Transport (Animals and Plants) Flashcards
Briefly describe the vascular system of insects.
● Open circulatory system
● Dorsal-tube shaped heart
● Respiratory gases not carried in blood
What is an open circulatory system?
● Transport medium pumped by the heart is not contained within vessels, but moves freely
● Transport fluid comes into direct contact with the cells
Briefly describe the vascular system of earthworms
● Vascularisation
● Closed circulatory system
● Respiratory gases carried in blood
What is a closed circulatory system?
● Blood pumped by the heart is contained within blood vessels
● Blood does not come into direct contact with the cells
Describe the advantages of a closed
circulatory system
● Blood pressure can be maintained
● Blood supply to different organs can vary
● Lower volumes of transport fluid required
What type of circulatory system do
fish have?
Single circulatory system
What is a single circulatory system?
● Circulatory system in which the blood travels through the heart once in one circuit
● Blood flows through the heart and is pumped around the body before returning to the heart
What type of circulatory system do
mammals have?
Double circulatory system
What is a double circulatory system?
● Circulatory system in which the blood flows through the heart twice in two circuits
● Blood is pumped from the heart to the lungs before returning to the heart. It is then pumped around the body, after which it returns to the heart again
What are the benefits of a double
circulatory system?
● Maintains blood pressure around the whole body
● Uptake of oxygen is more efficient
● Delivery of oxygen and nutrients is more efficient
● Blood pressure can differ in pulmonary and systemic circuits
Describe the double circulatory system in
humans
Blood flows through the heart twice in two circuits:
● Pulmonary circuit
● Systemic circuit
Name the four chambers of the
mammalian heart.
● Left atrium
● Right atrium
● Left ventricle
● Right ventricle
Describe the pathway of blood around
the body, naming the structures of the
heart
Pulmonary vein → Left atrium → Left ventricle →Aorta → Body → Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs
Where are the atrioventricular valves
found and what is their function?
● Found between the atria and ventricles
● Prevent the backflow of blood from the
ventricles into the atria
What are the two types of
atrioventricular valves?
● Bicuspid (left side)
● Tricuspid (right side)
Where are the semilunar valves found
and what is their function?
● Found between the ventricles and arteries
● Prevent the backflow of blood from the
arteries into the ventricles
Name the five types of blood vessel.
● Arteries
● Arterioles
● Capillaries
● Venules
● Veins
Describe the pathway of blood through
the blood vessels.
heart → arteries → arterioles →
capillaries → venules → veins → heart
What is the function of arteries?
Carry blood away from the heart to the
tissues, under high pressure
Relate the structure of arteries to their
function
Thick, muscular walls to handle high
pressure without tearing. Elastic tissue
allows recoil to prevent pressure surges.
Narrow lumen to maintain pressure
What is the function of veins?
Carry blood towards the heart under low
pressure.
Relate the structure of veins to their
function.
Thin walls due to lower pressure. Require
valves to ensure blood doesn’t flow
backwards. Have less muscular and elastic
tissue as they don’t have to control blood
flow.
What is the function of capillaries?
Form a large network through the tissues
of the body and connect the arterioles to
the venules.
Relate the structure of capillaries to their
function.
● Walls only one cell thick ∴ short diffusion pathway
● Very narrow, so can permeate tissues and red blood cells can lie flat against the wall, reducing the diffusion distance
● Numerous and highly branched, providing a large surface area
What is the function of arterioles?
Connect the arteries and the capillaries.
What is the function of venules?
Connect the capillaries and the veins
Relate the structure of arterioles and
venules to their function.
● Branch off arteries and veins in order to feed blood into capillaries
● Smaller than arteries and veins so that the change in pressure is more gradual as blood flows to the capillaries
What is the cardiac cycle?
● The sequence of events involved in one complete contraction and relaxation of the heart
● Three stages: atrial systole, ventricular systole and diastole
Describe what happens during ventricular diastole
The heart is relaxed. Blood enters the atria,
increasing the pressure and pushing open the AV valves. This allows blood to flow into the
ventricles. Pressure in the heart is lower than in the arteries, so SL valves remain closed.
Describe what happens during atrial
systole.
● The atria contract, pushing any
remaining blood into the ventricles
● AV valves pushed fully open
Describe what happens during
ventricular systole
The ventricles contract. The pressure in the
ventricles increases, closing the AV valves
to prevent backflow and opening the SL
valves. Blood flows into the arteries
Why is cardiac muscle described as myogenic?
