Organism Exchanges Flashcards
(42 cards)
1
Q
What are the main components of the human gas exchange system?
A
- Lungs
- Trachea
- Bronchi
- Bronchioles
- Alveoli
2
Q
What are the lungs?
A
A pair of structures made up of a series of branched tubules which end in airsacs called alveoli
3
Q
What is the trachea?
A
A flexible airway supported by rings of cartilage which prevent it from collapsing when air pressure decreases. The tracheal walls are made of muscle, and are lined with ciliated epithelium and goblet cells
4
Q
What are the bronchi?
A
Two divisions of the trachea, each leading into one lung. They produce mucus to trap dust particles and have cilia to push them up towards the throat
5
Q
What are the bronchioles?
A
Branching subdivisions of the bronchi. Their walls are made of muscle lined with epithelial cells, the muscle allows them to constrict to control air flow in and out of the alveoli
6
Q
What are the alveoli?
A
Air sacs at the end of the bronchioles that have elastic fibres which allow them to stretch when air fills them. The alveolar membrane is the gas exchange surface
7
Q
What is the process of inspiration?
A
- External intercostal muscles contract, internal intercostal muscles relax
- Ribs are pulled upwards and outwards, increasing thorax volume
- Diaphragm muscles contract, also increasing thorax volume
- Increased thorax volume means theres a reduced pressure in the lungs
- Atmospheric pressure is now greater than pulmonary pressure, so air is forced into the lungs
8
Q
What is the process of expiration?
A
- Internal intercostal muscles contract, external intercostal muscles relax
- Ribs move downwards and inwards, decreasing thorax volume
- Diaphragm muscles relax, also decreasing thorax volume
- Decreased thorax volume means theres an increased pressure in the lungs
- Pulmonary pressure is greater than atmospheric pressure, so air is forced out of the lungs
9
Q
What surrounds each alveolus?
A
A network of pulmonary capillaries
10
Q
Why is diffusion between alveoli and blood rapid?
A
- Red blood cell movement is slowed due to narrow capillaries, so there is more time for diffusion
- Walls of the alveoli and capillaries are very thin so there is a short diffusion pathway
- The total surface area of the alveoli and capillaries is very large
- Breathing keeps the blood being pumped around the alveoli which maintains the steep concentration gradient
11
Q
What is the exchange of CO2 and O2 between the alveoli and capillaries?
A
- CO2 moves from capillaries into the alveoli
- O2 moves from the alveoli to the red blood cells in the capillaries
12
Q
What is the gas exchange system of insects comprised of?
A
- An internal network called tracheae
- The tracheae are supported by strengthened rings to prevent them from collapsing
- The tracheae divide into smaller dead-end tubes called tracheoles which extend throughout all the body tissues of the insect
- There is a short diffusion pathway from a tracheole to any body cell
13
Q
How does the diffusion of respiratory gases of insects work?
A
- During respiration, oxygen concentration at the ends of the tracheoles decreaes
- This creates a diffusion gradient, which causes oxygen from the atmosphere to diffuse along the tracheae and tracheoles to cells
- As carbon dioxide is produced from respiration, an opposite diffusion gradient is established where it then diffuses out of the tracheoles and tracheae into the atmosphere
14
Q
What is mass transport in insects?
A
It is the contraction of muscles that squeeze the trachea, enabling mass movement of air in and out quickly
15
Q
Why does water being at the end of the tracheoles increase the rate of gas exchange?
A
- During major activity, muscle cells around the tracheoles undergo anaerobic respiration which produces lactate
- Lactate is a soluble product that lowers the water potential in the muscle cells
- Water therefore exits the tracheoles via osmosis into the muscle cells
- This means a higher volume of air can enter the tracheoles
16
Q
What are spiracles?
A
- Small pores on the body surface of insects that gas exchange takes place through
- They can be opened and closed by a valve
- They are typically closed to prevent water loss
17
Q
What are the main components of the digestive system?
A
- Salivary Glands
- Oesophagus
- Stomach
- Pancreas
- Ileum
- Large Intestine
- Rectum
18
Q
What are the salivary glands?
A
- Glands situated near the mouth
- Their secretions contain amylase
19
Q
What is the oesophagus?
A
A muscular tube that carries food from the mouth to the stomach
20
Q
What is the stomach?
A
- A muscular sac that has an inner layer that produces enzymes
- It’s role is to store and digest food, especially proteins
21
Q
What is the pancreas?
