Human Nutrition Flashcards
nutrition
the way in which an organism obtains and uses its food
digestion
the physical and chemical breakdown of food
heterotrophs
organisms that cannot make their own food
autotrophs
organisms that can make their own food
what are the 3 types of heterotrophs
omnivores
carnivores
herbivores
omnivore
an organism that eats both plant and animal material e.g humans
carnivore
eat animals only e.g pike
herbivore
eat plant material only e.g squirrels
draw a labelled digestive system diagram
pg 50 book 3
what are the 4 stages of digestion
- ingestion
- digestion
- absorption
- egestion
ingestion
putting food into our mouth
digestion
physical+ chemical breakdown of food
absorption
absorption of nutrients
egestion
removal of waste of digestion ie faeces
what are the types of digestion
mechanical and chemical
mechanical digestion
the physical breakdown of food ie chewing in mouth or churning in stomach
chemical digestion
the breakdown of food into smaller molecules by enzymes
what are the 4 types of teeth
incisors
canines
premolars
molars
what is the function of incisors
biting and cutting
what is the function of canines
gripping and tearing
what is the function of premolars and molars
chewing
what is the dental formula
2[i2/2 c1/1 pm2/2 m3/3]
how does physical digestion work?
teeth in the mouth physically breakdown food into smaller pieces
which increases the surface area for chemical digestion
how does chemical digestion work?
salivary amylase acts on starch in the food and breaks it down to maltose
oesophagus
carries food from mouth to stomach
peristalsis
the wave of muscular contraction of the gut wall that helps to move the food through the alimentary canal
what is the stomach
a muscular bag that holds/digests food
what muscles are in the stomach and what do they do?
sphincter muscles
regulate the opening and closing of the stomach
where is the stomach located
to the left of the liver just below the diaphragm
name 3 things in the stomach
hydrochloric acid
enzymes(pepsin)
mucus
function of mucus membrane
protects stomach wall from acid
prevents pepsin from breaking down stomach wall
function of pepsin
digests protein (chemical digestion)
function of hydrochloric acid
kills bacteria
what is chyme
a liquid produced when food is physically digested by churning and mixes with other things.
what are the functions of the small intestine
digestion and absorption
what are the 2 parts of the small intestine
duodenum
illeum
function of duodenum
digestion
function of illeum
absorption
what 3 organs are involved in the chemical breakdown of food in the small intestine
pancreas
liver
gallbladder
function of pancreas
secretes pancreatic juice
what is pancreatic juice
made up of
water
enzymes (proteases, lipase, amylase)
sodium bicarbonate
function of pancreatic amylase
breaks down starch to maltose
function of pancreatic lipase
breaks down lipids to fatty acids and glycerol
function of pancreatic protease
breaks down protein to peptides
location of the liver
to the right of the stomach beneath the diaphragm
function of the liver
PRODUCES BILE
breaks down red blood cells
stores fat soluble vitamins
produces heat
detoxifies the body ie drugs + alcohol
function of gallbladder
stores bile
what is bile
a green/yellow liquid that contains
-bile salts to emulsify fats
-sodium bicarbonate to neutralise chyme
how is bile carried to the duodenum
via the bile duct
what is a villus
an infolding in the interior lining of the small intestine. there are millions of these.
function of villi
increase the surface area to allow for more absortion
how do villi work?
each villus has its own blood supply to allow food molecules to enter the capillary and be transported to the liver
PROCESS= DIFFUSION
what are the adaptations of villi for absorption
wall of villi one cell thick
large blood supply
lots of them = more absorption
microvilli= more surface area
villus diagram
pg 56
function of lacteals
fatty acids and glycerol diffuse into lacteals which connects to lymph nodes as these cannot be transported in the blood
ie to transport fatty acids and glycerol
what happens to fatty acids and glycerol in the lacteals
fats are reformed and covered in a protein and they then move into the lymph vessels and there they are transferred back to the bloodstream
what is the process of absorption?
diffusion
where do absorbed materials go?
digested materials pass through the villi by diffusion
digested lipids and fat-soluble vitamins pass into lacteals which is connected to the lymphatic system where they are returned to the bloodstream
all other products go directly from the villi to the liver via the hepatic portal vein
what are the blood supplies to the liver
hepatic portal vein
hepatic artery
hepatic vein
hepatic portal vein
carries digested nutrients from the small intestine to the liver
hepatic artery
brings oxygenated blood to the liver
hepatic vein
carries deoxygenated blood and other nutrients from the liver
where do the nutrients go from the liver?
they travel to cells all over the body where they are needed
adaptations of the small intestine
ileum is very long- allows for digested food to come into contact with the ileum wall for longer
the folded wall and the villi increase the surface area for absorption
the cells lining the ileum are thin walled which allows for the rapid movement of substances through them
the wall is well supplied with blood vessels and lacteals to carry the digested food away
what are the parts of the large intestine
caecum
appendix
colon
rectum
what is the function of the caecum and the appendix?
they have no known function
how does the large intestine work
liquid waste material enters the large intestine
the colon absorbs water and mineral salts back into the blood
when water is removed waste becomes more solid
this semi solid waste is faeces
faeces are stored in the rectum and are released from the body through the anus
egestion
the removal of indigested waste from the gut
why is the large intestine called large
it has a larger diameter than the small intestine
function of colon
to absorb water and mineral waste back into the blood
symbiotic bacteria
bacteria that live on or in another organism where at least one of the organisms benefits
function of symbiotic bacteria
produce vitamins B + K
digest some cellulose
occupy space preventing the growth of pathogens
the bacteria have food and shelter in return
what are some fibre rich foods
brown pasta
brown bread
how does fibre work
it cannot be digested in our system
it absorbs water which makes faeces softer and easier to pass
provides bulk which keeps the contents of the gut moving
