8 - Transport in Animals Flashcards
What happens to the surface area: volume ratio as animals get larger? How does this impact an organisms transport systems?
larger sa:v ratio
therefore larger (multicellular) organisms need transport systems
they can not rely on diffusion
high metabolic demands
state the main features of an open circulatory system
no blood vessels, cells are bathed in fluid
What are the 4 types of classification for circulatory systems?
open, closed, single and double
An insect has an open circulatory system, describe how cells in the insect obtain nutrients and discard waste
There is a haemocoel (cavity) in the body surrounding the tissues. A fluid called haemolymph travels around the haemocoel and transfers nutrients, taking nitrogenous waste with it
State 3 disadvantages of an open circulatory system
- not very efficient
- system is fixed, does not change with metabolic demand
- haemolymph moves slowly - steep conc. gradients can not be maintained (equilibrium may be reached)
State the features of a closed circulatory system (4)
- liquid medium to transport substances
- blood vessels to carry blood
- a pump to move fluid round body
- respiratory pigment to transport oxygen
Describe a single circulatory system
in one circuit, the fluid (blood) only flows through the pump (heart) once
State a disadvantage of a single circulatory system
pressure decreases as is only moved through the pump (heart) once in a circuit
Describe a double circulatory system
in one circuit, the fluid (blood) only flows through the pump (heart) twice. once to collect oxygen from the exchange surface and the second to deposit the oxygen to the tissues
State 2 advantages of a double circulatory system
- higher blood pressure (increased rates of blood flow, therefore able to meet higher metabolic demand)
- blood flow can be changed (vasodilation, vasoconstriction)
What is the endothelium
one cell thick layer at the centre of blood vessels
How is the endothelium adapted to its function
one cell thick - short diffusion pathway
smooth - reduces friction, easy blood flow
What is the function of smooth muscle in a blood vessel
thick muscle layer. can constrict/relax to change size of lumen
What is the function of elastic fibres in a blood vessel
made of elastin
can stretch and recoil to even out blood flow and maintain pressure
What happens to the lumen in vasoconstriction
lumen becomes smaller
What happens to the lumen in vasodilation
lumen becomes wider
In general arteries do/do not have valves
In general arteries do not have valves
Which arteries DO have valves
Pulmonary artery and aorta
Why do arteries, in general, not have valves?
Blood is under high pressure as it is leaving the heart so the blood tends not to flow backwards
Why do arteries have thick walls?
Prevents from bursting due to high pressure
Why do veins have small amounts of elastin
low pressure, therefore, no need to stretch to regulate pressure
In general veins do/do not have valves
In general arteries do have valves
Veinns have lots/little amount of elastin
Viens have little amount of elastin
Why do veins have valves
Low pressure, risk of backflow of blood, valves prevent this backflow
How do pocket valves in veins work?
Blood flowing toward heart can pass through easily, blood flowing back pushes the flaps of the valve closed so blood is prevented from flowing back any further in this direction
Where are muscle pumps found and what do they do?
around veins
contract and squeeze veins aiding flow back to heart
What happens at the capillaries
Substances exchanged between blood and tissues
Where are substances exchanged between blood and tissues
The capillaries
State 2 features of capillaries
single layer of cells
pores (fenestrations)
Describe how the capillaries are adapted for their function
- single layer of cells - short diffusion pathway
- pores - WBC can pass out to fight infection
- RBCs must pass 1 by 1, maximum s.a. of contact with endothelium wall, max rate of diffusion
Name 5 substances that pass from blood into tissues
- vitamins/minerals/ions
- amino acids
- fatty acids
- oxygen
- hormones
Name 2 substances that pass from tissues into blood
- CO2
- Urea
State 4 adaptions of RBCs
Biconcave
Flattened
No nucleus
Haemoglobin
What is the function of Haemoglobin?
Binds to the oxygen to transport from lungs to respiring tissues (for aerobic respiration)
Haemoglobin + oxygen =
oxyhaemoglobin
define affinity
how easily/readily Hb binds to (loads) or releases (unloads) its oxygen
Define association with regard to Haemoglobin
Hb binding to oxygen (at a gas exchange surface)
Define disassociation with regard to Haemoglobin
Hb releasing its oxygen (at respiring tissues)
What would you expect Hb’s affinity for oxygen to be at gas exchange surfaces (eg. lungs/gills)
High
What would you expect Hb’s affinity for oxygen to be respiring tissues
Low
If Hb has a high affinity for oxygen, oxygen will be loaded/unloaded
If Hb has a high affinity for oxygen, oxygen will be loaded
If Hb has a low affinity for oxygen, oxygen will be loaded/unloaded
If Hb has a low affinity for oxygen, oxygen will be unloaded
In regards to haemoglobin, what does PO2 mean?
Partial pressure of oxygen
The saturation of haemoglobin with oxygen is 50%. On average, how many oxygen molecules does each haemoglobin carry?
