Mass Transport in Humans Flashcards
Blood flow through the heart, Heart structure, Pressure chambers, Valves, Cardiac output, Coronary heart disease, Antheroscleriosis, Thrombosis, Aneurysm, Risk factors, Gaseous exchange surfaces, Lung structure, Mechanism of breathing, Diffusion of gases, Pulminary ventilation, Lung disease, Mass flow, Circulation system, Major vessels, Structure of blood vessels, Tissue fluid, Lymphatic system
What is the function of the heart?
To pump blood around the body
How does blood flow through the heart (cardiac cycle)?
- Deoxygenated blood enters the heart through the vena cava and enters the right atrium. This increases the pressure in the right atrium above the pressure in the right ventricle causing the AV valve to open. The atrium muscles contract further increasing the pressure and forcing the remaining blood into the ventricle from the atrium
- The increased volume of blood in the ventricle increases the pressure above the atrium forcing the AV valve closed and opening the SL valve. The ventricular muscles contract further increasing the pressure and forcing the remaining blood into the lungs from the ventricle through the pulmonary artery
- Oxygenated blood enters the heart through the pulmonary vein and enters the left atrium. This increases the pressure in the left atrium above the pressure in the left ventricle causing the AV valve to open. The atrium muscles contract further increasing the pressure and forcing the remaining blood into the ventricle from the atrium
- The increased volume of blood in the ventricle increases the pressure above the atrium forcing the AV valve closed and opening the SL valve. The ventricular muscles contract further increasing the pressure and forcing the remaining blood through the aorta
Systole
Contractions of the heart muscle
Diastole
Heart muscle released
Branched off from the aorta and supply the heart muscle with blood
Coronary arteries
Why do valves only open one way?
It is due to tendons that anchor the valve
The volume of blood expelled from the left ventricle per minute
Cardiac output
Cardiac output formula
CO = SV X HR
SV - Stroke volume = the volume of blood expelled from the LV on one heart beat
HR - Heart rate = the number of cardiac cycles per minute
What is the process of atherosclerosis formation?
- The lumen of the artery is narrowed due to the build up of fatty deposits and chloestrol (atheroma) underneath the endothelium of the artery.
- Muscle fibres and calcium salts accumulate forming hard uneven patches called plaque. The plaque grows and bulges into the lumen of an artery
- The artheroma may cause reduced blood flow to the heart muscle cells beyond that point. This leads to muscle cells being deprived of sufficient oxygen during exercise. The cells respire anaerobically and produce lactic acid, which causes pain. The most common form of this problem is angina
- If the blood vessel is blocked completely the muscle cell gets no oxygen and die. This will cause a heart attack
What is the process of thrombosis formation?
- The plaque may rupture and trigger blood clotting over the damaged area. These clots build up very rapidly causing further blockage of the artery. This is known as a thrombus
- The clot may break up; travel in the blood stream and cause blockage elsewhere. This could lead to problems such as a stroke
What is the process of aneurysm formation?
. When the artery becomes blocked, blood flow through the area is restricted. The blood pressure builds up in front of the blockage and presses on the artery wall. This pressure causes the wall to weaken and it starts to bulge outwards. This is known as an aneurysm. The vessel may rupture, resulting in internal bleeding.
What 5 respiratory properties should surfaces have?
- Large SA
- Permeable
- Thin (low diffusion pathway)
- Moist (gases diffuse more readily in solution)
- Efficient transport system (maintains a concentration gradient)
Describe the lung structure
. Trachea - a tube like structure that carries air from he mouth to the lungs
. Bronchi - the trachea splits into two bronchi as it enters the lungs, which allows air to travel to the left and right lung
. Bronchioles - The bronchi further divides into smaller branches called bronchioles. These then supply the alveoli with air
Name the main structures of the alveoli and their function
. Provide a large SA for efficient diffusion
. Has a rich blood supply which maintains a large concentration gradient
. The cells are squamus which decreases the diffusion pathway
Fick’s law: Rate of diffusion =
(SA x Concentration gradient)/Diffusion distance
Inhalation
External intercostal muscles contact, internal intercostal muscles relax expanding the rib cage
The diaphragm contract and moves down
Lung volume increases
Pressure in lungs is less than outside so air moves in
Exhalation
Internal intercostal muscles contract, external intercostal muscles relax moving the rib cage in and down
The diaphragm contracts and moves up
The lung volume decreases
Pressure in lungs is more than outside so air moves out
How does oxygen diffuse into the blood?
