structure and functions (transport in humans)

why unicellulars don’t need exchange surfaces/transport systems

have a very large ___:__

have very large Sa:V ratio - distance from surface to centre is very smalll. diffusion/osmosis/active transport through cell membrane occur at a sufficient rate to meet the cell’s needs.

label amoeba with entry/exit of O2, CO2, H2O, nutrients and method to get them (UNOFFICIAL)

why multicellulars can’t rely on diffusion

distance between surface to centre is too large - diffusion to all cells would take too lon

so has to have transport systems to carry necessary substances

blood components + rough percentages

plasma - 55%

red blood cells - 44%

white blood cells + platelets - 1%

describe (structure) of red blood cell

biconcave disk, no nucleus (to make more space for haemoglobin)

describe (structure) of phagocyte (3)

multi-lobed nucleus, large, can change shape

describe (structure) of lymphocyte

large round nucleus, clear

describe (structure) of platelets

fragments of cells

describe (structure) of plasma

straw-coloured liquid

5 things in plasma - what they are, where they are going

• CO2 - waste product of respiration, transported to lungs

• Digested food/mineral ions - absorbed from small intestine, delivered to cells where necessary

• Urea - waste substance produced from breakdown of proteins by LIVER, transported to kidneys

• Hormones - chemical messengers from glands delivered to target tissues

• Heat energy - from exothermic respiration reactions, transferred to cooler parts of body/where heat is lost

2 adaptations of red blood cells + whats inside

• no nucleus → more space for haemoglobin

• biconcave disc → large Sa:V ratio, max diffusion of oxygen in/out

• haemoglobin → protein that binds to oxygen (to carry it around)

define pathogen

a microoorganism that can cause disease

phagocytosis process (3) sensitive _____ _______ detects ____…..

• sensitive cell membrane detects chemicals produced by pathogen

• when they encounter the pathogen they engulf it

• and release digestive enzymes on it

phagocytosis is a ____ immune response

non-specific

antibodies are -shaped _____ that are ______ to _______ on ________ of pathogen

antibodies are Y-shaped PROTEINS that are COMPLEMENTARY to ANTIGENS on SURFACE of pathogen

define antigen UNOFFICIAL

protein on surface of cell (so that immune system can detect them)

define antitoxin

complementary/specific substance released to neutralise the toxins released (by bacteria)

lymphocytosis process (2)

• antibodies attach to antigens and cause agglutination (clumping together) of pathogens

• pathogens are slowed down, phagocytes are signalled to come and engulf pathogens

what is the general role of the immune system

to prevent pathogen from reproducing/to kill it

how does vaccination happen

• Lymphocytes recognise the antigens in the bloodstream

• The activated lymphocytes produce antibodies specific to the antigen encountered

• Memory cells are produced from the lymphocytes

• Memory cells and antibodies subsequently remain circulating in the blood stream

what effect does having memory cells have on the immune system response

faster, more effective, response made quicker

how do platelets make a clot/scab (2)

• platelets release chemicals that form an insoluble mesh of fibrin across a wound

• traps red blood cells, forms clot

importance of blood clots and scabs

blood clots - prevent significant blood loss

scab formation - prevents entry of microorganisms

what are coronary arteries

and removes what

supply cardiac muscle tissue with oxygenated blood, nutrients and remove waste products

what are valves for

to prevent backflow of blood

why does the left ventricle have a thicker wall than the right

also left - blood is ____ _____ pressure

left ventricle needs more muscle to pump blood to the whole body vs just the lungs

left - blood is under higher pressure

ventricle vs atrium

Atrium on top

Ventricle below

(think alphabet)

bicuspid vs tricuspid valve

Bicuspid - left ventricle (red oxygenated blood)

Tricuspid - right ventricle (blue deoxygenated blood)

flow of blood through heart (start with deoxy coming in)

1. deoxygenated blood flows through vena cava into right atrium.

2. goes through tricuspid valve into right ventricle.

3. pumped up through semilunar valve, through pulmonary artery, to the lungs.

.

4. oxygenated blood enters left atrium through pulmonary vein.

5. goes through bicuspid valve into left ventricle.

6. pumped up through semilunar valve, through aorta to rest of body

in which ventricle is blood under higher pressure

left ventricle higher pressure - blood up to aorta to whole body

why does heartbeat increase with exercise

vigorous exercise = muscles respire more, need more O2 supplied and more CO2 waste removed, so heart beats faster

how it happens in body that heart rate increases

exercise increases CO2 waste output

receptors in aorta/carotid notice high CO2 levels

send signal to the brain for heart to pump more frequently + with more force, esp. to get rid of waste

brief description of CHD

coronary heart disease

• blockage of coronary arteries by fatty deposits (plaque) leads to increased risk of heart failure

what are the fatty deposits made of

plaque - cholesterol and fatty substances

coronary arteries blocked by _____ mean arteries _____ their _______. This means…

coronary arteries blocked by PLAQUE mean arteries LOSE their ELASTICITY. This means they can’t stretch to accommodate blood flow

reduced flow of blood to heart muscle = lack of oxygen = cell death/heart failure.

risk factors of CHD and explain (4)

obesity - extra weight puts strain on heart, can lead to type 2 diabetes which damages blood vessels

high blood pressure - increased force against artery walls, causes damage

smoking - chemicals cause plaque build up, high blood pressure

high cholesterol/lots of saturated fats in diet - increased/sped up build up of fatty deposits/plaque in arteries leads to blockages

what is the hepatic portal vein for UNOFFICIAL

vein that’s not really a vein because it doesn’t directly bring blood to heart

• carries deoxygenated blood from gastrointestinal tract (intestines, gallbladder, pancreas etc.) to liver to be filtered and stuff

	Artery	Vein	Capillary
pressure
de/oxy blood
lumen size
wall features
blood speed
valves

	Artery	Vein	Capillary
pressure	high	low	low
de/oxy blood	oxygenated (-pulmonary artery)	deoxygenated (- pulmonary vein)	both
lumen size	narrow	large	very small
wall features	thick, muscular, elastic fibres	thin walls	one-cell thick, ‘leaky'
blood speed	fast	slow	slow
valves	no	yes	no

	Artery	Vein	Capillary
function
adaptations	1	2

	Artery	Vein	Capillary
function	carry oxygenated blood away form heart to body	carry deoxygenated blood to heart from body	allow diffusion of gas/nutrients from blood to body cells
adaptations	thick walls with elastic fibres to withstand/acco- mmodate high pressure	valves prevent backflow of low pressure blood large lumen reduces resistance for low pressure blood	one-cell thick = short diffusion distance, easy/fast diffusion