Exchange Flashcards
Explain one advantage of concaved red blood cell compared to spherical one.
Greater surface area for oxygen diffusion
Describe two features of specialised exchange surfaces
- Large surface area to volume ratio
- Thin so shorter diffusion pathway
- Movement of environmental medium to maintain concentration gradient.
How do you calculate the SA of a cube?
Area of one side (length X length) X sides
How do you calculate the volume of a cube?
Length X width X height
How do you calculate the ratio of surface area to volume of a cube?
Surface area/ volume
How do you calculate the surface area of a sphere?
4 (pi) r^2
How do you calculate the volume of a sphere?
4/3 (pi) r^3
What is the equation for diffusion?
Diffusion= (surface area X difference in concentration) /length of diffusion path
How does mass transport of oxygen occur in insects?
Contraction of muscles through abdominal pumping enabling mass movements of air in and out
How does oxygen reach the working muscles in an insect?
Through the tracheoles
What is the advantage of having water at the end of tracheoles?
In periods of high activity, anaerobic respiration will create lactate which will reduce water potential of respiring cells causing them to take up water via osmosis. This loss of water from the tracheoles means gas is further inside them.
What are the tiny pores that gases enter and leave the insect via?
Spiracles
What are three ways gases move in and out of the tracheal system?
- Along the diffusion gradient
- Mass transport
- Movement of water at the end of the tracheoles
What are the main structure of gills?
Gill filaments
What increases the surface area of the gills?
Gill lamellae
Describe how counter current flow allows for effective gaseous exchange
Blood flows in the opposite direction to water, ensuring a concentration gradient allowing a maximum uptake of oxygen
Explain how parallel flow decreases gaseous exchange
Oxygen can only be absorbed by diffusion from higher in water to lower concentration in the blood. Equilibrium is quickly reached
How is a leaf adapted for gas exchange?
- Many stomata for short diffusion pathway
- Lots of air space in the mesophyl layer for movement of gases
- Large surface area of mesophyl cells.
How are the gas exchange systems of plants similar to insects?
- The cells using the gases are close to external air
- Diffusion occurs in the gas phase, not water
- Pores for air to enter and leave
What cell controls the opening and closing of stomata?
Guard cells
What is the name of the plants that are well adapted to dry environments?
Xerophytes
What is the process known as when a plant loses water?
Transpiration
How does a thick cuticle reduce transpiration?
Longer diffusion distance
How does rolled up leaves reduce transpiration?
Stomata end up on the inside of the leaf so the water vapour becomes trapped and the air is saturated with water. High water potential removing the potential gradient between inside and outside of the leaf
How does having hairy leaves reduce transpiration?
Trap moisture near to the leaf, increasing water potential in the air and reducing the gradient. Less water evaporated
Suggest why humans must have a high rate of gaseous exchange?
Large volume of cells and have to maintain high body temperature due to high metabolic rate
Why is the trachea supported by cartilage?
Prevent it collapsing when air pressure inside is low
What are the bronchi?
Two divisions of the trachea, each leads to a lung
What are bronchioles?
Branching divisions of the bronchi, getting smaller, leading to alveoli
What are bronchioles made of. Why?
Muscle, lines with epithelial cells. Controls the flow of air
What is the role of goblet cells and ciliated cells in the bronchi?
Goblet cells produce mucus to trap pathogens. Ciliated cells waft the mucus back up the throat to be swallowed.
What allows the alveoli to stretch and recoil?
Elastic fibres
During inspiration which muscles contract and relax?
External intercostal muscles and diaphragm contract.
Internal intercostal muscles relax
During expiration, which muscles contract and relax?
Internal intercostal muscles contract, external intercostal muscles and diaphragm relax.
What happens to the rib cage during inhalation?
Moves upwards and outwards increasing the volume of the thorax
What happens to the ribcage during exhalation?
Moves downwards and inwards, decreasing thorax volume
What happens to the pulmonary pressure during inhalation?
Decreases as thoracic volume increases. Atmospheric pressure is greater so air is forced into lungs
What happens to the pulmonary pressure during exhalation?
Increases as thoracic volume decreases. Atmospheric pressure is low, so air is forced out
How is air expelled from the lungs?
