Transport in animals Flashcards
Describe the open circulatory system usually found in invertebrates, including the transport medium, vessels and exchange. (4)
- (In insects) the transport medium is haemolymph. (1)
- There are very few vessels compard to other transport systems. (1)
- Haemolymph pumped straight from the heart to the haemocoel (body cavity). (1)
- Exchange occurs in the haemocoel, where haemolymph makes direct contact with cells and tissues. (1)
How is the open system’s inability to vary amounts of hameolymph at different tissues a limitation? (1)
It means that the system cannot adapt haemolymph amounts to meet changing demands in the insect’s body; steep diffusion gradients cannot be maintained efficiently. (1)
Fill in the gaps comparing open and closed circulatory systems:
While the transport medium in open circulatory systems is ___, it is ___ in closed circulatory systems. There is an abundance of blood vessels to carry the blood in closed systems, while there are very ___ in open systems. In closed systems, the transport medium is transported at a higher ___ ___ (making it quicker). Exchange occurs in the haemocoel in open systems, where the haemolymph is in ___ contact with cells, but in closed systems, this occurs in the ___ - blood never comes into ___ ___ with cells. (7)
- Haemolymph (1)
- Blood (1)
- Few (1)
- Blood pressure (1)
- Direct (1)
- Capillaries (1)
- Direct contact (1)
State three differences between single closed and double closed circulatory systems. (3)
- Found in fish/annelid worms; found in birds/mammals. (1)
- Two heart chambers; four heart chambers. (1)
- Low blood pressure; high blood pressure. (1)
- Slow rate of flow; fast rate of flow. (1)
- Blood returns the heart slowly (due to travelling through two capillary networks); blood returns to the heart quickly (due to only travelling through one capillary network). (1)
Fill in the blanks, naming each of the five vessels you need to know:
In a mammalian circulatory system, the heart sends the blood into ___. These branch into ___ which eventually lead into ___. This is where exchange happens. They rejoin into ___ which become ___, which carry the blood back to the heart. (5)
- Arteries (1)
- Arterioles (1)
- Capillaries (1)
- Venules (1)
- Veins (1)
What are the smooth, thin layers of cells in blood vessels called and what type of blood vessel’s walls solely consist of these? (2)
- Endothelium (1)
- Capillaries (1)
Blood in the arteries is at its highest pressure. How do arteries cope with this? (3)
- Artery walls have thick layers of elastic tissue which are able to expand and contract. (1)
- Smooth muscle controls the diameter and keeps the vessel open. (1)
- The thick layer of collagen withstands forces and supports the structure. (1)
Which blood vessels have the narrowest lumen and why is this a good adaptation for it? (2)
- Capillaries. (1)
- This maximises gaseous/nutrient exchange (decreased diffusion distance). (1)
Further explanation - the narrow lumen squeezes RBCs against the endothelium. In most parts of the body, the gaps between endothelial cells are large, so RBCs can get in these gaps.
Blood flow in the capillaries slows down. Why is this a defense mechanism and how does it do this? (3)
- If the pressure was as high as it is in the arteries and arterioles, the walls of the capillaries would be damaged OR the blood needs more time to exchange substances with cells. (1)
- The blood is under increased resistance due to its interaction with the capillary walls. (1)
- The cross-sectional area of the capillaries is larger than the arterioles, to ensure a drop in pressure. (1)
How are veins structured to carry blood back to the heart at a low pressure? (5)
- The walls are thin. (1)
- The lumen is wide, maximising blood flow. (1)
- Valves prevent back flow. (1)
- They are usually surrounded by muscles (1) in the body that compress the veins, pushing the blood along. (1)
What is the job of a venule? (1)
To carry the blood from the capillaries to the veins. (1)
How is vasodilation and vasoconstriction used in arterioles? (4)
- Vasodilation/vasoconstriction allows arterioles to direct the flow of blood into certain organs. (1)
- The contraction of smooth muscle (1) constricts the vessel, preventing blood flow into a capillary bed. (1)
- When the smooth muscle relaxes, the blood vessel dilates, allowing blood to flow into the capillary bed. (1)
Name three substances/molecules found in the plasma. (3)
- Water
- Albumin (1)
- (Dissolved) glucose (1)
- Mineral ions (1)
- Hormones (1)
- Fibrinogen (1)
- Globulins (1)
Albumin are proteins in the blood that maintain ___ ___. (1)
Osmotic potential; oncotic pressure (1)
Fill in the blanks about the production of tissue fluid:
Due to plasma proteins called ___, blood has a high solute potential compared to surrounding fluid. So, ___ moves into the blood via ___ (mainly in the ___) - this is called oncotic pressure. Blood entering the capillaries is affected by ___ of the heart still (___ pressure). At the arterial end of the capillaries, this pressure in ___ than the oncotic pressure. The volume of water being ___ ___ of the capillaries is greater than the volume of water entering.
This fluid fills the spaces between cells and is tissue fluid. (8)
- Albumins (1)
- Water (1)
- Osmosis (1)
- Capillaries (1)
- Contractions (1)
- Hydrostatic (1)
- Greater (1)
- Squeezed out (1)
Tissue fluid is mostly made up of the same things as plasma, but lacks…
- Red blood cells (1)
- Albumins (1)