Transport in animals- Blood and tissue fluid Flashcards
State 5 reasons why most animals need specialised transport systems.
- The demands of most multicellular animals are high- so diffusion over long distances is not enough to supply the quantities needed
- The SA:Vol ratio gets smaller as the multicellular organisms get bigger
- Molecules such as hormones or enzymes may be made in one place but needed in another
- Food will be digested in one orgna system but needs to be transported in every cell to be used for respiration
- Waste products of metabolism need to be removed from the cells and transported to excretory systems
Describe how diffusion distance, SA, Volume and SA:Vol ratio vary with increasing organism size.
Diffusion distance increases as the organism gets bigger
SA gets relatively smaller as the size increases
SA:Vol ratio gets smaller as the size increases.
Describe how the level of activity of an organism is related to demand for oxygen and glucose.
As the level of activity increases the more need for oxygen and glucose- respiration
Explain how volume is related to demand and surface area is related to supply. Also explain why supply meeting demand requires adaptations as organisms increase in size.
- A larger volume means a larger volume of cells which means a higher metabolic demand.
- Surface area gives a surface for the exchange of nutrients and gases- larger SA means a faster supply
- When SA:Vol ratio is so small that the organism cannot meet its metabolic demands adaptations are required to develop a more efficient transport system.
Define mass of fluid
When substances are transported in a mass of fluid with a mechanism for moving the fluid around the body
Define circulatory system
The transport system of an animal
Define closed circulatory system
A circulatory system where the blood is enclosed in blood vessels and does not come into direct contact with the cells of the body beyond the blood vessels.
Define open circulatory system
A circulatory system with a heart but few blood vessels to contain the transport medium. The blood vessels open up to a pool of blood called the haemoceol
Define haemolymph
The transport medium of blood in insects
Define single circulatory system
A circulatory system where the blood flows through the heart and is pumped out to travel all around the body before returning to the heart.
Define double circulatory system
A circulatory system where the blood travels twice through the heart for each complete circulation of the body. The first circulation blood is pumped by the heart to the lungs. In the second circulation oxygenated blood is pumped by the heart to the brain and body to supply cells with Oxygen
Define pulmonary circulation
The flow of blood away from the heart through the lungs where oxygenation occurs and then returns to the heart again
Define systemic circulation
Flow of blood away from the heart to the brain,liver, kidney, stomach and other organs, the limbs, and the muscles of the body, and then the return of this blood to the heart.
State some examples of organisms with each type of circulatory system.
Fish- Closed and single circulatory system
Insect- Open circulatory system, (single probs)
Human- Closed and double circulatory system
Describe the general features of circulatory systems.
- They have a liquid transport medium that circulates around the system
- They have vessels that carry the transport medium
- They have a pumping mechanism to move the fluid around the system.
Draw a table to show the similarities and differences between, and advantages and disadvantages of, open and closed circulatory systems.
Open: 1. Supply and disposal of materials is very slow 2. Blood flow can't be regulated 3. Blood flows at a slow velocity Closed: 1. Supply and disposal of materials is faster 2. Blood flow can be regulated 3. Blood flows at a fast velocity
Draw a table to show the similarities and differences between, and advantages and disadvantages of, single and double circulatory systems.
Double:
1. Double circulatory systems are important because they ensure that we are giving our tissues and muscles blood full of oxygen, instead of a mixture of oxygenated and deoxygenated blood.
2. Requires more energy
3. The blood pressure can be high in the systemic circuit, while remaining low and safe in the pulmonary circuit
Single:
1. Can only maintain one pressure- always low so doesn’t damage capillaries.
2. Fish aren’t as active so their system is sufficient for their needs
Explain the differences between the pulmonary and systemic circulations.
- Pulmonary circulation refers to the circulation of blood in which deoxygenated blood is pumped from the heart to the lungs and oxygenated blood is returned to back to the heart. Pulmonary circulation only occurs between the heart and the lungs.
- Systemic circulation refers to the circulation of blood in which oxygenated blood is pumped from the heart to the body and deoxygenated blood is returned back to the heart. Systemic circulation occurs between the heart and the entire body
List, in order, the sequence of blood vessel types that blood passes through once it leaves the heart.
Arteries, arterioles, capillaries, venules, veins
Define lumen
The hole in the centre of the blood vessel
State the names of the anatomical layers in arteries and veins
From outer to inner
- Tunica externa (collagen which provides structural support to maintain the shape and volume of the vessel)
- Tunica media (smooth muscle layer which contracts or relaxes changing the size of the lumen and a elastic layer which contain elastic fibres which allow it to stretch and recoil providing the vessel walls with flexibility.
- Tunica interma (single layer of cells called the endothelium comes into direct contact with the blood so is very smooth to allow blood to move without resistance)
State the names of the anatomical layers in capillaries
- Contain an endothelial layer.
Compare the relative proportions of elastin fibres, smooth muscle and collagen in the aorta, medium-sized arteries and arterioles and relate these to their function.
- Elastin fibres- Aorta > medium sized artery > arteriole
- Smooth muscle-Medium sized artery > arteriole >aorta
- Collagen- aorta > arteriole> medium sized artery
Arterioles
Describe the structure of capillaries.
- Very small
- Substances are exchanged through the capillary walls between the tissue cells and the blood
- The gaps between the endothelial cells that make up the capillary walls in most areas of the body are very large- where many substances pass out of the capillaries into the fluid surrounding the cells
Explain how capillaries are adapted for their function.
- Very thin walls- so have efficient diffusion of substances- endothelium is one cell thick
- They are small enough to form the immense networks needed to exchange substances between the blood and tissues
- Provide large surface area for diffusion
- Relatively slow movement of blood through the capillaries allows time for the exchange of materials by diffusion
Explain how the structure of veins makes them adapted for their function.
