Cardiovascular System (physiology)

What are the approximate size and shape of a human heart?

About 14 cm x 9 cm (the size of a fist), with the distal end called the apex.

What is the function of the Systemic Circulation?

It delivers blood to all body cells and carries away waste.

What is the function of the Pulmonary Circulation?

It eliminates carbon dioxide and oxygenates blood by traveling to the lungs.

What are the two layers of the fibrous pericardium that enclose the heart?

The visceral pericardium (inner layer) and the parietal pericardium (outer layer).

What is the function of the pericardial cavity?

It contains fluid that reduces friction around the heart.

What is the epicardium?

The outer layer of the heart wall that reduces friction.

What is the myocardium?

The middle layer of the heart wall, consisting mostly of cardiac muscle.

What is the endocardium?

The thin inner lining within the chambers of the heart.

What is the structure that separates the right and left sides of the heart?

The septum.

What is the structural and functional difference between atria and ventricles?

Atria are thin upper chambers that receive returning blood; ventricles are thick, muscular lower chambers that pump blood out of the heart.

What is another name for the left atrioventricular (AV) valve?

The bicuspid valve or mitral valve.

What is another name for the right atrioventricular (AV) valve?

The tricuspid valve.

Where is the aortic semilunar valve located?

Between the left ventricle and the aorta.

Where is the pulmonary semilunar valve located?

Between the right ventricle and the pulmonary artery.

What structures anchor the cusps of the bicuspid and tricuspid valves to the ventricle walls?

Fibrous cords called chordae tendineae.

What is the function of the chordae tendineae and papillary muscles?

They prevent the valves from being pushed up into the atria during ventricular systole.

What is a Ventricular or Atrial Septal Defect commonly called?

A "hole in the heart."

What is a cardiac cycle?

One complete heartbeat, consisting of systole and diastole.

What do the terms "systole" and "diastole" mean?

Systole is the contraction of a heart chamber, and diastole is the relaxation of a chamber.

In a blood pressure reading like 120/80, what do the two numbers represent?

The first (larger) number is systole (pressure during contraction), and the second (smaller) number is diastole (pressure during relaxation).

What is the term for low blood pressure?

Hypotension.

What is the term for high blood pressure?

Hypertension.

What are the four main factors affecting blood pressure?

1. Cardiac Output, 2. Blood volume, 3. Blood Viscosity, 4. Peripheral Resistance.

What creates the "lub dub" sound of a heartbeat?

The opening and closing of the heart valves.

What is a normal resting heart rate for adults?

60 to 100 beats per minute (bpm).

What does an Electrocardiogram (ECG/EKG) record?

The electrical events or changes during a cardiac cycle.

In an ECG, what does the P Wave represent?

Depolarization of the atria (atrial contraction or systole).

In an ECG, what does the QRS Complex represent?

Depolarization of the ventricles (ventricular contraction or systole).

In an ECG, what does the T Wave represent?

Repolarization of the ventricles.

What are tachycardia, bradycardia, and arrhythmia?

Tachycardia is a fast heart rate, bradycardia is a slow heart rate, and arrhythmia is an irregular heart rate.

Cardiac Conduction System - Step 1: Where does the electrical impulse originate?

The S-A Node (Sinoatrial node), which acts as the pacemaker.

Cardiac Conduction System - Step 2: Where does the impulse travel after the S-A Node?

Through the junctional fibers to the A-V Node (Atrioventricular node).

Cardiac Conduction System - Step 3: What pathway does the impulse take from the A-V Node?

Down the A-V Bundle (Bundle of His) and into the Left & Right Bundle branches.

Cardiac Conduction System - Step 4: What is the final destination of the electrical impulse in the ventricles?

The Purkinje Fibers.

Where in the brain is the cardiac center that controls heart rate located?

The medulla oblongata.

What effect do cardioinhibitor nerves (vagus) have on the heart?

They release acetylcholine, which decreases the heart rate.

What effect do cardioaccelerator nerves have on the heart?

They release norepinephrine, which increases the heart rate and force of contraction.

How do the structural properties of arteries differ from veins?

Arteries are strong, elastic vessels carrying blood away from the heart, while veins are thinner, less muscular, contain valves, and carry blood toward the heart.

What is the structural composition and critical function of capillaries?

They are composed of a single layer of squamous cells and allow the exchange of materials (oxygen, nutrients) between blood and tissues.

