digestive system bio GCSE

Peristalsis

Peristalsis

Muscle contraction to move food

Purpose of villi

Absorb nutrients into blood

Function of large intestine

absorbs excess water

Function of small intestine

Absorbing nutrients

Order from cells to organisms

Cell, tissue, organ, system, organism

Function of stomach

Produces hydrochloric acid, churns food by pummelling it with muscular walls

Function of liver

Processing bile to aid in fat digestion, absorbing nutrients, stores glycogen, processing alcohol/drugs

function of mouth

food broken down by chewing, analayse added

function of pancreas

Produces enzymes and releases these into the small intestine

function of oesophagus

uses peristalsis to push food down to stomach

function of gall bladder

stores bile

function of small intestine

absorb nutrients into bloodstream, produces enzymes for digestion

benefits of a large surface area in the small intestine

allows more time and chances for absorption

how is the small intestine adapted for absorption

villi and microvilli, active transport, large surface area, long, rich blood supply in villi, constant concentration gradient and rate of absorption due to diffusion in villi

liver cirrhosis

liver cant process the alcohol entering the liver

types of absorption into the gut

simple diffusion, facilitated diffusion, active transport

describe simple diffusion in the gut

small molecules travel into gut cells and then to the blood by moving from a high to a low concentration

describe facilitated diffusion in the gut

larger molecules, with the assistance of proteins in the cell surface of gut cells, move from a high to a low concentration

describe active transport in the gut

molecules in a high concentration in a gut cell/blood pump through the gut membrane using energy

why does absorption take place in the gut

after food is digested, products are left over and need to be absorbed into blood to be used

what does the liver do during digestion

produces bile salts, processes glucose and stores excess as glycogen, processes amino acids/fats

what can occur due to excessive alcohol intake

cirrhosis, ALD

what is ALD

alcoholic liver disease

what can happen to cause fatty liver disease

a build up of fat impairing the liver's function

digestion

breaking down food into smaller soluble molecules

what liver bile does

helps with the digestion of fats

what does active transport do in the small intestine

allows nutrients to be absorbed into the bloodstream

describe what happens during emulsification of fat

large fat molecules are broken into smaller fat molecules by bile salts

trypsin

pancreatic enzyme that digests protein

Examples of tissues

Muscular tissue, glandular tissue, Epithelial tissue

Enzyme

Biological catalyst that speeds up chemical reactions

What digestive systems are used for

Breaks down big molecules so they can be absorbed into the bloodstream

Why the stomach produces hydrochloric acid

Kills bacteria, gives the right pH for enzymes to work

Why liver bile it’s important in digestion

Neutralises stomach acid, emulsifies fats