets of cells (localised)
Hormonal:
- chemical signals
- transported in the blood
- longer acting/lasting
- travel slowly (speed of blood)
- general effects on variety of organs (general)
Endocrine system
A collection of glands which release hormones into the blood
Hormone definition
Chemical messengers that travel in the blood
Homeostasis definition
The process of maintaining a constant internal environment
ADH
Function: water balance
Release from: pituitary gland
Insulin
Function: blood-glucose balance
Release from: pancreas
Adrenaline
Function: speeds up heart rate/ increase blood pressure
Release from: adrenal glands
Testosterone
Function: secondary sexual characteristics
Release from: testes
Progesterone
Function: maintains uterus lining
Release from: ovary
Oestrogen
Function: builds up uterus lining, secondary sexual characteristics
Release from: ovary
4 homeostasis processes
Temperature-> thermo regulation
Blood sugar level -> glucoregulation
Body water content -> osmoregulation
Salts/ions -> osmoregulation
Nervous system
- central nervous system (CNS) made of brain and spinal cord, electrical signals travel along neurones attached by synapses.
- peripheral nervous system (PNS)
Reflex pathway
Involuntary
Only involve spinal cord
Faster
Reason for reflex
To prevent damage
What is a tropism
It is a plants growth response to a stimuli
Phototropism
- a growth in response to light
- positive or negative
- the shoot is positively phototropic - grow towards light
Geotropism
- a growth in response to gravity
* plants shoot is negative, plants roots are positive
How are tropisms in plants controlled
by plants hormones called auxin
Auxin in shoots
- produced in tip
* diffuses away from the tip, down the stem and stimulates cell elongation (not the growth of more cells)
How do auxins work
They move towards the shaded part of a shoot and elongate those cells
Auxin in roots
- produced in root tip
* auxin INHIBITS cell elongation in the tip allowing it to grow down into soul for water and to act as a anchor
What happens to the iris in bright light
- circular muscles contract
- radial muscles relax
- pupils constricts
What happens to the iris in dim light
- circular muscles relax
- radial muscles contract
- pupils dilates
Focusing on a nearby object
Light rays diverging so lens needs to refract light more
- Ciliary muscles contract
- Suspensory ligaments slack
- Lens more rounded
Focusing in a distant object
Parallel light rays so no need to refract light as much
- Ciliary muscles relax
- Suspensory ligaments pulled tight
- Lens flattens
Blood sugar level control
Normal blood sugar level -> too much glucose in blood -> pancreas -> hormone insulin -> liver (glucose to insoluble glycogen) -> normal blood sugar level
Maintaining temperature in cold
- hair erector muscle contract to lift hair up, traps a layer of insulating air
- no sweating
- vascoconstriction of blood vessels near surface
Maintaining temperature in warm
- hair erector muscle relaxes to allow hairs to flatten
- sweat produced; evaporation allows heat to be transferred away from body
- vasodilation of arterioles near body surface to allow heat within blood to be removed
Osmoregulation: negative feedback loop
- Water level rise by the hypothalamus in brain
- stimulates the pituitary gland to stop releasing ADH
- less ADH travels in blood to kidneys, and so the collecting duct becomes less permeable to water - less water is reabsorbed into blood stream.
