Chapter 14: Coordination and response Flashcards
Define nerve impulse:
an electrical signal that passes along nerve cells called neurons.
What does the human nervous system consist of?
- central nervous system (brain and spinal cord)
- peripheral nervous system (nerves that connect to CNS)
- coordination and regulation of bodily functions
Order of reaction of a reflex arc:
stimulus – receptor – sensory neuron – spinal cord – motor neuron – effector – response
define synapses:
a junction between two neurons
How do synapses work?
- stimulus triggers the release of chemical
- neurotransmitter is moved to end and released into gap
- chemical neurotransmitter diffuses across gap
- receptor binds to neurotransmitter
- starts the electrical signal in next neuron.
Define sense organs:
a group of receptor cells responding to specific stimuli.
function of cornea:
refracts light in eye
Function of iris:
controls how much light enters pupil
Function of lens:
focus light onto retina
Function of retina:
contains light receptors, cones (sensitive to colour) and rods (sensitive to light)
Function of optic nerve:
carries impulses to brain
What happens to the pupil of the eye in a high light intensity?
pupil gets smaller
circular muscles contract
radical muscles relax
What happens to the pupil of the eye in a low light intensity?
pupil gets bigger
circular muscles relax
radical muscles contract
What happens to the lens, ciliary muscle and suspensory ligament in the eye when looking at an object a far distance away?
lens: thin
ciliary muscle: relaxed
sensory ligament: tight
What happens to the lens, ciliary muscle and suspensory ligament in the eye when looking at an object that is nearby?
lens: thick
ciliary muscle: contracted
suspensory ligament: loose
Define hormone:
The chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs.
adrenaline source, role and effect:
source: adrenal glands
role: fight or flight response
effect: raises heart and breathing rate and dilates pupils
insulin source and function:
source: pancreas
function: lower blood glucose levels by converting it into glycogen in the liver
Define homeostasis:
the control of internal conditions within set limits
What happens when blood glucose levels get too high?
insulin is released from pancreas and glucose is taken up and made into glucagon in liver
What happens when blood glucose levels get too low?
glucagon is released from liver and it is broken down into glucose.
Symptoms of type 1 diabetes?
- very thirsty
- urinate a lot
- loose weight
- lots of glucose in urine
Treatment of type 1 diabetes?
carefully regulate diet
get regular injections of insulin
What does the brain do when our body temperature gets too low?
shunt vessels take blood away from skin surface (VASOCONSTRICTION)
sweat production stops
shivering instituted to use more energy
What does the brain do when our body temperature gets too high?0
arterioles in skin widen so blood is close to skin surface and looses heat to surroundings (VASODILATION)
sweat production increases to loose heat by evaporation
How does a synthetic plant hormone 2.4-D affect weeds?
It speeds up there growth and respiration so much that it uses it’s resources too quickly and dies.
