Endocrine System Ref: Principles of Anatomy and Physiology, Tortora and Derickson, 14th Ed: 615-756.

Communications between cells Cells releasing Signaling molecules:- Hormones, Factors and Neurotransmitters released by specific cells and Acting by: - Endocrine signaling - Paracrine signaling - Autocrine signaling

(a) Endocrine signaling Blood vessel Response (a) Endocrine signaling Response (b) Paracrine signaling Figure 45.2 Intercellular communication by secreted molecules. Response (c) Autocrine signaling

Endocrine GLANDS are releasing Hormones

Exocrine (Glands with Duct system) vs Endocrine (Ductless glands) and their release Fig. 11-1

Endocrine Organs Purely endocrine organs Pituitary gland Pineal gland Thyroid gland Parathyroid glands Adrenal glands: Cortex Medulla Endocrine cells in other organs Pancreas Thymus Gonads Hypothalamus Kidney GI system

Table 45.1a Table 45.1 Major Human Endocrine Glands and Some of Their Hormones

Table 45.1b Table 45.1 Major Human Endocrine Glands and Some of Their Hormones

General characteristics of Endocrine signaling System of ductless glands that secrete hormones Hormones are “messenger molecules” Released into blood from endocrine structures Act on distant target cells Target cells respond to hormones for which they have specific receptors The effects on target cells are dependent on the induced responses. Hormones are just molecular triggers

Hormonal Receptors The ability of a cell to respond to a hormone depends upon the presence of receptors for that hormone: on (over plasma membrane)=Extracellular Receptors in (Inside) the target cell. (Intracellular Receptors).

Water- soluble hormone Lipid- soluble hormone SECRETORY CELL Water- soluble hormone Lipid- soluble hormone VIA BLOOD Transport protein Signal receptor TARGET CELL OR Signal receptor Figure 45.6 Receptor location varies with hormone type. Cytoplasmic response Gene regulation Cytoplasmic response Gene regulation NUCLEUS (a) (b)

General Control of Hormones - Metabolism - Growth and development - Red cell production - Reproduction - Adaptive changes like stress responses - Fluid-electrolyte balance - Acid-base balance - Energy balance

Effectiveness of a hormone Depends on: - Plasma Concentration: - Responsiveness of Target Cells.

Effectiveness of a hormone Depends on: - Plasma Concentration depends on: -Rate of secretion: control mechanisms: - Negative feed back - Neuro-Endocrine reflexes - Diurnal (Circadian) rhythm of secretion -Transport in plasma -Peripheral conversion -Inactivation -Excretion

Effectiveness of a hormone Depends on: - Responsiveness of Target Cells. - Depends on the Number of receptors: - An increase in the number of receptors for a hormone is called up-regulation. - A decrease in the number of receptors for a hormone is called down-regulation. - Concentration of other hormones:

Effectiveness of a hormone - Concentration of other hormones: - Permissiveness: Example: Thyroid hormones increases number of receptors for epinephrine over target cells - Antagonistic actions by other hormones: Example: Progesterone and estrogen effects over uterine smooth cells. (Progesterone reducing estrogen receptors) - Synergistic actions: Example FSH and Testosterone which are both needed to maintain sperm production by testis.

Permissive Actions of Hormones Fig. 11-9

Pituitary Gland

The Hypothalamus and Pituitary Gland Fig. 11-13

http://www.as.wvu.edu/~rbrundage/lecture2c/sld012.htm

Summary of Posterior Pituitary Hormones The posterior pituitary does not synthesize any hormones; it only secretes them. Oxytocin is involved in: Milk ejection reflex of nursing mothers and emotional bonding. - Contraction of uterus Antidiuretic hormone (ADH)(also called Vasopressin) is involved in regulation of: - Water balance and osmolarity. - Blood Pressure

Anterior pituitary gland Hormones Tropic effects: (FSH, LH, TSH, ACTH) Nontropic effects: (Prolactin, MSH). Tropic and Nontropic: (GH)

Anterior Pituitary Gland Hormones

Anterior Pituitary Hormones and the Hypothalamus Fig. 11-17

Anterior Pituitary Hormones Fig. 11-15

http://anatomyofthefoot. com/function-of-the-anterior-pituitary-gland http://anatomyofthefoot.com/function-of-the-anterior-pituitary-gland.html