Bio diploma

inbreeding

inbreeding

causes alleles to become more or less frequent

gene flow

movement of alleles between populations

• immigration and emigration

Genetic drift

by chance results in nonadaptive changes

• founder effect

• bottleneck effect

founder effect

small number of individuals leave or are cut off from OG population

• creates new gene pool

bottleneck effect

population is reduced due to natural disaster

natality

births and immigration - increase population

mortality

death and emigration -decrease population

evolution

change in allele frequencies due to natural selection

genetic equilibrium

population is not evolving

• gene pool stability

hardy weinberg principle

1. no mutation (new alleles)

2. closed population

3. no natural selection

4. large population

5. random mating

mutations

change to Dna

• causes variation

pathway of sound

pinna → auditory canal → Tympanic membrane → ossicles → cochlea → organ of corti → auditory nerve → temporal lobe

cataracts

the lens starts to degenerate and become opaque

astigmatism

uneven curvature of part of the cornea. making light rays unable to meet the correct focal point

myopia

eyeball is elongated so light focuses in front of the retina

hyperopia

eyeball is short so light rays focus behind the retina

glaucoma

When the ducts that drain the aqueous humour in the eye get blocked. resulting in pressure build-up in the eye, and decolouration of cells

the 4 sensory receptors

thermoreceptors chemoreceptors photoreceptors mechanoreceptors

sensation

occurs when the neural impulses arrive at the cerebral cortex

perception

how the cerebral cortex interprets the meaning of the sensory information

sensory adaptation

the brain filters out redundant, insignificant information

photoreceptors

absorb light and allow us to sense different levels of light and shades of colour

chemoreceptors

is sensitive to chemical stimulation (taste, smell, and blood pH)

mechanoreceptors

responds to mechanical stimuli, such as that from pressure sound waves and gravity

thermoreceptors

triggered by changes in temperature

sclera

tough white protective fibrous, external layer of the eye

cornea

transparent part of sclera at front of eye bends light rays

choroid

absorbs scattered light and contains blood vessels

iris

regulates the amount of light that enters the eye

pupil

opening for light to enter the inner eye

ciliary muscles

changes the shape of the lens in order to focus light rays used when items are close up or far away

retina

thin layer of tissue that contains photoreceptors (cons and rods)

accommodation

the ciliary muscles relaxing or contracting to focus light when an object is far away: muscles relax and ligaments contract and lens flattensclose: muscles contract ligaments relax and lens becomes rounded

rods

sensitive to light work in dim light

cones

sensitive to colour (red, blue, green) focus images

fovea centralis

contains high density of cones and provides acute vision

lens

focuses light rays onto fovea centralis

aqueous humour

clear watery fluid in the anterior chamber maintains shape and provides oxygen and nutrients produced daily

vitreous humour

clear jelly-like fluid in the posterior chamber that maintains shape and bends light

pathway of light

cornea - lens - pupil - retina - fovea centralis - optic nerve - occipital lobe

pinna

external part of ear, funnels sound to the auditory canal

auditory canal

directs sound to the tympanic membrane

tympanic membrane (eardrum)

vibrates with sounds causing ossicles to vibrate

Ossicles

three small bones that transmit vibrations to the oval window, magnifying sound

Eustachian tube

air-filled tube allows equalization of pressure in the middle-ear

semicircular canals

fluid-filled structure providing information about body movement and position

cochlea

coiled tube that identifies sounds and converts them to nerve impulses

organ of Corti

consists of stereocilia lying on the basilar membrane which will move in response to movements in the fluid

rotational equilibrium

is maintained by the 3 semi-circular canals, each filled with jelly. –The hair cells in the ampullae (the base of each canal) are bent as fluid moves past them when the head is moved, sending information to the brain about posit

hormones that effect blood glucose

Raises: epinephrineglucagon Lowers: aldosteroneinsulinthyroxin

endocrine glands

ductless organs that produce hormones directly into the blood stream

hormones

chemical messengers that influence metabolism of cells, growth, development of body parts and homeostasis

endocrine system

made of glands and tissues that secrete hormones

hormone action on target cells

each target cell contains receptor proteins, hormones bind to their specific protein which triggers a reaction in the target cell

tropic hormones

their target are endocrine glands

pituitary gland

endocrine gland that has two lobes and is 1 cm in diameter. releases 8 hormones controlled by the hypothalamus

anterior pituitary gland

hormone-synthesizing gland. produces human growth hormone and prolactin

prolactin (PRL)

produces milk from mammary glands

posterior pituitary

stores and releases ADH and Oxytocin controlled by a nerve impulse

oxytocin

stimulates, milk production in mammary glands and contractions of the cervix

oxytocin feedback loop

stimulus on cervix/nipple → nerve impulse to hypothalamus→ posterior pituitary glad → release of oxytocin Active until the stimulus stops

