Exam 1 (Lecture) Flashcards
Why don’t hormones affect all cells they contact?
Cells must have specific membrane or intracellular receptors to which hormones can bind.
What is a target cell?
A cell that bears receptors for a hormone, drug, or other signaling molecule
What are the 2 major classes of hormones (endocrine, not paracrine)?
Water-soluble and lipid-soluble
Where are the receptors for water-soluble hormones located?
Cell membrane
Where are the receptors for lipid-soluble hormones located?
Inside the cell. Bind to intracellular receptors
Which class of hormone uses a 2nd messenger system to stimulate its target cell?
Water-soluble hormones
What is a G-protein?
A cell membrane protein coupled to cell surface receptors.
Upon stimulation of the receptor by an extracellular signaling molecule (i.e. hormone, neurotransmitter) bind to GTP to form an active complex which mediates an intracellular event (e.g. activation of adenylate cyclase)
Which class of hormone binds to its receptor inside the cell, migrates to the nucleus, and acts as a transcription factor?
Lipid-soluble hormones (steroids & thyroid hormone). Direct gene activation occurs when a hormone binds to an intracellular receptor, which activates a specific region of DNA, causing the production of mRNA and initiation of protein synthesis.
Which class of hormone induces a more rapid response?
Water-soluble hormones
Which class of hormone has effects that are typically of longer duration?
Lipid-soluble hormones
What is half-life?
The duration of time a hormone remains in the blood (shortest for water-soluble hormones)
What are the three ways endocrine glands/tissues are stimulated to release their hormones?
Humoral, neural, or hormonal stimulus
What is the difference between humoral and hormonal stimulation?
Humoral stimulation causes hormones to be released by altered levels of certain critical ions or nutrients
Hormonal stimulation causes hormones to be released by the action of another hormone (a tropic hormone)
What is a tropic hormone?
Hormones that have other endocrine glands as their target
What type of homeostatic mechanism regulates the blood level of most hormones?
Negative feedback
What are the hormones that are synthesized in the posterior pituitary?
No hormones are synthesized in the posterior pituitary
What are the hormones that are released from the posterior pituitary?
Oxytocin and ADH
What are the hormones that are synthesized in the anterior pituitary?
Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Adenocorticotropic hormone (ACTH) Thyroid-stimulating hormone (TSH) Prolactin (PL) Growth hormone (GH)
What are the hormones that are released from the anterior pituitary?
Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Adenocorticotropic hormone (ACTH) Thyroid-stimulating hormone (TSH) Prolactin (PL) Growth hormone (GH)
Which pituitary hormones have releasing hormones?
Growth hormone – Growth hormone releasing hormone (GHRH)
Thyroid stimulating hormone – Thyroid releasing hormone (TRH)
ACTH – Corticotropin-releasing hormone (CRH)
LH & FSH – Gonadotropin-releasing hormone (GnRH)
Which pituitary hormones don’t have releasing hormones?
Prolactin
Where do releasing hormones come from?
Hypothalamus
Which pituitary hormones have inhibiting hormones?
Prolactin – Prolactin-inhibiting hormone (dopamine)
GH – Growth hormone inhibiting hormone (GHIH, somatostatin)
Which pituitary hormones don’t have inhibiting hormones?
a. FSH
b. LH
c. ACTH
d. TSH
These don’t have inhibiting hormones because they are tropic hormones!
Which part of the brain is most closely associated with the function of the endocrine system?
Hypothalamus
Which hormones help maintain fluid balance?
ADH, aldosterone, and atrial natriuretic peptide
Where do the hormones that help maintain fluid balance come from?
ADH – Posterior pituitary gland (synthesized in hypothalamus)
Aldosterone – Adrenal glands (zona glomerulosa of adrenal cortex)
ANP – Specialized cells in the atria of the heart
What is the difference in the actions of hormones that help maintain fluid balance?
ADH
i. Prevents fluid loss and promotes conservation of bodily water
ii. Increases the reabsorption of water in the distal convoluted tubules and collecting ducts of the nephrons in the kidney
iii. Stimulates thirst, resulting in increased water intake, which lowers blood osmolality and helps to restore homeostasis
Aldosterone
i. Regulates blood sodium levels
ii. Increases sodium reabsorption in the distal convoluted tubule and collecting ducts of the nephrons in the kidney
iii. Conserves sodium (“water follows salt,” leads to water retention)
iv. Increases secretion of potassium by kidneys
Atrial natriuretic peptide (ANP, ANF (factor), or ANH (hormone))
i. Promotes fluid and sodium loss by the kidneys
ii. Result in decreased blood volume, blood pressure, and blood sodium concentration
iii. Inhibits aldosterone secretion and antagonizes its activity at the kidney
Which hormones are associated with the following: Na+ (sodium), K+ (potassium), Ca2+ (calcium), HPO42- (phosphate), and I (iodine).?
Na+ (sodium): Aldosterone, ANP K+ (potassium): Aldosterone Ca2+ (calcium): Calcitonin, PTH HPO42- (phosphate): PTH I (iodine): Thyroid hormone, T3, T4
What is thyroglobulin?
A hormone secreted by the thyroid gland, needed for synthesis of thyroxine and triiodothyronine
What is thyroxine?
A hormone secreted by the thyroid gland. Plays vital roles in digestion, heart and muscle function, brain development, and maintenance of bones
What is the difference between T3 and T4?