Elastic recoil of the lungs alongside relaxation of the external intercostal muscles and diaphragm
How do you calculate pulmonary ventilation?
Tidal volume X breathing rate
What is tidal volume?
Volume of air normally taken into the lungs each breath during rest
Why is there short diffusion pathway in the lungs?
Epithelial cells of the alveoli and the endothelial cells of the capillaries are very thin. The red blood cells are flattened against the capillary walls
What happens to the red blood cells in the capillaries which increases gaseous exchange?
Flatten themselves against the side of the capillary resulting in shorter diffusion pathway. They move slowly to increase diffusion time
How is conc gradient maintained in the lungs?
Breathing ventilates the lungs.
The heart circulates the blood around the alveoli
How is surface area increased in the lungs?
High number of alveoli and a network of capillaries surrounding each alveoli
What are the main risk factors for lung disease?
Infections
Occupation
Air pollution
Smoking
Genetic make up
What is COPD?
Chronic obstructive pulmonary disease
What is the difference between correlation and causation?
Correlation is when one variable changes, there is a change in another variable.
Causation is when one variable changes, it causes a change in the second variable.
What are the main parts of the digestive system?
Oesophagus, stomach, ileum, large intestine, rectum, salivary glands, pancreas
What are the two types of de=igestion?
Physical and chemical
What reaction do digestive enzymes catalyse?
Hydrolysis
What are the main types of hydrolytic enzymes?
Lipases, carbohydrases, proteases
What are the two enzymes involved in starch digestion?
Amylase (Starch into maltose)
Maltase (Maltose into alpha glucose)
Where is amylase found?
Salivary glands and pancreatic juice
Where is maltase found?
Lining the ileum as it is membrane bound
Besides maltase, what other disaccharides are present in our ileum? What do they digest?
Lactase (lactose into glucose and galactose)
Sucrase (sucrose into glucose and fructose)
What are lipids digested into?
Fatty acids and monoglycerides
What is a monoglyceride?
A glycerol and one fatty acid
What do the bile salts do and what is this process called?
Emulsification
Increase surface area by splitting lipids into droplets
What are proteins broken down into?
Amino acids
What does an endopeptidase hydrolyse?
The peptide bond in the central region of a protein moelcule.
What does an exopeptidase hydrolyse?
Terminal amino acids from a peptide creating amino acids and dipeptides
What does a dipeptidase hydrolyse?
Bond between two amino acids of a dipeptide
Which of the peptidases are membrane bound? What does this mean?
Dipeptidases.
Found on the cell surface membrane of the epithelial cells of the ileum.
What are the folds in the ileum and whats their function?
Villi, they increase absorption of nutrients.
What are the adaptations of villi?
Microvilli- Increases surface area
Thin wall- Short diffusion pathway
High blood supply- increases concentration gradient
By what processes are amino acids and monosaccharides absorbed?
Co-transport
What are the basic steps of co-transport?
- NA+ ions actively transported out of the cell into the blood
- This causes the diffusion of NA+ ions into the cell from the ileum lumen as a concentration gradient is created
- NA+ diffuses through a carrier protein with a glucose molecule
- Glucose moves into the blood via facilitated diffusion.
What is the first stage in lipid digestion?
Emulsification into lipid droplets
Why are lipid droplets formed?
Increases surface area for enzyme action
What is formed when lipids are digested by lipases?
Monoglycerides and fatty acids
What is formed from the monoglycerides, bile salts, and fatty acids
Micelle
What is the role of the micelle?
Carry the monoglycerides and fatty acids to the cell surface membrane
How do fatty acids cross the cell surface membrane?
Non-polar so move through simple diffusion
When the fatty acids and monoglycerides have crossed the cell membrane into an epithelial cell, what happens?
Transported to the endoplasmic reticulum where they are reformed into triglycerides
When triglycerides have been formed in the epithelial cell, what is the next stage in absorption?
Move to the golgi apparatus where they are modified and combined with proteins to form lipoproteins and packaged into vesicles for exocytosis
What are the vesicles called which are formed from triglycerides, proteins and cholesterol for absorption into the blood?
Chylomicrons
How do chylomicrons take lipids out of the epithelial cells?
Leave through exocytosis. Move into lacteals which are lymph vessels. These transport them into the blood stream.
