CARDIOVASCULAR SYSTEM: LECTURE 7

 LV volume

Only half of 120mL is injected.

Systole

Contracted

Diastole

Relaxed

First & Second Heart Sound

First: Lub 

Second: Dup

First sound lower than second due to larger opening.

Exercise

Shortening ventricular ejection & filling phase, increasing cardiac output during exercise, etc.

Doctor Heart Measurements

Measures systemic arteries, & their range. 

Max & min systemic arteries.

Heart Pumping

Pulsatile Pump, pumps lumps of blood.

Elastic Artery

Large 

Tunica media made of elastin protein = stretch & elastic

Elastic Artery (Systole):

Receives pressure spike of ventricle pumping (expands) to protect capillaries

Stores some of the contraction as elastic energy

Elastic Artery (Disatole):

Stored elastic energy maintains flow of blood out into the arterial tree

Muscular Arteries

Most common.

Distribution of blood

Rate of blood flow is adjusted using smooth muscle to vary vessel radius, to direct blood flow to most used systems. 

Muscular Arteries Cross Section

Endothelial cells → Tunica interna/intima → Tunica Media → Tunica Externa/Adventitia.

All blood vessels have tunica interna.

Muscular Arteries (Tunica Media/Middle Tunic)

Smooth muscle arranged circularly around the middle tunic under the autonomic nervous system.

Contract = vasoconstriction

Relax = Vasodilation

r = F⁴

Tunica Adventitia/Externa

Mostly collagen

Overstretching mechanism of vessel

Elastic → Muscular Artery Transition

Tunica media: elastin → smooth muscle

Companion vein

Vein accompanying arteries.

Vein

Much thinner walls = lots of lumen = lots of blood

Similar flow.

Arteriole

Thin (3 layers of smooth muscle or less)

Thicker muscular wall relative to their size. 

Greatest pressure drop

Control blood flow into capillary beds

Capillary (Exchange Vessels)

Very thin = slows blood flow resulting in more efficient exchange

Made of endothelial cells

Exchange of nutrients, gases & waste between blood and tissue cells via interstitial fluid.

Capillary → interstitial fluid via hydrostatic pressure & osmosis for vice versa

Hydrostatic Pressure

Drives fluid out of capillaries

Oedema

Too high hydrostatic pressure = too much fluid out around tissues

Lymphatic System

Collects excess fluid left from osmosis

Venule (Venous system)

Very thin vessels made of endothelial cells & CT.

Low flow & pressure allows WBC to stick & exit vessels to attack infection.

Veins

Small change in venous blood pressure = large change in venous volume.

Larger veins (especially in legs), have bicuspid valves which prevent backflow.

Leg muscles contracting & relaxing during walking, acts as venous pump

Hypovolumetric shock

~20% of total blood volume loss = not enough blood to pump.

Coronary Artery

Arise from aorta & supply heart muscle

Atherosclerosis

Build up of fatty fibrous plaques inside blood vessels.

Angina

Chest pain caused by running low on oxygen (ischemia) due to coronary arteries being narrowed to ~20% of its normal cross section.

Severe ischemia = myocardium infarction (heart attack)