Unit I Endocrine System & Blood

What is a hormone?

A chemical messenger secreted by glands to regulate body functions.

How do paracrine hormones differ from other hormones?

They act on nearby cells rather than distant targets.

What is a target cell?

A cell with receptors for a specific hormone.

Name the major organs in the endocrine system.

Hypothalamus, pituitary, thyroid, parathyroid, adrenal, pancreas, ovaries, testes.

What is the difference between exocrine and endocrine glands?

Exocrine glands secrete through ducts; endocrine glands release hormones into the bloodstream.

How does the endocrine system differ from the nervous system?

The endocrine system is slower, using hormones; the nervous system is fast, using electrical signals.

How does the hypothalamus communicate with the pituitary gland?

It communicates via releasing and inhibiting hormones.

What is a tropic or tropin hormone?

It stimulates another gland to release hormones.

Why is growth hormone important?

It is essential for childhood growth and declines with age.

What is necessary for the production of thyroid hormones?

Iodine.

What does the adrenal medulla release directly into the blood?

Epinephrine and norepinephrine.

What are the three zones of the adrenal cortex and their hormones?

Zona glomerulosa: Aldosterone, Zona fasciculata: Cortisol, Zona reticularis: Androgens.

What is the stress hormone?

Cortisol.

Name two paired glands in the body.

Adrenal glands and gonads (ovaries/testes).

What is the main tissue type in the pancreas?

Exocrine tissue (acini cells).

What is the difference between hyperglycemic and hypoglycemic?

Hyperglycemic refers to high blood sugar; hypoglycemic refers to low blood sugar.

What hormones are important for growth and development?

Growth hormone (GH), thyroid hormones, insulin, sex hormones.

What disorder is caused by hypersecretion of growth hormone?

Gigantism in childhood and acromegaly in adulthood.

What is the result of hyposecretion of ADH?

Diabetes insipidus.

What causes hypothyroidism?

Iodine deficiency or Hashimoto’s disease.

What causes hyperthyroidism?

Graves’ disease or tumors.

What does excess PTH secretion lead to?

Hypercalcemia and bone loss.

What syndrome is caused by excess cortisol?

Cushing syndrome.

What is diabetes mellitus?

High blood sugar due to insulin issues; Type 2 is the most common.

What role does blood play in homeostasis?

Transports gases, nutrients, hormones, and regulates temperature.

What are the functions of the circulatory system?

Transport, protection, regulation.

What are the two main components of blood?

Plasma and formed elements.

What are the three plasma proteins?

Albumin, globulins, fibrinogen.

What are the formed elements in blood?

Red blood cells (RBCs), white blood cells (WBCs), platelets.

What does hematocrit measure?

The percentage of RBCs in blood.

What are two properties of blood?

Viscosity (thickness) and osmolarity (solute concentration).

Why is erythrocyte survival important?

For oxygen transport.

Why are RBCs more efficient in humans?

They have adaptations that enhance oxygen transport.

How do RBCs carry oxygen?

Hemoglobin binds to oxygen.

Why don't RBCs consume oxygen?

They lack mitochondria.

What is hematopoiesis?

The process of producing all formed elements.

What is erythropoiesis?

The process of producing red blood cells (RBCs).

What is leukopoiesis?

The process of producing white blood cells (WBCs).

Where do all formed elements originate from?

Hematopoietic stem cells.

What hormone stimulates RBC production?

Erythropoietin (EPO), produced by the kidneys.

What triggers RBC homeostasis?

Low oxygen levels stimulate the kidney to release EPO, leading to more RBCs.

What factors can increase erythropoietin production?

Hypoxia, blood loss, and high altitude.

What is sickle cell disease?

A genetic disorder of RBCs that persists due to malaria resistance.

What is the difference between antigens and antibodies?

Antigens are markers on cells; antibodies attack foreign antigens.

What is one action of an antibody?

Agglutination (clumping of foreign cells).

What are the blood type antigens and antibodies for type A?

Type A has A antigen and anti-B antibody.

What are the blood type antigens and antibodies for type B?

Type B has B antigen and anti-A antibody.

What are the blood type antigens and antibodies for type AB?

Type AB has A and B antigens with no antibodies.

What are the blood type antigens and antibodies for type O?

Type O has no antigens and anti-A & anti-B antibodies.

How is blood type inheritance determined?

By the ABO genes inherited from the parents.

What does the Rh group indicate?

The presence (Rh+) or absence (Rh-) of the Rh antigen.

Why is Rh- status important?

It can cause complications in pregnancy if the mother is Rh- and the baby is Rh+.

What is hemolytic disease of the newborn?

When the mother’s antibodies attack Rh+ fetal blood.

Why are there few WBCs in blood?

They primarily reside in tissues.

What are the functions of leukocytes (WBCs)?

Immunity and defense.

What are the types and functions of WBCs?

Neutrophils: Bacteria killers; Lymphocytes: Adaptive immunity; Monocytes: Macrophage precursors; Eosinophils: Fight parasites and allergies; Basophils: Release histamine and heparin.

What causes an increase in WBC count?

Infections or inflammation.

What are the most and least abundant types of WBCs?

Neutrophils (most), basophils (least).

What do histamine and heparin do?

Histamine dilates vessels; heparin prevents clotting.

Why is it important to count RBCs?

To diagnose anemia and assess oxygen capacity.

What is the difference between leucopenia and leukocytosis?

Leucopenia is low WBC count; leukocytosis is high WBC count.

What is leukemia?

A blood cancer characterized by excess WBCs, which can be acute or chronic.

Why can leukemia be harmful?

Excess WBCs disrupt normal blood function.

What are platelets, and where do they originate?

Cell fragments from megakaryocytes.

What is hemostasis?

The process of blood clotting.

Which formed element is primarily involved in hemostasis?

Platelets.

What is the most immediate step in hemostasis?

Vascular spasm.

What is the most effective step in hemostasis?

Coagulation.

What is the difference between extrinsic and intrinsic coagulation?

Extrinsic is triggered by external damage; intrinsic is triggered by internal vessel damage.

What is the shared coagulation pathway?

Both extrinsic and intrinsic pathways lead to fibrin formation.

What is the beginning clotting factor for the extrinsic pathway?

Factor III (tissue factor).

What is the beginning clotting factor for the intrinsic pathway?

Factor XII.

What activates the common coagulation pathway?

Activation of Factor X.

What is fibrinolysis?

The breakdown of clots via plasmin.

What prevents clot formation?

Anticoagulants like heparin and plasmin.

What is anemia?

A condition characterized by low RBCs or hemoglobin.

What is hemophilia?

An inherited clotting disorder.

What is thrombosis?

A clot formed in an unbroken vessel.

What is an embolism?

A moving clot that blocks blood flow.