Digestive system Flashcards
Define system
a group of organs working together to perform a function
Define nutrition
process by which an organism obtains the energy and materials it needs from its environment,
in order to live, grow and reproduce.
What are Autotrophic organisms
organisms that make their own food from inorganic materials
And explain the two types of autotrophic organisms
- Photosynthetic: use light energy to make the food e.g. green plants
- Chemosynthetic: use chemical energy to make food e.g. bacteria around undersea volcanic vents
What are heterotrophic organisms
can’t make their own food - need to obtain it from other organisms
Types of heterotrophic organisms
- omnivores: eat both plants and animals e.g. humans
- herbivore: eat only plants e.g. cows
- Carnivore; eat only meat e.g. Wolf
define digestions
The breaking down of food into smaller pieces to enable them to be taken into the body and used
What is mechanical digestion
Physical breakdown of food by cutting and grinding of teeth and churning of stomach
Define peristalsis
wave of muscular contraction that drives food along alimentary canal
What is chemical digestion
Using digestive enzymes and acid to break food into small soluble molecules that can be absorbed by the body.
Name the four stages of nutrition
- Ingestion taking food into the alimentary canal
- Digestion breaking down complex organic molecules into smaller molecules which are easier to absorb
- Absorption taking materials through the intestine wall into the body by Diffusion and Active Transport
- Egestion getting rid of undigested material from the body.
Labels of the digestive system
- Mouth
- Oesophagus
- Liver
- Gall bladder
- Stomach
- Pancreas
- Duodenum
- Ileum
- Colon
- Appendix
- Rectum
- Anus
What is the function of the mouth
- It’s where ingestion takes place.
- Both chemical and mechanical digestion occur there
- The tongue tastes food, and forms bolus
What is the function of the Teeth
Mechanical breakdown of food
What is the function of the salivary glands
Produce saliva, lubricates food, amylase breaks down starch. They are exocrine glands (have ducts)
What is the function of the Epiglottis
Prevents food entering lungs
What is the function of the Oesophagus
Peristalsis moves food to stomach
What is the function of the Stomach
- Produces Bile – which is stored in gall bladder
- Bile salts neutralise chyme (acid stomach contents) in duodenum
- Emulsifies fats to increase surface area for lipase
What is the function of the Liver
- Produces Bile – which is stored in gall bladder. It contains the pigment bilirubin
- Bile salts neutralise chyme (acid stomach contents) in duodenum
- Emulsifies fats to increase surface area for lipase
- It’s an exocrine gland
What is the function of the Pancreas
It’s both an endocrine and exocrine gland
Exocrine produces:
1. Pancreatic juice is alkaline to neutralise acid stomach contents
2. Lipase to digest fats
3. Amylase to digest carbohydrates
4. Protease to break down polypeptides to amino acids
Endocrine produces:
1. insulin (islets of langerhans)
What is the function of the Duodenum
Bile and pancreatic juice added here
What is the function of the Ileum
Completes digestion
Absorption of products of digestion through villi
What is the function of the Appendix
- Immunity role
2. Vestigial organ
What is the function of the Colon
Absorbs water.
Symbiotic bacteria produce vitamins B and K and prevent pathogenic bacteria establishing by outcompeting them.
What is the function of the Rectum
Stores and expels faeces
What is the function of the Anus
Site of egestion when its sphincter muscle relaxes
What are the four types of teeth and their function
- Incisors: Flat and sharp for cutting food
- Canines: Pointed for tearing and gripping food
- Pre-Molars: Flat and ridged for crushing and
grinding food - Molars: Flat and ridged for crushing and
grinding food
Is the dental formula of an adult human
I 4/4 C 2/2 P 4/4 M6/6
Name the digestive enzymes, their pH, their action site and their role
- Amylase: pH 7 - 8 in the Mouth. pH 8-10 in the small intestines. Breaks Starch to maltose
- Pepsin: pH 1 – 2 in the Stomach. Breaks Protein to polypeptide
- Lipase: pH 8-10 in the small intestines. Breaks Fats to glycerol and fatty acids
- Protease: pH8-10 in the small intestines. Breaks Proteins to Amino Acids
What Are the benefits of fibre in the diet
Stimulates peristalsis and prevents constipation by absorbing water i.e. eases digestive transit
Villi diagram labels
- Microvilli
- Villi
- Lacteal
- Epithelium
- Capillary network
- Arteriole
- Venule
- Lymph vessel
What are villi
Villi are finger like projections or folds of the small intestine wall which greatly increase the surface area for absorption
What is lacteal
Lacteal absorbs fatty acids and glycerol which recombine to form fats. These are carried to the thoracic duct and then into the blood in the subclavian vein.
What is the function of the hepatic portal vein
- Capillaries absorb all other products of digestion e.g. amino acids, glucose, minerals, vitamins and
substances such as alcohol - These pass directly to the liver via the hepatic portal vein
- From there they are transported to all cells of the body in the blood through the Hepatic Vein
give the different functions of the liver
- Produces bile which neutralises acid chyme, and emulsifies fats
- Breaks down red blood cells to bilirubin and
breaks down excess amino acids to urea - Stores glycogen, fat soluble vitamins A and K as well as iron
- Detoxifies e.g. breaks down alcohol, antibiotics etc.
- Produces heat: all the numerous chemical reactions produce heat which aids homeostasis
What is a balanced diet
contains all the required nutrients in the correct proportions
What is undernourished
means not having enough nutrients
What is malnourished
not having the correct balance of nutrients i.e. too much or too little of certain nutrient
What is a food pyramid
Gives an indication of the proportions of the various food groups that should be taken.
This varies with factors like age, sex and activity.
