Chapter 8 Flashcards
What is the need for transport systems.
The metabolic demands of most animals are high so diffusion over long distances is not enough to supply demands.
SA:V ratio gets smaller as organisms get bigger.
Hormones and enzymes may be needed in one place but made in another.
Food is digested in one organ system, but needed to be transported to other cells.
Waste products if metabolism need to be removed.
What do all circulatory systems have?
They have a liquid transport medium that circulates around system.
Vessels that carry the transport medium.
Pumping mechanism to move fluid around system.
What circulatory system do mammals have?
They have a closed, double circulatory system.
The blood passes through the heart twice in each circuit.
There is one circuit which send blood to the lungs from the heart to pick up oxygen and unload carbon dioxide and then returns back to the heart.
Another circuit where blood flows through the heart and is pumped out to travel all around the body before returning to heart.
Why do mammals require a double circulatory system?
They require a double circulatory system to manage the pressure of blood flow.
The blood flows through the lungs at lower pressure. This prevents damage to the capillaries in the alveoli and also reduces speed at which the blood flows, enabling more time for gas exchange.
The oxygenated blood from the lungs then goes back through the heart to be pumped out at a higher pressure to the rest of the body. This is important to ensure that all the blood reaches all the respiring cells in the body.
What do arteries do and how are they adapted?
They carry blood away from the heart and into arterioles.
Their muscle layer are more thicker than veins so that constriction and dilation can occur to control volume of blood.
Their elastic layer is thicker than veins to help maintain blood pressure and the walls stretch and recoil in response to heart beat.
They have thick walls to help prevent the vessels bumping due to high pressure.
They have narrow lumens to transport blood at high pressure.
What do the capillaries do and how are they adapted?
Capillaries form capillary beds as exchange surfaces, which are many branched capillaries. They also connect the arterioles to the vein.
Capillaries have walls that are only a single cell thick because they exchange materials between blood and tissue.
They are also narrow to slow blood flow and for red blood cells to fit through and squashed against the walls, and this maximises diffusion.
What do veins do and how are they adapted for their function?
They carry blood back into the heart.
Veins have thin walls with wide lumens and valves because they transport blood at low pressure
Their muscle layer is thin so cannot control blood flow.
They have a thin elastic layer because the pressure is low.
The walls are the thin as pressure is low and this means the vessels are easily flattened which helps the flow of blood up to the heart.
What is diastole?
The heart relaxes
Atria and ventricles fill with blood
Volume and pressure of the blood in the heart builds as the heart fills, but pressure in atria is at a minimum.
What is systole?
Atria and ventricle contract.
Pressure inside heart increase and blood is forced out of the right side of the heart to the lungs.
Volume and pressure of blood in heart at low at end of systole, and blood pressure in arteries are at a maximum.
What is SAN?
It is a wave of electrical excitation begins in the pacemaker area called the SAN, causing atria to contract and so initiates heartbeat.
It initiates the electrical impulse to start atrial systole.
What is AVN?
Picks up impulse from SAN.
Delays signal
Allows atria to fully contract and completes blood flow into ventricle.
Stimulates the bundles of HIS. It is a conducting tissue made of fibres, which penetrate through the septum between the ventricles.
What is bundle of HIS?
Transports impulse from AVN to apex.
At apex, purkyne fibres spread out through the walls of ventricles on both sides.
Spread of excitation triggers contractions of the ventricles, starting at the apex.
Contractions at the apex allows more efficient emptying of the ventricles.
Spreads impulses along the ventricles
It makes sure atria have stopped contractions before the ventricles start.
What is tissue fluid?
The fluid where cells are soaked in to facilitate substance exchange between cells and blood.
What is oncotic pressure?
It is the tendency of water moving into blood by osmosis generated by plasma proteins. Leave through fenestrations in capillary walls.
Plasma proteins in blood cause a difference in water potential between the blood and the tissue fluid, therefore osmosis can occur.
Oncotic pressure describes how likely is the water going into blood due to presence of proteins.
What is hydrostatic pressure?
It is generated by heart contractions
Changes according to locations
Arterial- blood enters
Venous- blood leaves
What is blood?
55% of blood is plasma- a yellow liquid
45% is ethrocytes
The function of blood is transport co2 and o2, digested food, nitrogenous waste, platelets, cells and antibodies in immune response.
Maintains blood temperature
What is lymph?
5-10% of tissue fluid drains into lymphatic capillaries.
Lymph contains less oxygen and nutrients than tissue fluid, but more fatty acids which are absorbed from small intestine.
Lymph is moved along lymph vessels by contractions of surrounding muscle. Lymph vessels have valves which stop backflow.
Lymphocytes build up at lymph nodes, and produce antibodies.
Lymph re-enters blood.
What is myogenic?
Cardiac muscle- own rhythm at 60 bpm.
What do the cardiac muscle do?
Have thick muscular layer
Myogenic- contracts and relax without nerves or hormones
Never fatigues as long as it have a supply of oxygen
What are coronary arteries?
Supply cardiac muscle with oxygenated blood
These branch off from the aorta
If they become blocked cardiac muscle won’t receive oxygen, therefore will not be able to respire and cells will die.
Results in myocardial infarction