What is a precapillary sphincter?

A circular, valve-like muscle at the arteriole-capillary junction that opens and closes to control blood flow.

What is the difference between vasoconstriction and vasodilation?

Vasoconstriction is the narrowing of a blood vessel, while vasodilation is the expanding of a blood vessel.

What three mechanisms help blood return to the heart through the slow, low-pressure venous system?

1. Contraction of the diaphragm, 2. Pumping action of the skeletal muscles (skeletal muscle pump), 3. Valves in the veins that prevent backflow.

What causes varicose veins?

They occur when valves fail or blood pools in the veins.

Which blood vessel is the largest artery leaving the left ventricle?

The aorta (including ascending, arch, descending, and abdominal sections).

What do the coronary arteries do?

They supply blood to the heart itself.

What does a defibrillator do?

It shocks the heart to treat life-threatening cardiac arrhythmia and allows it to re-establish its normal rhythm.

What is Takotsubo Cardiomyopathy?

Also known as "Broken Heart Syndrome," it is a condition where the left ventricle enlarges and takes a shape similar to a Japanese octopus trap.

What is a heart murmur?

An unusual sound (like a whooshing or swishing noise) heard during a heartbeat, which may or may not indicate a valve problem.

What is Mitral Valve Prolapse (MVP)?

A condition where the mitral valve shifts out of place, creating a clicking sound at the end of a contraction, sometimes leading to blood leaking backward.

What is regurgitation in the context of heart valves?

The backward flow of blood through a damaged or prolapsed valve, which forces the heart to work harder and can lead to heart failure.

What is a Myocardial Infarction (MI)?

An obstruction to the coronary artery, commonly called a "heart attack."

How do heart attack symptoms generally differ between men and women?

Men often experience sudden immense pressure in the chest center radiating to the arms/neck, while women may experience breathlessness, overwhelming chronic fatigue, dizziness, or gastric upset.

How can blood tests help diagnose a heart attack?

Damaged heart muscles slowly leak certain proteins/enzymes into the blood, which can be detected.

What is Atherosclerosis (Arteriosclerosis)?

A condition where deposits of fatty materials (like cholesterol) form a plaque in the arteries, reducing blood flow.

What is an aneurysm?

A localized, blood-filled balloon-like bulge in the wall of a blood vessel.

What is a stroke and what are its two main types?

A stroke occurs when blood flow to the brain is cut off; it can be hemorrhagic (blood vessel breaks/leaks) or ischemic (blood vessel is blocked).

What are the two basic components of blood as a connective tissue?

Cells (RBC, WBC, platelets) which make up 45%, and Plasma (water, proteins, vitamins, etc.) which makes up 55%.

What does a hematocrit measure?

The percentage of blood cells (typically 45%) versus fluid plasma (55%) after blood is centrifuged.

What are the scientific names for red blood cells, white blood cells, and platelets?

Erythrocytes (RBC), Leukocytes (WBC), and Thrombocytes (platelets).

What is the shape and defining cellular feature of mature red blood cells?

They are biconcave discs and lack a nucleus.

What is hematopoiesis?

The formation of blood cells, which occurs in the bone marrow.

What essential trace element is required as the binding site for oxygen on hemoglobin?

Iron.

What happens to old and damaged erythrocytes after their 120-day lifespan?

They are phagocytized by macrophages primarily within the bone marrow, liver, and spleen.

RBC Breakdown - Step 1: What happens to the globin portion of hemoglobin?

It is broken down into amino acids, which are sent back to the bone marrow to produce new erythrocytes.

RBC Breakdown - Step 2: What happens to the iron from the heme group?

It is stored in the liver or spleen (as ferritin/hemosiderin) or carried by transferrin back to the red bone marrow.

RBC Breakdown - Step 3: What happens to the non-iron portion of the heme group?

It is degraded into the waste product biliverdin, then converted into bilirubin.

RBC Breakdown - Step 4: How is bilirubin removed from the body?

It travels to the liver to manufacture bile, which gut bacteria convert to urobilinogen/stercobilin, giving feces its brown color and urine its yellow color.

What is Erythropoietin (EPO)?

A hormone that increases the production of red blood cells.

What is the structural capacity of a single hemoglobin molecule for oxygen?

Each hemoglobin molecule has four heme groups with iron ions, so it can bind up to four oxygen molecules.

