Topic 5 - Homeostasis and Response Flashcards
(33 cards)
What happens to the eye in a bright light?
Light receptors in the eye detect bright light
reflex is triggered to make the pupil smaller (avoid damage)
Circular muscles in the iris contract
radial muscles relax
What happens to the eye in dim light?
Circular muscles relax
radial muscles contract
makes the pupil wider (more light enters)
To look at near objects
Ciliary muscles contract which loosens the suspensory ligaments
The lens becomes more curved
Increases amount of light refracted
To look at distant objects
Ciliary muscles relax which tightens the suspensory ligaments
The lens becomes less curved
Decreases amount of light refracted
What problems do long-sighted people have?
Lens is the wrong shape and doesn’t refract the light enough
Eyeball is too short
Images of near objects are focused behind the retina
What lens is used to correct long-sightedness?
Convex lens (curves outwards) Refracts light rays onto the retina
What problems do short-sighted people have?
lens is the wrong shape and refracts too much light
Eyeball is too long
Images of distant objects are focused in front of the retina
What lens is used to correct short-sightedness?
Concave lens (caves inwards) Makes light rays focus on the retina
What are the 3 treatments for vision defects?
Contact lenses
Laser eye surgery
Replacement lens surgery
Excess glucose is stored as
glycogen
When blood glucose levels are too high
Insulin is secreted from the pancreas
insulin makes the glucose turn into glycogen
blood glucose is lowered
When blood glucose levels are too high
Glucagon is secreted from the pancreas
Glucagon makes the liver turn glycogen into glucose
Blood glucose levels are increased
How do the kidneys make urine
Take waste products from the blood
What is the process when substances are filtered out of the blood as they pass through the kidney
filtration
What is the process called in which useful substances are absorbed into the blood
selective reabsorption
What 3 substances are removed from the body and is in urine
Urea
Ions
Water
Urea
Proteins can’t be stored in the body so they are converted into fats and carbohydrates which can be stored
occurs in the liver
process is called deamination
How are ions taken into the body?
Consumption of food
What happens if the ion/water content in the body is wrong?
Disrupt balance between ions
too much/little water is drawn into cells by osmosis
Damage cells/don’t work efficiently
How are ions lost
Sweating
Is the amount of ions lost regulated?
No
maintained by the kidneys
Right amount of ions are reabsorbed by the kidney
The body has to _ _ _ _ _ _ _ _ _ _ / _ _ _ _ _ _ the water coming in against the water going out
constantly balance
2 ways water is lost
Water is lost from the skin by sweating
Water is lost from the lungs when exhaling
Can you control the ways water is lost
No
Balanced by the amount we consume
and the amount removed by the kidney
