Transport In Mammals Flashcards
What is the most efficient form of respiration?
The most efficient form of respiration which releases the most energy from a given amount of glucose is aerobic respiration and this requires a good supply of oxygen. Sublime oxygen to respond tissues is one of the most important functions of an animal’s transport system. At the same time waste products such as carbon dioxide can be removed.
Why do mammals have a greater requirement for oxygen than most other animals?
Mammals have greater requirements for oxygen than most other animals because they use respiration to generate heat inside their bodies, to help keep their body temperature constant. Diffusion is not sufficient in mammals and a transport system is required to distribute oxygen quickly to all body cells and to remove waste products.
What is the main transport system of animals?
The main transport system of animals is the blood system or the circulatory system. The circulatory system is a system that carries fluids around an organism’s body. It is made of the pump-the heart and a system of interconnecting tubes-the blood vessels.
Why is the circulatory system called the closed blood system?
A circulatory system made up of vessels containing blood is called a closed blood system. The blood always remains within these vessels and so the system is known as the closed blood system.
What is double circulation?
A circulatory system in which the blood passes through the heart twice on one complete circuit of the body is called a double circulation.
What is systemic circulation?
The part of the circulatory system that carries blood from the heart to all of the body except the gas exchange surface and then back to the heart is called the systemic circulation. Blood is pumped out of the left ventricle into the aorta and travels from there to all parts of the body except the lungs. It returns to the right side of the heart in the vena cava.
What is pulmonary circulation?
The part of the circulatory system that carries blood from the heart to the gas exchange surface and then back to the heart is called the pulmonary circulation.
The blood is then pumped out of the right ventricle into the pulmonary arteries which carries it to the lungs. The final part of the journey is along the pulmonary veins, which returns it to the left side of the heart.
Define an artery.
An artery is a vessel with thick, strong walls that carry high pressure blood away from the heart. Small arteries are called arterials.
Define a vein
A vein is a vessel with relatively thin walls that carries low pressure blood back to the heart. Small veins are called venules.
Define a capillary.
A capillary is the smallest blood vessel. Linking arterioles and venules taking blood close to almost every cell in the body are tiny vessels called capillaries.
What is the function of arteries?
The function of arteries is to transport blood away from the hearts swiftly and at high pressure to the tissues.
When blood pressure is high the lumen will widen, reducing the pressure a little while at lower pressure the arteries recoil to increase the pressure by giving small push and raising the blood pressure a little.
Describe the structure of the artery.
The artery is made up of three layers.
An inner layer which is made up of a layer of endothelium (lining tissue) consisting of a layer of flat cells (squamous epithelium) fitting together like jigsaw pieces plus a layer of elastic fibers. The endothelium is very smooth minimizing friction with the moving blood.
A middle layer containing smooth muscle collagen and elastic fibers.
An outer layer containing elastic fibers and collagen fibres.
What is smooth muscle?
Smooth muscle is a type of muscle that can contract steadily over long periods of time to maintain high blood pressure.
What is the function of collagen?
Collagen provides strength to withstand high blood pressure.
What is squamous epithelium?
Squamous epithelium is one or more layers of thin, flat cells forming the lining of some hollow structures, for example the blood vessels and alveoli.
What is the function of elastic fibers?
Elastic fibers are allowed to stretch which reduces the likelihood that they will burst. Elastic Fibers stretch as the high blood pressure surges into them and then recoil inwards as the pressure drops.
What is the blood pressure measured in?
Blood pressure is still measured in the old units of mmHg (millimeters of mercury) and refers to the distance which a column of mercury is pushed up the arm of a U-tube. KPa is the SI unit.
What is the diameter of the artery close to the heart and the wall thickness?
Arteries have the thickest walls of any blood vessel. The aorta the largest artery has an overall diameter of 2.5 cm close to the hearts and a wall thickness of about two millimeters.
Which layer of arteries contains the largest amount of elastic fibers?
The middle layer which is by far the thickest part of the wall contains a large amount of elastic fibers. These allow the wall to stretch as pulses of blood surge through at high pressure. Arteries further away from the hearts have fewer elastic fibers in the middle layer but have more muscle fibers.
What is an elastic artery?
Elastic arteries are relatively large arteries, which have a lot of elastic tissue and little muscle tissue in their walls. The function of an elastic arteries to carry blood from the heart on the first part of its journey towards its final destination. The overall effect is to even out the blood flow. However the arteries are not entirely effective in achieving this. An example of an elastic artery is the aorta.
What is a muscular artery?
Muscular arteries are those arteries that are closer to the final destination of the blood inside them than elastic arteries, they have more smooth muscle in their walls which is able to contract slowly and steadily to alter the diameter of the artery and therefore control the volume of blood that can flow through it. This allows them to constrict and dilate. The proportion of elastic tissue decreases.
What do muscular arteries divide into?
Muscular arteries divide to form even smaller vessels called arterioles. These also contain a lot of smooth muscle in their walls. Their narrowness provides resistance to blood flow, causing it to slow down, which provides extra time for exchange of gases and nutrients as the blood flows through the capillaries in the tissues.
What is vasoconstriction?
The walls of arterioles have a nerve supply. Nerve impulses from the brain can cause their smooth muscle to contract. The narrowing of a muscular artery or arterial caused by the contraction of the smooth muscle in its walls is called vasoconstriction.
What is the function of vasoconstriction?
Vasoconstriction can be used to reduce blood flow to a particular area and divert it to other tissues.
What is vasodilation?
