Posterior Pituitary Lobe Hormones

• Study notes derived from the provided text are listed below.

Posterior Pituitary Lobe

• Neurohypophysis is another name for the posterior pituitary lobe in addition to the infundibulum.
• The hypothalamus is technically part of the posterior pituitary lobe.

Posterior Pituitary Hormones

• Oxytocin is amino acid based and binds to membrane-bound receptors.
• Oxytocin stimulates uterine contractions and uses positive feedback.
• Positive feedback with oxytocin leads to increased intensity of uterine contractions, ending in birth.
• Contractions stimulated by oxytocin are strong, regular, and less than 5 minutes apart regulated by positive feedback.
• Oxytocin triggers milk ejection, a "letdown" reflex where lactating individuals release milk upon hearing a baby cry.
• Oxytocin is utilized to induce labor since one would not naturally go into labor without it.
• Oxytocin plays a role in sexual arousal and satisfaction in males and non-lactating females and is associated with fidelity in men.
• The hypothalamus produces oxytocin and the posterior pituitary secretes it: oxytocin
• Antidiuretic Hormone (ADH) helps avoid dehydration preventing urine formation acting as a water-conserving hormone in the kidneys.
• ADH's effects on osmoreceptors detect changes in osmotic pressure, dehydration elevates sodium concentration in blood, and triggers ADH secretion.
• High osmolarity can be caused by dehydration, high sodium in blood which causes ADH to preserve water and promote water consumption.
• Low osmolarity which can be caused by drinking a lot of water and low sodium levels in blood causes ADH to be not released and water loss increases restoring osmolality.
• Alcohol inhibits ADH release, leading to copious urine output and increased urination.
• ADH deficiency results in diabetes insipidus.
• Diabetes insipidus causes abnormal increase in urine output, fluid intake, and thirst.
• Symptoms of diabetes insipidus include dilute urine, increased urinary frequency, nocturia, and enuresis.
• Death of ADH-producing cells in the hypothalamus and posterior pituitary gland can cause ADH deficiency.
• ADH overproduction leads to Syndrome of Inappropriate ADH Secretion (SIADH).
• SIADH results in decreased urine output and a strong taste.
• SIADH symptoms include hyponatremia, elevated urine osmolality and excessive urine sodium excretion and volume overload.
• Hypovolemia, or ADH-secreting tumors can cause SIADH.

Anterior Pituitary Lobe

• The adenohypophysis refers to the anterior lobe, composed of glandular tissue.
• The hypophyseal portal system includes the superior hypophyseal artery, capillaries, portal vein, and ends in the rest of the body.
• FLAT PeG is a mnemonic for anterior pituitary hormones: FSH, LH, ACTH, TSH, PRL, GH.

Growth Hormone (GH)

• The name "Growth Hormone" can be misleading, as it does not directly cause growth.
• Growth Hormone (GH) is amino acid-based.
• GH is under hormonal regulation by the hypothalamus.
• Somatotropic cells produce GH in the anterior lobe.
• GH stimulates cells, but particularly targets bone and skeletal muscle and promotes protein synthesis, encouraging use of fats for fuel.
• GH's effects are mediated by Insulin-like Growth Factors (IGFs).
• Insulin-like Growth Factor (IGF) is AA based, produced by the liver, and under hormonal control by the anterior pituitary and GH.
• Some IGFs are produced locally within bones and muscle (MGF).
• GH secretion is controlled by the hypothalamus and antagonistic hypothalamic hormones
• Growth Hormone-Releasing Hormone (GHRH) stimulates GH release and is secreted by the hypothalamus.
• Growth Hormone-Inhibiting Hormone (GHIH) inhibits GH release.
• High GH levels in the blood inhibits GHRH and GH and stimulates the release of GHIH.
• GH stimulates the liver to secrete IGF which targets bone growth and protein synthesis in skeletal muscle.
• GH directly stimulates lipolysis in adipose tissue for growth and breaks down glycogen storages for glucose.
• GH deficiency in infants causes hypoglycemia and neurological deficits if not replaced.
• In childhood GH deficiency causes Pituitary Dwarfism and have typical body proportions but are shorter in stature.
• GH deficiency in adults causes the loss of lean tissue mass.
• Excess GH in childhood causes Pituitary Gigantism and acromegaly in adults, leading to extremities enlargement.

Prolactin (PRL)

• Prolactin stimulates milk production.
• Prolactin secretion is controlled by Prolactin-Inhibiting Hormone (PIH) produced in the hypothalamus.
• PIH, which is dopamine, inhibits prolactin release.
• Neural sucking inhibits PIH which allows for the release of milk.
• Prolactin-Releasing Hormone (PRH) secreted by the hypothalamus triggers release of Prolactin.
• Blood levels rise toward the end of pregnancy, suckling stimulates PRH and encourages continued milk production.
• Prolactin deficiency causes poor milk production.
• Prolactin overproduction causes inappropriate milk production in females, and impotence and breast enlargement in males.

