The heart and Circulation

Question 1

The Heart - general

Answer 1

-the heart causes flow due to one way arteries
systole = peak pressure of blood during contraction
diastole = pressure fallen to during relaxation
heart rate = number of ventricular systoles in 1 minute
cardiac output = amount of blood pumped out of heart in 1 minute

Question 2

4 Valves?

Answer 2

tricuspid
mitral
aortic
pulmonary

Question 3

Venous Return

Answer 3

arteries - blood flows as a result of high pressure produced by the ventricles

• veins do not contain high pressure like arteries
• one way valves
• pressure changes as a result of muscular movements or breathing
• extended periods of standing still prevent the muscle pump from working

Question 4

Fetal Circulation

Answer 4

• blood from placenta is carried to fetes by umbilical vein
• half of this enters ductus venous and is carried to inferior vena cava
• enters right atrium
• opening between right + left atrium (foramen ovule), and most blood flows through this hole directly into left atrium from right atrium, thus bypassing pulmonary circulation
• blood flows into left ventricle and out through aorta into systemic circulation
• some of the blood entering the right atrium, right ventricle and is pumped into pulmonary artery
• fetus, special connection between pulmonary artery and the aorta - doctor arterioles, which directs most of this blood away from the lungs

Question 5

Blood Pressure control

Answer 5

• to maintain homeostasis and to regulate the perfusion rate of various tissues in the body
• control of BP b altering the following variables: HR, stroke volume, vascular resistance, blood volume

Question 6

Circulation in pregnancy

Answer 6

• diaphragmatic haemodynamic attractions, blood loss at delivery, cardiac output elevated 1-2hours pp
• cardiac output and BP return to pre pregnancy state
• reduction in progesterone = removal of excess tissue
• diuresis of up to 2l in first week.

Question 7

How blood pressure works in pregnancy

Answer 7

• Although blood volume increases, which would increase BP, high levels of progesterone dilate veins and blood vessels to balances out BP levels
• However, too much vasodilation can cause blood to not transport properly and increased surface area