A
- A gland situated below the stomach
- Produces pancreatic juice which contains proteases to hydrolyse proteins, lipase to hydrolyse lipids, and amylase to hydrolyse starch
22
Q
What is the ileum?
A
- A long muscular tube that further digests food
- The inner walls are folded into villi, and on the epithelial cells of these villi are microvilli which largely increases surface area
- This is where products of digestion are absorbed into the bloodstream
23
Q
What are the two stages digestion takes place in?
A
- Physical breakdown
- Chemical digestion
24
Q
What is the process of physical breakdown?
A
- If food is large, the teeth break it down into smaller pieces
- This makes food possible to digest and also provides a large surface area for chemical digestion
- Food is churned by muscles in the stomach wall which further breaks it up
25
What is the process of chemical digestion?
- Enzymes hydrolyse large, insoluble molecules into smaller, soluble ones
- Enzymes are specific so more than one is required to hydrolyse a large molecule
26
How does carbohydrate digestion work?
- Amylase produced in the mouth and pancreas hydrolyse alternate glycosidic bonds of the starch molecule into maltose
- Maltose is hydrolysed into alpha glucose by maltase which is produced by the ileum lining
27
What is the process of carbohydrate digestion in humans?
1. Saliva enters the mouth and is mixed with the food during chewing
2. Saliva contains salivary amylase which starts hydrolysing the starch to maltose. The saliva also contains mineral salts which maintain an optimum neutral pH
3. Food enters the acidic stomach, denaturing the amylase
4. Food moves into the small intestine and mixes with the pancreatic juice which contains pancreatic amylase. The pancreatic juice also contains alkaline salts which maintain a neutral pH
5. Muscles in the intestine wall push the food along the ileum, which produces maltase from its epithelial lining. The maltase is a membrane-bound disaccharidase which hydrolyses the maltose into alpha glucose
28
What does sucrase hydrolyse?
Sucrose into fructose and glucose
29
What does lactase hydrolyse?
Lactose into galactose and glucose
30
What are lipases?
Enzymes produced in the pancreas that hydrolyse the ester bond found in triglycerides to form fatty acids and monoglycerides ( a glycerol molecule with a single fatty acid attached )
31
How are lipids digested?
- Lipids are split into tiny droplets called micelles by bile salts which are produced by the liver in a process called emulsification
- This increases the surface area to speed up lipase action
32
What are the three peptidases used in protein digestion?
- Endopeptidase
- Exopeptidase
- Dipeptidase
33
What does endopeptidase do?
Hydrolyses the peptide bond between amino acids in the middle of a protein molecule, forming a series of peptide molecules
34
What does exopeptidase do?
Hydrolyses the peptide bonds on the terminal amino acids of the peptide molecules formed by endopeptidase, releasing dipeptides and single amino acids
35
What does dipeptidase do?
Hydrolyses the bond between the two amino acids of a dipeptide
36
What is the structure of gills?
- They are located behind the head and are made up of gill filaments
- Gill lamellae are situated at right angles to the filaments, which increases the surface area of the gills
37
How does countercurrent exchange work for more oxygen intake?
- Blood that is already containing a lot of oxygen meets water, which has its maximum concentration of oxygen. Diffusion oxygen from the water to the blood occurs
- Blood that is containing little oxygen meets water which has had most of its oxygen removed. Diffusion of oxygen from the water to the blood still occurs
- The diffusion gradient is maintained across the entire width of the lamella, meaning about 80% of the available oxygen in the water is absorbed into the blood of the fish
38
What are some adaptations of a plant leaf for gas exchange?
- Many stomata so short diffusion pathway
- Many interconnecting airspaces throughout the mesophyll for easy contact of gases
- Large surface area of mesophyll cells for rapid diffusion
39
What are the stomata?
- Small pores typically on the underside of leaves
- Each stoma are surrounded by a pair of guard cells which open and close it, controlling the rate of gaseous exchange
- Stomata also can close to prevent water loss
40
How do insects limit water loss?
- Small surface area: volume ratio to minimise the area over which water is lost
- Waterproof cuticles over body surfaces
- Spiracles can be closed
41
How do plants limit water loss?
- Thick cuticle to act as a waterproof barrier
- Rolling up of leaves to protect lower epidermis, where the stomata are. The curled up region becomes saturated with water vapour so has a high water potential to maintain no gradient between inside and outside of leaf
- Hairy leaves trap moist air next to leaf surface which lowers water potential gradient for less evaporation
- Stomata in pits or grooves to also trap moist air to reduce water potential gradient
42
How are amino acids and monosaccharides absorbed?
Co-transport in the ileum