- Have wider lumen than arteries- help blood move through under low pressure
- Very little elastic or muscle tissue
- Contain valves to prevent backflow
- Blood flow is helped though the veins by contraction of the body muscles surrounding them
- They take de-oxygenated blood back to the heart under low pressure
Describe the function of valves in veins and explain how they work.
- They are flaps or infoldings of the inner lining of the vein
- When blood flows in the direction of the heart the valves open so the blood can pass through
- If the blood starts to flow backwards the valves close to prevent this from happening
Describe 3 adaptations that enable the body to return low pressure blood to the heart against gravity.
- Valves
- Many bigger veins run between big active muscles in the legs. When they contract they squeeze the veins forcing blood towards the heart.
- Breathing movement of the chest act as a pump- pressure changes and the squeezing actions move blood in the veins of the chest towards the heart
Describe the processes of vasoconstriction and vasodilation, and how this affects blood flow through capillaries.
- Arterioles have more smooth muscle but less elastin than arteries- little pulse surge but can constrict or dilate to control the flow of blood
- When the smooth muscle in the arteriole contracts it constricts the vessel and prevents blood flowing into a capillary bed- vasoconstriction
- When the smooth muscle relaxes- blood flows in the capillary bed- vasodilation
List the components of blood and describe their functions.
- Plasma- yellow liquid- carries a variety of other components (dissolved glucose, amino acids, mineral ions, hormones)
- Plasma also transports large plasma proteins- albumin, fibrinogen and globulins
- Plasma also transports- red blood cells- carry oxygen and white blood cells and platelets
State the functions of blood as a whole.
Main function is transport of : 1. Oxygen and Co2 2. Digested food from small intestine 3. nitrogenous waste products from cells to excretory organs 4 .chemical messages (hormones) 5. Food molecules 6. Platelets 7. Cells and antibodies involved in immune response
Define blood plasma
A yellow liquid that makes up 55% of blood volume. It carries a lot of stuff
Define tissue fluid
The solution surrounding the cells of multicellular organisms
Define lymph
Modified tissue fluid that is collected in the lymph system
Draw a table to compare the components of blood, tissue fluid and lymph.
- Red blood cells- B - Too big to get through capillary walls into tissue fluid
- White blood cells- B, Few in TF, L- Most are in lypmh system, only enter tissue fluid when there’s infection
- Platelets-B - Only present in tissue fluid if the capillaries are damaged
- Proteins-B, few in TF, only antibodies in L- Most plasma proteins are too big to get through capillary walls
- Water- B,TF,L- TF and L have higher water potential than blood
- Dissolved solutes- B, TF, L - can move freely between them
Describe how total cross sectional area of blood vessels varies across the circulatory system.
- As the total cross-sectional area of the vessels increases, the velocity of flow decreases.
- Blood flow is slowest in the capillaries, which allows time for exchange of gases and nutrient
Define the term hydrostatic pressure
The pressure created by water in an enclosed sytem
Define the term oncotic pressure
The tendency of water to move into the blood by osmosis as a result of plasma proteins
Define the term filtration pressure
The net driving force which pushes fluid into tissue spaces and out of vascular sites.
The net result between capillary osmotic pressure and hydrostatic pressure.
Describe how blood pressure / hydrostatic pressure varies across the circulatory system.
- It is higher near arteries and next in capillaries next to arterioles
- Lower near venules
Describe how the oncotic pressure and hydrostaic pressure in capillaries is produced.
- The plasma proteins give blood in the capillaries a relatively high solute potential- low water potential- compared with the surrounding tissue fluid
- As a result water has a tendency to move into the blood in the capillaries from the surrounding fluid by osmosis- oncotic pressure
- However as water flows through the arterioles into the capillaries it is still under pressure from the surge of blood that occurs from the heart contraction- hydrostatic pressure
- This is higher than the oncotic pressure- so water is squeezed out of capillaries by hydrostatic pressure- forms tissue fluid.
- As the blood moves towards venous system the hydrostatic pressure falls, so now the oncotic pressure is stronger- water moves back into capillaries by osmosis.
Draw, label and annotate a diagram to explain the movement of liquid into or out of a capillary (include example calculations).
- When the hydrostatic pressure is higher than the osmotic pressure there is a net flow of fluid out of the capillary
- When the hydrostatic pressure is lower than the oncotic pressure there is a net flow of fluid into the capillary by osmosis
Describe the structure and function of the lymphatic system.
- Not all of the fluid re-enters the capillaries at the vein end - some excess tissue fluid is left over.
- This extra fluid gets returned to the blood through the lymphatic system
- The smallest lymph vessels are called the lymph capillaries
- Excess tissue fluid passes into the lymph vessels- one inside it’s called lymph
- Valves in the lymph vessels stop the lymph going backwards
- Lymph gradually moves towards the main lymph vessels in the thorax, where it’s returned to the blood- near the heart.
Draw a diagram to outline the transfer of liquid between the blood, tissue fluid and lymph in the body.
- From the blood it goes to the tissue fluid and most gets reabsorbed to the blood
- The liquid that doesn’t drains off to the lymph where it gets transported in lymph vessels back to the blood plasma
Describe the difference between the walls of arteries and veins
- Arteries don’t have valves
- Arteries have a folded epithelium
- Arterires have a thicker muscle/ elastic tissue/ tunica media
- Arteries have thicker collgen/ tunica externa
State how the hydrostatic pressure is generated in the heart
By the contracting of the ventricles
Explain hwy he hydrostatic pressure of the blood drops as the blood moves away from the heart
- More smaller vessels which have a larger cross-sectional area
- Reduced resistance to blood flow
- The arteries stretch and expand
- Loss of fluid from the capillaries
