Exchange Flashcards
What is ingestion?
Taking food in
What is the order of organs in digestion?
Teeth, salivary glands, stomach, small intestine, large intestine, rectum and anus
What role in digestion do teeth play?
Mechanical: incisors cut and tear food, molars mash food to increase surface area for enzyme action
What role in digestion do salivary glands play?
Produces saliva to lubricate food to swallow and has salivary enzymes such as amylase (amylose to maltose)
What role in digestion does the stomach play?
Glands secrete HCl (correct pH for enzymes and sterilises food)
Produces pepsin (endopeptidase)
Mechanical digestion when stomach ‘churns’
What are parts of small intestine?
Duodenum (start):
Bile and pancreatic acid are added
Peristalsis occurs
Jejunum (middle)
Ileum (end):
Villi and microvilli lining ileum
Dipeptidases (dipeptides to amino acids) and disaccharidases (disaccharides to monosaccharides) are added
End of ileum monomers are absorbed across small intestine lining into blood in capillaries
What part in digestion do large intestines play?
Reabsorbs water into blood
What does the rectum do?
Stores undigested food
What does the anus do?
Egestion (removal)
What are endopeptidases?
Enzymes that break central regions of polypeptide chains
Long chains into smaller chains
What are exopeptidases?
Enzymes that break peptide bonds on the ends of polypeptide chains
What are dipeptidases?
Enzymes that break dipeptides into amino acids
Where is bile produced?
Produced in liver and stored in gall bladder
What does bile do?
Emulsifies lipids and neutralises pH
What is a chylomicron?
Vesicle to transport lipids
Describe lipid absorption
Monoglycerides and fatty acids in lumen of intestine diffuse (simple) across membrane into the epithelial cells
They then go into the smooth ER and are recombined into triglycerides
They then move into the golgi apparatus where they are converted into chylomicrons and lipoproteins and cholesterol are added
They then move out of the cell by exocytosis into lacteal (too big to be absorbed into blood)
They are then absorbed into the blood
What is another word for chest?
Thorax
What is inspiration?
Breathing in:
External intercostal muscles contract
Pulls ribcage up and out
Diaphragm contracts and flattens
Increases volume in thorax, therefore decreasing the pressure
External air moves down pressure gradient and into lungs
What is expiration?
Breathing out:
Internal intercostal muscles contract
Pulling ribcage down and in
Diaphragm relaxes and arcs
Less volume in thorax, therefore increasing pressure
Internal air is forced out of the lungs down the pressure gradient
What does COPD stand for?
Chronic obstructive pulmonary disease
What are the risk factors that increase the probability of someone suffering from COPD?
Smoking Air pollution Genetics Infections Occupation (exposure to harmful chemicals/dust)
Define correlation
When a change in 1 of 2 variables is reflected in a change of the other variable
Define causation
When you can claim that the one variable actually causes the other variable
Describe the path of oxygen in humans
Oxygen in the air moves in down the trachea into the bronchi. It then enters the bronchioles and then alveoli, where the oxygen dissolves in the surfactant in the alveoli, allowing it to diffuse over the epithelial and endothelial cells into the blood.
Describe the tracheal system of an insect
Oxygen moves into the insect through spiracles, passing through the dust filter
Tracheae are held open by rings of chitin (collapse prevention)
Tracheoles extend throughout the insect’s body tissues, carrying oxygen directly to respiring cells and removing carbon dioxide
There is a short diffusion pathway between the tracheoles and the body cells.
What are the key points for countercurrent flow?
Water and blood flow in opposite directions so blood is always meeting water with a higher oxygen concentration
This means concentration/ diffusion gradient is maintained across the whole length of the gill lamella
Therefore diffusion of oxygen into the blood can occur across the whole length of the gill lamella
This ensures maximum possible gas exchange is achieved
