The Heart and CVD Flashcards
(35 cards)
What is systole and diastole?
Systole= period of contraction
Diastole= period of relaxation (longer than systole)
What is atrial systole?
When the heart is full of blood and ventricles are relaxed, both atria contract and blood passes down to the ventricles. The atrioventricular valves open due to blood pressure. (70% of blood passes down passively)
What is ventricular systole?
Atria relax, ventricle walls contract. Pressure of blood forces semi lunar valves open, blood passes into aorta and pulmonary arteries.
What is cardiac diastole?
The atria and ventricles relax, elastic recoil of blood lowers pressure. The coronary arteries fill.
How does the cardiac muscle receive adequate nutrients and oxygen?
Through the coronary circulation.
What are the walls and septum of the heart composed of?
Cardiac muscle.
Why is the atrial walls thinner than the ventricular walls.
Blood from the atria travel a short distance, only to the ventricles. The right ventricles is thicker as it pumps blood to the lungs and the left ventricles are the thickest as it pumps blood around the body at a long distance.
What does the term myogenic mean?
The heart tissue being able to relax and contract rhythmically at its own accord.
What causes atrial systole that leads on to ventricular systole?
Initially the heart is at cardiac diastole. The return of deoxygenated blood from the body enter the vena cava, when the atria are full they contract. Which later on leads to ventricular systole.
Which region of the heart has the highest inherent rhythm? Where is this situated?
The sino-atrial node or the pacemaker. Situated in the wall of the right atrium.
What is the structure and function of the arteries?
Arteries carry blood away from the heart. It has thick muscular walls and lots of elastic tissue to withstand high pressure (no need for valves). Elastic tissue allows the vessel to stretch to prevent damage, the recoiling pushes blood. It has a small lumen to maintain pressure.
What is the structure and function of veins?
It has a large lumen due to the low pressure of blood flow. It has thin muscular walls which contract to push blood along the vein. It has valves to avoid blood flow.
What is the structure and function of capillaries?
Wall made up of 1 cell thick endothelium, has a small lumen. No pulse, valves or muscle.
What is mass flow?
The mass transport system are used to carry raw materials from specialised exchange organs to the body cells and to remove metabolic waste. The mass transport system is the circulatory system as when the heart pumps blood around the body it supplies and disposes.
Why is water a polar molecule? What type of bond forms between water molecules?
It has an uneven distribution of charge, one side slightly negative whilst the other side is slightly positive, this makes it dipole. Hydrogen bonding forms as the negative and positive ends of the molecules attract.
What properties makes water good at transporting substances?
Water is cohesive due to its polarity creating strong attractions between other water molecules this helps water to flow making it a good solvent.
How does water’s dipole nature make it a good solvent for ionic substances?
The slightly positive end of the water molecules will be attracted to the negative ion and vice versa.
What is atherosclerosis?
Fatty deposits can build up and block an artery or increase its chance of being blocked by a blood clot. In the coronary arteries this results in a heart attack. If the supply of blood to the brain is restricted it can cause a stroke. Narrowing of other arteries can cause tissue death and gangrene.
What are the stages of atherosclerosis?
- The endothelium becomes damaged and dysfunctional, a result from high bp which puts extra strain on the layers of cells
- Once the inner lining of the artery is breached there is an inflammatory response, white blood cells move into the artery wall, these cells accumulate chemicals from the blood (cholesterol) a fatty deposit builds up (atheroma)
- Calcium salts and fibrous tissue also build up resulting in a hard swelling, a plaque. The artery wall looses some of its elasticity
- Plaque causes the lumen to narrow which causes high bp (dangerous positive feedback)
Why does the blood clot in arteries?
- Rapid blood clotting is vital, the blood clot seals the break in the vessel and limits blood loss and prevents entry of pathogen. - When platelets come into contact with the damaged wall they change from flattened discs to long, thin projections. They stick to the exposed collagen forming a platelet plug.
What are the stages of the blood clotting cascade?
- Platelets and damaged tissue release a protein called thromboplastin
- Thromboplastin activates an enzyme that catalyses the conversion of the protein prothrombin into an enzyme called thrombin, vitamin K and calcium ions must be present for the conversion to happen
- Thrombin then catalyses the conversion of the soluble plasma protein, fibrinogen into the insoluble protein fibrin
- A mesh of fibrin forms that traps more platelets and rbc’s to form a clot
What is blood pressure?
Known as hypertension is a measure of the hydrostatic force of the blood against the walls of a blood vessel. Systolic pressure is the highest and diastolic is the lowest.
What do we use to measure blood pressure?
A sphygmomanometer is the traditional device.
Lipoproteins are composed of phospholipids, cholesterol and proteins. Describe how amino acids join together to form the three-dimensional structure of a protein.
- Peptide bonds between an amino acid group and a carboxyl group
- Sequence of amino acids is the primary structure
- Folding of primary structure with bonds such as disulfide bonds between the R groups