As unoxygenated blood is pumped into the lungs and into the capillaries surrounding the alveoli a concentration is established, oxygen moves into the blood across the epithelial membrane and the wall of the capillary from a high concentration to a lower concentration. At the same time carbon dioxide moves from the blood into the alveoli
Pulmonary ventilation =
Ventilation rate (min-1) x tidal volume (dm3)
What is smoking a risk factor of?
Asthma and emphysema
What is air pollution a risk factor of?
Asthma
What is infection a risk factor of?
Tuberculosis
What is an occupation with exposure to irritants a risk factor of?
Fibrosis, asthma and emphysema
What is genetic pre-disposition a risk factor of?
Fibrosis and asthma
What is the need for a circulatory system?
It ensures all cells in multi-cellular organisms have blood, water and dissolved substances
Mass flow
The bulk movement of liquids (and gases) due to a pressure difference
Closed systems
(Liquids within tubes) are more efficient than open systems. It is easier to generate and maintain a pressure gradient
What factors effect whether or not there is a specialised transport medium?
. SA:V
. How active the organism is
The artery which takes blood from the aorta to the liver (provides oxygen)
Hepatic artery
The vein which takes blood from the liver to the vena cava
Hepatic vein
The vein which takes blood from the intestines to the liver contains absorbed food molecules
Hepatic portal vein
The artery which takes blood from the aorta to the kidney
Renal artery
The vein which takes blood from the kidney to the vena cava
Renal vein
What is the main structures of an artery?
Endothelial layer
Middle (elastic layer)
Outer layer
What does the endothelial layer of an artery do?
It is one cell thick and gives a smooth layer which reduces friction and gives smooth flow
What does the middle (elastic layer) do?
It contains a large amount of elastic protein fibres which allows the wall to stretch as pulse of blood flows past stopping the pressure rising too high. It then recoils once blood passes maintaining a pressure on the blood. It also contains a smooth muscle layer which can contract constricting the vessel and reduce the volume of blood passing through the vessel
What does the outer layer do?
It is made of fibrous proteins that give support and strength to the wall of the artery, helping it to resist damage due to the high pressure’s of the blood
What is the structure of the arteriole?
They connect arteries to capillaries, this means they are smaller in diameter compared to the artery, so have greater friction causing a fall in blood pressure.
The elastic layer for an arteriole is thinner than the artery as the blood pressure is lower.
The muscle layer is thicker than the artery to reduce/increase the flow into the organ
What is the structure of a capillary?
It only has an endothelial layer and a supporting basement membrane made of fibrous proteins as it is involved in exchange of material between blood and cells. The diameter is small, increasing the friction and decreasing the blood pressure
What is the structure of veins?
They carry blood back to the heart under low pressure meaning the muscle lay is very thin as there is no need for vaso-constriction and the elastic layer is also thin.
Veins also contain valves. As the residual blood is under low pressure the blood is moved along the veins by the squeezing action of the skeletal muscles when they contract
What is the use of wall spaces in capillaries?
There are gaps between the cells and the endothelial cells which allow rapid formation of tissue fluid and WBC to pass tissue spaces
What is tissue fluid formed from?
Blood plasma
What forces act across the capillary wall which affect the movement of fluid?
Hydrostatic pressure and water potential differences
Describe how tissue fluid is formed and how it is returned to the circulatory system
FORMATION
High hydrostatic pressure of the blood forces fluid out of the capillary leaving large proteins on the capillary.
RETURN
Low water potential in the blood/capillary (due to plasma proteins) causes water to enter the capillaries by osmosis. Excess tissue fluid is removed via the lymph vessels
What happens if the lymphatic system stops working?
Swelling occurs
How does excess tissue fluid get removed via the lymphatic system?
The fluid drains into open-ended tubes (lymphatic vessels) which are merged together forming a network running through the body eventually emptying back into the blood stream through veins in the neck region.