What color differences exist between oxyhemoglobin and deoxyhemoglobin?

Oxyhemoglobin (plenty of oxygen) is bright red, while deoxyhemoglobin (low oxygen) is dark red (not blue).

What are the five different kinds of leukocytes (white blood cells)?

Neutrophils, Eosinophils, Basophils (granulocytes); and Monocytes, Lymphocytes (agranulocytes).

What precursor cell buds to form platelets (thrombocytes)?

Megakaryocytes (which is why platelets are considered cell fragments).

What is the composition of blood plasma?

It is 92% water, containing nutrients, gases, vitamins, and plasma proteins.

What is the function of Albumins, the most abundant plasma proteins?

Manufactured by the liver, they serve as binding proteins (transporting fatty acids/steroids) and are the most significant contributor to the osmotic pressure of blood.

What is the function of Gamma Globulins in the blood plasma?

Produced by plasma cells, they are involved in immunity and are known as antibodies or immunoglobulins.

What is the primary function of Fibrinogen in the blood plasma?

It is produced by the liver and is essential for blood clotting.

Hemostasis - Step 1: What happens during Blood Vessel Spasm?

The release of serotonin acts as a vasoconstrictor to narrow the vessel.

Hemostasis - Step 2: What is platelet plug formation?

Platelets gather to close the opening in the damaged blood vessel.

Hemostasis - Step 3: What is the final step, Coagulation?

Thrombin converts fibrinogen to fibrin, which forms over the plug and reinforces it, creating a scab.

Why are newborns given a Vitamin K injection?

To prevent a bleeding disorder called Vitamin K Deficiency Bleeding (VKDB) or hemorrhagic disease of the newborn.

How is ABO blood typing determined?

By the genetically determined presence or absence of two glycoprotein antigens, A and B, on the surface of red blood cells.

What happens in the body during a transfusion reaction with incompatible blood?

Antibodies attach to the foreign antigens on the infused erythrocytes, causing them to clump together (agglutination), which blocks small blood vessels.

What is the difference between a thrombus and an embolus?

A thrombus is an abnormal blood clot, while an embolus is a blood clot that has moved to another place (e.g., lungs or brain).

Why is Carbon Monoxide (CO) considered a "silent killer"?

CO binds to hemoglobin and prevents oxygen from binding, leading to fatal poisoning often without symptoms.

What is Aplastic Anemia?

A condition where the bone marrow does not produce enough red blood cells.

What is Pernicious Anemia?

Anemia caused by a deficiency in Vitamin B12.

What is Sickle Cell Anemia and its genetic mechanism?

A genetic disorder causing abnormally shaped blood cells; it is codominant, meaning 'Aa' yields the sickle cell trait while 'aa' causes the full disease.

What is Leukemia?

Cancer of the blood characterized by an overproduction of white blood cells that take the place of red blood cells.

What is Sepsis or Septicemia?

A potentially deadly blood poisoning caused by an infection entering the bloodstream.

What is Thrombocytopenia?

Low production of platelets, which causes excessive bleeding or bruising.

What is Hemophilia?

An X-chromosome linked disorder causing a failure of the blood to clot properly.

What causes Jaundice in newborns?

The liver not functioning fully yet, causing bilirubin to build up and create a yellow skin color; treated with fluorescent lights.

What is Hemochromatosis?

A disorder where the body cannot eliminate excess iron, leading to iron overload, liver disease, and other organ abnormalities (treated with chelation therapy).

What is Beta Thalassemia?

A blood disorder that reduces the production of beta-globin (a component of hemoglobin), resulting in anemia.

What is the function of the Umbilical Vein in fetal circulation?

It carries oxygen-rich blood from the pregnant person to the fetal inferior vena cava.

What is the function of the Umbilical Arteries in fetal circulation?

They carry oxygen-depleted fetal blood, including wastes and carbon dioxide, to the placenta.

Fetal Shunt: What does the Ductus Venosus do?

It branches from the umbilical vein, allowing much of the freshly oxygenated blood to bypass the fetal liver and go directly to the fetal heart.

Fetal Shunt: What is the Foramen Ovale?

An opening in the interatrial septum that allows blood to bypass the lungs by flowing directly from the right atrium to the left atrium.

Fetal Shunt: What is the function of the Ductus Arteriosus?

A short vessel connecting the pulmonary trunk to the aorta, diverting blood away from the fetal lungs and into systemic circulation.