The widening of a muscular artery or arterial, caused by the relaxation of the smooth muscle in its walls is called vasodilation.
Apart from vasodilation and vasoconstriction what else do smooth muscle respond to in the blood?
Smooth muscle can also respond to hormones in the blood.
What is the function of capillaries?
The function of capillaries is to take blood is closest possible to all cells, allowing rapid transfer of substances between cells and blood.
What is a capillary bed?
Cappillaries form a network throughout every tissue in the body except the brain, cornea and cartilage. Such networks are sometimes called capillary beds.
What is the size of capillaries and why do they have such a size?
The small size of capillaries is of great importance in allowing them to bring blood as close as possible to each group of cells in the body. The human capillary is approximately 7 micrometers in diameter about the same size as a red blood cell. The walls of capillaries are extremely thin because they are made up of a single layer of endothelial cells.
How close are the red blood cells carrying oxygen brought to the cells outside of the capillary?
As red blood cells carrying oxygen squeeze through a capillary, they are brought to within his little as 1 micrometer of the cells outside the capillary that need the oxygen.
How is endothelium formed?
In most capillaries, there are tiny gaps between individual cells that form the endothelium. These gaps are important in allowing some components of the blood to see through the spaces between the cells in all the tissues of the blood.
What happens as blood leaves a capillary bed?
As blood leaves the capillary bed, the capillaries gradually join with one another, forming large vessels called venules. These join to form veins.
What is the function of veins?
The function of veins is to return blood to the heart.
Why do veins not have thick walls?
By the time blood enters a vein its pressure has dropped to a very low value. In humans a typical value for venous blood pressure is about 5mmHg or less. This very low pressure means that there is no need for veins to have thick walls. They have the same three layers as arteries but the middle layer is much thinner and has far fewer elastic fibers and muscle fibers.
How do veins ensure that blood flows within one direction?
Many veins run within or very close to several leg muscles. Whenever you tense these muscles they squeeze inwards on the veins in your legs, temporarily raising the pressure within them. To keep the blood flowing in the right direction veins contain half moon valves or semilunar valves formed from their endothelium.
What is a semilunar valve?
Semilunar valve is a half moon shaped valve, such as the ones in the veins and between the ventricles and arteries. In the veins these valves allow blood to move towards the heart but not away from it. So when you contract you like muscles the blood in the veins is squeezed up through the valves but cannot pass down through them.
What happens to the value of blood pressure in the circulatory system?
Blood leaves the heart at high pressure and then gradually loses this pressure as it passes through muscular arteries, arterials, capillaries, venules and veins. This happens in both systems-the systemic and pulmonary system. The pressure of blood leaving the heart is much greater in the systemic system than in the pulmonary system.
What is plasma?
Plasma is a pale yellow liquid component of blood in which the blood cells float. it carries a very large range of different substances in solution. These include nutrients such as glucose and waster products such as urea that are being transported from one place to another. Solutes also include plasma protein. Blood plasma also transports heat around the body.
What are plasma proteins?
A range of several different proteins dissolved in blood plasma, each with their own function; many of them are made in the liver.
What is tissue fluid?
An almost colourless fluid that fills the spaces between body cells. It forms from the plasma that leaks through the gaps between the cells of the tissues. Almost one-sixth of your body consists of spaces between your cells.
Tissue fluid=Plasma-(large plasma proteins+ red blood cells).
Compare the composition of tissue fluid to blood plasma.
Tissue fluid is almost identical in composition to blood plasma. However it contains far fewer protein molecules than blood plasma, because they are too large to escape easily through the capillary and endothelium. Red blood cells are much too large to pass through, so tissue fluid do not contain these, but some white blood cells can squeeze through and move freely in tissue fluid.
What is the volume of liquid that leaves the capillary to form tissue fluid dependent on?
The volume of fluid that leaves the capillary to form tissue fluid is the result of two opposing forces. At the arterial end of a capillary bed the blood pressure inside the capillary is enough to push fluid out of the tissue. However there is a greater concentration of dissolved proteins in the blood plasma than in tissue fluid. Creating a water potential gradient in the venule end. Overall more fluid flows out of capillaries than into them so there’s a net loss of fluid from the blood as it flows through a capillary bed.
Explain what happens at the venule end of a capillary bed during loss of fluid from the blood.
At the venule end of a capillary bed The blood pressure inside the capillaries is lower, so there is less tendency for water to be pushed out of the capillaries into the tissue. The water potential gradients caused by the difference in the concentration of dissolved proteins is still similar to that of the arterial end. Now the net movement of water is from the tissue fluid back into the capillaries.
What is oedema?
If your blood pressure is too high too much fluid is forced out of capillaries and tissue fluid may accumulate in the tissues. This buildup of fluid is called oedema. One of the roles of arterioles is to reduce the pressure of the blood that enters the capillaries, in order to avoid this.
Where does exchange of materials between cells and blood occur?
Tissue fluid forms the environment of each individual body cell. Exchange of materials between cells and the blood occur through the tissue fluid ( as capillaries cannot reach each and every cell).
In our body why do many processes take place to maintain the composition of tissue fluid at a constant level?
Within your body many processes take place to maintain the composition of tissue fluid out of constant level. Provide an optimum environment in which cells can work. These processes contribute to the overall process of homeostasis.
What is homeostasis?
Homeostasis is the maintenance of a constant internal environment and includes the regulation of glucose concentration, water, pH, metabolic wastes and temperature.
How much blood do we have in our body?
You have about 5dm3 of blood in your body with a mass of about 5 kg or 5 litres.
