chapter 6 - exchange Flashcards
What type of structures will give you a large surface area to volume ratio
Small structures/animals such as mouse and small cubes
What type of structures will give you a lower surface area to volume ratio
Larger animals such as polar bears for example
Why surface area to volume ratio important
The surface area of a cell is the cell-surface membrane, this is the site of exchange between interior and its exterior external environment. The surface must be big enough to allow sufficient exchange to support the contents (the volume of the cell)
Red blood cells and the surface area to volume ratio described
Red blood cells are biconcave discs. The sheep increases the surface area to volume ratio of the cell. This increases the efficiency of diffusion of oxygen and carbon dioxide into and out of the cell. This is an adaptation to increase surface area to volume ratio
How surface area to volume ratio limits cell size
A cell is a metabolite were many different reactions occur. The number of reactions increase as the volume of a cell increases. The greater the surface area the larger the amount of raw materials that can enter at any one time. As a cell grows the surface area to volume ratio decreases, at some point in its growth it’s SA/V Ratio become so small that its surface area is too small to supply its raw materials to its volume at this point the cell cannot get larger.
Heat loss with surface area to volume ratio
Endothermic animals in colder environments are generally larger. The larger the animal the smaller the surface area to volume ratio therefore there is less of an area to lose heat from.
What is an amoeba cell
An amoeba cell is a single celled organism. It has a large surface area to volume ratio therefore it can accomplish the exchange it needs by simple diffusion across its body surface
What is ficks law
rate of diffusion = SA X concentration
distance
Rate of diffusion equals surface area times concentration difference divided by distance
What is an Insects gas exchange system
The tracheal system - all insects or Aerobic organisms, They obtain oxygen from their environment in order to respire and survive. The tracheal system delivers oxygen to every cell in the body.
What are spiracles for insects
Spiracles-are openings on either side of the abdomen through which oxygen and carbon dioxide can enter and leave the body by diffusion.
What are valves in the tracheal system for insects
valves- used to open and close the spiracles
What are trachea in the tracheal system for insects
trachea- They are a network of large tubes held open by rings of chitin through which air passes
What are tracheoles in the tracheal system of insects
tracheoles are smaller branches tubes with no chitin that air passes along. they end in the middle of the insect
What are air sacks in the tracheal system of an insect
They are due to muscle contraction, to pump air in and out of the trecheal system in very active insects
Describe the tracheal system
Air enters the insect body through the spiracles which are controlled by the valves. Oxygen defuses down a concentration gradient through the trachea. Then oxygen will diffuse down the branched tracheoles. loooooo at the end of the branched tracheole there is a thin moist interface for the exchange of gasses between air and the living cell. oxygen diffuses into the liquid of the tracheole interface then diffuses into the cytoplasm of the adjacent cell. at the same time carbon dioxide (waste product) diffuses out of the cell and eventually out the tracheal system down a concentration gradient.
Why does the tracheal system limit the size of insects
The tracheal System is very efficient but For it to be effective the diffusion pathway must be short as diffusion is not a fast process. This then limit the size that insects can be
What are the gas exchange organs for fish
The gills
describe the structure of a gill
a gill Is located between the BUCCAL cavity and the OPERCULUM cavity. They are composed of many filaments that are each covered in many lamellae.
What is an adaptation of a filament
Each filament is covered in many lamellae. Giving a large surface area for gas exchange
Another adaptation is that each filament is thin (one cell thick) Ensuring that there is a short diffusion distance between the blood in the lamellae and the water
What would occur if the movement of water was parallel to the movement of blood
This would not provide a favourable concentration gradient as the exchange reaches equilibrium and therefore a concentration gradient isn’t maintained all the way down the Lamelle
What is the counter current flow system in fish
The counter current flow gas exchange system in fish ensures that the most oxygen rich water comes in contact with the most oxygen rich blood therefore the most oxygen poor water comes in contact with the most oxygen poor blood. Blood and water flow in opposite Directions to each other. There is always a concentration gradient for oxygen to diffuse into the blood. This is maintained for the whole length of the
lamellae To achieve maximum saturation of the blood. Carbon dioxide defuses out of the blood and into the water down its concentration gradient at the exact same time.
What do highly active fish do to ensure they are provided with sufficient oxygen in their blood
They swim with their mouths open, to maintain a high water flow across the gills to provide sufficient oxygen to their blood for high rate of respiration.
What are some adaptations for xerophytes (cactus/desert plants)
leaves are reduced to spines/ needles to prevent water loss by evaporation and help to shade the plant. mentains a small surface area to volume ratio to reduce water loss
Shallow roots that cover a lot of surface area of the soil therefore this maximises the diffusion of water into the plant. And roots also penetrate deep into the soil to maximise water diffusion from the water table.
