L5- cardiovascular system: heart and vascular system

What is the primary function of the cardiovascular system

Ensuring controlled and continuous blood flow

What is homeostasisimportant in (6)

• transport of nutrients

• Transport of metabolic products

• Heat distribution

• Immunological defence

• Regulation of pH and osmolality

Systemic circulation

Everything other than the pulmonary circuit

Pulmonary circulation

Between the lungs and the heart

Which side of the heart has high vs low pressure

• left:systemic: high pressure

• Right: pulmonary: low pressure

What is the unidirectional flow of blood controlled by

Valves

Why is unidirectional flow important (3)-

• dont want waste product to return form where it is being removed from

• Want to drop off oxygen

• Removal of co2

How does the volume of blood entering the pulmonary and systemic loops differ

It doesn’t despite the differences in size

Where in the heart do blood vessel emerge from

The base of the heart

Where is the base of the heart

At the top (fools decided this)

Where is the apex of the heart

At the bottom

Which vessels carry blood away from the heart

Aorta and pulmonary artery

Which blood vessels return blood to the heart

Vena cava (inferior and superior) and pulmonary veins

Pericardium

Fluid filled sac within which the heart sits

Types of valve (2)

• atrioventricular

• Semilunar

What are the type of av valves and which side are they found

• tricuspid → on the right

• Mitral/ bicuspid→ on the left

Where are the av valves found

Between the atrias and the ventricles

What are the types of semilunar valves and which side are they found

Pulmonary(tricuspid)→right

Aortic(tricuspid)→ left

What do the semilunar valves do

prevent back flow of blood into the heart

What are the valves attached to

Papillary muscles by the chordate tendineae

Process or filling and emptying of the ventricle

• pressure gradient drives flow of blood into the ventricle

• Causes the mitral valve to open

• Ventricle contracts

• pressure reincreases further

• Causes mitral valve to shut

• Ventricle contract more

• Pressure of blood exceeds pressure the semi lunar valves can maintain so they open

• Mitral valve remains shut

• Blood exits via the aorta

Stroke volume

The volume of blood pumped by a ventricle per beat

Cardiac output

The total volume of blood pumped per ventricle per minute

Equation ofr cardiac output

Cardiac output = stroke volume x heart rate

Venous return

The amount of blood returning to the heart

Under steady state conditions what is VR the same as

CO

What are arteries used for and what features make them Abel todo this

Distribution→ high pressure, elastic vessles

What are arteriales used for and what features do they have that allow them to complete this role

Resistance→ high resistant vessles,control the blood flow to tissues

What role do capillaries have and what features make them able to do so

Exchange → thin walled vessles arranged in parallel

What role do veins have and what features make them able to do so

Capacitance (collection and storage) → low pressure capacitance vessles,one way valves

In which vessel is there the greatest drop in blood pressure and why is this necessary

in the arterioles→ necessary to regulate the blood flow to indivual tissues/organs to prevent damage

What is blood flow through the vascular system driven by

A pressure gradient

Is change in pressure or actual pressure more important In determining blood flow velocity

Change in pressure → teh greater the change between either end the grater hte velocity

Why does the pressure of a fluid in motion decrease with distance

Due to friction

What is pattern does pressuer have in the systemic circulation

Pulsátiles of decreasing and increasing in the ventricles, arteries and arteriales

Systolic pressure

Maximum pressure achievable

Diastolic pressure

Minimum pressure

What is teh value for systolic pressure in ventricle and arteries

120

What us the value fro systolic pressure In the arteries

80

Pulse pressure

Teh difference between systolic and diastolic pressure

Why does systemic pressure have a greater range than pulmonary pressure and what are these ranges

Systemic (120/80), pulmonary (25/9)

Because pulmonary is mainly based in capillaries where pressure must be low

Why does the pulsátile pattern decrease through the vascular system

You dont want any drastic changes in the capillaries as this can cause damage/leay tissues

What is blood flow is vessels proportional to

The pressure gradient

What else affects blood flow in vessels

Resistant

What is blood flow proportional to in terms of resistance

1/resistance

What is Darcy’s law

Blod flow = change in pressure/ resistance

What determines resistance

Length of blood vessel (L), radius of blood vessel (r ), viscosity of blood (eta)

Poiseuille’s law

Blood flow= ((change in pressure) x pi x r^4)/ 8 x eta x length

What is the most importantly physiological factor in regulation of resistance and why

Radius→ is to the power of 4 and 8,pi,L and eta normally dont chagne

Blood flow(rate)

Volume per minute

Blood velocity

Distance travelled per minute

What is blod velocity dependent on

Flows and cross sectional area of vessels

Equation ofr blood velocity

Velocity = blood flow / cross sectional area (=pi x r^4)

Why is blood velocity not highest in capillaries s

They ahve a parallel arrangement so you have to consider the total cross sectional area of all capillaries in that vasucalrbed not just one therefore total cross SA is greatest in capilares

Where is blood velocity highest

Aorta→ where CSA is smallest