L03 Digestive System Flashcards
Oral/Buccal Cavity
food is broken down mechanically by the teeth and chemically by enzymes such as amylase
Salivary glands
produce saliva, moistens food making it easier to swallow
Epiglottis
Flap of cartilage behind the root of the tongue which covers the opening of the trachea when swallowing food
Oesophagus
muscular tube
connects the throat with the stomach
peristalsis helps the food move down
Small intestine
aka duodenum
food partially digested, it is altered by fluids from the liver and by bile.
lined with villi - increase SA
Large intestine
reabsorbs fluid
Rectum
Stores faeces until they are expelled
Anus
faeces leaves by the process of defecation
anal sphincter muscle control the opening and closing
Stomach
Muscular walls churn food
produces enzymes such as proteases which break down food
hydrochloric acid activated the enzymes
pepsin digests some proteins
Pancreas
uses the hormones insulin and glucagon to regulate blood sugar levels
uses bicarbonates to neutralise stomach acid
uses amylase to digest polysaccharides, lipase to digest lipids and trypsin for proteins
Mechanical digestion
Food is physically broken down to make it smaller
chewing action - teeth break down food
Stomach churning
Bile emulsifies lipids
Chemical digestion
nutrients broken down by enzymes
Buccal cavity, food dissolved with saliva, saliva contains amylase
Stomach mixes food with enzymes and hydrochloric acid
Proteins are broken down by pepsin in the stomach and small intestine
Role of pancreatic juice
help digest fats
Role of bile
produced by liver, stored in gall bladder
help absorb fats
enters small intestine through bile duct
emulsifies fats and neutralises stomach acid
Adaptions of the intestines for absorption
Villi and microvilli - increase SA, efficient absorption
Villi contain blood vessels and lacteal
Lacteal
Lymphatic capillaries that absorb dietary fats in the villi of the small intestine
The role of the liver in assimilation
Excess glucose is converted into glycogen to be stored or broken down by respiration
Assimilation
the movement of digested food molecules into the cells of the body where they are used, so that they become part of those cells
What does the liver do?
break down toxins such as alcohol
Symptoms of irritable bowel syndrome (IBS)
Stomach pain and cramping
Changes in bowel habits
Bloating
Excessive wind - flatulence
Sudden need to go to the toilet
Feeling like bowels have not fully emptied
Mucus passing from the anus
Biological explanation of IBS
Food moves through the digestive system too quickly or too slowly
too quickly = diarrhoea, not enough water absorbed by intestines
too slowly = constipation, too much water absorbed
Can be caused by problems absorbing bile
Causes of IBS
increased sensitivity to certain foods
problems digesting food
Symptoms of coeliac disease
indigestion
stomach pain
bloating
flatulence
diarrhoea
constipation
anaemia
loss of appetite
tiredness
children not growing at expected rate
Biological explanation for coeliac disease
autoimmune condition
immune system mistake gliadin, found in gluten, as a threat the the body so attacks it.
causes damage to villi - flattens
body cannot absorb nutrients efficiently
Causes of coeliac disease
Genetics
Mutations
Introducing gluten to a baby’s diet before 6 months increases their risk of developing the condition
Autoimmune Condition
An illness that occurs when the body tissues are attacked by the body’s own immune system.
Symptoms of gallstones
Abdominal pain
excessive sweating
jaundice
itchy skin
diarrhoea
loss of appetite
Biological explanation to gallstones
high levels of cholesterol in the gall bladder
high levels of a waste product called bilirubin in the gallbladder
chemical imbalances cause tiny crystals to develop, these grow into solid stones
Causes of gallstones
imbalance in the chemical make up of bile
age 40+
liver cirrhosis, Chron’s disease, IBS (any condition that affects the flow of bile)
Relative with gallstones