Thyroid Gland

• The thyroid gland produces thyroid hormone and calcitonin.
• Thyroid hormone is a major metabolic hormone.
• Calcitonin lowers blood calcium.

Thyroid Hormone (TH)

• Thyroxine (T4) has two tyrosines with three bound iodine atoms.
• Triiodothyronine (T3) has two tyrosines with four bound iodine atoms.
• Thyroid hormone is involved with glucose oxidation, increasing metabolic rate, and heat production, maintaining blood pressure, regulating tissue growth, developing skeletal and nervous system, maturation and reproductive capability.
• Hypothyroidism can be genetic of acquired
• Hypothyroidism during pregnancy or infancy can cause cretinism which includes low metabolic rate, growth retardation GOITER and developmental delays
• Hypothyroidism in adults can cause Myxedema which is skin and tissue disorders, low metabolism, GOITER.
• Grave's disease is a hyperthyroid disorder which is autoimmune in nature.
• Hyperthyroidism is the overactivity of the thyroid gland, inflammation of the tissues around the eyes causing swelling, increase in metabolic rate, nervousness, weight loss, protruding eyeballs, and goiter.

Adrenal Glands

• The adrenal medulla is neural tissue and part of the sympathetic nervous system (SNS).
• The adrenal cortex secretes steroid hormones called corticosteroids.
• The adrenal cortex synthesizes and releases steroid hormones called corticosteroids.
• The zona glomerulosa produces mineralocorticoids like aldosterone.
• The zona fasciculata produces glucocorticoids like cortisol.
• The zona reticularis produces gonadocorticoids, mainly androgens.
• Cortisol is involved in stress response while not under feedback regulations and has a circadian pattern with high levels in the morning.
• Glucocorticoids promote gluconeogenesis, lipolysis, proteolysis, insulin resistance, and suppress inflammation and immune function.
• Hyposecretion of cortisol causes Addison's disease and glucocorticoid and mineralocorticoid deficits.
• Hypersecretion of cortisol causes Cushing's syndrome and increases glucocorticoid levels.
• Cushing's disease is caused by excess ACTH.
• Hyperglycemia, skeletal muscle atrophy, bone loss, edema, redistribution of adipose tissue causing Buffalo hump, and poor wound healing are symptoms of Cushing's disease.

Gonads: Females

• Females develop if testosterone is NOT secreted.
• Estrogen causes maturation of female reproductive organs, promotes ovulation, and secondary sex characteristics.
• Estrogen synthesis is controlled by hypothalamic hormones.
• Progesterone, in combination with estrogen, influences breast development, menstrual cycle regulation, and endometrium regulation.
• Progesterone is secreted by the luteal body, and is under hypothalamic control.
• Menopause is the cessation of menstruation.

Lecture Quiz

• Prolactin (PRL) stimulates milk production, and its secretion is inhibited by PIH (dopamine) from the hypothalamus.
• Antidiuretic Hormone (ADH) is needed to avoid losing a substantial amount of fluid to urine formation.
• The HPA axis consists of the Hypothalamus, Pituitary, and Adrenal glands.
• Cortisol is the primary hormone secreted from the HPA Axis.
• GH secretion from the anterior pituitary gland, increases IGF, bone growth, blood glucose, and lipids.
• Regulatory hormones secreted by the hypothalamus with "releasing" in their name increase anterior pituitary hormones' secretion.

Gonads

• If testosterone IS secreted in female development = male
• If testosterone is NOT secreted in female development = female
• Estrogen promotes and establishes and progesterone protects.

Gonads : Male

• Testosterone is crucial for male brain development driving sex drive and aggression.
• Testosterone promotes the growth of facial and body hair, baldness.
• Testosterone supports sperm production, prostate growth, and erectile function in male sex organs.
• RBC production in the bone marrow is supported by the presence of Testosterone.
• Testosterone supports bone density maintenance and affects muscle mass and strength.
• Andropause is the age-related decline in circulating testosterone.
• The regulation of testosterone and spermatogenesis occurs at the Hypothalamic-Pituitary-Gonadal Axis.
• Aldosterone, a water conserving hormone promotes the exchange of two minerals in the DCT to recover sodium but rid the body of potassium.
• Aldosterone secretion is controlled by both hormonal and humoral cues
• It increases blood pressure.
• Stress increases aldosterone secretion via HPA axis.
• ANP is an antagonist to aldosterone, and the entire process is under negative feedback control.
• Addison's Disease is a HYPO-secretion of aldosterone that includes; mineralocorticoids and glucocorticoids, severe dehydration, hypotension, low blood glucose, low Na+, high K+.
• Aldosteronism is a HYPER-secretion of aldosterone that includes; adrenal cortex tumor, overactivity of the cells in the zona glomerulosa, hypertension and edema, and a loss of K+.
• Androgens are main secretions of the adrenal cortex
• Adrenogenital syndrome occurs in Males leading to early puberty as well as early sex characteristics and drive and in females leading to masculinization beard growth and increased sex drive
• NE and EPI are very similar with only one methyl difference, they are secreted in the adrenal medulla.

