Digestive system Flashcards
Ingestion-
Ingestion- the taking of food, drugs, liquids, or other substances into the body by mouth.
Digestion
Digestion – the breakdown of large insoluble molecules, into smaller soluble molecules which can be absorbed
Absorption
Absorption – The passage of the soluble products of digestion from the gastro-intestinal tract into the blood, lymph vessels, cells and tissues.
Assimilation
Assimilation - Incorporation of digested materials from food into the tissues. e.g. anabolic reactions
What is the enzyme for Starch
amylase
What is the enzyme for Maltose
maltase
What is the enzyme for Proteins
Pepsin ,Trypsin, chymotrypsin
What is the enzyme for Peptides
Carboxypeptidase
What is the enzyme for Lipids
lipase
What doe starch get broken down into
Maltose
What doe maltose get broken down into
glucose
What do proteins get broken down into
peptides
What do peptides get broken down into
amino acids
What do lipids get broken down into
fatty acids and glcerol
Where is amylase
Mouth
What are the general structures of GI tract
see paper
Label GI tract
See picutre
Identify the different parts see pcitire (3)
See notes
What is the mucosa
A mucous membrane (makes mucus) 3 parts: A) Epithelium – varies in different parts of gut - it often indents to form glands Epithelium in upper GI tract is mainly non-keratinised stratified squamous epithelium
) Areolar loose connective (lamina propria)
- Contains blood vessels, lymph (vascular support for the epithelium) - Often contains mucosal glands - Lymphoid follicles, and plasma cells are also often found here. - Function is support, absorption, immunity
C) Thin double layer of smooth muscle (muscularis mucosa) – this moves the mucosa
Submucosa
Made of areolar (loose) connective tissue
With many larger bv’s and lymph vessels
And the enteric nervous system (ENS), a network of neurones (AKA Meissner’s plexus)
Can contain mucous secreting glands.
- Muscle layer (muscularis)
In upper GI tract is skeletal muscle
Eg in mouth, pharynx, upper oesophagus
In lower GI tract is smooth muscle – not under voluntary control
There are usually two layers (apart from stomach); the inner layer is circular, and the outer layer is longitudinal.
These layers of smooth muscle are used for peristalsis (rhythmic waves of contraction), to move food down through the gut.
- Serosa v
Adventia layer (or serosa)
outermost layer of loose connective tissue - covered by the visceral peritoneum. Contains blood vessels, lymphatics and nerves.
Label inner lining of oesphagus
1- epithelia
2 - lamina propria
3, musculaire mucosa
4, submucosa
What is picture H
see hand out
Describe the stomach ? what does it do ?
A muscular bag
Produces enzymes to break down food
Contains acid to kill microorganisms and help enzymes work
Acid does not digest your food for you!
special chemicals called enzymes break down the food even more. pepsin, an enzyme produced by stomach mucosa which helps to digest protein molecules to peptides.
Small intestine function
More enzymes added to finish digestion
Absorption of digested food takes place here
In the small intestine, the broken down food gets into the blood so the body can use it.
Here food is mixed with digestive juices from the liver and pancreas.
Label diagram of general digestive organs
See sheet 1 mouth 2 pharynx 3 tongue 4 oesophagus 5 pancreas 6 stomach 7 liver 8 gallbladder 9 duodenum 10 ascending colon 11 ileum 12 anus 13 rectum 14 sigmoid colon 15 jejunum 16 descending colon and transverse colon (bit touching stomach )
What happens in Small intestine
Duodenum
Ileum
Breaks down carbohydrates
Protein
Fat
In the small intestine, the broken down food gets into the blood so the body can use it.
Here food is mixed with digestive juices from the liver and pancreas.
Large intestine
The large intestine is about 1.5 metres long.
In the large intestine, the body absorbs a lot of water back from the digested food.
Water goes from food into the blood stream
Rectum
When your food has been through the Large Intestine only waste products remain (Rectum).
Semi-solid faeces are formed after 12-36 hours in the large intestine. Faeces are stored in the rectum until they are egested
anus
faeces exit through your anus. This is called egestion.
Anus, a ring of muscle which prevents faeces from leaving the body until ready
How do you determine the energy value of food
4.2 is the value of the specific heat capacity of water, in joules per gram per degree Celsius – the number of joules taken to raise the temperature of water by 1ºC.
1 cm3 of water has a mass of 1 g.
If the number is more than 1000 J/g, express it as kilojoules (kJ):
1 kilojoule = 1000 joules
Energy lreeased from food = mass water x temperature rise/ mass of food sample
The sympathetic and parasympathetic nervous system in regards to digestion
The SNS is responsible for the Flight or Fight response of the body.
When we get scared, the SNS increases our heart rate and provides energy to our muscles in preparation for action.
In order to provide more energy to the heart, lungs and muscle, it inhibits (slows or stops) digestion by directing blood flow away from the digestive tract.
The PNS is responsible for stimulating digestion by increasing blood flow to the digestive tract. The PNS stimulates salivary gland secretion and increases peristalsis. This increases the digestion of food and absorption of nutrients.
How does nervous control work in digestion
When food touches an organ it puts pressure on special receptors that are in the lining of the organ.
The receptors send nerve impulses (messages) to the brain.
The brain then sends a message back to the organ (e.g. the stomach ) and tells it what to do (like telling the gastric glands to release gastric juice or telling the muscles of the stomach to start contracting).
What nerves are involved in digestion
Two types of nerves help to control the action of the digestive system.
Extrinsic (outside) nerves come to the digestive organs from the unconscious part of the brain or from the spinal cord .
Acetylcholine causes the muscle of the digestive organs to squeeze with more force and increase the “push” of food and juice through the digestive tract. Acetylcholine also causes the stomach and pancreas to produce more digestive juice.
Adrenaline relaxes the muscle of the stomach and intestine and decreases the flow of blood to these organs.
Intrinsic (inside) nerves, which make up a very dense network embedded in the walls of the oesophagus, stomach, small intestine, and colon.
The intrinsic nerves are triggered to act when the walls of the hollow organs are stretched by food.
They release many different substances that speed up or delay the movement of food and the production of juices by the digestive organs
What is number 9 on digestive organs
duodenum
What is number 10 on digestive organs
ascending colon
What is number 11 on digestive organs
ileum
What is number 12 on digestive organs
anus
What is number 13 on digestive organs
rectum
What is number 14 on digestive organs
sigmoid colon
What is number 15 on digestive organs
jejunum
What is number 16 on digestive organs
transcending colon ( next to stomach) and descending colon
What is number 1 on digestive organs
mouth