CVS Part 1 & 2 Flashcards
Overview of why we need a cardiovascular system (5 functions)
- for transport of o2 and substrates (glucose, AA and FA) to cells.
- to transport co2 and metabolites from cells for excretion.
- distribution of hormones around the body (eg. adrenaline and insulin)
- transport of defence mechanisms (eg. involving immune system)
- thermoregulation
Describe the conduction pathway of electrical activity through the heart
(1) Electrical activity generated in SA node (non-contractile tissue)
spreads out into atria to produce (2) contraction
(3) Electrical activity enters AV node (non-contractile tissue)
(4) Delays conduction before stimulating ventricles - allows ventricles to fill correctly -
(5) Excitation conducts rapidly through bundle of His into ventricles
(6) Excitation through purkinje fibres is conducted throughout the ventricles producing contraction and ejection
What does “stroke volume” mean
volume of blood ejected from the heart per beat
What does “heart rate” mean
number of heart beats per min
What does “stroke volume” mean
volume of blood ejected from the heart per beat
What does “cardiac output” mean
Volume of blood ejected from the heart per min (ml/min)
What does “blood flow” mean
Volume of blood circulating per min
What does “blood pressure” mean
Pressure of circulating BF on blood vessel walls
What does “total peripheral resistance” mean
Resistance of blood vessels to blood flow
How do you calculate “cardiac output”
heart rate x stroke volume
What leads to heart failure?
A drop in stroke volume leads to poor cardiac output
how do you calculate arterial blood pressure
cardiac output x total peripheral resistance
What causes hypertension
high total peripheral resistance leads to high blood pressure - hypertension
Blood helps regulate body temperature. What happens when it is cold?
the blood vessels lying close to the skin constrict to reduce blood flow, saving the heat within the body.
What does pulmonary circulation involve?
oxygen-depleted blood from body tissues runs from the right atrium to the right ventricle of the heart into the right and left pulmonary arteries, which carry the blood into the right and left lungs.
What does pulmonary circulation involve?
oxygen-depleted blood from body tissues runs from the right atrium to the right ventricle of the heart into the right and left pulmonary arteries, which carry the blood into the right and left lungs.
(Screenshot 2022-09-21 at 16.21.10)
What does pulmonary circulation involve?
oxygen-depleted blood from body tissues runs from the right atrium to the right ventricle of the heart into the right and left pulmonary arteries, which carry the blood into the right and left lungs.
(Screenshot 2022-09-21 at 16.21.10)
Summary: The pulmonary circulation is between the heart and the lungs
What does systemic circulation involve?
pumping oxygen-rich blood into the aorta. The aorta gives off smaller arteries that gradually branch into smaller vessels called arterioles.
Near the body tissues, these arterioles further divide into smaller vessels called capillaries. These capillaries form small networks called capillary beds, in which blood flow is reduced. This reduction in blood flow allows the exchange of gases, nutrients and waste products between the blood and tissues.
Then the capillaries regroup to form venules, which eventually drain into veins, and eventually into the two largest veins called the superior vena cava and the inferior vena cava, which collect blood from the entire body and empty into the right atrium. And once more, the pulmonary circulation cycle restarts.
Summary: the systemic circulation is between the heart and the rest of the body
connections between two arteries are called
an arterioarterial anastomosis
connections between two veins are called
a venovenous anastomosis.
What is the hepatic portal venous system responsible for?
it directs the nutrient rich blood from the capillary beds of the digestive tract to the capillary beds of the liver.
What are Anastomoses?
they are connections between blood vessels that serve as backup in case of an occlusion of an artery or vein.
Where is the heart located?
It sits slightly shifted over to the left side in the mediastinum. It sits on top of the diaphragm.
What is the serous pericardium?
It is a sac of fluid that the heart sits in
What is the innermost layer of the heart called?
endocardium
What is the endocardium made of?
a thin layer of endothelium
Where does deoxygenated blood enter through?
through a blood vessel called the superior vena cava or through another vessel called the inferior vena cava in the right atrium
name the veins of the heart?
superior and and inferior vena cava
What is the coronary sinus?
this is a third opening of the right atrium which collects blood from coronary vessels returining from the myocardium
What separates atria from the ventricles?
atrioventricular valves
What is the name of the valve that allows blood into the right ventricle?
tricuspid valve
what is pulmonary circulation?
deoxygenated blood leaving the right ventricle through the pulmonary artery to the lungs and oxygenated blood entering the left atrium via the pulmonary vein.
what is pulmonary circulation?
deoxygenated blood leaving the right ventricle through the pulmonary artery to the lungs and oxygenated blood entering the left atrium via the pulmonary vein.
what is the largest artery in the body?
aorta
what is systemic circulation?
oxygenated blood leaving the left ventricle of the heart to be pumped around the body. Deoxygenated blood enters through the right atrium.
Why is the left ventricle the strongest chamber of the heart?
Its because its part of the systemic circulation so it needs to pump blood around the body.
What is systolic blood pressure?
This is the pressure in the arteries when the ventricles are squeezing out blood under high pressure.
What is diastolic blood pressure?
This is when the ventricles are filling up more with blood, so its going to be slightly lower pressure.
What is cardiac output?
This is the amount of blood that is pumped out by either ventricle over a period of time.
What is venous return?
This is the rate at which the veins return blood back to the atria.
Where is the sino-atrial node?
In the right atrium
How do you decrease heart rate?
By inhibiting calcium channels using calcium channel blockers (CCBs) like verapamil and If channels using lvabradine
Cardiac cycle:
- ventricular filling followed by atria contraction
- isovolumetric contraction
- isovolumetric relaxation
- ejection
Cardiac cycle X@
- Atrial contraction
- Isovolumetric ventricular contraction
- Rapid ventricular ejection
- Reduced ventricular ejection
- Isovolumetric ventricular relaxation
- Rapid ventricular filling
- Reduced ventricular filling
What does Starling’s law state?
‘Increase in filling pressure and subsequent ventricular end-diastolic pressure produces an increase in contractile energy of cardiac myocytes’
