Digestion Flashcards
The three types of mucosa of the stomach
Mucous- mucous- secretion Parietal- pepsin- breaks down protein -pepsinogen Chief- HCl - activates pepsin - gastric hormones- create hunger feeling
How does food move through stomach
Peristalsis
How does food leave the stomach and where does it go
Chyme leaves the stomach and enters the duodenum of the small intestine
- forced out by the mixing waves of stomach
- leaves via sphincter
What does the small intestine do
Absorption and digestion
The small intestine is made up of what three sections
The duodenum, jenenum, ileum
The mucosa?
The inner lining, which is highly folded to increase surface area, with Villi
What are the pancreatic juices ?
Pancreatic amylase
Trypsin
Ribonuclease and deoxyribonuclease
Pancreatic lipase
Intestinal juices
Intestinal amylase
Intestinal peptidase
Intestinal lipase
Is the digestion of bile mechanical? How?
Mechanical , bc bile Is a digestive aid, nike salts emulsifies fats, breaking down the fats into many droplets
Why is the small intestine so effective at absorbing materials
Because of the massive surface are, folded internal later with villi which is very long
Hepatic portal vein
A vein that goes straight to liver
Materials that enter the blood stream?
Simple sugars
Amino acids
Water
Materials that enter the lacteals
Fatty acids and glycerol
How does stomach mechanically digest
Waves of muscular contractions
Churn and mix the food with the gastric juices with forms chyme, ph of 3
What is the lacteal?
It’s collects materials and places them into the lymphatic system
All the materials absorbed by the small intestine, enter the what?
The hepatic portal vein
Bile? Where is it produced ? Where is it stored?
Bile is produced in the liver, it is a bi product of erythrocyte breakdown.
Bile is stored in the gall bladder.
What is the villi?
- constantly moving
- finger like extensions
Does some absorption occur through the concentration gradient and villi active transport ?
True
What doesn’t the Boyd absorb very well?
Minerals
What influences mineral absorption ?
Gender, males can absorb calcium better than females
How is the large intestine different than the small intestine?
- 1.5 m long
- large diameter
- ascending and descending colon
- rectum
- anal canal
- movement through the large intestine is very slow
- no villi means no absorption
- no digestive juices secreted, no digestion
- lining secretes mucous to help move poop along
What occurs in the large intestine?
- water and electrolyte absorption
- bacteria breaks down remaining food residue
- storage area for faeces
- bacteria fermentation- produces half a litre in flatus (gas) each day
What does faeces contain?
Water Undigested food Bile pigments ( give odour) Remains of cells broken away from digestive system Bacteria
What is excretion?
The removal of metabolic wastes
The lungs, skin, kidneys and liver excrete.
What is defecation?
The discharge of faeces from the body.
What is elimination?
Waste and Undigested materials are removed from the Body.
Excretion and defection are types of elimination.
Why is pooing not excretion, by defection ?
Bc pooing is a faeces and not a metabolic waste.
List the hormones that regulate digestion ?!
CCK- cholecystokinin
Gastric inhibitory peptide
Secretin
Gastrin
What are the digestive system problems?
Constipation
Diarrhoea
Bowel cancer
Coeliac disease
What is the cause of constipation?
- Lack of fibre, protein
- when the movement of the large intestine are reduced and the contents remain there for a long amount of time
What are the effects of constipation?
Defecation can be difficult and painful, faeces are harder and drier than usual.
Diarrhoea causes?
Irritation in the small intestine
Bacterial infection or the small intestine
Food and diet
What are the effects of diarrhoea ?
Frequent defection of watery faeces
May die from dehydration
What are the causes of bowel cancer?
Cancer of the large intestine, linked to diet, a high diet in animal fat and protein and low in fibre
What are the effects of bow cancer
Cancer, bleeding, pains, death, but easily preventable
What is coeliac disease?
Unable to tolerate a protein called gluten
What is the effect of coeliac disease?
Immune system responds by destroying villi In the small intestine
Rashes, malnourished, cramps
What does the kidney do?
Ride body of metabolic wastes (water, urea, creatinine, ions)
Regulates balance of water, salt and ph of blood
Highly vascular( 0.25 blood going through at all times, 1.2L)
What are the three stages of the nephron function
Glomerular filtration
Selective re absorption
Active secretion
In glomerular filtration, what occurs?
- Definition: filtration of blood at the kidneys
- High pressure = more filtration
- Afferent renal artery has high blood pressure bc it is wider than efferent
- podocytes- finger like extensions absorb materials forced out of the blood
- Taken into the glomerular capsule as filtrate
Composition of filtrate
180L per day, 1% leaves as urine
Ions, water, urea, glucose, vitamins, salts
What is selective reabsorption
- Reabsorption of selected substances
- substances reabsorption: na, k, Cl, ca,
- micro villi: brush villi, high surface area,
- the long proximal tubule and distal tubule contribute to high surface area
What is active secretion?
Addition of substances from the blood into the filtrate
What’s secreted: h, k, drugs,neater, antiderietic hormone
High permeability : high water Reabsorption
What is the composition of urine?
Urea Na, Cl ions Amino acids Proteins Creatinine 1.5L per day
What is deamination?
Breakdown of amino acids into the liver to ammonia which forms urea, which is transported to the kidneys for removal
What is the digestive system
Ingestion Mechanical digestion Chemical digestion Movement Absorption Elimination
What is mechanical digestion?
Breakdown of food into smaller particles, by the mouth and jaw without chemically altering its form
What is chemical digestion?
Breakdown of food into smaller particles by the digestive enzymes and mucous
What does saliva do?
Begin chemical digestion, beginning with starch digestion
What does the mesentery tissue do?
Surrounds the internal organs for support
How does mechanical digestion occur in the mouth?
By the teeth and tongue, easier to swallow and increases its accessibility to chew
What are th types of teeth
Incisors Can Canines Premolars Molars
What are the the three salivary glands
Parotid gland
Submandibular gland
Sublingual gland
What is the tongue responsible for?
For moving food around in the moth to for a lump for swallowing called the bolus
What is peristalsis
A wave of muscle contractions
How is food moved down the alimentary canal
By peristalsis
What aids food down the oesophagus?
Movement of food is lubricated by the secretion of mucous from the inner lining
What is the sphincter ?
A round muscle which contracts to open and close
The cardiac sphincter ?
Allows food into the stomach and prevents food from leaving the stomach
Cause of indigestion and heart burn?
When the cardiac sphincter doesn’t close properly and the acid goes upwards, sometimes eat too much spicy food too
Functions of stomach?
A temporary holding tank A mixing chamber Connects the oesophagus to the duodenum Very extendible Mechanical digestion Chemical digestion Produce of hormones gastric juices
What is the stomach and effective storage tank??
BECAUse it stores and breaks down reading for absorption
What is the basic units of the food material?
Carbohydrates- glucose
Proteins- amino acids
Lipids- fatty acids and glycerol
What is the role of carbohydrates, proteins and lipids?
Carbs- provides Body with energy
Proteins- build and repaid tissues
Lipids- a supply and store of energy
Where in the digestive system is this food material broken down?
Carb- begins in mouth
Proteins- small intestine
Lipids- small intestine