2
What is the name of the shape of an oxygen dissociation curve
sigmoidal curve (s-shaped)
Describe the cooperative nature of oxygen binding to Haemoglobin
- when oxygen binds to 1 of the 4 bonding sites, the affinity of the remaining 3 increase
- each molecule causes a conformational change in the Hb, exposing the haem group more for the other oxygens
- called positive cooperation
How does the partial pressure of CO2 change the affinity of haemoglobin for oxygen?
Reduces affinity (easier to unload)
- CO2 is an acidic gas
- lowers the pH
- change in shape of haemoglobin
How and why does foetal haemoglobin vary from normal adult haemoglobin?
- foetal haemoglobin has a higher affinity for oxygen
- so foetal blood takes oxygen from maternal blood
- enables foetus to survive and grow
An oxygen dissociation curve is shifted to the left. How does this change the Haemoglobin?
Affinity for oxygen is higher
Hb loads oxygen more easily
An oxygen dissociation curve is shifted to the right. How does this change the Haemoglobin?
Affinity for oxygen is lower
Hb loads oxygen less easily
State the 3 ways CO2 is transported in the blood
small amount- dissolved in blood plasma
small amount- combines with amino groups in polypeptide chains in Hb to form carbaminohaemoglobin (HHb)
most-transported inside of cytoplasm of RBC to form hydrogen carbonate ions
What is albumins role in the blood?
Maintains water potential
What is fibrinogens role in the blood?
Essential for the clotting process
What is oncotic pressure?
The tendency for water to move in or out of the blood by osmosis due to a difference in water potential caused by proteins
What is the role of tissue fluid?
Lets materials be exchanged from the blood by diffusion before diffusing into cells
What can be exchanged between blood and tissue fluid
Water, oxygen, CO2, urea, glucose, amino acids, vitamins and minerals (anything but cellular components of blood and proteins)
net flow in the capillaries is calculated by
hydrostatic pressure - osmotic pressure
Where does excess fluid in tissue fluid go?
Drained by lymphatic system, the fluid (Lymph) is returned to circulation close to the heart
Describe 2 features of the lymphatic capillaries
Surrounded by muscle pumps and have valves as lynph is at low pressure trying to return to heart
What would happen if excess tissue fluid is not drained
Build up of fluid would lead to swelling or Edema
Which side of the heart pumps blood to the lungs
Right
Which blood vessel carries oxygenated blood from heart to body
Aorta
Which vessels brings deoxygenated blood back to the heart
Vena cava
Which vessels supply the cardiac muscle with oxygen
Coronary arteries
What is the septum
wall dividing the left and right side of the heart
What valves are located in the ventricle and stop backflow of blood leaving the heart
Semilunar valve
Where is the semilunar valve located
Left ventricle
What valve is located at the bottom of the left atrium?
tricuspid valve
What valve is located at the bottom of the right atrium?
bicuspid valve
What is diastole and what happens to blood flow during it
Heart is fully relaxed and blood enters to atria and ventricles
What happens after diastole?
Atrial systole
What happens in atrial systole? (blood, pressure, valves…)
Muscles in atrium contract, increasing pressure, forces AV valves open, blood flows into ventricles
What happens in ventricular systole?
Ventricles contract, increasing pressure, Av valves closed and semilunar valves open, forcing blood out of the heart
How many systole and diastole are in one complete heartbeat
1 diastole, 1 atrial systole, 1 ventricular systole
What is cardiac output?
The volume of blood pumped out of the heart in one minute
What controls our body’s steady heart rate, why?
The heart itself, it does not need nay external nerve input, therefore the body does not need to waste any energy maintaining a resting heart rate
Name the 2 nodes that control our heart rate
Sino-atrial node
Atrioventriucular node
What do the nodes in our heart do
Specialised group of muscle cells found in the wall of our right atrium that produce a wave of excitation
Describe the role of the nodes step by step in maintaining our heart beat
1 – SA node produces wave of excitation that spreads over both atria causing them to contract
2 – Wave is transmitted to AV node where impulse is delayed slightly
3 – impulse passes to bundle of His (made of Purkinje fibres) that pass through septum and round ventricles causing them to contract from bottom up
What does ECG stand for?
Electrocardiogram
What do ECGs measure?
the electrical impulses in the heart
What do P waves on ECGs signify?
depolarisation of the atria
What does the QRS complex on ECGs signify?
depolarisation of the ventricles
What does the T wave on an ECG signify?
Repolarisation of the ventricles
What is bradycardia
An abnormally slow heart rate
What is an abnormally slow heart rate called?
Bradycardia
What is tachycardia
An abnormally fast heart rate
What is an abnormally fast heart rate called?
Tachycardia
What is an ectopic heartbeat
Irregular heartbeat
What is an irregular heartbeat called?
Ectopic heartbeat
What is atrial fibrulation?
Atria repeatedly contracting (spasming)
How would you recognise atrial fibrillation on an ECG trace?
Many small P-waves, impulses not passed on to ventricles so irregularly spaces QRS complexes
Name the 4 layers in arteries and veins in order starting from the inside
Endothelium
Elastin
Smooth muscle
Collagen
