Cardiology Basics: Heart Pump and Circulatory System

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Questions and Answers

What is the main function of the lymphatic system in relation to the capillaries?

To control the flow of blood through the capillaries

To absorb nutrients from the capillaries

To regulate the pressure in the capillaries

To return lost plasma protein to the blood circulation (correct)

What is the primary mechanism by which gas and nutrient exchange occurs in the capillaries?

Facilitated diffusion

Active transport

Diffusion (correct)

Osmosis

What is the role of the veins in the circulatory system?

To provide a high resistance, high pressure pathway for blood to return to the heart

To control the flow of blood to the tissues

To return deoxygenated blood from the tissues to the heart (correct)

To distribute oxygenated blood to the tissues

How do the valves in the veins assist in the return of blood to the heart?

They open when the venous pressure is driving blood flow towards the heart, and close when pressure drops to prevent backflow Signup and view all the answers

What is the role of the precapillary sphincters and arterioles in the circulatory system?

To control the amount of blood that flows into the capillaries Signup and view all the answers

What are the local metabolic changes that occur in skeletal muscle during activity, and how do they affect the smooth muscle of the arterioles?

Decreased PO2, increased PCO2, increased acid production, and increased temperature, leading to arteriolar smooth muscle relaxation and increased blood flow Signup and view all the answers

What is the main function of the heart according to the text?

To circulate blood around the body Signup and view all the answers

Where does blood get oxygenated in the circulatory system?

In the lungs Signup and view all the answers

What happens during atrial systole?

Atria contract Signup and view all the answers

What occurs during ventricular diastole?

Blood returning to the heart Signup and view all the answers

Which chamber of the heart receives deoxygenated blood from the periphery?

Right atrium Signup and view all the answers

What allows us to return blood from the lower limb to the heart, especially when we are standing upright?

Valves in the veins and skeletal muscle contraction Signup and view all the answers

Who was the first to recognize the role of valves in the veins in assisting blood flow back towards the heart?

William Harvey Signup and view all the answers

Where does the major pressure drop occur in the circulatory system?

Arteries Signup and view all the answers

Which part of the nervous system controls the diameter of arterioles to match tissue needs?

Sympathetic nervous system Signup and view all the answers

What causes the smoothing of blood flow by the time it reaches the capillaries?

Elastic nature of vessels Signup and view all the answers

Why is diastolic blood pressure in the left ventricle different from diastolic pressure in the arteries?

Elastic nature of vessels and aortic valve function Signup and view all the answers

What is the primary function of the arterial system?

To act as a pressure reservoir for blood flow Signup and view all the answers

What causes the semilunar valves to open during systole?

Increased pressure in the ventricles Signup and view all the answers

What happens to the major arteries during systole?

They bulge or stretch like a balloon being inflated Signup and view all the answers

What causes the aortic valve to close at the start of diastole?

Increased pressure in the aorta Signup and view all the answers

What drives the continuous flow of blood through the arteries during diastole?

Elastic recoil of the major arteries Signup and view all the answers

What does the term 'diastolic pressure' refer to?

The lowest pressure in the arteries before ventricular contraction Signup and view all the answers

What happens when the ventricles begin to contract?

The pressure in the ventricles rises and exceeds the pressure in the atria. Signup and view all the answers

What happens to the AV valves when the ventricular pressure exceeds the atrial pressure?

The AV valves slam shut, creating the first heart sound. Signup and view all the answers

What happens to the semilunar valves during the isovolumic phase of ventricular contraction?

The semilunar valves remain closed until the ventricular pressure exceeds the pressure in the arteries. Signup and view all the answers

What happens to the semilunar valves when the ventricular pressure exceeds the pressure in the arteries?

The semilunar valves open to allow blood flow. Signup and view all the answers

What happens at the end of systole, when diastole begins?

The ventricular pressure drops below the arterial pressure, and the semilunar valves are pushed shut, creating the second heart sound. Signup and view all the answers

What can happen to diseased or damaged heart valves?

They can become stiff or leaky, causing a murmur. Signup and view all the answers

Study Notes

Smooth Muscle Activity

Smooth muscle activity can be affected by local metabolic products and hormones
Localized skeletal muscle activity leads to:
Decreased PO2
Increased PCO2
Increased acid production
Raised temperature
Arteriolar smooth muscle relaxation
Decreased resistance
Increased flow of oxygenated arterial blood to the working muscle

Blood Circulation

Precapillary sphincters and arterioles control the amount of blood that flows into the capillaries
Flow through capillaries is slow, allowing for efficient exchange of gases and nutrients by diffusion
Capillary walls are slightly leaky, allowing some plasma protein to leak into the interstitial fluid
The lymphatic system returns lost protein to the blood circulation

Veins

Veins provide a low resistance, low pressure pathway for blood to return to the heart
Valves in the veins are oriented to open when venous pressure is driving blood flow towards the heart
Valves close when pressure drops, preventing backflow

Heart

The heart is a dual pump that circulates blood around the body and through the lungs
Blood enters the atrial chambers at a low pressure and leaves the ventricles at a higher pressure
High arterial pressure provides energy to force blood through the circulatory system

Cardiac Cycle

Ventricular diastole (relaxation):
Blood returns to both sides of the heart
Deoxygenated blood from the periphery enters the right atrium
Oxygenated blood from the lungs enters the left atrium
Atrial contraction (atrial systole):
Filling of the ventricles is completed
Accounts for only 20% of ventricular filling in the resting state
Ventricular contraction (ventricular systole):
Contraction of the ventricles
The combination of veins with valves and skeletal muscle contraction allows for blood return from the lower limb to the heart

Blood Flow

Pressure gradient generated by ventricular contraction drives blood flow through the circulation
Blood flow is pulsatile in the arteries but becomes smoothed by the time it reaches the capillaries
The major pressure drop occurs in the arterioles, which provide the single largest resistance to flow
Arterioles are controlled by the sympathetic nervous system, adjusting blood flow to match tissue needs for oxygen and energy

Arterial System

The arterial system functions as a pressure reservoir
Blood leaves the arterial system continuously through the capillaries, but enters only intermittently from the heart
The ventricles contract during systole, causing the semilunar valves to open and blood to flow into the arterial system
The aortic valve closes at the start of diastole, preventing blood from flowing back into the ventricles from the aorta

Blood Pressure

Systolic pressure is defined as the peak pressure reached during the cardiac cycle
Diastolic pressure is the lowest pressure reached during the cardiac cycle, immediately before the contracting ventricle pushes blood into the arteries again
The arterial pressure decreases during diastole due to the elastic recoil of the major arteries

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Description

Learn about the dual pump function of the heart that circulates blood around the body and through the lungs. Understand how blood flows from atrial chambers to ventricles at different pressures, providing energy to force blood through the circulatory system.