hsc biology - mod 8 non-infectious disease

negative feedback loops

a system which maintains homeostasis through counteractive measuers

1. stimulus

2. receptor

3. control centre

4. effector

5. response

receptors

sensory cells which detect a stimulus

effectors

muscles, organs, glands which respond to the control centre which receives the stimulus from the receptor

control centre

the CNS which receives signals from receptors detecting stimuli

positive feedback loop

a system which responds to a stimuli by providing a response which amplifies the stimuli

e.g. birth

osmoregulation

homeostasis of the water content of blood to ensure optimal blood pressure.

osmoreceptors

receptors which detect water concentration

anti-diuretic hormone

chemical messenger released by the pituitary gland which communicates with the kidney to control water released into urine. the hypothalamus will detect the water concentration first

homeostasis

maintenance of an internal environment at a constant state despite external environments

•enzymes have specific conditions under which they can operate at an optimal level.

•outside these conditions enzyme activity decreases or can become denatured.

epidemiological studies

a scientific process of answering a question by using data from a population

pinna

outer ear: funnels in sound

external auditory canal

outer ear: funnels in sound toward the tympanic membrane

tympanic membrane

middle ear: also known as ear drum. a thin translucent membrane which vibrates according to the sound waves

malleus

middle ear: ossicle which beats like a hammer on the incus. serves to amplify sound waves

incus

middle ear: ossicle shaped like an anvil which beats on the stapes and amplifies sound. still kinetic energy

stapes

middle ear: ossicle shaped like a loop connected to the oval window. still kinetic energy

oval window

membrane that separates the

middle ear from the fluid-filled inner ear

round window

Vibration pass from the oval window into the upper canal of the cochlea and then through the lower canal to the ___. acts as a valve, relieving built-up pressure from the wave set up in the perilymph of the cochlea.

cochlea

inner ear: fluid filled structure composed of 3 canals. also a spiral structure containing hair cells which convert kinetic to electrical energy.

vestibule

contains vestibular nerve which carries impulses form the organ of balance to the brain

semicircular canals

detect movemnets of the head…

conjunctiva

epithelial cells on the eye for protection

cornea

first bending of light in the eye occurs here. protects eye. dome shaped and transparent. focuses light for clear vision.

aqueous humor

water + salt filled chamber in the front of the eye

iris

pigmented muscle which contracts and expands to control the size of the pupil.

lens

a biconvex clear hard flexible structure which bends light a second time to focus an image on the retina

suspensory ligaments

the string like ligaments which hold the lens

ciliary muscles

the muscles connected to the suspensory ligaments which control the elongation of the lens

vitreous humor

water filled chamber which holds the turgidity of the eye

sclera

the white tough part which encapsulates the eye

retina

part on the back of the eye composed of photoreceptors. this is where an image is received and flipped

macula

small, highly sensitive, central area of the retina at the back of the eye, responsible for sharp, detailed central vision, including reading, driving, and recognizing faces, as well as most color vision

fovea

part of the macula responsible for colour perception

myopia

short sightedness caused by an elongated eyeball. focused image falls before the retina

hyperopia

long sightedness caused by a short eyeball. focused image falls after the retina

photoreceptor cells

rod and cone cells located in the retina responsible for receiving focused light energy to convert into electrochemical impulses

rod cells

long cells which receive focused light distributed over most of the retina. absent in the fovea. contains visual pigment rhodopsin which is extremely sensitive to light

• 125 million

cone cells

pointed cells which receive focused light most densely found in the fovea in the macula. responsible for interpreting colour. contains iodopsins responsible for different wavelengths of light

cataracts

the clouding of a lens. causes blurred vision by reducing transmission of light. increased sensitivity to glare

macular degeneration

the degeneration of cells beneath the retina called retinal pigment epithelium. prevents light from being focused successfully. affects the ability to recognise faces + read

• leading cause of legal blindness. 50% of blindness in Aus is caused by this

• caused by lifestyle smoking, diet, uv exposure

spectacles

a physical lens used to bend light rays to fix hyperopia and myopia

convex lens

a lens shaped like an open mouth which bends light inwards to fix the focus point of hyperopia

concave lens

bends light outwards to diverge rays which would fall before the retina (myopia)

contact lenses

same principal as spectacles but adjusted to the curvature of the eye

cataract surgery

replacing the cloudy lens in an eye with an artificial one

LASIK surgery

reshaping a cornea with lasers to fix myopia or hyperopia

filtration

removing nitrogenous wastes and other water soluble wastes from the blood in the nephron

reabsorption

returning essential components to the blood. amino acids + vitamins + sodium ions etc

secretion

the removal of waste from the body. disposal of waste in the collecting duct through the urinary tract. urine formation

glomerulus

a network of capillaries in the nephron key in the first part of filtration. blood cells and proteins are retained in the blood while water and dissolved substances like amino acids diffuse through

bowman’s capsule

capsule which collects filtered plasma to begin making urine

afferent arteriole

the junction connecting the artery to the glomerulus

proximal convoluted tubule

part of the nephron where reabsorption of essential amino acids, water and ions occurs via active transport

distal convoluted tubule

part of the nephron where reabsorption occurs, connected to the collecting duct

loop of henle

where reabsorption occurs. descending = passive transport + osmosis

collecting duct

part of the nephron where urine begins to form (secretion). connected to the ureter

haemodialysis

when kidney function goes below 10% toxins build up requiring this technological process. requires dialysis machine and dialysate

1. blood flows through catheter through fistula

2. blood travels through fine fibres (semi-permeable membrane)

3. dialysate solution passes in the opposite direction

4. waste products diffuse down the concentration gradient

5. filtered blood returns to the arm