Digestive - Digestion Flashcards
What is the function of the buccal cavity?
Food is chewed and broken down
What is the function of the salivary glands?
Produces saliva that moistens food making it easier to swallow
What is the function of the epiglottis?
Flap of cartilage covering trachea when swallowing
What is the function of the oesophagus?
Muscular tube that connects throat and stomach
Peristalsis - squeezing action by muscles that helps food move downwards to stomach
What is the function of the stomach?
Sac with muscular walls - churn food to break up
Produce hydrochloric acid and enzymes to break food
What is the function of the small intestine (duodenum)?
Chyme (partially digested food from stomach) is chemically altered by fluids from liver and bile
Lined with villi - finger like projections in intestinal wall - increase surface area to help absorption of nutrients into blood
What is the function of the large intestine?
Reabsorbs fluids and processes waste products to be eliminated from body
What is the function of the rectum?
Last part of colon that links to anus - stores faeces
What is the function of the anus?
Where faeces leaves body - anal sphincter muscle controls opening and closing
What is the function of the liver?
Processes and eliminates toxins Processes and eliminates metabolic waste Stores glucose, vitamins and minerals Produces many kinds of proteins Produces bile
What is the function of the gallbladder?
Small pouch under liver - stores bile produced by liver
Empties after meal and refills
What is the function of the bile duct?
Small tube-like structure
Role to carry bile from gallbladder to duodenum
What is the function of the pancreas?
6-inch long gland that secretes insulin and glucagon that regulate glucose - blood sugar levels
What is the function of the pancreatic duct?
Carries enzymes from pancreas to small intestine
Before opening into SI, the duct unites with the bile duct that delivers bile from liver to gallbladder
How does food move down the oesophagus?
Peristalsis - squeezing action by muscles that helps food move downwards to stomach
What are the two types of digestion?
Mechanical and chemical
What is mechanical digestion?
Food physically broken up into smaller pieces
What is chemical digestion?
Enzymes act on small pieces of food to allow chemical reaction to take place - large macro nutrients broken into smaller molecules to be absorbed
Where does mechanical digestion take place?
Mouth - chew food
Stomach - churns food - produces chyme - provides digestive enzymes with easier access to nutrients - increases surface area for them
Where does chemical digestion take place?
Small intestine - macronutrients too big to pass into bloodstream so broken down by hydrolysis - breaks chemical bond - carried out by specific enzymes
Where is salivary amylase produced?
Salivary glands
What does salivary amylase break down?
Carbs
What is produced by salivary amylase?
Maltose
Where does salivary amylase act?
Mouth
Where is pepsin produced?
Stomach
What does pepsin break down?
Proteins
What is produced by pepsin?
Polypeptides
Where does pepsin act?
Duodenum
Where is lipase produced?
Pancreas
What does lipase break down?
Lipids
What is produced by lipase?
Fatty acids and glycerol
Where does lipase act?
Duodenum
What are the stages of chemical digestion?
1) Amylase in saliva breaks down carbs into maltose
2) Hydrochloric acid in stomach activates pepsin + stops amylase working - food + HCl = chyme
3) Chyme leaves stomach - low pH - alkaline salts added to bile (also found in pancreatic juices)
4) Bile added to chyme + then pancreatic juices added
5) By time chyme arrives to SI - nutrients are in form that can be absorbed
6) Digestive enzymes break down any molecules left in SI to be absorbed
What is the role of the pancreas?
Pancreas produces pancreatic juices - delivered to duodenum
Pancreatic juices contain enzymes that break down macro-nutrients and digest fats
What is the role of the liver?
Liver produces bile that emulsifies fats and neutralises stomach acid/ chyme
What is the role of bile?
Fats and water don’t mix - lots of water in SI so salts in bile act as detergent - breaks up fats into tiny globules (miscelles) that form an emulsion
This gives fat globules a large surface area making it easier for enzymes to reach fat molecules
What is absorption in small intestine?
Nutrients extracted from food are absorbed into bloodstream
The walls have adaptations so they can carry out function
Sugars, amino acids, minerals and water soluble vitamins enter blood via diffusion
What are the adaptations to the villi?
Large surface area - micro-villi - finger like extensions of cell membrane that increase surface area
Large network of capillaries - reduces distance nutrients have to travel to get to blood
Lacteal - lymphatic vessels which transport products of fat absorption
What is assimilation?
The movement of digested food molecules into cells of the body where they are used, so they become part of cells
How does assimilation happen in liver?
Any excess glucose is absorbed ant transported to liver
Converted to glucogen
Glucose can also be used by liver in respiration
