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137 Cards in this Set

  • Front
  • Back
The _____ and _____ systems are the major controllers of the flow of information between different cells and tissues.
Endocrine; nervous
What are some examples of protein hormones?
Growth hormone, prolactin, parathyroid hormone, glucagon, insulin, and adrenocorticotophin
How are peptide hormones produced?
By the cleavage of a larger protein.
How is thyroid hormone produced?
By iodination and coupling of tyrosine.
Define endocrine secretion.
Internal secretion of hormones into the blood stream to convey information to target cells.
Define exocrine secretion.
Secretion outside of circulation, ex. through sweat glands or GI ducts.
Define the paracrine effect.
When hormones act on neighboring hormone-producing cells or non-hormone producing cells. One hormone regulates another hormone.
Define autocrine hormone.
When hormone acts on receptors located on the same cell. A hormone regulates its own secretion.
Define intracrine hormone.
A hormone that acts inside the cell without being released.
Define the synergistic effect.
When two or more hormones work together to produce a particular result.
Define the permissive effect.
A hormone enhances the responsiveness of a target organ to a second hormone or it increases the activity of a second hormone.
Define the antagonistic effect.
The actions of one hormone antagonize the effects of another. It blocks the receptor of another hormone. Ex. beta 1 blockers lower blood pressure.
What is the precursor of a steroid?
Cholesterol.
What is the precursor of thyroid hormone?
Iodine.
List the four types of cell surface receptors.
G-protein coupled receptors, growth factor receptors, cytokine receptors, and ligand-regulated transporters.
What type of hormone is associated with cell surface receptors?
Peptide hormones, ex. insulin, growth hormone, and prolactin.
What type of hormones are associated with intracellular receptors?
Steroids, thyroid hormone (T3 & T4), vitamin D, aldosterone, cortisol, and androgens.
What are the three g-protein subunits?
α (αi and αs), β, and y.
What are the four secondary messenger systems that use g-protein coupled receptors?
Adenylate cyclase, calcium, calmodulin, and inositol 1, 4, 5 triphosphate (IP3).
What are some hormones that are mediated by g-protein coupled receptors?
Catecholamines, prostaglandins, adrenocorticotrophin hormone, glucagons, parathyroid hormone, and thyroid-stimulating hormone.
What is the second messenger for growth factor receptors?
Tyrosine kinase.
Cytokine receptors mediate the actions of what hormone?
Growth hormone.
Growth hormone receptors lack a _____ _____ domain.
Tyrosine kinase.
What is the second messenger for ligand-regulated transporters?
Ion flux.
What are the effects of nitric oxide synthase (NOS)?
It is a vasodilator and leads to the stimulation of soluble guanylyl cyclase activity.
What is an example of a hormone that uses ligand-regulated transporters?
Atrial natureic peptide, which decreases blood pressure.
What are the three main differences between nuclear receptors and cell surface receptors?
Nuclear receptors are in the nucleus, on DNA

Nuclear receptors must be bound to a carrier protein in the blood

Nuclear receptor hormones are lipophillic, so they can pass through the membrane
How do nuclear receptors control gene expression?
By binding to DNA response elements in the promoters of the target genes or to other transcription factors.
What are the two ways the hypothalamus is connected to the pituitary gland?
Nerve fibers from the supraoptic and paraventricular nuclei to the posterior pituitary. Portal blood vessels connecting sinusoids with the capillary plexus in the anterior pituitary.
Name the six anterior pituitary hormones.
FLAT PIG

Follicule-stimulating hormone (FSH)
Luteinizing hormone (LH)
Adrenocorticotrophin hormone (ACTH)
Thyroid-stimulating hormone (TSH)

