Blood

Composition

• Red blood cells (45%)
• White blood cells (less than 1%)
• Platelets (less than 1%) -Plasma (55%)

Functions

• Transports oxygen and carbon dioxide
• Transports nutrients and waste products
• Regulates body temperature
• Fights infection
• Clotting

Blood groups

• ABO blood group system
  • Antigens A, B, and O on red blood cells
  • Antibodies A and B in plasma
  • Blood types: A, B, AB, and O
• Rh blood group system
  • Rh antigen (D) on red blood cells
  • Rh-positive (D+) or Rh-negative (D-)

Plasma

Composition

• Water (92%)
• Proteins (7%)
  • Albumin
  • Globulins
  • Fibrinogen
• Electrolytes (1%)
  • Sodium
  • Potassium
  • Chloride
  • Bicarbonate
• Hormones
• Vitamins

Functions

• Transports nutrients, waste products, and hormones
• Maintains blood volume and pressure
• Regulates body temperature
• Lubricates joints

Red Blood Cells (Erythrocytes)

Structure

• Biconcave discs, about 7 micrometers in diameter
• No nucleus or other organelles
• Filled with hemoglobin

Function

• Transports oxygen from the lungs to the tissues
• Transports carbon dioxide from the tissues to the lungs

White Blood Cells (Leukocytes)

Structure:

• Several types of WBCs, each with a different structure and function
• All WBCs have a nucleus and other organelles -WBCs are larger than RBCs

Functions

• Fight infection
• Protect the body from foreign invaders

Types

• Neutrophils
• Lymphocytes
• Monocytes
• Eosinophils
• Basophils

Platelets (Thrombocytes)

Structure:

• Small, irregularly shaped cells, about 2-3 micrometers in diameter
• No nucleus or other organelles
• Produced in the bone marrow
• Circulate in the blood until activated
• Activated platelets aggregate and form a clot
• Platelets have lifespan of 10-14 days

Function:

• Stop bleeding by forming a clot

ABO blood group system

Antigens and antibodies

• Blood group antigens are proteins or carbohydrates on the surface of red blood cells.
• Blood group antibodies are proteins in plasma that react to specific antigens.
• The ABO blood group system has three antigens: A, B, and O.
• The ABO blood group system has two antibodies: anti-A and anti-B.

Blood transfusions

• Blood transfusions are when blood is given from one person (the donor) to another person (the recipient).
• The donor’s blood must be compatible with the recipient’s blood.
• Incompatible blood can cause a transfusion reaction, which can be fatal.

Rh factor

• The Rh factor is another blood group antigen, that is either present (+) or absent(-).
• People who are Rh-positive have the Rh factor on their red blood cells, while people who are Rh-negative do not.
• The Rh factor is important in pregnancy. If a Rh-negative mother is pregnant with a Rh-positive baby, the baby’s red blood cells can cross the placenta and trigger the mother’s immune system to produce anti-Rh antibodies. These antibodies can then cross the placenta and attack the baby’s red blood cells, leading to a condition called erythroblastosis fetalis, which can cause anemia and other serious health problems in the baby.

Hemoglobin

Structure:

• Protein consisting of four polypeptide chains, called globins
• Contains an iron porphyrin ring called a heme group

Function:

• Hemoglobin carries oxygen from the lungs to the tissues and carries carbon dioxide from the tissues to the lungs.

Hematocrit

• The percentage of red blood cells in a blood sample.

Packed cell volume

• Synonym for hematocrit.

Mean corpuscular volume

• The average size of red blood cells.

Blood pressure

• Blood pressure is the pressure exerted by the blood against the walls of the arteries.
• Systolic blood pressure is the maximum pressure during a heartbeat.
• Diastolic blood pressure is the minimum pressure between heartbeats.
• Pulse pressure is the difference between systolic and diastolic blood pressure.

Cardiac cycle

• The cardiac cycle is the sequence of events that occur during one heartbeat.
• Systole is the contraction of the heart muscle.
• Diastole is the relaxation of the heart muscle.
• Heart sounds are the sounds produced by the heart during the cardiac cycle.
• An electrocardiogram (EKG) is a recording of the electrical activity of the heart during the cardiac cycle.