Explain the process of gas exchange in plants
Gases into the leaf through the stomata which are controlled by the guard cells. Then the gases diffuse into the air spaces in the leaf which are in direct contact with the spongy Palaside mesophyll cells / cells within the leaf.
Why do plants not need a ventilation system
Because their leaves are exposed therefore the air surrounding them is constantly being replaced
What happens during photosynthesis to gas exchange
During photosynthesis (daylight hours) this increases the concentration of oxygen in the sub stomatal air spaces. And there is a decrease in carbon dioxide concentration this increases the concentration gradient for these gases increasing diffusion rate.
What is the function of the guard cells in gas exchange in plants
Guard cells open and close the pores which controls the rate of gas exchange and water loss
The raspatory system gas exchange key features
Trachea-bronchus/bronchi -bronchioles-alveoli
What is the structure and function of alveoli
Alveoli are mini air sacs Which are located at the end of the bronchioles, between the alveoli there are collagen and elastic fibres. Which allowed the alveoli to stretch as they filled with air during inspiration. Alveoli have a short diffusion distance for gas exchange
What are bronchioles
Bronchioles are a series of branching subdivisions of the bronchi. The walls are made of muscle lined in epithelial cells. Muscle allows them to constrict so they can control the flow of air in and out of the alveoli.
What is the structure and function of the Bronchi/bronchus
They are two divisions of the trachea. Each subdivision leads to 1 lung. They also produce mucus to trap dirt and have cilia. Longer bronchi are supported by cartilage
What is the structure of the trachea
The trachea is a flexible air way that is supported by rings of cartilage which prevents trachea from collapsing. The back of the trachea is supported by muscle and elastic tissue, the muscle tissue allows the trachea to contract and relax. The elastic tissue allows the trachea to expand/become extended.Cartilage does not surround the whole of the trachea and only supports the trachea in a C shape
What is the function of the cilia
Cilia what away mucus from the throat. And it prevents mucus from getting into the lungs.
Mucus secreting cells secrete mucus to protect the mucus membranes and trap the mucus
How does oxygen and carbon dioxide defuses from the alveoli to the capillaries vice versa
The alveoli are supported by a network of capillaries over the surface of the alveoli. The alveolar epithelium and the capillary endothelium are very thin to allow efficient rates of diffusion. both gassed flow along a concentration gradient
What events occur during inspiration
Inspiration is the act of breathing in
The pressure of the lungs is greater than the pressure of the atmosphere. External intercostal muscles contract while internal intercostal muscles relax. The ribs are pulled upwards and outwards increasing the volume of the throax. The diaphragm muscles contract causing the diaphragm to flatten increasing the volume of the throax. This increased the volume of the throax results in reduction of the pressure of the lungs and air is forced into the lungs
What events occurred during expiration
Expiration is the event of breathing out
When the pressure of the lungs is lower than the pressure of the atmosphere. Internal intercostal muscles contract while external intercostal muscles relax. The ribs move downwards and inwards decrease in the volume of the throax. The diaphragm muscles relax causing the diaphragm to be pushed up again, therefore further decreasing the volume of the throax. the decreased volume in the throax increases pressure in the lungs. The pulmonary pressure is now greater than the atmospheric pressure so air is forced out of the lungs
Define pulmonary ventilation
Pulmonary ventilation is the total volume of air that is moved into the lungs in one minute
Define tidal volume
Tidal volume is the volume of air normally taken in at each breath when the body is at rest.
Define ventilation/breathing
The number of breaths taken in one minute this is normally around 12 to 20 breaths
what is the equation for pulmonary ventilation rate
Pulmonary ventilation rate = tidal volume(dm3) X breathing/ventilation rate(min-1)
What is vital capacity
Vital capacity is the maximum amount of air you can exhale after inhaling.
What is residual volume
Residual volume is the volume of air remaining in the lungs after maximum exploration.
What is total lung capacity
Total lung capacity is the volume of air in the lungs upon maximum effort of inspiration.
