Chapter 20 Part A

Endocrine system

Communication through secretion of hormones

Hormones

Can only affect target cells or organs that have receptors for that specific hormone

Feedback loop

Hormone secretion that regulates by a self adjusting system

Negative feedback loop

-Maintains appropriate levels of hormones

-Get back to set point

-Ex. Sense too many growth hormone - need to dial back

Main type

Positive feedback loop

Ex. Oxytosin stimulates contractions

-Body pushes past the set point

-Ex. Puberty: All sorts of hormones secreted a lot

Endocrine system: Short term or long lasting?

Long lasting

Ex. Growth hormones (pretty permanent)

Hypothalamus

Major control center of the endocrine system (also controls the pituitary gland)

What does the hypothalamus secrete

Regulatory hormones that control the release of anterior pituitary hormones: releasing and inhibiting hormones

What specific things does the hypothalamus produce and what does it control

-Oxytocin and antiduretic hormone (ADH) (secreted by the pituitary)

-Controls the stimulation of the adrenal gland medulla

Infundibulum

Connects the pituitary and hypothalamus

Pituitary gland divided into what

Anterior and posterior lobes

Anterior pituitary gland

-Secretes many hormones

-Highly vascular

Tropic hormones

-Act on other structures

Ex. thyroid stimulating H → acts on thyroid

What hormones does the anterior pituitary secrete (7)

-Growth hormone (GH)

-Follicle stimulating hormone (FSH)

-Luteinizing hormone (LH)

-thyroid stimulating hormone (TSH)

-adrenocortioctropic hormone (ACTH)

-prolactin (PRL)

-Endorphins

• Morphine

Growth hormone

(anterior pituitary)

Promotes growth and development of tissues

Follicle stimulating hormone (FSH)

(anterior pituitary)

*tropic

acts on the ovaries and testes

-assists with production of sperm and eggs

Luteinizing hormone

(anterior pituitary)

*tropic

-stimulates sex h production

-estrogen

-testosterone

thyroid stimulating hormone

(anterior pituitary)

*tropic

-stimulates the thyroid to secrete its h’s

adrenocorticotropic hormone (ACTH)

*tropic

-acts on the adrenocortex to secrete its h’s

Prolactin (PRL)

Stimulates milk production in mammals

Endorphins

Body’s natural pain killers (Impulses in the brain tell us we are in pain → block pain receptors)

• Morphine (Synthetic endorphin that blocks pain receptors

Pituitary dwarfism

Hyposecretion of GH during childhood

Proportional

Occurs when growth plates are open

Gigantism

Hypersecretion of GH during childhood

Proportional

Occurs when the growth plates are open

Acromegaly

Hypersecretion of GH during adulthood

-plates closed

-still have GH

-GH goes to face, hands, and feet

Posterior pituitary gland (and two mentioned hormones)

Hormones synthesized in the hypothalamus stored in the post pituitary gland

Ex. antidiuretic hormone (ADH)/ vasopressin: reduces fluid loss via urine

-Oxytocin: Stimulates contraction of the uterus during childbirth

Synthetic oxytocin

Pitocin - speeds up childbirth