Transport of respiratory gases

• Oxygen is transported in the blood bound to hemoglobin in red blood cells.
• Carbon dioxide is transported in the blood in three forms: bicarbonate ions (HCO3-) in plasma, dissolved carbon dioxide gas (CO2) in plasma, and bound to hemoglobin as carbaminohemoglobin.
• The Bohr effect is the decrease in the affinity of hemoglobin for oxygen at higher partial pressures of carbon dioxide.
• Myoglobin is a protein that stores oxygen in muscle cells.

Arteries and veins

Arteries

• Arteries carry blood away from the heart.
• Arteries have thick, elastic walls that can withstand the high pressure of the blood. -The largest artery in the body is the aorta.

Veins

• Veins carry blood back to the heart.
• Veins have thin walls that are not as elastic as arteries.
• The largest vein in the body is the vena cava.

Capillaries

• Capillaries are small blood vessels that allow the exchange of substances between the blood and the tissues.
• Capillaries have thin walls that allow the passage of small molecules, such as oxygen and carbon dioxide.
• The smallest capillaries are called arterioles, and the largest capillaries are called venules.

Lymphatic system

Lymph nodes:

• Small organs that filter lymph and remove harmful substances.
• Located throughout the body, especially in the neck, armpits, and groin.

Tonsils:

• Two small masses of lymphatic tissue located at the back of the throat.
• Trap and destroy bacteria and other foreign particles.

Spleen:

• A large organ located on the left side of the abdomen.
• Filters blood and removes old red blood cells and other foreign particles.
• Also stores red blood cells.

Thymus:

• A small organ located in the upper chest.
• Produces T cells, which are a type of white blood cell that helps to fight infection.
• The thymus gland is most active during childhood and adolescence, and then gradually shrinks with age.

Cardiovascular disease

Heart attack:

• A sudden, severe reduction of blood flow to the heart, which can cause serious damage or death.
• Caused by a blockage in the coronary arteries, which are the arteries that supply blood to the heart.

Stroke

• A sudden, severe reduction of blood flow to the brain, which can cause serious damage or death.
• Caused by a blockage in the arteries that supply blood to the brain, such as the carotid arteries or the vertebral arteries.

Hypertension

• High blood pressure
• Increases the risk of heart attack, stroke, and kidney failure.
• Can be caused by a variety of factors, such as genetics, obesity, and smoking.

Congenital heart defects:

• Heart defects that are present at birth.
• Can range from mild to severe, and some can be life-threatening.
• Some congenital heart defects can be treated with surgery or other medical interventions.

Homeostasis

Feedback loops:

• Control mechanisms that maintain the internal environment of an organism within narrow limits.
• Negative feedback loops counteract changes and restore the internal environment to its set point.
• Positive feedback loops amplify changes and move the internal environment away from its set point.

Regulation of blood pressure:

• Blood pressure is regulated by several negative feedback loops, including the baroreflex and the renin-angiotensin-aldosterone system.
• The baroreflex is a reflex that senses changes in blood pressure and adjusts the heart rate and blood vessel diameter to maintain blood pressure within a narrow range.
• The renin-angiotensin-aldosterone system is a hormonal pathway that regulates blood pressure by controlling the volume and composition of the extracellular fluid.

Regulation of body temperature:

• Body temperature is regulated by several negative feedback loops, including the thermoregulatory center in the hypothalamus and the autonomic nervous system.
• The thermoregulatory center in the hypothalamus senses changes in body temperature and adjusts the body’s heat production and heat loss to maintain body temperature within a narrow range.
• The autonomic nervous system controls the dilation and constriction of blood vessels in the skin and the sweating response to regulate heat loss.

Regulation of blood glucose levels

• Blood glucose levels are regulated by several negative feedback loops, including the endocrine pancreas and the liver.
• The endocrine pancreas produces insulin and glucagon, which are hormones that control the uptake and release of glucose by cells.
• The liver stores and releases glucose as needed to maintain blood glucose levels