Understanding Hematocrit and Blood Components

Hematocrit

Hematocrit is a blood test that measures the percentage of red blood cells in your blood.

High hematocrit levels

High hematocrit levels include dehydration, high altitudes, heart/lung disease, and shock.

Low hematocrit levels

Low hematocrit levels include anemia, blood loss, bone marrow damage, pregnancy, and nutrient deficiencies.

Erythropoietin (EPO)

EPO helps make red blood cells.

Bone marrow

RBC are made in bone marrow, soft spongy tissue found in the center of many bones.

Hemoglobin

Hemoglobin is an iron-containing protein that binds to oxygen in the lungs and releases it through tissues.

Spectrin

Spectrin is a major component of the RBC exoskeleton that helps maintain flexibility.

Ankyrin

Ankyrin connects the spectrin cytoskeleton and maintains cell shape.

Iron deficiency anemia

Iron deficiency anemia is the most common type of anemia caused by a lack of iron.

Vitamin B-12 deficiency

Vitamin B-12 deficiency is caused by a lack of B12 in diet or absorption.

Megaloblastic anemia

Megaloblastic anemia is caused by a lack of B12 or folate (B9) in diet, leading to the production of unusually large red blood cells.

Sickle cell anemia

Sickle cell anemia is an inherited condition that is a type of hemolytic anemia.

Aplastic anemia

Aplastic anemia is a rare/life-threatening anemia in which not enough new blood cells are made.

Hemolytic anemia

Hemolytic anemia is a condition where RBCs die faster than normal.

Universal Donor

Universal Donor (O negative) can donate blood to any other blood type.

Universal Receiver

Universal Receiver (AB positive) can receive blood from any other blood type.

Antigen

An antigen is a substance found on the surface of red blood cells that determines your blood type.

Antibodies

Antibodies are proteins that your immune system produces to attack foreign substances, including red blood cells with different antigens.

Neutrophils

Neutrophils are the most common WBC, first responders to infection, phagocytose bacteria and fungi, and stain lilac or purple.

Eosinophils

Eosinophils are involved in allergic reactions and parasitic infections, stain orange or pink, and have large granules in their cytoplasm.

Basophils

Basophils release histamine during allergic reactions, stain dark blue-violet, and have large, dark granules.

Monocytes

Monocytes transform into macrophages which engulf large particles and cellular debris, and have a large, kidney-shaped nucleus.

Lymphocytes

Include B cells (produce antibodies) and T cells (directly kill infected cells), small with a round nucleus.

Platelets

Platelets are produced in the bone marrow from cells called megakaryocytes.

Vitamin K

The most important factor for blood clotting, which acts as a co-factor for several proteins (clotting factors) necessary for the coagulation cascade.

Blood clot removal

Blood clots can be removed with medication, catheters, or surgery.

Centrifuged blood appearance

When centrifuged, blood should appear as distinct layers with a clear, straw-colored plasma layer at the top, a thin whitish 'buffy coat' layer in the middle containing white blood cells and platelets, and a red blood cell layer at the bottom.

Factors affecting centrifuge ratios

Centrifugation time, temperature, speed, and things like barriers can make centrifuge blood ratios off.

Pulmonary circuit

Carries deoxygenated blood from the heart to the lungs to be oxygenated.

Systemic circuit

Carries oxygenated blood from the heart to the rest of the body.

Heart wall layers

The endocardium (inner lining), the myocardium (middle muscle layer), and the epicardium (outer layer), all of which are part of the heart wall.

Pericardium

The protective sac that surrounds the entire heart; consists of a fibrous outer layer and a serous inner layer, with the visceral layer of the serous pericardium being the same as the epicardium.

Heart sounds

Heart sounds are the result of the opening and closing of the heart valves.

First heart sound

Caused by the closure of the atrioventricular (AV) valves, which include the mitral and tricuspid valves, described as the 'lub'.

Second heart sound

Caused by the closure of the semilunar valves, which include the aortic and pulmonary valves, described as 'dub'.

P wave

Represents the electrical activity of the atria (upper heart chambers) depolarizing.

QRS complex

Represents the electrical activity of the ventricles (lower heart chambers) depolarizing.

T wave

Represents the electrical activity of the ventricles repolarizing (relaxing) after contraction.

SA node

The pacemaker of the heart, initiating the electrical impulse.

AV node

A slight delay occurs here to allow the atria to fully contract before the ventricles begin to depolarize.

Bundle of His

The pathway connecting the AV node to the ventricular walls.

Bundle branches

These branches further divide to distribute the electrical signal throughout the ventricles.

Purkinje fibers

The electrical signal in the heart travels from the AV node, through the bundle of His, down the interventricular septum, and then finally reaches the Purkinje fibers, which then spread the signal throughout the ventricles to cause them to contract.

Sodium and potassium ions

Sodium ions enter the cell while potassium ions leave, restoring equilibrium.

Right atrium

Receives oxygen-poor blood from the body.

Right ventricle

Pumps oxygen-poor blood to the lungs.

Left atrium

Receives oxygen-rich blood from the lungs.

Left ventricle

Pumps oxygen-rich blood to the body.

Tricuspid valve

Leads from the right atrium to the right ventricle.

Pulmonary valve

Leads from the right ventricle to the pulmonary artery.

Mitral valve

Leads from the left atrium to the left ventricle.

Aortic valve

Leads from the left ventricle to the aorta.

Gap junctions

Enable direct communication between adjacent cells by allowing the transfer of ions and small molecules.

Heart muscle (myocardium)

Appears striated under a microscope, made up of branched, interconnected cells called cardiomyocytes, and functions by rhythmically contracting and relaxing to pump blood throughout the body.

Foramen Ovale

Becomes Fossa Ovalis in the adult.

Umbilical Vein (intra-abdominal part)

Becomes Ligamentum teres in the adult.

Ductus Venosus

Becomes Ligamentum venosum in the adult.

Umbilical Arteries

Become medial umbilical ligaments and superior vesicular artery (supplies bladder) in the adult.

Viscosity

Higher viscosity (thicker blood) creates more resistance to flow.

Diameter

A larger diameter results in significantly lower resistance to flow.

Vessel length

Longer vessels have greater resistance to flow.

Aldosterone

Signals certain organs, like your kidneys and colon, to increase the amount of sodium they send into your bloodstream or the amount of potassium released in your urine.

Antidiuretic hormone (ADH)

A chemical produced in the brain that causes the kidneys to release less water, decreasing the amount of urine produced.

Tunica intima

The innermost layer, which lines the lumen and contains endothelial cells, creating a frictionless surface for blood to move through.

Tunica media

The middle layer, made up of smooth muscle and elastic fibers, regulating blood flow and pressure by changing the diameter of the blood vessel.

Tunica adventitia

The outermost layer, made up of connective tissue, nerves, and small blood vessels, providing structural support and attaching the blood vessel to surrounding tissue.

Continuous nonfenestrated capillaries

The most common type of capillary with small gaps between endothelial cells, found in the skin, muscles, fat, and nervous system.

Continuous fenestrated capillaries

Have larger openings, called fenestrations, allowing for the quick exchange of substances like nutrients and blood, found in the kidneys, small intestine, and endocrine glands.

Baroreceptors

Monitor blood pressure by detecting changes in the stretch of blood vessel walls.

Chemoreceptors

Sense changes in the chemical composition of the blood, primarily levels of oxygen, carbon dioxide, and pH.

-ogen, -blast, and -pro

The first or create.

-cyte

A more mature cell.

Aorta

Where the most pressure is found.