New Content: Endocrine System and Blood

What are the general functions of blood?

Transport, buffering, defense, and clotting.

What are the two main components of blood?

Plasma and formed elements.

What is the primary component of plasma?

Water, which makes up more than 90% of plasma by volume.

What role do albumins play in blood?

They regulate osmolarity and function as carrier molecules.

What are globulins in blood?

Proteins that also function as carrier proteins.

What is the purpose of clotting factors in blood?

They play an essential role in blood clotting.

What does a Complete Blood Count (CBC) measure?

It provides detailed information about blood contents, including WBC, RBC, hemoglobin, hematocrit, and more.

What does HGB stand for in a CBC?

Mass of hemoglobin found in a given volume of blood.

What does HCT represent in a CBC?

Hematocrit, the proportion of blood volume occupied by red blood cells.

What is erythropoiesis?

The process of red blood cell formation.

What triggers the release of erythropoietin (EPO)?

Hypoxia and testosterone signal EPO release.

What is the Bohr Effect?

Oxygen is more readily released from hemoglobin when carbon dioxide concentration increases and pH decreases.

What is the Haldane Effect?

Hemoglobin has less affinity for carbon dioxide when oxygen concentration is high in the blood.

What is the structure of hemoglobin?

A globular, tetrameric protein formed from 2 alpha and 2 beta chains (adult) or 2 alpha and 2 gamma chains (fetus).

What is oxyhemoglobin?

Hemoglobin that is bound to oxygen.

What is deoxyhemoglobin?

Hemoglobin that has no oxygen bound.

How does carbon monoxide affect hemoglobin?

CO competes for the same binding site as O2 and has a higher binding affinity, which can lead to undetectable symptoms until severe.

What is sickle cell anemia?

A genetic blood disorder characterized by the production of abnormal hemoglobin, leading to distorted (sickle-shaped) red blood cells.

What is the most common heritable blood disorder?

Sickle cell disease

What causes sickle cell disease?

A single point mutation in the beta globin gene

Why is sickle cell disease prevalent in regions with high malaria rates?

It provides a survival advantage against malaria.

What is a major effect of the sickle cell mutation?

It causes misfolded beta chains, leading to sickle-shaped red blood cells (RBCs).

What are the consequences of sickled RBCs?

They are prone to clogging and have a decreased ability to unload oxygen.

What happens to heme during erythrocyte recycling?

Heme is converted to biliverdin, then bilirubin, which is transported to the liver.

What is the fate of iron from erythrocytes?

Iron is bound to transferrin and transported to the bone marrow for erythropoiesis.

What are leukocytes?

Cells of the immune system.

What are the two main classifications of leukocytes?

Granulocytes and agranulocytes.

What percentage of leukocytes are neutrophils?

50-70%

What is the primary function of neutrophils?

They are efficient killers of bacteria.

What is the role of eosinophils?

They combat multicellular parasites and contribute to allergies.

What do basophils secrete?

Histamine, serotonin, heparin, and prostaglandins.

What are the two types of agranulocytes?

Lymphocytes and monocytes.

What is the function of B-lymphocytes?

They are responsible for producing antibodies.

What is infectious mononucleosis commonly known as?

The kissing disease.

What virus most commonly causes infectious mononucleosis?

Epstein-Barr virus (EBV).

What are the symptoms of infectious mononucleosis?

Flu-like symptoms.

What is the treatment for infectious mononucleosis?

There is no specific treatment; it usually clears up in a few weeks.

What determines blood type?

Carbohydrate markers on the plasma membrane of erythrocytes.

What is the universal donor blood type?

O-

What is the universal recipient blood type?

AB+

What is hemolytic disease of the newborn?

An attack on fetal RBCs by the maternal immune system.

What causes hemolytic disease of the newborn?

The fetus is Rh+ while the mother is Rh-.

What is the treatment for hemolytic disease of the newborn?

Injection of anti-Rh antibodies into the mother.

What is hemostasis?

The process of stopping blood loss.

What occurs during the vascular spasm phase of hemostasis?

Smooth muscle constricts to limit blood flow.

What is the role of platelets in hemostasis?

They adhere to the site of damage and form a platelet plug.

What is the coagulation phase in hemostasis?

Reinforcement of the platelet plug by a fibrin mesh.

What is the general definition of endocrine cells?

Endocrine cells release chemical messengers (hormones) into the bloodstream, affecting only cells with receptors for those hormones.

What are the general properties of hormones?

Hormones regulate physiological processes, vary in chemical structure, are released in very low quantities, diffuse through plasma, and bind to receptors on target cells.

What is upregulation in the context of hormone receptors?

Upregulation refers to the process of increasing receptor levels on target cells.

What is downregulation in the context of hormone receptors?

Downregulation refers to the process of decreasing receptor levels on target cells.

What is permissiveness in hormone action?

Permissiveness is when one hormone regulates the receptor levels of another hormone.

How do hormones differ from neurotransmitters in terms of release?

Hormones are amplitude-modulated and levels never approach zero, while neurotransmitters are released in an 'all or nothing' manner.