Tropic hormone feedback loop

hypothalamus → releasing hormone → Anterior pituitary → stimulating hormone → target gland increase levels of hormone negatively feedback

gonadotropin releasing hormone GnRH

causes release of folicle-stimulating hormone and luteinizing hormone

hypersecretion

too much hormone being released

hyposecretion

not enough or no hormone being released

human growth hormone (HGH)

stimulates muscle bone and connective tissue growth

hypersecretion of HGH

childhood: person becomes very tall adulthood: large hands, feet, and jaw. bones widen do not lengthen

hyposecretion of HGH

child does not grow resulting in them being extremely short

thyroid gland

lies below larynx and has 2 lobes. requires iodine to make thyroxine

thyroid-stimulating hormone (TSH)

produced in the anterior pituitary gland, stimulates thyroid gland to produce thyroxin tropic

thyroxin

increases the rate body metabolizes/ releases ATP effects skeletal muscles and kidneystriggered when muscles need ATP

hypothyroidism

underproduction of thyroxin childhood: shorter than average, mental development delays Adults: tired, cold, puffy skin, weight gain

hyperthyroidism

overproduction of thyroxin symptoms: anxiety, weight loss, warm and fast heart weight

thyroxine feedback loop

when body needs ATP → Hypothalamus→ releasing hormone → anterior pituitary gland → thyroid releasing hormone → thyroid glad → thyroxine increased thyroxine levels in bloodstream negatively feedback to hypothalamus

goitre

caused when there is no thyroxine in the bloodstream to stop the production of TSH caused by a lack of iodine

calcitonin

lowers blood calcium levels by stimulating the increased uptake of calcium in the bones

calcitonin feedback loop

high levels of calcium in blood → thyroid gland → calcitonin decreases calcium in blood negatively feeds back on thyroid

parathyroid glands

4 small glands on thyroid, release parathyroid hormone

parathyroid hormone (PTH)

triggers bones to release calcium and stimulates the uptake of calcium absorption in the kidneys and small intestine

PTH feedback loop

low blood calcium → parathyroid glands → parathyroid hormone raise of calcium in bloodstream negatively feeds back

adrenal glands

located on top of the kidneys, composed of the outer cortex ad inner medulla

adrenal medulla

produces epinephrine and norepinephrine which regulates short-term stress response

adrenal cortex

long term stress response produces cortisol and aldosteronesupplements hormones in gonads

long term stress

kidney absorbs sodium and waterblood volume and pressure raisesprotein and fat metabolize and glucose is releasedinflammation and immune cells are suppressed

cortisol

triggers an increase in blood glucose levels, suppresses immune system glucocorticoid

adrenocorticotropic hormone (ACTH)

targets adrenal cortex, causes the release of cortisol tropic

cortisol feedback loop

Hypothalamus → releasing hormone → anterior pituitary gland → ACTH → adrenal cortex → cortisol raise in cortisol in bloodstream negatively feeds back

aldosterone

stimulates kidneys to increase absorption of sodium in blood stream. raises blood pressureminrtalcoroid

aldosterone feedback loop

low sodium/low blood pressure → adrenal cortex → aldosterone rise in blood pressure and sodium negatively feeds back

gonadocorticoids

supplement hormones in the gonads, secondary sexual characteristics

Addison disease

damage to the adrenal cortex resulting in hyposecretion symptoms: low blood sugarsodium and potassium imbalancerapid weight lossweakness

hyposecretion aldosterone

low blood pressure due to loss of sodium and increase urine

hypersecretion aldosterone and cortisol

high blood pressureaneurysms/heart attackspoor immune system (cortisol)

pancreas

located behind stomach ad is connected to small intestine, contains islets of langhans

islets of langhans

secrete insulin and glucagon contains beta and alpha cells that secrete insulin and glucagon

insulin

circulates through body and makes cells more permeable to glucose. promotes the conversion liver to turn glucose to glycogen

glucagon

stimulates conversion of fats glycogen back to glucose which is released into the bloodstream

insulin feedback loop

blood glucose rises (after meal) → pancreas (beta cells) → insulin → lower blood glucose (negative feed back)

glucagon feedback loop

low blood glucose → pancreas (alpha cells) → glucagon → blood glucose rises (negative feedback)