What are the essential features of gas exchange surfaces
A large surface area compared with the volume of the organism (millions of alveoli)
A short distance for gas to diffuse (alveoli and capillaries are only one cell thick and cells are flattened)
A large difference in concentration, on opposite sides of the surface due to movement of air and movement of blood to maintain a diffusion gradient
Partially permeable moist surface to allow oxygen and carbon dioxide to diffuse easily
Describe how oxygen defuses into the capillaries from the alveoli
Red blood cells are slowed as they pass through the capillaries allowing more time for diffusion to occur. The distance between the alveoli and the red blood cell is reduced as the red blood cells are flattened against the capillaries walls. The walls of both the alveoli and capillaries are very thin allowing for a short diffusion distance. Alveoli and pulmonary capillaries have a large total surface area. Breathing movements constantly ventilate the lungs and the action of the heart circulating blood around the alveoli,Maintaining a steep concentration gradient of the gases. Blood flow through the pulmonary capillaries also maintains a steep concentration gradient.
Describe simple diffusion in terms of oxygen diffusing into the blood in the human gas exchange system
Simple diffusion-high concentration to a low concentration,air moves from high partial pressures to low partial pressures. these gases exchanging are often carbon dioxide and oxygen in this example.
alveolar air
Alveolar air Is very different from inhaled air, the gas exchange in lungs occurs between alveoli and the red blood cells and capillaries. The volume of blood in the pulmonary capillaries is smaller than the volume of air in the alveoli. The gas exchange process brings partial pressure of oxygen and carbon dioxide in the blood to the same level as in the alveolar air
What is the function of the oesophagus
The oesophagus is a tube in the digestive system that carries food to the stomach
What is the function of the stomach
The stomach is a muscular sac with an inner layer which produces enzymes. Its role is to store and digest food especially proteins. The stomach has glands that produce enzymes that digests proteins.
What is the function of the small intestine/ilium
The small intestine is a long muscular tube, through this further digested by enzymes in the small intestine which are produced in the glands. The inner walls of the small intestine are folded into villi which give them a larger surface area. The surface area increases further increases by microvilli on the epithelial cells of each Villus.
what is the function of the large intestine
The large intestine absorbs water, most of the water that is absorbed is water from secretions of the digestive glands
What is the function of the rectum
The rectum is the final section of the intestine. faeces is stored here before being removed via the anus. This process is called EGESTION
what is the function of the salivary glands
They are situated in the mouth and pass the secretions via a duct. They contain enzymes (amylase) for hydrolysis of starch.
What is the function of the pancreas
The pancreas is a large gland situated below the stomach it produces pancreatic juice. The secretion contains proteases to hydrolyse proteins, lipase to hydrolyse lipids, and amylase to hydrolyse starch (pancreatic amylase)
What is physical digestion
Physical digestion is where larger pieces of food is broken down into smaller pieces by the teeth, this makes it possible to ingest food but it also provides a large surface area for chemical digestion. And example of this is when food is churned by the stomach walls.
what is chemical digestion
It is the hydrolysis of large insoluble molecules into smaller soluble ones. It is carried out by enzymes. All digestive enzymes function by hydrolysis what a water molecule is added. Enzymes are specific so more than one enzyme is needed to hydrolyse a large molecule
Carbohydrate digestion
salivary Amylase is secreted into the mouth when saliva enters the mouth. This starts hydrolysing starch into maltose (disaccharide) it contains mineral salts that help to maintain pH around neutral this is the optimum pH for salivary amylase. then the acid in the stomach denatures the amylase from the mouth and prevents further hydrolysis of the starch. Food enters the small intestine where it mixes with pancreatic juice which contains pancreatic amylase. This hydrolyses starch to maltose.
Which enzyme hydrolyses sucrose
sucrase
Which enzyme hydrolyses lactose
lactase
Lipid digestion
Lipids are hydrolysed by enzymes called lipases. They are produced in the pancreas and hydrolyse ester bonds found in triglycerides to form fatty acids and monoglycerides. A monoglyceride is a glycerol molecule with a single fatty acid molecule attached. Lipids (fats and oils) or split up into droplets called micells by bile salts. Which are produced in the liver this is called emulsification and increases the surface area of the lipids so that the action of lipases is sped up. Bile salts bind to fat droplets and break them down.
Protein digestion
Proteins are hydrolysed by peptidases (proteases) there are a number of different proteases
ENDOPEPTIDASES-Hydrolyse peptide bonds between amino acids in the central region of a protein molecule. forming peptides.
EXOPEPTIDASES-Hydrolyse peptide bonds on the terminal amino acids of the peptide molecules formed by endopeptidases in this way they progressively release dipeptides and single amino acids.