Prolactin
I-
Growth hormone (GH)
Describe the function of growth hormone (GH).
Stimulates growth, cell reproduction, and regeneration.
Describe the function of adrenocorticotrophin hormone (ACTH).
Increases production of androgens and corticosteroids from the adrenal cortex.
Describe the function of luteinizing hormone (LH).
Triggers ovulation and corpus luteum development in females. Stimulates Leydig cell production of testosterone in males.
Describe the function of follicule-stimulating hormone (FSH).
Regulates development, growth, and maturation of sex characteristics and regulates reproductive processes in the body.
Describe the function of thyroid-stimulating hormone (TSH).
Regulates the endocrine function of the thyroid gland.
Describe the function of prolactin.
Stimulates milk production.
What hormones are stored in the posterior pituitary?
Vasopressin / ADH: retention of fluids due to dehydration
Oxytocin: causes contraction of myometrium and milk ejection
What percentage of the adrenal gland consists of adrenal cortex?
90%.
What are the three layers of the adrenal cortex?
Zona glomerulosa, zona fasciculata, and zona reticulata.
Which steroid hormone does the zona glomerulosa produce?
Mineralocorticoids, such as aldosterone.
Which steroid hormone does the zona fasciculata produce?
Glucocorticoids, such as cortisol.
Which steriod hormone does the zona reticulata produce?
Sex hormones, mostly androgens.
Which pituitary hormone regulates the adrenal cortex?
Adrenocorticotrophin hormone (ACTH).
What two factors can cause aldosterone secretion?
Low blood volume and hyperkalemia.
Describe the renin-agiotensin-aldosterone system.
Decreased blood volume increases renin secretion. Renin --> angiotensinogen --> angiotensin I --> angiotensin II. Angiotensin II increases aldosterone production.
What is the function of aldosterone?
It increases Na+ reabsorption, increases H+ secretion, and increases K+ secretion.
What are the two main functions of glucocorticoids?
Stimulation of gluconeogenesis and anti-inflammatory effects.
What are the three mechanisms by which glucocorticoids increase gluconeogenesis?
Increased protein catabolism, decreased glucose utilization and insulin sensitivity, and increased lipolysis (provides glycerol for gluconeogenesis).
Define primary adrenocortical insufficiency.
In Addison's disease, the adrenal gland does not produce enough cortisol and aldosterone.
Define secondary adrenocortical insufficiency.
The anterior pituitary gland doesn't produce enough adrenocorticotrophin hormone (ACTH), which stimulates production of cortisol.
Define adrenocortical excess.
In Cushing's syndrome, there is an overproduction of cortisol.
Define hyperaldosteronism.
In Conn's syndrome, there is an overproduction of aldosterone which causes hypertension.
What three neurotransmitters are synthesized in the adrenal medulla?
Epinephrine, norepinephrine, and dopamine.
What are the main roles of triodothronine (T3) and thyroxine (T4) during development and in the adult?
They play a role in cell differentiation during development and help maintain thermogenic and metabolic homeostasis in the adult.
Describe the structure of the thyroid gland.
The thyroid gland contains a series of follicules, which contain colloids surrounded by a single layer of thyroid epithelium. Colloid is a fluid with large amounts of thyroglobulin.
Describe the synthesis of thyroid hormones.
Iodine (I-) is oxidized to I2 (the reactive form) by a peroxidase enzyme.

Tyrosine is incorporated into thyroglobulin, which reacts with I2 to form monoiodotyrosine (MIT) and diiodotyrosine (DIT).