Parathyroid Gland (PTH)

• PTH raises low blood Calcium levels antagonistic to calcitonin.
• Cells are in cords with oxyphil and chief cells.
• Humoral regulation controls the chief cells which secrete PTH .
• Low blood calcium activates osteoclasts leading to bone resorption.
• Calcium/phosphate ions are released into the blood.
• Increases Ca absorption from food in the intestine, promotes Vitamin D activation, and increasing kidney Ca absorption in kindey nephron
• Hypersecretion; hypercalcemia; leaching bone mineral, and depresses the nervous system.
• Hyposecretion; deficiency which cause membrane hyperpolarization

Regulation of Blood Glucose

• Glucagon lowers glucose.
• Insulin raises low glucose.
• Glucagon and insulin are antagonistic.
• Insulin activates GLuT increasing cellular transport.
• Very little/not enough insulin, causes an imbalance which leads to DM (diabetes mellitus).
• DM type 1 is genetic: very little production
• DM type 2 is acquired : cell resistant to insulin
• ~4% of pregnant women suffer from gestational diabetes- acquired

RAAS (Renin-Angiotensin-Aldosterone System)

• Renin-Angiotensin-Aldosterone System is a potent anti-hypotensive system to raise BP by increasing body sodium concentration and vasoconstriction
• It starts out atypical/backwards: BP falls, kidneys secrete renin.
• Renin - is an enzyme that coverts plasma Angiotensinogen in LIVER to ang I where ACE converts blood Ang I, to Ang II (angiotensin II the potent vasoconstrictor)
• Primary Target Actions include :
• Brain Stem
• Adrenal cortex
• Vasoconstiriction
• Posterior Pituatary gland

Blood

• Blood is a connective tissue consisting of cells suspended in extracellular matrix.
• Blood volume is about 8% of body weight, approximately 4-5L for females, and 5-6L for males.

Whole Blood Functions

• Functions include: Distribution, Regulation and Protection
• Transportation of gasses, waste and hormones
• Regulation of body temperature, pH, and fluid volume
• The whole components of blood from the bodies defense against blood loss during injury

Plasma composition

• 90% water
• Proteins, nutrients, Gases, hormones, electrolytes, etc.
• " Serum" is the remaining plasma in the blood and prevents blood clotting. (without fibrinogen)

Formed elements

• Erythrocytes (RBC) or platelets; Non-nucleated
• Platelets; NO nucleus; responsible for clots
• Leukocytes (WBC); TRUE CELL responsible for defense for injury of disease

Erythrocytes

• Anucleated
• Composed of 97% Hb which carries O2
• " Spectrin" gives RBC the flexibilty to change shape
• ATP is generated by cellular processes.

Hemoglobin Structure

• Quaternary structure
• Two alpha/beta globing that carry a heme bound to iron which delivers 4 oxygens at a tme.
• Hemoglobins are also carried bound to: Carbon Dioxide(CO2) NOT on heme group
• Hb has a high affinity to iron and wants to keep the delivered iron inside and available; not deliver.
• Hyperbatic Chambers counter act the negative aspect of hemoglobin on CO2 transport so O2 is delivered.
• Children 14-20 g/100mL
• Men 13-18 g/100mL
• Women 12-16 g/100mL
• Hypoxia; the kidney releases Erythropoietin; stimulates RBS to create RBC this improves blood Oxygen

Erythrocytes (RBCs)

• Biconcave shape for flexibility
• Anucleated: NO nuclease which = can't divide
• Function for about 100-120 days
• During bloodloss the body reabsorbs iron from the bilirubin molecules and reuses, therefore its toxic to have freely
• ABO Blood Groups
• A Glycoproteins + anti B antibodies =receive A/O can't receive B; agglutinates
• B Glycoproteins + anti A antibodies =receive B/O can't receive A; agglutinates
• A and B NO antibodies = receive A/B/O- is referred to as a " universal recipient" - does NOT agglutinate
• O NO gylcoproteins - Anti A and B bodies, therefore receives "O" also referred to as the " universal donor" therefore DO NOT agglutinates.
• If Rh diff in Mom & Dad (Rh- versus Rh+)
• Second baby is likely to be fatal
• " Erythroblastosis fetalis" Mom abs attak fetal cells second round of pregnancy

Lecture Quiz

• Renin converts what is secreted into circulation

• Glucagon, Epreniphrine, Cortisol, Growth Hormone

• All raise blood glucose levels

• Hypokalmeia, hypotensive, urine diluted; frwuent

• Are symptoms of Diabetes Insipidus

• Hyperglycemia, Hyerphagia, Ketoacidosisa, osmitc diuresis

• Symptoms of insulin resistance and deficiency

• Epinephrine (adreanal medulla), norephinephrine(symphatic pre ganglionic fiber.

• All lead to increase HR, increase in Blood Glucose, Metabolic Function increase .