pubh bio session 10

Arteries

carry blood away from the heart.

Capillaries

provide exchange between blood and tissues

Veins

carry blood towards the heart.

Circulatory system

is a conduit of vessels that conducts blood to the entire body (so that all cells are near a constant blood supply)

Arteries

thick walled, elastic and muscular to withstand pressure exerted by blood pumped by the beating heart – Aorta is largest artery

Arterioles

smaller than arteries, have muscular walls that constrict or relax to control blood pressure

Capillaries

simple epithelial lining, very thin walled. Functional unit for exchange between blood and tissue cells

Venules

smaller than veins

Veins

thinner walls than arteries, have valves to maintain blood flow in right direction since much lower pressure in them, muscles squeeze them to help blood flow

– Inferior vena cava and Superior vena cava are largest veins

myocardium

heart is made up of cardiac muscle cells

Myocardial cells

contract and relax in a coordinated rhythm to keep blood moving efficiently.

Right Atrium

receives deoxygenated blood from the body

Right Ventricle

pumps blood to the lungs (pulmonary circuit)

Left Atrium

receives oxygenated blood from the lungs

Left Ventricle

pumps blood to the rest of the body (systemic circuit)

Diastole

Relaxation Phase

Systole

Contraction Phase

Blood pressure (BP)

is the force exerted by circulating blood on the walls of blood vessels

Cardiac Output (CO)

Amount of blood pumped by the heart per minute

Cardiomyopathy

Disease or weakening of the heart muscle (myocardium) → reduced pumping ability.

Arrhythmias

Electrical conduction disturbances cause the heart to beat:

• Too fast (tachycardia)

• Too slow (bradycardia)

• Irregularly (fibrillation or flutter)

can prevent effective pumping or lead to sudden cardiac arrest.

Arteriosclerosis

General term meaning “hardening of the arteries.”

• Arteries lose elasticity and flexibility, making it harder for them to expand and contract with blood flow.

• Leads to increased blood pressure and reduced circulation.

Atherosclerosis

A specific type of arteriosclerosis — “narrowing of arteries” caused by plaque buildup inside the arterial walls.

• Plaque is made up of cholesterol, fat, calcium, and cellular debris

Coronary Artery Disease (CAD)

develops when the inner lining of coronary arteries becomes damaged or inflamed, sometimes starting in childhood.

Recommended Sodium Intake

less than 2300 mg/day ( 1 teaspoon of salt)

Average American intake: ~3400 mg/day

• For individuals with hypertension: Limit to ~1500 mg/day

stroke

Occurs when the blood supply to the brain is interrupted or severely reduced

• Brain cells begin to die within minutes due to lack of oxygen and nutrients

Ischemic Stroke

(~90%)

• Caused by a blocked artery reducing blood flow to the brain

Thrombotic Stroke

Blood clot forms directly in an artery supplying the brain

Embolic Stroke

 Artery is blocked by debris (plaque or clot) that travels downstream and lodges in a brain artery

Hemorrhagic Stroke

(~10%) • Caused by a leaking or burst blood vessel

• Often linked to years of hypertension that weaken vessel walls