T3 contains 3 iodine atoms, whereas T4 contains 4 iodine atoms
What is a goiter?
An enlarged protruding thyroid gland. Occurs if myxedema results from a lack of iodine
What is the difference between Type I and Type II diabetes?
Type I:
Type II:
What are the hallmarks of diabetes?
Polyuria (increased urination), polydipsia (increased thirst), and polyphagia (increased hunger)
How does stress affect the adrenal glands?
Glucocorticoids are released in response to stress through the action of ACTH. Glucocorticoids, like cortisol, are glucose-sparing stress-related hormones
Know the causes and characteristics of pituitary dwarfism.
Growth hormone deficiency in children
Know the causes and characteristics of gigantism (giantism).
Hypersecretion of growth hormone during childhood. GH targets the still-active epiphyseal plates, person becomes abnormally tall (often 8ft) but has relatively normal body proportions
Know the causes and characteristics of gigantism (giantism).
Hypersecretion of growth hormone during childhood. GH targets the still-active epiphyseal plates, person becomes abnormally tall (often 8ft) but has relatively normal body proportions
Know the causes and characteristics of acromegaly.
Hypersecretion of growth hormone during adulthood (after epiphyseal plates have closed). “Enlarged extremities” characterized by overgrowth of bones of the hands, feet, and face
Know the causes and characteristics of diabetes insipidus.
ADH deficiency. Polydipsia, polyuria, polyphagia
Know the causes and characteristics of hyperthyroidism.
Common cause is Graves’ disease, an autoimmune disease where anti-TSH receptor antibodies bind to TSH receptors on the thyroid and stimulate continuous thyroid hormone release. Feedback mechanism is short-circuited because the production and release of thyroid hormone is not dependent on TSH
Know the causes and characteristics of Cushing’s Syndrome.
Caused by excess of glucocorticoids
Characterized by elevated blood glucose, loss of muscle and protein from bone, and hypertension and edema due to salt and water retention
Signs are moon face (due to edema) and “buffalo hump” (due to redistribution of fat to back of neck)
Know the causes and characteristics of Addison’s Disease.
Usually involves deficits in both glucocorticoids and mineralocorticoids
Weight loss, drops in plasma glucose and sodium levels, elevated potassium levels
Severe dehydration and hypotension are common
What is physiological basis of each sign of diabetes?
Polyuria – Glucose spilling into the urine
Polyphagia – Inability of cells to utilize glucose
Polydipsia – Glucose spilling into the urine results in osmotic diuresis, giving rise to dehydration and increased thirst
What are the formed elements of blood?
Erythrocytes, leukocytes, thrombocytes
What are the fluid elements of blood?
Plasma
What are the functions of blood proteins?
Function as carriers. All contribute to osmotic pressure and maintain water balance in blood and tissues
Albumin – 60% of plasma proteins; produced by liver; main contributor to osmotic pressure
Globulins – 36% of plasma proteins. 3 types: alpha, beta, and gamma
Gamma Globulins – Antibodies released by plasma cells during immune response
Fibrinogen – 4% of plasma proteins; produced by liver; forms fibrin threads of blood clot
How is oxygen carried in the blood?
Oxygen binds to hemoglobin on erythrocytes. Hemoglobin is an oxygen-binding pigment that is responsible for the transport of most of the oxygen in the blood. Composed of the protein globin bound to the red heme pigment
What is hematocrit?
The percentage of erythrocytes in whole blood
What is anemia? Is it a symptom or a disease? What are the causes?
Reduced oxygen carrying capacity of blood. “Lacking blood”
Anemia is a symptom, not a disease
What is polycythemia? What is leukopenia?
Polycythemia: An abnormal excess of RBCs
Polycythemia vera is the result of bone marrow cancer, results in increased blood viscosity, increased blood volume, and extremely high hematocrit
Secondary polycythemias are the result of the body’s response to low oxygen environments or excess erythropoietin (EPO)
Leukopenia: An abnormally low white blood cell (WBC) count
Which factors regulate RBC and WBC formation?
RBC Formation:
– Hematopoiesis, or blood cell formation, occurs in the bone marrow
– Erythropoiesis, the formation of erythrocytes, is controlled by the hormone erythropoietin, which is released by the kidneys in response to hypoxia
– Low O2 levels in blood stimulate kidneys to produce erythropoietin
WBC Formation
– Leukopoiesis, white blood cell formation, is regulated by the production of interleukins and colony-stimulating factors (CSFs)
– Involves differentiation of hemocytoblasts along 2 pathways: lymphoid and myeloid stem cells
What is the stem cell from which all blood cells originate?
Hemocytoblast
Which leukocytes are myeloid in lineage?
Neutrophils, eosinophils, basophils, and monocytes
Which leukocytes are lymphoid in lineage?
Plasma cells and effector T cells
Which leukocytes are granulocytes?
Neutrophils, eosinophils, basophils
Which leukocytes are phagocytic?
Neutrophils, monocytes (develop into macrophages)
Which leukocytes are lymphocytic?
Lymphocytes
What are platelets? What cell do they come from?
Function: Platelets are not complete cells, but fragments of cells called megakaryocytes. Critical to the clotting process, forming the temporary seal when a blood vessel breaks
Origin: Fragments of megakaryocytes. Stimulus for platelet formation is thrombopoietin
