Flashcards in Transport in animals Deck (46):
What is the transport medium in open circulatory systems?
What is the body cavity in open circulatory systems called?
Why do animals require transport systems?
Rate of diffusion too low
High metabolic rates
Low SA:V ratios
Molecules (e.g. enzymes and hormones) need to be transported to specific tissues
What are internal transport systems for?
To transport nutrients and oxygen around the body
What are some examples of organisms with open circulatory systems?
Some invertebrates, such as arthropods (including insects) and molluscs
What are some examples of organisms with closed circulatory systems?
All vertebrates and many invertebrates (e.g annelid worms, cephalopods)
What is the transport medium in closed circulatory systems?
What are some examples of organisms that have single circulatory systems? (blood passes through heart once per circulation)
Fish, annelid worms
What are some organisms that have a double circulatory system? (Blood pumped to lungs and returns to heart carrying oxygen, then to body tissues before returning to heart
Birds and mammals
What is circulation to the lungs called?
What is circulation to the respiring tissues called?
What are the advantages of a closed double circulatory system?
Blood pressure is maintained
Oxygenated and deoxygenated blood does not mix
Lower volumes of transport fluid required
Blood supply to different tissues can be varied depending on demand
Delivery of oxygen and nutrients more efficient
What do elastic fibres provide in blood vessels?
What is the role of smooth muscle in blood vessels?
To adjust lumen size
What is the role of collagen in blood vessels?
What are the main differences between veins and arteries?
Veins have a larger lumen and arteries have more elastic tissue. Veins have valves typically.
What is the typical diameter of an artery?
What is the typical diameter of a capillary?
What is the typical diameter of a vein?
Why do arterioles contain a high proportion of smooth muscle?
The muscle can contract to narrow the lumen (vasoconstriction) or relax to widen the lumen (vasodilation), controlling blood flow
What are the key features of capillaries?
Thin walls (single layer of squamous epithelial cells with gaps between them). The walls are permeable to allow diffusion of particles into tissue fluid
Why do arteries have a high proportion of elastic tissue?
To stretch and recoil, preventing rupture when the heart pumps
Why do veins have wide lumens and valves?
For smooth blood flow at low pressures and prevent backflow of blood
Which 2 pressures are the key to tissue fluid formation?
Osmotic and hydrostatic
What is hydrostatic pressure?
The pressure exerted by a fluid in confined spaces
Why are cells bathed in tissue fluid?
To enable the exchange of materials: oxygen and nutrients enter cells, waste products leave
At which end does the hydrostatic pressure outweigh the osmotic?
At which end does the osmotic pressure outweigh the hydrostatic?
What is oncotic pressure?
A form of osmotic pressure exerted by proteins, notably albumin, in a blood vessel’s plasma
What approximate percentage of tissue fluid enters the lymphatic system rather than re-entering the blood?
What is the function of lymph?
Important part of the immune system (e.g. phagocytes in lymph notes ingest bacteria)
What proportion of blood is plasma and what proportion is cells/platelets?
55% plasma, 45% cells and platelets
Why is there less solute in tissue fluid than in blood?
Many substances (e.g. oxygen, glucose, amino acids) diffuse into cells. There are no plasma proteins (e.g. albumin, fibrinogen)
What is the difference between lymph and tissue fluid?
Lymph contains less oxygen and nutrients, a greater proportion of fatty acids and a large number of leucocytes
How do leucocytes enter the lymphatic system
They (particularly t lymphocytes) are added to the lymphatic system after maturing in the thymus
What is the equation for the conversion of haemoglobin into oxyhaemoglobin?
Hb + 4O2 -> Hb(O2)4
What percentage of oxygen in the blood is transported by haemoglobin?
98% (2% in solution in plasma)
What proportions of carbon dioxide is found dissolved in the plasma, combined with haemoglobin, and as HCO3- ions?
5% in plasma
10-20% combined with haemoglobin
75-85% converted to hydrogen carbonate ions
What is the equation for the conversion of carbon dioxide into hydrogen carbonate ions?
CO2 + H2O <> H2CO3 <> HCO3- + H+
Catalysed by carbonic anhydrase
Why is a large proportion of CO2 in the blood converted into HCO3-?
To maintain a steep CO2 concentration gradient between respiring tissues and blood
What is the chloride shift?
HCO3- ions move out of erythrocytes and into the plasma, and Cl- ions move into the erythrocytes to replace them
What is the Bohr effect?
Haemoglobin’s oxygen affinity decreases when CO2 is present. Oxygen is released from haemoglobin more easily when carbon dioxide is present
What is partial pressure?
The pressure exerted by a particular gas in a mixture
Why does fetal haemoglobin have a higher affinity for oxygen than adult haemoglobin?
So that oxygen can be passed from the mother’s haemoglobin to the foetus’s haemoglobin in the placenta
What is a slow heart rate called?