What is the significance of the signal peptide in peptide hormones?

The signal peptide directs the hormone to the correct intracellular organelle for processing.

How are amino acid derivative hormones synthesized?

Amino acid derivative hormones are biochemically synthesized from amino acids and stored within vesicles.

What factors influence hormone secretion?

Hormone secretion can be influenced by changes in critical physiological factors, direct nervous system input, actions of other hormones, and mechanical stresses or cellular metabolism.

How are water-soluble hormones excreted?

Water-soluble hormones are smaller than the kidney filtration barrier and are excreted in urine.

What is the half-life of a hormone?

The half-life is the time required to reduce the blood concentration of a hormone by 50%.

What are G-protein coupled receptors (GPCRs)?

GPCRs are integral membrane proteins that bind hormones extracellularly and interact with G-proteins intracellularly.

What is the role of cAMP in hormone signaling?

cAMP activates Protein Kinase A (PKA) and is degraded by phosphodiesterase (PDE).

What are the features of one-transmembrane spanning receptors (1-TMS)?

1-TMS receptors are integral membrane proteins with an extracellular region that binds hormone and an intracellular kinase domain that activates enzymes directly.

What are nuclear receptors and their function?

Nuclear receptors are found inside the cell, act as transcription factors, and their binding leads to dissociation from heat shock proteins and translocation to the nucleus.

What disease is caused by a mutation in the thyroid stimulating hormone receptor?

Grave's disease (hyperthyroidism) is caused by a mutation in the thyroid stimulating hormone receptor.

What is the hypophyseal portal system?

The hypophyseal portal system connects the hypothalamus and anterior pituitary via two capillary beds in series.

What hormones are released by the hypothalamus that act on the pituitary gland?

The hypothalamus releases hormones such as releasing and inhibitory hormones that regulate pituitary function.

What is the role of leptin in the endocrine system?

Leptin is a hormone involved in regulating energy balance and inhibiting hunger.

What is the function of erythropoietin?

Erythropoietin stimulates the production of red blood cells in response to low oxygen levels.

What is the function of insulin?

Insulin regulates glucose levels in the blood by facilitating cellular uptake of glucose.

What is the role of calcitriol?

Calcitriol is the active form of vitamin D and helps regulate calcium levels in the body.

What is the function of angiotensin II?

Angiotensin II regulates blood pressure and fluid balance by constricting blood vessels.

Where is the pituitary gland located?

Inferior to the hypothalamus

What are the three lobes of the pituitary gland?

Anterior, intermediate, and posterior lobes

What are the subdivisions of the anterior lobe of the pituitary gland?

Pars tuberalis and pars distalis

What hormones are secreted by the posterior pituitary gland?

Oxytocin and Antidiuretic Hormone (ADH)

What is the function of oxytocin?

Stimulates milk ejection and uterine contractions during pregnancy

How does antidiuretic hormone (ADH) affect the renal system?

Increases expression of aquaporin channels for water absorption

What is the role of oxytocin in social behavior?

Promotes feelings of contentment, reduces anxiety, and induces calmness

What is the primary function of growth hormone?

Stimulates growth and cell reproduction

What hormone is produced by the parafollicular cells of the thyroid gland?

Calcitonin

What is the structure of the thyroid gland?

Made up of two lobes connected by a vascularized band called isthmus

What is thyroglobulin?

The substrate for thyroxine stored in thyroid follicles

What is the first step in thyroxine synthesis?

Iodide ions are transported into follicular cells

What stimulates the synthesis and storage of thyroglobulin?

Thyroid Stimulating Hormone (TSH)

What forms T4 in the thyroid gland?

Two DIT molecules join together

What happens to iodinated thyroglobulin within follicular cells?

It is taken up by endocytosis and thyroxine is released by proteolytic enzymes

What are the types of pituitary adenomas?

Benign, invasive, and carcinoma

What are common symptoms of pituitary adenomas?

Over-secretion of hormones, eye disorders, severe headaches, and under-secretion of hormones

What is the significance of the isthmus in the thyroid gland?

It connects the two lobes of the thyroid gland

What is the effect of vasoconstriction in the cardiovascular system?

Increases blood pressure

What is the role of thyroid peroxidase in thyroxine synthesis?

Oxidizes iodide to iodine for attachment to thyroglobulin

What hormone is released into the blood bound to proteins such as TBG or albumin?

Thyroxine

What are the effects of Thyroxine on the lungs?

Increased ventilation

How does Thyroxine affect the liver?

Increased basal metabolic rate

What effect does Thyroxine have on muscle tissue?

Increased protein catabolism

What is one effect of Thyroxine on the heart?

Increased heart rate and force of contraction

What hormone is mainly secreted by the parathyroid glands?

Parathyroid hormone (PTH)

What is the effect of parathyroid hormone on bones?

Increased resorption

How does parathyroid hormone affect the kidneys?

Increased calcitriol production

What is the location of the adrenal glands?

Embedded in adipose tissue in the superior regions of the kidneys

What hormone is produced in the zona glomerulosa of the adrenal gland?

Mineralocorticoids, e.g., aldosterone