2 DIT --> throxine (T4)
DIT + MIT --> triiodothyronine (T3)

Iodinated thyroglobulin is stored in the follicular lumen.
Thyroid regulating hormone is secreted by the _____ and stimulates the secretion of _____ by the anterior pituitary.
Hypothalamus; thyroid-stimulating hormone (TSH).
What does T3 regulate?
TRH receptors in the anterior pituitary, which inhibits TSH secretion.
About 99% of T3 and T4 are bound to which plasma protein?
Thyroxine binding globulin (TBG).
Thyroid hormones act synergistically with growth hormone and somatomedins to promote bone _____ and _____.
Bone formation and maturation.
How do thyroid hormones affect maturation of the CNS?
Maturation of the CNS is dependent on thyroid hormone, a deficiency causes mental retardation.
What effect does hyperthyroidism have on the CNS in adulthood?
Hyperexcitability and irritability.
What effect does hypothyroidism have on the CNS in adulthood?
Slowed speech, somnolence, impaired memory, and decreased mental capacity.
What effect does thyroid hormone have on the ANS?
It is equivalent to sympathetic stimulation.
How does thyroid hormone affect basal metabolic rate (BMR)?
Oxygen consumption and BMR are increased in all tissues except the brain, gonads, and spleen. This causes heat production and aids in temperature regulation.
How does thyroid hormone affect cardiac output and ventilation rate?
Heart rate, stroke volume, and ventilation rate increase.
Thyroid hormone generally _____ metabolism to compensate for the increased oxygen consumption rate.
Increases.
The parathyroid glands regulate serum _____ and _____ levels.
Calcium and phosphorus.
What is the function of parathyroid hormone (PTH)?
It raises serum calcium levels and lowers serum phosphorus concentration.
Parathyroid hormone (PTH) is synthesized and secreted by the _____ cells of the parathyroid glands.
Chief cells.
What produces symptoms of hypoparathyroidism (hypocalcemia)?
Severe decreases in serum Mg2+ inhibits parathyroid hormone (PTH) secretion.
What is the second messenger for parathyroid hormone (PTH)?
cAMP.
Describe the process though which parathyroid hormone (PTH) increases serum calcium levels and decreases serum phosphate levels.
PTH increases bone resorption, which brings calcium and phosphate from bone minerals to the extra cellular fliud (increases hydroxyproline excretion).

PTH increases renal phosphate excretion in the proximal tubules (phosphaturic effect).

PTH increases renal calcium reabsorption in the distal tubule.
What are the three major cells in the islets of Langerhans?
Alpha cells, beta cells, and delta cells.
What do alpha cells secrete?
Glucagon.
What do beta cells secrete?
Insulin.
What do delta cells secrete?
Somatostatin and gastrin.
What type of junction links cells in the islets of Langerhans?
Gap junctions.
What percentage of cells in the islets of Langerhans are beta cells? Alpha cells? Delta cells?
60% beta cells, 25% alpha cells, and 10% delta cells.
What is the major factor that controls glucagon regulation?
Blood glucose concentration.
What is the second messenger system for glucagon?
cAMP.
What are the six ways is which glucagon increases blood glucose concentration?
Glucagon increases glycogenolysis, prevents recycling of glucose into glycogen, increases gluconeogenesis, increases blood fatty acid and ketoacid concentration, increases lipolysis, and increases urea production.
What are the three ways in which insulin decreases the blood glucose concentration?
Insulin increases glucose uptake into target cells, promotes glycogenesis, and decreases gluconeogenesis.
How does insulin decrease blood fatty acid and ketoacid concentrations?
By stimulating fat deposition, inhibiting liplysis, and inhibiting ketoacid formation in the liver.
Besides decreasing blood glucose concentration, insulin can also decrease blood _____ concentration.
Insulin decreases blood potassium concentration by increasing K+ uptake into cells.
Define ketoacidosis.
High concentration of ketone bodies, usually in type I diabetes, which can lead to a coma if uncontrolled.
What is the function of somatostatin?
Regulates insulin and glucagon release. Somatostatin indirectly decreases GI motility, secretion, and absorption.
What is the precursor of melatonin?
Serotonin.
The pineal glands is similar to the adrenal medulla in the sense that it transduces signals from the _____ nervous system into a hormonal signal.
Sympathetic nervous system.
Prostaglandins are derived from a chemical called _____ _____.
Arachidonic acid.
What is the function of placenta?
It provides oxygen and nutrients to the fetus and allows for disposal of fetal waste.
What is the function of estrogen in females?
In females estrogen promotes the development of secondary sex characteristics and regulates the menstrual cycle.
What is the first sign of pregnancy (detected by pregnancy tests)?
Human chorionic gonadotrophin (HCG).
What three drugs inhibit prostaglandin synthesis?
Non-sterioidal anti-inflammatory drugs, indomethacin, and ibuprofen. They inhibit the cyclooxygenase enzyme used in prostaglandin synthesis.
Which enzyme converts arachidonic acid into a prostaglandin?
Cyclooxygenase.
Arachidonic acid is converted by the enzyme _____ into leukotrienes, which are largely responsible for the symptoms of asthma.
Lipoxygenase.
Define spermatogenesis.
The maturation of spermatogonia into sperm.
Describe the progression from spermatogonia to sperm (5 steps).
Spermatogonia --> primary spermatocyte --> secondary spermatocyte --> spermatids --> sperm.
Define spermiogenesis.
The gradual differentiation from spermatids to mature sperm.
What is the function of a Sertoli cell?
To support and nurture germ cells; may be involved in the regulation of spermatogenesis.
Where are Sertoli cells located?
They line the seminiferous tubules.
The _____ system controls spermatogenesis.
Endocrine.
What enzymes does the acrosome contain?
Acrosin, angiotensin converting enzyme, and prostaglandin.
Why are enzymes in the acrosome important?
The enzymes aid in penetration of the protective layer around the egg.
What is the function of gonadotropin releasing hormone (GnRH)?
It stimulates the production and release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
LH and FSH both bind to specific receptors on _____ cells and _____ cells within the testis.
Leydig cells and Sertoli cells.
Testosterone, the major secretory product of the testes, is a primary inhibitor of _____ hormone secretion in males.
Luteinizing.
What are the three main functions of testosterone?
Development of external genitalia, development of secondary sex characteristics, and testicle descent into the scrotum.
What is the function of inhibin?
To inhibit follicule-stimulating hormone (FSH) release.
Male fertility depends on the _____ and _____ of sperm.
Number and motility.
Erection is controlled by the _____ system.
Parasympathetic.
Which neurotransmitter mediates increased blood flow to the penis?
Nitric oxide, released in response to parasympathetic nerve stimulation.
What is the function of cGMP?
It causes vascular smooth muscle to relax, so that blood can flow into the corpora cavernosa of the penis.
Emission is controlled by the _____ system.
Sympathetic. Ejaculation is controlled by both sympathetic and parasympathetic.
What do Leydig cells secrete?
Testosterone, in response to luteinizing hormone (LH).
The seminiferous tubules contain all _____ cells at various stages of maturation and their supporting _____ cells.
Germ; Sertoli.
Define oogenesis.
The transformation of oogonia into mature oocytes.
Describe the maturation of an oocyte and follicle.
Oogonia --> primary oocyte --> secondary oocyte + sperm --> mature ovum.

