5. Circulation Flashcards
What are the three buffer systems of the circulation?
- phosphate system
- carbonic acid/bicarbonate system
- protein buffer
Together, they maintain a pH between 7.35 and 7.45 in the blood
What is the RBC stem cell?
A hemocytoblast
What does hemorrhage mean?
Bleeding
How does blood coagulation occur?
Blood coagulation occurs when a clot of insoluble fibrin is formed from fibrinogen. The transformation of fibrinogen is produced by the enzyme thrombin
How does the blood flow through a four chambered heart?
Oxygen-depleted blood enters the right atrium via the vena cavae and moves to the right ventricle by passing the tricupsid valve.
Right ventricle pumps blood through the pulmonary valve into the pulmonary trunk (pulmonary artery) from where it flows into the lungs
The now oxygen-rich blood travels via the pulmonary veins into the left atrium and to the left ventricle by passing the mitralis/mitral valve.
Left ventricle contracts to pump the same amount of blood through the aortic valve into the aorta from where it flows throughout systemic circulation.
Ventricle power/strength of the left ventricle thus has to be greater than the right ventricle
What are the four main blood vessels that enter or leave the heart?
Leave: aorta (oxygen-rich) and pulmonary valve (oxygen-depleted)
Incoming: vena cava caudalis and vena cava cranialis (both enter the right atrium
What is systole and diastole?
Ssystole is a cycle of contraction, diastole is a cycle of relaxation. The systole and diastole is performed by the myocardium
What are baroreceptors and what do they do?
Baroreceptors are located in the walls of arteries at strategic positions in the body. Over teh short term, if blood pressure falls, baroreceptor reflexes increase heart rate and force of contraction and promote vasoconstriction. The reverse happens if blood pressure rises.
What are chemoreceptors and what do they do?
Chemoreceptors respond to CO2. When CO2 rises and pH decreases, chemoreceptors transmit signals to the vasomotor center which excites it to produce vasoconstriction, this increases blood pressure. They also signal to the cardioaccelerator center which increases cardiac output –> more blood moves through the lungs and this allows the excretion of CO2 and the intake of CO2 to increase
What is the role of kidneys in blood pressure regulation?
IN mammals, kidneys alter the amount of water that is filtered from blood and excreted in ureine. Water loss in urine decreases the volume of blood and this in turn decreases blood pressure.
What are the four hormones that regulate urine volume?
angiotensin II
ADH
aldosterone
ANP
Which compounds are essential for the clotting process?
Calcium and vitamin K. Any deficiency in either of these may lead to clotting problems. Vit K is needed for the liver to produce prothrombin (inactive thrombin).
What is the function of the spleen?
It has a rich blood supply and acts as a reservoir of red blood cells. When there is a sudden loss of blood, as happens when a haemorrhage occurs, the spleen contracts to release large numbers of red blood cells into the circulation. The spleen also destroys old red cells and makes new lymphocytes but it is not an essential organ because its removal in adult life seems to cause few problems.
What is the vessel that carries blood to the main organs of the body?
Aorta
What is the vessel that carries blood to the brain?
Carotid artery
What is the vessel that carries blood to the kidneys?
renal artery
What is the vessel that carries blood from the intestines to the liver?
hepatic portal vessel
What is the vessel that carries blood to the heart muscle?
coronary artery?
In haemostasis, which molecule polymerises to become the insoluble blood clot?
Fibrin. Fibrin is a monomer that polymerises to form a “soft clot”, then crosslinking between fibrin produces a stable, web-like “hard clot”.
Which enzyme converts fibrinogen to fibrin?
Thrombin is the enzyme. It is not present until prothrombinase converts prothrombin to thrombin.
In blood clotting, what activates “factor X”
Factor X is a plasma protein produced by the liver. In the extrinsic pathway, factor III combines with factor VII to form an “enzyme complex” that activates Factor X.
The Frank-Starling law of the heart describes the proportional relationship between which of the following pairs?
The blood volume in the ventricles and stroke volume. States that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart. That is, stroke volume increases so that all the blood that enters the heart is pumped out.
What will cause the sinoatrial (SA) node to depolarize more frequently?
Norepinephrine (released by the sympathetic nervous system) acting on the SA node increases heart rate and blood pressure. Parasympathetic stimulation along the vagus nerve decreases heart activity.
How are cardiac cells mechanically attached to each other?
By their intercalated discs
