Endocrine structure and function

Pituitary gland histology basophil

Blue for basophil

HORMONE secreted from PARAFOLLICULAR CELLS of THYROID GLAND

CALCITONIN

most important CORTICOSTEROID secreted by ZONA FASCICULATA CELLS of the ADRENAL CORTEX

CORTISOL

posterior pituitary (neurohypophysis)

Composed of the rounded lobe called the PARS NERVOSA and the INFUNDIBULUM which connects the posterior pituitary to the hypothalamus. (makes up one quarter of the pituitary gland) Contains axons and stores OXYTOCIN(OT) and ANTIDIURETIC HORMONE (ADH) and is released when a nerve signal is sent from the hypothalamus.

Adrenal Medulla

Medulla forms the inner core of the adrenal gland. Very vascular. Releases the catecholamines EPINEPHERINE and NOREPINEPHRINE (biogenic amines) in response to sympathetic nervous system. (75% of hormone released is epinephrine and 25% is norepinephrine) Prolong flight-or fight response caused by activation of the sympathetic division.

Pancreas histology Exocrine cells

Purple cells (more cuboidal)

Pituitary gland histology acidophil

Red

Thyroid gland histology follicle cavity

Spaces in between that are clear.

THYROID HORMONES secreted from FOLLICULAR CELLS

TRIIDODTHYRONINE(T3) and TETRAIODOTHYRONINE (T4)

Pituitary gland (hypophysis)

balls out by anterior of brain. Located in the sella turcica of the sphenoid bone.

Thyroid gland histology follicle cells

cuboidal cells

Thymus

Anterior to the heart on its superior aspect in mediastinum. Has maturing T-lymphocytes (Specific white blood cells) migrate to thymus after formation in bone marrow and secrete THYMIC HORMONES (THYMOSIN, THYMULIN, THYMOPOIETIN) which participate in maturation of T-lymphocytes.

Thyroid Gland

Anterior to trachea. Contains left and right lobes with a midline called the Isthmus. Histologically contains thyroid follicles, wall of each follicle has cuboidal epithelial cells called follicular cells that surround the central lumen. Lumen contains a viscous fluid called colloid. Thyroid releases the THYROID HORMONE(TH) which has two types, TRIIDODTHYRONINE(T3) and TETRAIODOTHYRONINE (T4), and CALCITONIN.

Hypothalamus

Attached to pituitary gland by a stalk (infundibulum).Has direct control over release of hormones of pituitary gland. Has indirect control over the release of hormones of thyroid gland, adrenal gland, liver, ovaries and testes.Synthesizes Oxytocin (OT) and antidiuretic Hormone (ADH) which is stored in posterior pituitary.

anterior pituitary (adenohypophysis)

Has three main parts. PARS DISTALIS(round portion of anterior pituitary),PARS INTERMEDIA (region between pars distalis and posterior pituitary), and PARS TUBERALIS (thin wrapping around the infundibulum). (makes up 75% of the pituitary gland) Secretes the THYROID-STIMULATING HORMONE (TSH), FOLLICLE STIMULATING HORMONE (FSH), PROLACTIN (PRL), LUTEINIZING HORMONE (LH), ADRENCORTICOTROPIC HORMONE (ACTH), and GROWTH HORMONE (GH).

Adrenal Cortex

Has yellow color due to stored lipids. SECRETES CORTICOSTEROIDS.Outside of adrenal gland. Zona glomerulosa (outer layer) synthesize mineralocorticoids that regulate electrolytes, main one is ALDOSTERONE (regulates Na and K). Zona fasciculate (middle layer) synthesize glucocorticoids CORTISOL and CORTICOSTERONE (increase nutrient levels in blood). Zona Reticularis (inner layer) releases gonadocorticoids ANDROGEN and ESTROGEN (sex hormones, androgen converted to estrogen in females)

Pancreatic Islets Histology

Lighter pink cells

Thyroid gland histology follicles

Lines of light purple

Pineal gland

Located at the posterior to epithalamus of the diencephalon. Secretes MELATONIN.

Ovaries

Located in female reproductive system. Produce reproductive egg and estrogen from androgen which has been converted.

Testes

Located in the male reproductive system. Produce sperm, androgens, and testosterone.

Parathyroid Gland

Located on posterior of the thyroid gland two dots on each side.Has two types of cells Chief cells and Oxyphil cells. Chief cells secrete PARATHYROID HORMONE(PTH):increase blood calcium levels.

Pancreas

Located posterior to the stomach between the small intestine and the kidney. Has both endocrine and exocrine functions. Endocrine portion contains pancreatic islets that have two primary types of cells, the ALPHA CELLS-that secrete GLUCAGON, and the BETA CELLS- that secrete INSULIN.

Pituitary gland histology chromophobe

No color

Pituitary gland histology

Notice anterior and posterior lobes

Adrenal glands

Paired pyramid shaped endocrine glands anchored on the superior surface of each kidney. Consists of the adrenal cortex and the adrenal medulla.

Thyroid gland histology colloid

Pink blob in center

Thyroid gland histology Parafollicular cells/C cells

White space in clusters between follicles

ADRENAL MEDULLA SECRETES

the hormones EPINEPHRINE and NOREPINEPHRINE