animal transport Flashcards
(48 cards)
What do small organisms use for diffusion of nutrients and why
They have a large surface area to volume ratio and a small demand for oxygen so they can use their cell surface membrane for diffusion of nutrients
What do larger organisms use instead of diffusion and why
They have a smaller surface area to volume ratio and a Higher metabolic rate so a greater demand for oxygen.
The distance from the surface to inner cells is also too far
So Gas exchange through diffusion is not efficient To meet this high demand
so they use specialised surfaces for gas exchange
What is the circulatory system
Its an organ system that permits blood to circulate
What is blood and its role
Blood is a tissue fluid which transports vital components (O2, CO2, hormones, blood cells) around the organism to and from cells in the body to enable: respiration, help fight disease and maintaining homeostasis (stable temperature and PH)
Open circulatory system vs close circulatory system
Open system - blood isn’t enclosed in vessels but flows freely through the body cavity
Closed system - blood is enclosed inside blood vessels
What are the disadvantages of an open circulatory system
There is a lack of a steep concentration gradient so rate of diffusion is slower
Single vs double circulatory systems
Single system - blood only passes through the heart once for each circuit of the body
Double system - the blood passes through the heart twice for each circuit of the body
What are the advantages of having a double circulatory system
- as oxygenated Blood returns to the heart from the lungs, it can be pumped at a higher pressure So they reach the lungs/rest of the body faster
- oxygenated and deoxygenated blood do not mix Which maintains steep concentration gradients at exchange surfaces
What are the limitations of a single circulatory system
- Blood is pumped at a lower pressure as it doesn’t come back to the heart from the lung to be pumped again so slower flow of blood round the body
- Oxygenated and deoxygenated blood can mix so less of a concentration gradient
What is an incomplete double circulatory system
- Blood goes through the heart twice so it can be pumped out at a higher pressure
- but there is only one ventricle so oxygen deoxygenated blood are mixed so there is a less steep concentration gradient so diffusion at exchange surfaces is slower
Compare fish and mammal circulatory system
- Both are closed and have a heart both carry oxygen using haemoglobin both have arteries veins capillaries
- Fish is a single circulation with one artery and one ventricle so no Septum in the heart and only two chambers, Blood pressure stays lower so less efficient at supplying oxygen to tissue
- Mammals have a turbo circulatory system with four chambers in the heart and a septum, Blood is maintained at a high pressure so more efficient at transporting oxygen required for high demand Due to high metabolic rate
What are the vessel components of a double circulatory system from smallest to biggest
Capillaries arteries veins
veins structure and function
- Returns blood to the heart at low pressure
- made of thin walls made of mainly collagen tissue; to Provide structural support to carry large amounts of blood
- containing less elastic tissue because of the lower pressure blood
- has a wide lumen which allows less resistance to blood flow
- has valves to prevent backflow
arteries structure and function
- carries blood away from the heart at a high pressure
- strong walls containing muscle fibres; Which contracts and relaxes to change the size of the lumen to control blood pressure,
elastic fibres: needed to withstand the blood at high pressure whilst preventing bursting, Allowing stretch and recoil and prevents blood flowing backwards to heart
collagen tissue; Provide structural support to carry large amounts of blood - Contains a narrow lumen to maintain pressure
Capillary structure and function
- Supply all cells with oxygen for respiration and take away waste e.g. CO2.
- Made of one cell thick walls and has a narrow lumen, just wide enough for a red blood cell to bring blood into close contact with body tissue allowing a shorter diffusion distance for materials between capillary and cells.
- The walls are not needed to be strong as most of the pressure has been lost.
- highly branched allowing a high SA, shorter distance and makes sure each cell has enough supply of oxygen
systole vs diastole
contraction vs relaxation
oxygen + haemoglobin =
oxyhaemoglobin
what are Arterioles
- branch off arteries leading to capillaries
- have thinner and less muscular walls as they have lost some pressure,
- they feed oxygenated blood into capillaries
what are Venules
- larger than capillaries but smaller than veins and arteries
- Receive deoxy blood from the capillaries to go through veins
What is tissue fluid and its function
It is a fluid that surround cells in tissues, it enables exchange of substances between blood and cells. it contains dissolved solutes liked O2, amino acids, glucose and other nutrients which is supplied to cells in exchange for waste products such as CO2.
what type of pressure influences formation of tissue fluid
hydrostatic pressure - (pressure exerted by the liquid in capillary ) higher at arterial end of capillary than venous end as by then fluid would have moved out
oncotic pressure - type of osmotic pressure which stays the same but is induced by plasma proteins
how is oncotic pressure only reliant on concentration of plasma proteins in blood fluid
plasma proteins are the on ones too large to process out through the capillary wall Causing an imbalance of plasma proteins between the blood and tissue fluid resulting in oncotic pressure
how is tissue fluid formed and how does gas exchange occur at the capillaries
At the arteriole end of the capillary (where the hydrostatic pressure is greater inside the capillaries than in the tissue fluid) plasma is forced out by mass flow containing dissolved solutes eg glucose, O2, amino acids and hormones forming tissue fluid where it exchanges substances with the cells.
At the venule end, we have a lower hydrostatic pressure Then oncotic pressure because of the higher Concentration of plasma protein so some water is drawn back into the capillary by osmosis with urea and CO2.
what happens to the excess tissue fluid
moves into the lymphatic capillary which contains lymphatic fluid and valves to stop backflow
