Anatomy Lecture 21- Pituitary and Pineal Glands

What are the types of hormones?

1) Small peptides, polypeptides, proteins: (ex: vasopressin, insulin), dissolve in blood Hydrophilic: Cell surface receptor; second messengers alter the cell’s metabolism and produce hormone specific responses

What is the difference between transport of hydrophillic and hydrophobic hormones?

Hydrophillic can travel in the blood and have a cell surface receptor (ex: small peptides, polypeptides, proteins, amino acids). Hydrophobic need a carrier protein in blood but easily enter the cell (ex: steroids).

What are the types of hormonal control menchanisms?

Endocrine- reaches cells by movement through bloodstream (slow). Paracrine- goes to neighboring cells. Autocrine- goes to own cell.

What is the function of the pituitary gland?

1) Hormones from the hypothalamus travel via the hypophyseal portal system 2) causes endocrine cells in the anterior pituitary to release other hormones 3) travels in bloodstream to other tissues

What are the parts of the pituitary gland?

Pars nervosa/posterior/neurohypophysis- stores hormones made in hypothalamus (neural). Pars distalis/anterior/adenohypophysis- makes its own hormones, wraps around pars nervosa (infundibulum/pituitary stalk)(developed from ectodermal tissue).

What groups of hormones are secreted from the pituitary?

Hormones that act on non-endocrine tissues (GH and prolactin) and those that act on other endocrine glands (ACTH).

What is the histology of pars intermedia?

Has follicles known as Rathke’s cysts. (if too large can push on optic nerve causing vision problems)(produces melanocytes stimulating hormones)

What is the histology of pars distalis?

Basophils (purple body)- thyrotrophs (TSH), gonadotrophs (FSH and LH), corticotrophs (ACTH). Acidophils (hot pink body)- somatotrophs (GH), mammotrophs (PRL). Chromophobes- unstained cytoplasm undifferentiated cells.

What hormones are involved in cortisol regulation?

CRH (corticotropic releasing hormone) from hypothalamus, ACTH from (adrenocorticotropic hormone) anterior pituitary. Regulates glucocorticoid from the adrenal cortex, stress has a stimulating effect.

What disease is caused by excessive cortisol? What can cause this?

Cushing’s syndrome. Excess cortisol-like medication, tumor.

What hormones are involved in the thyroid?

TRH (thyroid releasing formone) from hypothalamus, TSH (thyroid stimulating hormone) from anterior pituitary, T3 (triiodothyroxine) and T4 (thyroxine) from thyroid.

What causes hyper or hypothyroidism? Which can cause swelling of the thyroid gland?

High or lo T3 and T4. Hyperthyroidism causes Goiter.

What hormones are involved in the gonads?

GnRH (gonadotropic releasing hormone) from hypothalamus, FSH (follicle stimulating hormone) and LH (lutenizing hormone) from anterior pituitary (single gonadotroph can release both).

What is the difference in FSH and LH function in females and males?

FSH causes production of eggs by the ovaries in females and production of sperm cells in males. LH causes ovulation, development of corpus luteum, and estrogen production in females and stimulates testes to produce testosterone in males.

What hormones are involved in growth?

GHRH (growth hormone releasing hormone) from hypothalamus, GH (growth hormone) from anterior pituitary.

What is the function of GH?

Increases the use of glucose in muscles and bone, decreases use of glucose by non growing cells. Stimulates liver cells to release triglycerides into blood and release IGF-1 (insulin growth factor), whcih stimulates the growth of long bones and soft tissue by stimulating chondrocytes.

What are GH disorders in childhood and adulthood?

During childhood- gigantism and dwarfism. Adulthood- acromegaly.

What hormones are involved in milk synthesis?

PIH (prolactin inhibiting hormone) from hypothalamus, prolactin from anterior pituitary. Secretion is caused by inhibition of PIH. Suckling during lactation is stimulus for prolactin secretion.

What is the histology of pars nervosa?

Unmyelinated axons make up the infundibulum, pituicytes (large and pale) are glial cells (light purple nucleus) (axonal health), fenestrated capillaries make up the capillary plexus of the pars nervosa, herring bodies are neurosecretory terminals (temporary storage of hormones).

What hormones are stored in and released from the posterior pituitary?

ADH and oxytocin.

What is the function of ADH?

Produced in the supraoptic nucleus, stored in herring bodies. Stimutated by low H2O, causes increased permeability of collecting ducts and increases blood pressure by constricting blood vessels.

What is the function of oxytocin?

Produced in paraventricular nucleus, stored in herring bodies. Released during child birth, causes contraction of smooth muscles in uterus and stimulates milk ejection.

How is the pineal gland developed? Where is it located? What is the histology? WHat does it do?

Roof of posterior diencephalon. Posterior end of corpus callosum. Pinealocytes are neuron-like (kinda large light purple nucleus), interstitial cells are glial-like (small dark purple). Modulates sleep patterns and seasonal cycles.

What hormones are involved in the circadian rhythms?

5-HT (serotonin) production is stimulated by light and produced by Raphe neclei in the brain stem. Melatonin production is stimulated in dark and produced by the pineal gland.

How does the circadian rhythm check its accuracy?

Exposure to sunlight leads to retinal ganglion cell and melanopsin (light sensitive pigment) stimulation. This sends light-dark signals to the SCN (superchiasmatic nucleus) which inhibits melatonin production.

What causes calcification of the pineal gland? What is it called? What can it cause?

Salts like calcium and magnesium phosphate. Fluoride causes phosphate crystals. Brain sand- microcrystals or corpora arenacea- concentric lamellate. Decreases number of functioning pinealocytes and melanin production.