Biology - Circulatory System

Function of the Circulatory System

• Transportation of oxygen and carbon dioxide

• Distribution of nutrients and transport of wastes

• Maintenance of body temperature

• Circulation of hormones and white blood cells

Components of the Circulatory System

• Heart

• Blood vessels

• Blood

Systemic Tract

The part of the circulatory system that carries blood from the heart to the body and returns blood back to the heart.

Pulmonary Tract

The part of the circulatory system that carries blood from the heart to the lungs and returns blood back to the heart.

Heart Valves

• The opening and closing of valves are responsible for the “Lub Dub” sound of the heart

• Papillary muscles on AV valves contracts to prevent valve prolapse (opening in the wrong direction)

Heart Valve Disorder

• Hear ‘murmurs’ occur when a valve doesn’t completely shut and blood can flow backwards

• causes an increased heart rate to compensate for inefficiency

• may require valve replacement surgery

How does the heart get blood

The heart recives it’s own supply from coronary arteries

Atherosclerosis

narrowing of the arteries resulting from plaque build up

Heart attack

if the coronary arteries are blocked, the heart muscle will be deprived of oxygen or nutrients

Heart attack symptoms

chest pain or discomfort, pain or discomfort in one or both arms, back, neck, jaw, or stomach, shortness of breath, sweating, nausea, and lightheadedness. 

Heart attack treatment

Aspirin, nitroglycerin, CPR, Thrombolytics (Clot-Busters), Coronary Angioplasty and Stenting, Coronary Artery Bypass Graft (CABG) Surgery

Blood Pressure

the pressure that blood exerts on blood vessel walls and is an important measure of cardiac function

Depends on:

• Cardiac output - the amount of blood pumped by the heart each minute, also dependent on blood volume

• Resistance - flexibility of arteries, diameter of arteries, and viscosity of blood

Blood Pressure Values

• The cardiac cycle refers to the alternating contractions of the atria and ventricles called systole, and diastole

• measured with a sphygmomanometer (also known as a blood pressure cuff) and reported with two values

  • Systolic pressure - the pressure in the vessels when the ventricles are contracting and pushing blood out into the body (the top number)

  • Diastolic pressure - the pressure in the vessels when the ventricles are relaxing and filling with blood (the bottom number)

Normal blood Pressure

120 over 80

Hypertension

High blood pressure

can damage arterial walls (lead to aneurisms), and put strain on heart (cause heart failure or heart attack)

Caused by arteriosclerosis (from smoking or poor diet), lack of exercise, stress, and genetics

- Persistent hypertension is one of the risk factors for strokes, heart attacks, heart failure, aneurysms, and kidney failure

Hypotension

Low blood pressure

generally not problematic, but can lead to dizziness or fainting if pressure becomes too low

Caused by standing quickly, pregnancy, reduced heart function, blood loss, and dehydration

Blood

• Adults have 4-6L of blood in their body

• Approx 45% is cells and 55% is plasma

• Plasma is 90% water and 10% dissolved substances(Blood proteins, glucose, vitamins, minerals, and waste products)

Types of Cells in Blood

• Erythrocytes

• Leukocytes

• Platelets

99% is erythrocytes and 1% is leukocytes and platelets

Erythrocytes

• Red Blood Cells (RBC)

• contain hemoglobin: Heme(iron) + Globin(protein)

• transport oxygen

• have cell surface markers that determine the ABO blood group

Leukocytes

• White blood cells

• Part of the immune system’s response

• Envelop and digest foreign cells by creating pus OR

• produce antibodies to disable toxins

Platelets

• Cell fragments that activate fibers needed for blood clotting

Anemia

• Blood disorder

• insufficient number of red blood cells

Leukemia

• Blood disorder

• cancer of the bone marrow

• causes an over production of young/not fully formed leukocytes

Thrombophilia

• mutation causing the over production of clotting factors OR

• prevention of clot breakdown

• leads to heart attacks and pulmonary embolisms

• is a side effect of some medications

Hemophilia

• Disorder which results in prolonged bleeding after injury

• because of a genetic mutation on clotting factors

Arteries

• Thick, strong, elastic vessels

• 3 layers

  • endothelium

  • smooth muscle

  • connective

• carry high pressure, oxygenated blood away from heart

Capillaries

• walls are one cell thick

• connect the smallest arterioles to the smallest venules

• site of gas, nutrient, and waste exchange

Veins

• Softer thinner vessels

• less smooth muscle and elastic tissue than arteries

• walls contain valves to prevent backward flow of blood

• carry low pressure, deoxygenated blood

Capillary fluid exchange

• Pushes fluid out of capillaries.

• Pulls fluid back into capillaries.

• Fluid moves out at the start of capillaries.

• Fluid moves back in at the end of capillaries.

• Collects extra fluid and returns it to the blood.

Aneurysm

• blood vessel disorder

• bulging and possibly bursting of the arteries

• very serious

Varicose Veins

• blood vessel disorder

• bulging of the veins

• valves don’t work

• not super serious, just looks bad

Bruising

• blood vessel disorder

• Bursting of the capillaries

• not serious

Fainting

• Temporary loss of consciousness due to reduced blood flow to the brain.

• Common Causes: Dehydration, low blood pressure, sudden changes in position, stress, or heart issues.

• Symptoms: Dizziness, lightheadedness, nausea, sweating, blurred vision.

3 most fatal disorders

• heart attack

• aneurysm

• Leukemia