biology - HDS and HCS

hrs + hcs

what are enzymes

enzymes are biological catalysts. they speed up the rate of chemical reactions without themselves being chemically changed at the end of reactions

physical digestion

involves the breaking up of food into smaller pieces

how does physical digestion occur

chewing (teeth), churning (stomach), bile emulsification

why does physical digestion occur

to increase surface area to volume ratio of the ingested food so that enzymes can digest it more efficiently

chemical digestion

involves breaking down large molecules into small soluble molecules

why does chemical digestion occur

small soluble molecules can be easily absorbed by cells in the small intestine into the bloodstream

digestion in the mouth

chewing breaks up solid food into smaller pieces. this increases the surface area to volume ratio to increase the rate of starch digestion by salivary amylase

peristalsis

the rhythmic wave-like contractions of the muscles

digestion in the stomach

walls of the stomach are lined with gastric glands that secrete gastric juice (contains hydrochloric acid and pepsin). pepsin digests proteins into polypeptides

digestion in small intenstine

aided by secretions from the live, gall bladder and pancreas

the liver

the largest gland in the body, produces bile

where is bile stored

in the gall bladder

what does bile do

bile emulsifies lipids by breaking up large fat droplets into tiny fat droplets. this increases the surface area to volume ratio to increase the rate of lipid digestion by lipase

pancreatic amylase

digests starch to maltose

trypsin

digests proteins to polypeptides

pancreatic lipase

digests lipids to fatty acids and glycerol

small intestine: maltase

digests maltose to glucose

small intestine: peptidase

digests polypeptides to individual units of amino acids

small intestine: intestinal lipase

digests lipids to fatty acids and glycerol

carbohydrates (starch and maltose)

digested into glucose

proteins

digested into amino acids

lipids

digested into fatty acids and glycerol

large intestine

absorbs remaining water and mineral salts from undigested matter - formation of faeces (egestion)

absorption of products

amino acids, fatty acids, sugars are absorbed into the bloodstream then carried by the circulatory system to tissues around the body

components of blood

plasma, white blood cells, red blood cells, platelets

function of plasma

transports water, proteins and dissolved substances together with blood cells and platelets around the body

function of red blood cells

transport oxygen to other body cells

adaptation: biconcave shape

increases the surface area to volume ratio of the cell, to increase the rate of diffusion of oxygen

adaptation: absence of nucleus

allows more haemoglobin to be packed in the cell and thus more oxygen can be transported

adaptation: contains haemoglobin

haemoglobin combines reversibly with oxygen

function of white blood cells

produce anitbodies that identify and neutralise pathogens and engulf pathogens

types of white blood cells

phagocyte and lymphocyte

function of lymphocide

destroy foreign particles by phagocytosis

function of platelets

involved in blood clotting (not true cells)

AB blood type

universal receiver, can only donate to AB

O blood type

universal donor, can only receive from O

B blood type

can receive from O and B, can donate to AB and B

A blood type

can receive from O and A, can donate to AB and A

what happens when a patient receives blood incompatible to its own blood type

their immune system will attack the donor’s blood cells with antibodies

structure of the arteries

thick, elastic and muscular wall to help the artery withstand high pressure of blood flowing through

function of artery

transports blood away from the heart

structure of the vein

thin, elastic and muscular wall, valves to prevent the backflow of blood

function of the vein

transports blood towards the heart

structure of the capillary

one-cell thick wall, to reduce the distance for higher rate of diffusion of oxygen, carbon dioxide, nutrients and waste products, slow rate of blood flow to allow diffusion to take place efficiently

function of capillary

allow for the exchange of oxygen, carbon dioxide, nutrients and waste products between tissue fluid and blood by diffusion

function of tissue fluid

surrounds tissues and cells and supplies them with oxygen and glucose

explain coronary heart disease

unhealthy lifestyles may result in the build up of fatty deposits along the walls of the coronary arteries, this narrows the lumen of the coronary artery, reducing the supply of blood to the heart muscles. if a coronary artery is blocked significantly, the heart muscles would then be starved of oxygen and glucose, leading to tissue death and thus a heart attack

after effects of heart attack

the damage to the heart muscle is permanent. the rest of the healthy heart muscles would need to work harder to pump more blood in order to compensate for the damaged heart muscle

risk factors that could lead to a heart attack

poor diet (consume food high in cholesterol and fats), poor lifestyle (smoking, lack of exercise, stress) genetic factors (family history of heart diseases)