Endocrine Endocrine Function Influences growth metabolism and homeostasis

Endocrine

Endocrine Function ● ● ● Influences growth, metabolism, and homeostasis over prolonged periods Secretes hormone products into interstitial spaces which are then absorbed into the blood and transported throughout the body Hormonal control is much slower than nervous control, but the effects of the endocrine system are much longer lasting Key Features of Endocrine Glands ● ● ● A rich capillary blood supply is necessary for secretion and reception of hormones Endocrine glands are, by definition, ductless Organelles required to synthesize specific hormones are in great supply

Hormone Classifications Amino Acid Derivatives ● Hormones derived from the amino acid tyrosine ● Epinephrine, norepinephrine, and thyroxine Polypeptide Hormones ● Hormones with a peptide structure ● Insulin, prolactin, NGF, EGF, GH, PTH, TSH, enkephalin, TRH, ADH Steroids ● Hormones derived from cholesterol ● Testosterone, cortisol, aldosterone, progesterone, estradiol

Pituitary Gland ● Controlled by hypothalamus ● Infundibulum serves as a communication channel between the hypothalamus and pituitary ● The hypothalamohypophyseal neural tract is the passageway for two hypothalamic hormones to the posterior pituitary ● The hypothalamohypophyseal portal system carries hypothalamic hormones that regulate secretion from the anterior pituitary ● The anterior pituitary secretes hormones that regulate lactation, metabolism, growth, stress response, and reproduction

Pituitary Gland A: Adenohypophysis (anterior pituitary): 1. Pars distalis. 2. Pars intermedia 3. Pars tuberalis B: Neurohypophysis (posterior pituitary): 1. Infundibulum 2. Pars nervosa A B

A E D B C

Practice

Adenohypophysis A: Chromophobes B: Basophilic chromophils Gonadotrophs– FSH and LH Corticotrophs– ACTH Thyrotrophs– TSH C: Acidophilic chromophils Somatotrophs– GH Mammotrophs– Prolactin

B C A

Practice

Neurohypophysis A: Pituicytes H: Herring Bodies A

Review Fill in the missing hormones secreted from the pituitary or list their respective functions Hormone Function FSH Follicle maturation and spermatogenesis LH Causes follicle maturation and testosterone production in leydig cells ACTH Stimulates adrenal cortex TSH Stimulates T 3 and T 4 secretion from thyroid GH Controls growth Prolactin Stimulates mammary glands ADH Stimulates water resorption Oxytocin Smooth muscle contraction and milk letdown

Thyroid 4 B A: Follicular cells B: Parafollicular cells A

Parathyroid A: Adipose tissue. C: Capillaries P: Principal or chief cells O: Oxyphil cells

B A

Practice

A B

Pancreas A: Islets of Langerhans contain four different cells: 1. α-cells 2. β-cells 3. δ-cells. 4. PP– cells A

Stomach Gastrin or G-cells A: Parietal cell. B: Chief cell. A B

Adrenal Gland A A: Zona glomerulosa B: Zona fasciculata C: Zona reticularis D: Medulla B C D

Practice

Clinical Connections

Pheochromocytoma • Neuroendocrine tumor of the adrenal medulla • Results in excessive secretion of catecholamines • Diagnosed by measuring plasma or urine levels of catecholamines Source: http: //en. wikipedia. org/wiki/Pheochromocytoma

Enteroendocrine Cell A: Argentaffin cells A B: Central Lacteal B

Practice

Review Know the following hormones, where they are secreted, their function, and target organ. Anterior Pituitary FSH LH ACTH TSH GH Prolactin Posterior Pituitary ADH Oxytocin Thyroid T 3 and T 4 Calcitonin Parathyroid PTH Pancreas Glucagon Insulin Somatostatin Pancreatic Peptide Stomach Gastrin Adrenal Aldosterone Cortisol DHEA Argentaffin Cell CCK Secretin Serotonin