(LESSON 14) Circulatory System: Blood and Heart Flashcards
Subdivisions of the Circulatory System
Cardiovascular system and lymphatic system
Cardiovascular System
blood, heart, and blood vessels
erythrocytes
Red Blood Cells(RBC’s).
- Most numerous formed element:
- Cells in a cubic millimeter:
- Females: 4.3 to 5.2 million
- Males: 5.1 to 5.8 million
- 25 trillion are present in the bloodstream of a healthy adult
- Cells in a cubic millimeter:
- 7.5 microns in diameter
- biconcave discs
- anucleate bag of hemoglobin (aka: no nucleus. Hemoglobin: oxygen-carrying protein)
- Transport oxygen and CO2
Leukocytes
White Blood Cells (WBC)
- Less numerous than erythrocytes
- 4800 to 11,000/cubic millimeter
- Crucial to body’s defense against disease
- Spherical in shape
- Only formed elements that are complete cells (nucleus and oragnelles)
Buffy Coat
Thin gray layer at the junction of erythrocytes and plasma. Contains **leukocytes **(white blood cells) that protect the body and thrombocytes (platelets) which are cell fragments that help stop bleeding.
Hematocrit
“Blood fraction” The percentage of blood volume that consists of erythrocytes. Averages 45 but varies. Males=47%+/-5% and females si 42%+/-5%. In newborns can be 42-68%. Leukocytes and platelets consititute less than 1% of blood volume and plasma makes up remaining 55%
Blood plasma
straw-colored, sticky fluid. About 90% water.
- Contains over 100 different kinds of molecules such as Na+ and C1-.
- Nutrients such as simple sugars, amino acids, and lipids.
- Wastes such as urea, ammonia, CO2
- Also oxygen, hormones, and vitamins
- 3 proteins: albumin, globulins and fibronogen
Albumin
Protein in blood plasma. Helps keep water from diffusing out of the bloodstream into the extra cellular matrix of tissues.
Globulins
Protein in blood plasma. Includes both antibodies and the blood proteins that transport lipids, iron, and copper.
Fibrinogen
Protein in blood plasma. involved in a series of chemical reactions that achieves blood clotting with other protein and nonprotein molecules.
Coagulation
When blood stands, the chemical reaction that occurs, producing:
- a clot entangles the formed elements
- a clear fluid called serum
(Serum is plasma from which clotting factors have been removed)
Features of Blood Cells
(Formed elements of blood)
- Neither erythrocytes nor platelets are true cells
- Erythrocytes lack nuclei and organelles
- Platelets are merely cell fragments
- Most of the formed elements cannot divide. They survive in the blood stream for just a few hours to a few months, being replaced by new cells produced in the bone marrow. Formed elements are broken down and components recycled.
The main classes of blood cells
[image]
Diapedesis
(Leaping Through)
The process where leukocytes leave the capillary walls, targeting infection sites producing dangerous chemicals.
- Leukocytes actively squeeze between endothelial cells that form the capillary walls
- cells travel to the infection site by **amoeboid motion: **forming flowing cytoplasmic extensions that move them along, functioing outside of the bloodstream in loose connective tissue.
Leukocytosis
When a leukocyte count exceeds 11,000/cubic millimeter during an infection or inflammation.
5 types of leukocytes
2 groups
- Granulocytes: contain many obvious granules
- neutrophils-
- eosinophils
- basophils
- Agranulocytes: lack obvious granules
- lymphocytes
- monocytes
From most abundant to least abundant:
“Never Let Monkeys Eat Bananas”
Neutrophils, lymphocytes, monocytes, eosinophils, basophils
Platelets
AKA Thrombocytes.
- Platelets are not cells but cytoplasmic fragments.
- They contain chemicals needed for clotting.
- Hemophilia—sex-linked disorder occurring primarily in males; factor VIII deficiency
Hematopoiesis
AKA Hemopoiesis.
The process by which blood cells are formed.
- Occurs in red bone marrow at the rate of 100 billion cells/day
Hemocytoblast
Blood stem cells that create:
- erythrocytes
- leukocytes
- platelets
Bone Marrow
Occupies the interior of all bones. If all bone marrow in the skeleton were combined it would form the second largest organ in the body, next to the skin.
- Red Marrow
- Yellow Marrow
Red Marrow
The only marrow that actively generates blood cells. Red hue is derived from the immature erythrocytes it contains.
Yellow marrow
Dormant. Makes blood cells only in emergencies that demand increased hematopoiesis. Color reflects the many fat cells it contains.
Genesis of Erythrocytes
Erythropoiesis
- An immature erythrocyte produces large numbers of ribosomes.
- Erythrocytes synthesize hemoglobin.
- Erythrocytes retain hemoglobin but reject the nucleus and most organelles.
Erythrocyte Destruction
- The cell can’t grow, divide, or synthesize protein.
- It becomes “old” in approximately 100 days.
- The spleen traps and fragments degenerating erythrocytes.
- Iron is salvaged, heme is degraded to bilirubin, and the rest of the cell is digested by macrophages.

