Transport in animals
Features of the transport system
Transport in mammals
Transport of oxygen
Circulatory systems
Open
Closed
Structure/function of blood vessels
The heart
The cardiac cycle
Ventricular systole
Diastole
Atrial systole
3
4
2
5
1
6
Valves
Control of heartbeat
Blood
Red blood cells
Plasma
Transport of CO2
As haemoglobin carbonate ion
Bound to haemoglobin as carbamino-haemoglobin
In solution in plasma
Reactions in red blood cells
Carbon dioxide in the blood diffuses into the red blood cells.
Carbonic anhydrase catalyses the combination of CO2 with water, making carbonic acid.
Carbonic acid dissociates into H and HCO3 ions.
HCO3 ions diffuse out of the red blood cell into the plasma.
To balance the outflow of negative ions and maintain electrochemical neutrality. chloride ions diffuse into red blood cells fro the plasma. This movement is called the chloride shift.
H+ ions cause oxyhaemoglobin to dissociate into oxygen and haemoglobin. The H ions combine with the haemoglobin to make haemoglobinic acid. This removes hydrogen ions and so the pH of the red blood cell does not fall.
Oxygen diffuses out of the red blood cell into the tissues.
Intercellular or tissue fluid
Blood capillaries
They provide a large surface area for exchange of materials.
Have thin, permeable walls
Blood flows slowly through capillaries allowing time for exchange of materials.
Arterial end of capillary bed
Blood is under pressure from the pumping of the heart and muscle contraction in artery and arteriole walls. The high hydrostatic pressure pushes liquid outwards from the capillary to the spaces between the surrounding cells.
Plasma is a solution and its low solute potential tends to pull water back into the capillary, by osmosis.
The hydrostatic pressure is greater than the plasmas solute potential, so water and solutes are forced out through the capillary walls into spaces between the cells.
Solutes, such as glucose, oxygen and ions, are used during cell metabolism so their concentration in and around cells is low, but in the blood is higher. This favour diffusion from the capillaries to the tissue fluid.
Venous end of capillary bed
Tissue fluid surrounding cells picks up CO2 and wastes, which diffuses down a concentration gradient from the cells, where they are made, and into the capillaries, where thy are less concentrated.
Not all fluid passes back into the capillaries. 10% drains into lymph capillary of lymphatic system.
The plasma proteins are more concentrated in the blood because so much water has ben lost. The solute potential of the remaining plasma is more negative. The osmotic force pulling water inwards is greater than the hydrostatic force pushing water outwards so water passes back into the capillaries by osmosis.
The bloods hydrostatic pressure is lower than the arterial end because much fluid has been lost.
A system of vessels with branching network to distribute the transport medium to all body
Have a respiratory pigment which increases volume of oxygen that can be transported
Have halves to maintain flow in one direction
Has a pump (heart) for moving blood
Has a suitable medium in which to carry materials
The blood doesn't move around the body in blood vessels but it bathes the tissues directly while held in a cavity called the haemocoel.
Double circulatory system
The systematic circulation serves the body tissues. The left side of the heart pumps the oxygenated blood to the tissues. Deoxygenated blood from the body returns from the right side of the heart.
In each circuit the blood passes through the heart twice, once through the right side and once through the left.
The pulmonary circulation serves in the lugs. The right side of the heart pumps deoxygenated blood to the lungs. Oxygenated blood returns from the lungs to the left side of the heart.
The blood moves in blood vessels. (in a single circulation or a double circulation).
The atrium walls contract and the blood pressure in the atria increases. This pushes the blood through the tricuspid and bicuspid valves down into the ventricles, which are relaxed.
The ventricle walls contract and increase blood pressure in the ventricles. This forces blood up through the semilunar valves, out of the heart, into the pulmonary artery and the aorta. The blood cannot flow back from the ventricles into the atria because the tricuspid and bicuspid valves are closed by the rise in ventricular pressure. The pulmonary artery carries deoxygenated blood to the lungs and the aorta carries oxygenated blood to the rest of the body.
The left atrium relaxes and receives oxygenated blood from the pulmonary vein.
When full, the pressure forces open the bicuspid valve between the atrium and the ventricle.
Relaxation of the left ventricle draws blood from the left atrium.
The left atrium contracts, pushing the remaining blood into the left ventricle, through the valve.
With the left atrium relaxed and the bicuspid valve closed, the left ventricle contracts. Its strong muscular wall exerts high blood pressure.
This pressure pushes blood up out of the heart, through the semi lunar valves into the aorta and closes the bicuspid valve, preventing backflow of blood into the left atrium.
Valves prevent backflow of blood.
The atria-ventricular valves, semilunar valves (at base of the aorta) and pulmonary artery and semilunar valves in veins all operate by closing under high blood pressure, preventing blood flowing backwards.
The sides ofth heart work together. The atria contract at the same time, followed by the ventricles contracting together. A complete contraction and relaxation of the whole hart is called a heartbeat.
Contraction of cardiac muscle myogenic. The wall of the right atrium has cluster of cardiac cells, the Sino-atrial node, acts as pacemaker.
The impulses cause the cardiac muscle in each ventricle to contract simultaneously, from the apex upwards.
The AVN passes the excitation down the nerves of the bundle of His and the left and right bundle branches and to the apex of the heart. The excitation is transmitted to purknje fibres in the ventricle walls, which carry it upwards through the muscles of the ventricle walls.
The ventricles are insulated from the atria by a thin layer of connective tissue, at the atria-ventricular node. The AVN introduces a delay in the transmission of the electrical impulse. The muscles of the ventricles do not start to contract until the muscles of the atria have finished contracting.
A wave of electrical stimulation arises at the SAN and spreads over both atria, so they contract together.
A tissue made up of cell (45%) in a solution called plasma (55%).
They are red because they contain the pigment haemoglobin, the main function in which is to transport oxygen from the lungs to the respiring tissues. Red blood cells are unusual in 2 ways.
Biconcave discs (larger surface area and thin centre for diffusion) and have no nucleus (more room for haemoglobin).
A pale yellow liquid, 90% water, containing solutes such as food molecules (glucose, amino acids, vitamins and minerals), waste products, hormones and plasma proteins (distributes heat).
Haemoglobin binds to oxygen in the lungs, and releases it in the respiring tissues.
Oxygen+Haemoglobin=Oxyhaemoglobin
In both arteries and veins
The middle layer, the tunica media, contains elastic fibres and smooth muscle. It is thicker in arteries than in veins. In arteries the elastic fibres allow stretching to accommodate changes in blood flow and pressure as blood is pumped from the heart.
Innermost layer is the endothelium, which is1 cell thick and surrounded by the tunica intima. It is a smooth lining, educing friction with a minimum resistance to blood flow.
The outer layer, the tunica externa, contains collagen fibres, which resist overstretching.
Arteries
Capillaries
Veins
Carry blood away from the heart. Their thick, muscular walls withstand the bloods high pressure, derived rom the heat. They branch into smaller vessels called arterioles, tat further subdivide into capillaries.
Form a vast network that penetrates all the tissues and organs of the body. Blood from the capillaries collect into venuoles, which take blood into their veins, which return it to the heart.
Have a larger diameter lumen and thinner walls with less muscle than arteries, making blood pressure and flow rate lower. For veins above the heart, blood returns to the heart by gravity. It moves through other veins by the pressure from surrounding muscles. Veins have semi lunar valves along their length ensuring flow in one direction and preventing backflow.