DIPEPTIDASES-hydrolyse the bond between two amino acids of a dipeptide. Dipeptidases are membrane-bound and are a part of the cell surface membrane of epithelial cells in the ileum.
structure of the ileum/small intestine
villi and microvilli- increase SA increasing rate of absorbsion
epithelial cell-network if capillaries for absorption
contain muscle- able to move, mentains diffusion gradients as their movement mixes the contents of the ileum. ensures products of digestion are absorbed
well supplied with blood vessels-carry away absorbed molecules and hence mentaining a diffusion gradient
absorption of glucose
Sodium ions and glucose ions are co transported into the epithelial cell at the same time by facilitated diffusion and the use of a protein. That is now a high concentration glucose in the epithelial cell and that is a low concentration of glucose in the blood the blood is constantly moving in the capillaries. That is a low concentration of sodium ions in the epithelial cell as they are actively transported by a carrier proteins out of the cell and into the capillary [sodium potassium pump] this process requires energy in the form of ATP for active transport.
Absorption of triglycerides
Larger lipid droplets are broken into smaller droplets when they fused with bile salts this process is called emulsification. This increases the surface area of the lipid droplets So lipase can digest the lipids. Bile is produced in the liver and it’s stored in the gallbladder and it is released into the small intestine.lipids are insoluble, and so they diffuse through the phospholipid bilayer of epithelial cells as they are hydrophobic and non polar. lipid droplets are transported to the smooth ER and golgi apparatus, where they are recombined to triglycerides. triglycerides associate with cholesterol and lipoproteins to form CHILOMICRONS. chilomicrons move out the cell by exocytosis and enter the lacteal, then into a blood vessel.
Describe asthma lung disease
Triggered by smoke, pollen, allergens, Anxiety, exercise and even cold air
The muscles in the bronchi and bronchioles walls contract the diameter of the airway is reduced more mucus is secreted oh and the diameter of the airways is reduced even further. Cells can release a chemical called histamine and histamine causes the lining to become swollen.
Breathing becomes very difficult as they airways have narrowed, produces a wheezing sound as it is forced through a narrow airway less oxygen will diffuse into the blood through the Alveoli.
inhaler-contains drugs to relax muscles. and avoid allergens.
Fibrosis lung disease [pulmonary fibrosis]
Permanent thickening of the lining of the lungs causes hard fibrous lumps [nodules] they form in the middle of the connective tissue that surrounds the alveoli. This makes the lungs very stiff and they lose their elasticity they are no longer able to expand normally during inhalation and do not collapse fully during exhaling. breathing becomes shallow.
shortness of breath, less oxygen taken in, chronic dry coughs, pain and discomfort in the chest, fatigue due to less O2 and less energy.
mining, quarrying industry, dust mites,
emphysema lung disease
The lungs contain elastic tissue made of elastin. in emphysema the elastin is permanently stretched. lungs can’t force air out the alveoli and sometimes alveoli burst. reducing exchange of O2.
tobacco causes WBC to release protein digesting enzymes that break down alveolar walls. elastase enzyme breaks down elastin and elasticity is reduced.
Consequences-hard to move out of the lungs reduced surface area for gas exchange therefore blood is not oxygenated very well, causes shallow breathing and wheezing
no direct treatment, stop smoking to worsen
Pulmonary tuberculosis lung disease
Pulmonary TB It’s caused by a disease called myobacterium tuberculosis. This bacteria is an aerobe and it needs oxygen and therefore the bacteria grows best and tissues with high oxygen concentration such as the lungs.
Symptoms-Persistent cough, tiredness, loss of appetite, Coughing up blood, chest pain, fever
Transmission-When people with TB cough, sneeze, laugh or talk they release tiny droplets of mucus and saliva containing the bacteria into the air transmission occurs when bacteria is inhaled.
Treatment-Involves a combination of 3 to 4 antibiotics. These are given over a 6 to 9 month period,To make sure the whole course of the treatment is completed so the bacteria is killed. However TB strains are very resistant to antibiotics and vaccination is only 70 to 80% effective.
Give examples of antagonistic muscles
The external intercoastal muscles and the internal intercostal muscles
What does antagonistic mean
when two pairs of something work together but in opposite directions. For example when the internal intercostal muscles contract the external intercostal muscles relax
How do you know whether the diaphragm contracts or relaxes during inspiration or expiration
The diaphragm does whatever the external intercoastal muscles do. For example during inspiration the external intercoastal muscles contract therefore the diaphragm also contracts and moves upwards and outwards
how do you know whether the volume of the throax/ throatic cavity increases Or decreases during inspiration
During inspiration pulmonary pressure is lower than atmospheric pressure. Therefore air forced into the lungs. Four pulmonary pressure to be low the volume of the thoracic cavity must increase.
Define pulmonary ventilation
The total volume of air that has moved into the lungs during one minute