It initiates its own contraction without
outside stimulation from nervous
impulses
Explain how the heart contracts.
● SAN initiates and spreads impulse across the atria, so they contract
● AVN receives, delays, and then conveys the impulse down the bundle of His
● Impulse travels into the Purkyne fibres which branch across the ventricles, so they contract from the bottom up
What is an electrocardiogram (ECG)?
A graph showing the electrical activity in
the heart during the cardiac cycle.
Explain the characteristic patterns
displayed on a typical ECG
● P wave - depolarisation of atria during atrial systole
● QRS wave - depolarisation of ventricles during ventricular
systole
● T wave - repolarisation of ventricles during ventricular
diastole
Describe the structure and function of
erythrocytes.
● Type of blood cell that is anucleated and
biconcave
● Contains haemoglobin which enables the
transport of oxygen and carbon dioxide to and from the tissues
What is plasma?
● Main component of the blood (yellow liquid) that carries red blood cells
● Contains proteins, nutrients, mineral ions,
hormones, dissolved gases and waste. Also
distributes heat
Describe the role of haemoglobin.
Present in red blood cells. Oxygen
molecules bind to the haem groups and are
carried around the body, then released
where they are needed in respiring tissues.
How does the partial pressure of oxygen
affect oxygen-haemoglobin binding?
Haemoglobin has variable affinity for oxygen depending on the
partial pressure of oxygen, p(O2):
● At high p(O2), oxygen associates to form oxyhaemoglobin
● At low p(O2), oxygen dissociates to form deoxyhaemoglobin
Write an equation for the formation of
oxyhaemoglobin.
Hb + 4O2 ⇌ Hb*4O2
What do oxyhaemoglobin dissociation
curves show?
Saturation of haemoglobin with oxygen (%),
plotted against partial pressure of oxygen
(kPa). Curves further to the left show that the
haemoglobin has a higher affinity for oxygen.
Explain the shape of oxyhaemoglobin
dissociation curves.
Sigmoidal curve (S-shaped):
● When first O2 molecule binds, it changes the tertiary structure of haemoglobin so that it is easier for the second and third molecules to bind
● Third molecule changes the tertiary structure of haemoglobin so that it
is more difficult for the fourth molecule to bind
How does fetal haemoglobin differ from
adult haemoglobin?
Has a higher affinity for oxygen than adult
haemoglobin due to the presence of two
different subunits that allow oxygen to bind
more readily.
Why is the higher affinity of fetal
haemoglobin important?
Enables the fetus to obtain oxygen from
the mother’s blood.
Compare the dissociation curves of adult
and fetal haemoglobin.
Fetal haemoglobin dissociation curve to the left.
At the same partial pressure, % oxygen saturation is greater due to fetal
haemoglobin having a higher affinity.
Predict the shape of the dissociation
curves of animals adapted to low oxygen
level habitats.
● Haemoglobin has a greater affinity for oxygen
● Haemoglobin is saturated at a lower p(O2)
● ∴ dissociation curve to the left
How is carbon dioxide carried from
respiring cells to the lungs?
● Transported in aqueous solution in the plasma
● As hydrogen carbonate ions in the plasma
● Carried as carbaminohaemoglobin in the blood
What is the chloride shift?
● Process by which chloride ions move into the erythrocytes in exchange for hydrogen carbonate ions which diffuse out of the erythrocytes
● One-to-one exchange
Why is the chloride shift important?
It maintains the electrochemical
equilibrium of the cell.
What is the function of carbonic
anhydrase?
Catalyses the reversible reaction
between water and carbon dioxide to
produce carbonic acid.
Write equations to show the formation of hydrogen carbonate ions in the plasma.
Carbonic anhydrase enzyme catalyses:
CO2+ H2O ⇌ H2CO3
(carbonic acid)
Carbonic acid dissociates:
H2CO3 ⇌HCO3 - (hydrogen carbonate ions) + H+
State the Bohr effect
The loss of affinity of haemoglobin for
oxygen as the partial pressure of carbon
dioxide increases.
Explain the role of carbonic anhydrase in the Bohr effect.
● Carbonic anhydrase is present in red blood cells
● Catalyses the reaction of carbon dioxide and water to form carbonic acid, which dissociates to produce H+ ions
● H+ ions combine with the haemoglobin to form haemoglobinic acid
● Encourages oxygen to dissociate from haemoglobin
what is tissue fluid
