ENDOCRINE SYSTEMENDOCRINE SYSTEM Works more slowly than nervous Works more slowly than nervous

system, releasing hormones into system, releasing hormones into the blood that can control virtually the blood that can control virtually all body cellsall body cells

Works with nervous system to Works with nervous system to coordinate functions of all body coordinate functions of all body systemssystems

Function of HormonesFunction of Hormones Help regulate:Help regulate:

Chemical compositions and volume of Chemical compositions and volume of internal environment (interstitial fluid)internal environment (interstitial fluid)

Metabolism and energy balanceMetabolism and energy balance Contraction of smooth and cardiac muscle Contraction of smooth and cardiac muscle

fibersfibers Some immune system activitiesSome immune system activities

Control growth and developmentControl growth and development Regulate operation of reproductive Regulate operation of reproductive

systemsystem Help establish circadian rhythmsHelp establish circadian rhythms

Endocrine glandsEndocrine glands Do not secrete products into ducts like Do not secrete products into ducts like

exocrine glands exocrine glands Secrete their products (hormones) into Secrete their products (hormones) into

the interstitial fluid surrounding the the interstitial fluid surrounding the secretory cells, then diffuse from blood secretory cells, then diffuse from blood into the interstitial fluid where they into the interstitial fluid where they interact with their target cellsinteract with their target cells

Include pituitary, thyroid, parathyroid, Include pituitary, thyroid, parathyroid, adrenal, and pineal glandsadrenal, and pineal glands

HypothalamusHypothalamusControl Center for Control Center for

internal environmentinternal environment

Regulates nervous and endocrine systems via 3 mechanisms:1. Direct neural control over adrenal medulla

2. ADH and Oxytocin production3. Regulatory hormone production (RH and

IH) controls pituitary gland directly and all other endocrine glands indirectly

Pineal glandPineal gland small endocrine gland in the brainsmall endocrine gland in the brain

shaped like a tiny pine coneshaped like a tiny pine cone located near the center of the brain, located near the center of the brain,

between the two hemispheresbetween the two hemispheres produces melatonin, a hormone that produces melatonin, a hormone that

may weakly modulate wake/sleep may weakly modulate wake/sleep patterns. patterns.

Pituitary Gland (= Pituitary Gland (= Hypophysis)Hypophysis)

Gross Anatomy:Gross Anatomy: Infundibulum Infundibulum adenohypophysis (anterior) adenohypophysis (anterior) neurohypophysis neurohypophysis (posterior) (posterior)

Posterior:Posterior: Storage shed for Storage shed for ADH and oxytocin both ADH and oxytocin both produced in hypothalamusproduced in hypothalamus

Anterior:Anterior:7 peptide hormones7 peptide hormones

Hypophyseal Portal System Hypophyseal Portal System Portal system:Portal system:

two capillary networks two capillary networks in serial arrangementin serial arrangement

Named after their Named after their destinationdestination

Portal veins:Portal veins: blood blood vessels that link two vessels that link two capillary networkscapillary networks

Thyroid GlandThyroid Gland Anterior surface of trachea Anterior surface of trachea

just inferior of thyroid just inferior of thyroid cartilage (or Adam’s apple)cartilage (or Adam’s apple)

Two lobes connected by Two lobes connected by isthmusisthmus

Thyroid folliclesThyroid follicles and thyroid and thyroid hormonehormone

C cellsC cells and Calcitonin and Calcitonin

Four Parathyroid Four Parathyroid GlandsGlands

Located on posterior surface of thyroid Located on posterior surface of thyroid (superior and inferior) (superior and inferior)

Parathyroid Parathyroid hormone (PTH) hormone (PTH)

Function: Function: antagonist antagonist to Calcitonin. to Calcitonin.

Thymus GlandThymus Gland Inside thoracic

cavity immediately posterior to sternum

Largest just before puberty

Thymosin (important for immune system)

Adrenal or Suprarenal Adrenal or Suprarenal GlandGland

Cortex:Cortex: corticosteroid production aldosterone, cortisol, sex hormonealdosterone, cortisol, sex hormone

Medulla: modified sympathetic Medulla: modified sympathetic ganglionganglion adrenaline and adrenaline and noradrenaline noradrenaline

Pancreas Part of endocrine and Part of endocrine and digestive systems. digestive systems. (99% exocrine)(99% exocrine) Pancreatic islets Pancreatic islets or islets of Langerhansor islets of Langerhans

cells: glucagon cells: glucagon (stimulates liver to convert glycogen to glucose)

cells: insulin cells: insulin (promotes movement of glucose through cell membrane)

cells: somatostatincells: somatostatin