Anatomy/Cardiovascular System

The cardiovascular system, also known as the circulatory system is a topic in Anatomy and Physiology. It was last tested in 2015 and is expected to return for the 2019 season.

Functions

 * Transportation: The cardiovascular system transports nutrients, oxygen, and hormones to the cells and metabolic wastes like carbon dioxide away from the cells.


 * Protection: Circulating throughout the blood are leukocytes (white blood cells) and other defenses against antigens.


 * Regulation: Homeostasis is maintained in the body through regulation of pH, temperature, and water content of cells.

Formulas
To determine the values for these calculations, data like blood pressure and heart rate must be measured with a sphygmomanometer. When this is being used, a doctor puts a cuff around the arm and pumps it up, exerting pressure and cutting off blood flow. As the pressure is being released, the blood starts to flow again, and doctors listen to these sounds to measure the systolic pressure and diastolic pressure. Heart rate can be measured by counting the number of beats felt during a minute and doesn't require any machinery.


 * Heart Rate (HR): Number of heartbeats per minute
 * Stroke Volume (SV): Amount of blood pumped out of the heart in one beat: Stroke Volume = End Diastolic Volume - End Systolic Volume (SV = EDV - ESV)
 * Pulse Pressure (PP): The difference between systolic pressure (SP) and diastolic pressure (DP) - Pulse Pressure = Systolic Pressure - Diastolic Pressure (PP = SP - DP)
 * Cardiac Output (CO): Amount of blood pumped out of the heart in one minute - Cardiac Output = Heart Rate x Stroke Volume (CO = HR x SV)
 * Mean Arterial Pressure (MAP): The average pressure in the arteries during one cardiac cycle - Mean Arterial Pressure = 2/3 Diastolic Pressure + 1/3 Systolic Pressure (MAP = 2/3 DP + 1/3 SP) OR Mean Arterial Pressure = Diastolic Pressure + 1/3 Pulse Pressure (MAP = DP + 1/3 PP)

The Heart
The heart is the main organ of the cardiovascular system. It is a muscular organ about the size of one's fist and weighs between 7-15 ounces. It acts as a pump and propels blood throught the blood vessels. The average heart beats about 100,000 times a day, circulating about 2,000 gallons of blood through about 60,000 miles of blood vessels. An adult has, on average, 5 to 6 quarts of blood. The average adult resting heart rate is 72 bpm (beats per minute).

The heart is located in the middle of the thorax with part of it offset slightly to the left. It is underneath the sternum (breastbone) and is surrounded by the lungs. It sits on the diaphragm and is protected by the ribcage. It is inside of a sac known as the pericardium.

In general, the left side of the heart (which is located on the right side in a diagram) is the pump for the systemic circuit, which takes blood to and from the body. The right side of the heart (which is located on the left in a diagram), is the pump for the pulmonary circuit, which takes blood to and from the lungs.

All about the heart, including chambers, parts of the heart, and blood flow through the heart. Main Parts in Order of Blood Flow (also includes vessels leading in and out of the heart): Superior Vena Cava/Inferior Vena Cava, right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary artery, pulmonary capillary bed(lungs), pulmonary veins, left atrium, bicuspid (mitral valve), left ventricle, aortic valve, aorta, arteries, arterioles, capillaries, venules, veins, Superior vena cava/inferior vena cava.

Main Functions of the Heart

a. The Atrium. The atrium's function is to transport blood to the ventricles. The right atrium's job is to receive oxygenated lacking blood from the body. The Left Atrium's function is to receive oxygenated blood from the lungs. (NOTE: if you are looking at a diagram of the heart, the right atrium would be on the left side, and the left atrium would be on the right side because you are looking in front of the heart.)

b. Ventricles. The ventricles job is to receive blood from the atrium and then pump it to a location. The right ventricle is supposed to pump oxygen lacking blood from the right atrium to the lungs/pulmonary capillary beds to be filled with oxygen, released of carbon dioxide and it is brought back to the heart to the left ventricles, which pump the blood to all parts of the body.

c. Valves. The valves in the heart are supposed to stop blood from going into the wrong place at the wrong time. For example, the tricuspid's job is to stop blood from the right atrium from going to the right ventricles at the wrong time. Main valves in the heart include the tricuspid valve, the pulmonary valve, the bicuspid valve, and the aortic valve.

