introduction to CVS

What is the function of the cardiovascular system ? 

1. Oxygen + nutrient transport 

2. Removal of waste products 

3. Transportation of hormones 

4. Maintenance of body temperature 

How is blood volume distributed

Rate of blood flow dependent on the cardiac output + vessel diameter ( resistance to blood flow ) 

Phenomenon in arterioles/ arteries	Effect on resistance to blood flow	Changes leading to
Vasoconstriction	Increase	Increased contraction of circular smooth muscle in wall
Vasodilation	Decrease	Decreased contraction in circular smooth muscle in wall

What are the properties of vessels ? 

Area of circulatory system	Functions	Features
Arteries	Pressure reservoir → elastic → can recoil → maintain blood pressure	Thick + elastic of walls  Large radius
Arterioles + capillaries	Arterioles: determines blood flow to tissues  Capillaries:  site of exchange	Arterioles: highly muscular + innervated / small radius  Capillaries: thin walls + large total cross sectional area/ small radius
Veins	Blood reservoir	Thin walls  Highly distensible Large radius

What is systolic pressure + how it happens

Systolic pressure

Peak pressure in arteries

Blood is pumped into them during ventricular systole

What is diastolic pressure + how it happens

Diastolic pressure

Lowest pressure in arteries

Blood is drained downstream in ventricular diastole

How does pressure change in left ventricle+ causes

Pressure changes: High pressure → no pressure

Causes Cycle of systole + diastole

How does pressure change in left arteries + causes

Pressure change High pressure  Slight variation of pressure → X go to zero

Causes Contraction in systole  Variation in line w/ cycle of diastole + systole  Pressure X go to 0 bc elastic recoil of arteries

How does pressure change in arterioles + causes

Pressure changes Slightly lower pressure  Great pressure drop Slight variation of pressure → X go to zero

Causes Highest resistance in arterioles  Variation in line w/ cycle of diastole + systole  Pressure X go to 0 bc elastic recoil of arteries

How does pressure change in capillaries + causes

Pressure changes Lower pressure

Causes High resistance + farther away from the heart

How does pressure change in venules and veins + causes

Pressure changes Lowest pressure → pressure needs to be > atrial pressure

Causes Pressure has dissipated from overcoming great resistance in capillaries + arterioles

How do arteries act as a pressure reservoir

1. Elastic walls distend in cardiac systole as more blood flows through than drains into the narrow arterioles 

2. Elastic recoil of arteries during cardiac diastole → blood is driven forward when heart X pump 

Why is the speed of blood flow different in different areas of circulatory system?

Area of circulatory system	Structures causing high/ low resistance	Speed of blood flow
Arteries	Large radius → low resistance	High → high cross sectional area
Arterioles + capillaries	Small diameter → high resistance	Low → low cross sectional area
Veins	Large radius → low resistance	High → adjacent muscles contract to maintain blood flow

How is the heart’s performance measured ?

 

Measurements	Details
Cardiac output	Meaning: volume of blood pumped by each ventricle per minute  → shows blood flow through peripheral tissues  Cardiac output: heart rate X stroke volume  Affected by the diameter of blood vessels
Pulse pressure	Difference bwt systolic + diastolic pressure
Mean arterial pressure  used to regulate blood pressure	Average blood pressure in arteries → closer to diastolic pressure bc heart spends more time in diastole → diastolic pressure + ⅓ pulse pressure

What conditions can you hear heart sounds + why

Behaviour of blood flow	Can sound be heard	How the pressure cuff causes the sound
No blood flowing ( occluded artery )	N	Inflate cuff  → Cuff pressure > arterial pressure  → artery completely occluded
Turbulent blood flow	Y	Cuff pressure reduced to hear first sound produced by systolic pressure  → arterial pressure > cuff pressure transiently w/ each pulse to produce turbulent flow
Blood flows smoothly ( laminar flow )	N	Cuff pressure < diastolic pressure  → last sound: diastolic pressure

Principle of sphygmomanometer ( measures blood pressure ): \ and what are Korotkoff sounds

1. Compression of brachial artery to measure systolic + diastolic pressure

Korotkoff sounds: sounds produced in the pulsation of blood flow