Primordial follicle --> primary follicle --> secondary follicle.
Define zona pellucida.
The amorphous acellular glycoprotein which surrounds the primary oocyte.
What is the function of ooctye maturation inhibitor (OMI)?
It suspends the meiotic process of the oocyte. OMI prevents premature formation of the secondary follicle before puberty.
When does a primary ooctye complete its first meiotic division?
Shortly before ovulation.
When does a secondary oocyte complete its second meiotic division?
After fertilization.
What do the remains of the follicle become after fertilization?
Corpus luteum.
On which day of the menstrual cycle does ovulation occur?
Day 14.
Ovulation is triggered by a surge of _____ hormone production.
Luteinizing hormone (LH). Ovulation normally follows the LH peak by 12-24 hours.
What two hormones does the corpus luteum secrete?
Progesterone and estrogen.
What controls hormone production of the corups luteum?
Human chorionic gonadotropin (HCG).
What is the function of progesterone?
It promotes thickening of the endometrium.
What is the corpus albicans?
White scar tissue from the degenerated corpus luteum (if the oocyte is not fertilized).
In which trimester does the corpus luteum degenerate? What replaces it?
The corpus luteum degenerates after the 1st trimester and is replaced by placenta.
What enzymes does the sperm use to penetrate the zona pellucida?
Neuraminidase, acrosin, prostaglandin, and angiotensin converting enzyme.
What occurs during the follicular phase of menustruation?
Maturation of the follicle.
What occurs during the luteal phase of menustruation?
Corpus luteum formation.
What occurs during the secretory phase of menustruation?
Shedding of the endometrium.
How long does it take for an embryo to become a fetus?
Eight weeks.
What is the function of prostaglandin during labor?
It dilates the cervix.
What is the function of placenta during labor?
It produces relaxin, which prepares ligaments of the pelvic bone for birth.