Heart Diagram

Labels

1. Aorta (Aortic Arch)

2. Superior Vena Cava

3. Right Pulmonary Artery

4. Right Pulmonary Veins

5. Right Atrium

6. Tricuspid Valve

7. Right Ventricle

8. Inferior Vena Cava

9. Left Pulmonary Artery

10. Left Pulmonary Veins

11. Left Atrium

12. Mitral Valve (It is a bicuspid valve)

13. Aortic Valve (It is a tricuspid valve)

14. Left Ventricle

15. Aorta (Abdominal Aorta)

A helpful playlist of videos on the heart

Blood Vessel
All three types, arteries, veins, capillaries, and also arterioles and venules. You will need to know their structure, their functions, and how they are alike and different. There are three layers to all vessels except for capillaries, which have one epithelial cell thick walls to let nutrients and other materials to go through.

a. Arteries and Arterioles. These blood vessels carry blood away from the heart. For the most part, they carry oxygen rich, "red" blood, but there is one exception. The pulmonary arteries carry oxygen poor, "blue" blood away from the heart to the lungs. These vessels have very thick muscle cell layers since they need to pump the blood. Arteries are the vessels that lead immediately from the heart and other that lead from those. Arterioles are basically very small versions of arteries, with much fewer muscle cells. They feed to the capillaries.

b. Veins and venules. These blood vessels carry blood back to the heart from the rest of the body. For the most part, they carry oxygen poor, "blue" blood, but there is one exception. The pulmonary veins carry oxygen rich, "red" blood back to the heart from the lungs. These vessels have very small muscle layers and have valves. Venules are very small versions of veins. They directly take blood from the capillaries.

c. Capillaries. Capillaries are the smallest types of blood vessels. It is in the capillaries that oxygen exchange and other exchanges of nutrients and wastes take place. It is so because capillaries only have a cell thick wall made of epithelial cells, and materials can easily pass through. Arterioles feed into capillaries and venules take used blood from it.

Blood
There are three main components of blood:

Red Blood Cells (Erythrocytes)- these blood cells are formed in the red bone marrow and are formed in the process of hematopoiesis (or more specifically, erythropoiesis). These cells lack a nucleus and are used to carry oxygen to the cells throughout the body. Each erythrocyte has a lifespan of about 120 days, and at the end of their lifespan, they are filtered out of the blood in the spleen. Erythrocytes also cannot reproduce. These cells contain hemoglobin- a protein that is used to allow the erythrocyte to carry oxygen.

Platelets (Thrombocytes)- These blood cells are also formed in the red bone marrow and are formed in the process of hematopoiesis. These cells also do not contain a nucleus. These cells are produced from fragmentation of a larger precursor cell- the megakaryocyte. These cells help allow the blood to clot. Therefore this cell is necessary for the process of hemostasis- the process by which bleeding stops.

White Blood Cells (Leukocytes)- These blood cells are also formed in the red bone marrow and are formed in the process of hematopoiesis. Leukocytes help aid in the immune system. There are many different kinds of leukocytes, including: lymphocytes, basophils, neutrophils, eosinophils, monocyte, macrophage.


 * Types of White Blood Cells
 * Granulocytes - Granulocytes are white blood cells that have differently stained granules when viewed under a microscope. Granulocytes are Basophils, Neutrophils, and Eosinophils.
 * Basophils - Basophils are a type of White Blood Cell, and more specifically a granulocyte. It is actually the least common white blood cell in the body. They are thought to be associated with allergies, as they can secrete a substance known as histamine.
 * Agranuloctyes - Agranulocytes are white blood cells that lack visible granules in the cytoplasm and have spherical or ovoid nuclei. Agranulocytes are Lymphocytes and Monocytes.
 * Lymphoctyes - Lymphyoctyes makeup about 25% of all white blood cells in the blood (2nd most numerous) and are often found in lymphatic tissue. They contain a large, purple staining nucleus that takes up most of the volume of the cell.
 * Monocytes - These white blood cells are less common, making up only around 3-8% of the total amount of white blood cells in the blood. They are the one of the largest cells in the body and contain a U-shaped nucleus.

Hematopoiesis
Hematopoiesis is the process by which all blood cells (erythrocytes, thrombocytes, and leukocytes) are made. All the blood cells start out as a stem cell. Then the stem cell specializes to eventually become one of the types of blood cells.

Circulatory System Disorders
Arteriosclerosis - the thickening and hardening of the arteries typically due to age.

Atherosclerosis - the thickening and hardening of blood vessels due to plaque buildup.

Hypertension - also known as high blood pressure, is a disorder that can occur as a result of stress, injury, or other disorders.

Hypercholesterolemia - high blood cholesterol.

Stroke - cerebrovascular accident or cerebral hemorrhage occurs when blood flow to the brain is obstructed.

Myocardial infarction (MI) - otherwise known as a heart attack, occurs when blood flow to the heart is blocked. Symptoms include lightheadedness, fatigue, pain or discomfort in the abdomen, chest, or arms, abnormal heartbeat, anxiety, or a "sense of doom".

Cardiogenic Shock

Lymphoma

Atrial fibrillation - the irregular rhythm of the atria of the heart.

Congestive Heart Failure

Kawasaki's Disease