Exam 1 A&P II

Hormones

•Signaling molecules secreted into bloodstream

•Travel to nearby and distant cells

•Part of Endocrine system

•Different than paracrine factors and neurotransmitters, which travel through extracellular fluid (ECF) to nearby cells

Endocrine system definition

glands, tissues, and cells that secrete hormones

What are the 9 “classic” endocrine glands?

• hypothalamus

• pituitary gland

• pineal gland

• thyroid gland

• parathyroid glands

• thymus

• adrenal gland

• pancreas

• gonads

  • ovaries

  • testes

Is the nervous system a fast or slow response compared to the endocrine system?

• fast (basically instant; ms)

• also quick to stop

Is the endocrine system a fast or slow response compared to the nervous system?

• slow (seconds-days)

• persistent effect (being slow allows persistence)

What is the adaptation to long-term stimuli for the endocrine vs nervous system?

• nervous: adapts quickly (will get used to stimuli)

• endocrine: adapts very slowly (can take years to months)

What is the area of effect for the endocrine vs nervous system?

• nervous: targeted/specific (must directly innervate cells)

• endocrine: some hormones are very general and some are more specific

Exocrine gland properties

• not for intercellular communication

• secrete substances through ducts (secrete things not used for cellular communication)

• Ducts

• secretions produce extracellular effects

What are ducts in exocrine glands?

• tubes that deliver secretions to either

  • an epithelial surface

  • The mucosa of digestive tract

What types of secretions produce extracellular effects?

•Sweat (cools down the body)

•Saliva (moistens food)

•Digestive enzymes

•Mucus

Endocrine gland properties

•For intercellular communication

•Produce hormones that cause intracellular changes to target cells

•No ducts

•Penetrated by capillaries- hormones secreted into them

Endocrine vs. Exocrine vs. Nervous

•Intercellular communication

•Slow, long-lasting

•Secretes into bloodstream

Endocrine vs. Exocrine vs. Nervous

•Not for intercellular communication

•Causes extracellular effects

•Secretes into duct

Endocrine vs. Exocrine vs. Nervous

•Intercellular communication

•Fast, short effects

•Secretes into synaptic cleft

Hormone Secretion properties

• Hormones are not synthesized and secreted at constant rates

• Rhythmic secretions

  • Circadian rhythm- daily cycles

  • Monthly cycles

• Stimuli (tells endocrine gland to secrete)

  • Neural

  • Hormonal

  • Humoral

What is neural stimuli for hormone secretion?

• Nerve signals to endocrine glands

Ex: sympathetic stimulation of adrenal medulla (ANS)

What is hormonal stimuli for hormone secretion?

• Hormones from another source stimulate secretion (another endocrine gland)

Ex: Hypothalamus hormones stimulate anterior pituitary

What is humoral stimuli for hormone secretion?

• Blood levels of substances (other than hormones) stimulate hormone secretion

Ex: high blood glucose

What are the three classes of hormones?

• Steroids

• Monoamines

• Peptides

Steroid hormones are derived from what?

fat (cholesterol)

Monoamine hormones are derived from what?

one amino acid

Peptide hormones are derived from what?

multiple amino acids

Monoamine and Peptide Hormone Transport Properties

• hydrophilic (loves water)

• travel in blood plasma (mostly H2O)

Steroid Hormone Transport Properties

• Hydrophobic

• bind to transport proteins like albumin (blood plasma protein) to travel through blood

What is a hormone receptor?

A receptor on or in target cells that hormones bind in order to affect cells

Hormone receptor properties

• specificity

• sensitivity

• by type of hormone

What does specificity mean for hormone receptors?

Hormones only affect cells that have the correct receptor for that hormone

Why can one hormone affect some cells but not others?

Only target cells with matching receptors respond.

What does sensitivity mean in hormone signaling?

How strongly a target cell responds to a hormone. More receptors/sensitivity = stronger response.

What happens after long-term exposure (months/years) to high hormone levels?

Cells make fewer receptors, so they become less sensitive.

Where do different hormone types bind?

• Peptide and monoamine hormones bind to membrane receptors

• steroid (hydrophobic but lipidphilic) hormones bind to intracellular receptors inside the cell/nucleus (go thru plasma membrane into cell)

What is signal amplification in hormone action?

A small hormone signal can produce a much larger effect inside the cell.

Why are hormones considered very potent?

One hormone (monoamine/peptide) can activate many second messengers or enzymes, creating a strong response. Or, it can directly affect gene transcription (steroids)

How do steroid hormones usually create effects?

They directly affect gene transcription inside the cell, so they do not need second messengers.

How do peptide and monoamine hormones usually create effects?

They bind to receptors and activate second messengers, like cAMP and protein kinase.

True or False? Most cells have receptors for multiple hormones

True

What are synergistic hormone effects?

When multiple hormones work together to increase an effect.

Ex: FSH and testosterone help sperm production.

What are permissive hormone effects?

One hormone enhances/allows a cell’s response to another hormone

Ex: estrogen gives cells of uterus permission to respond to progesterone

What are antagonistic hormone effects?

Hormones have opposite effects on a cell

Ex: insulin and glucagon

Why are hormones cleared from the body?

the effects of the hormone eventually need to stop

How are hormones cleared from the body?

• They are degraded by the liver and kidneys

• Metabolic clearance rate (MCR)

How are hormones cleared by the liver and kidneys?

• Liver: excretes broken-down hormones into bile

• Kidney: excretes broken-down hormones into urine

What is the metabolic clearance rate?

• Rate hormone is removed from blood

• Faster MCR, faster the hormone is cleared

What makes up the cardiovascular system?

heart and blood vessels

What makes up the circulatory system (umbrella term)?

heart, blood vessels, and blood

Why is the circulatory system the umbrella term?

It includes what circulates through the body (blood)

What are the two circuits of the circulatory system?

pulmonary circuit and systemic circuit

What does the pulmonary circuit do?

brings blood to the lungs to get O2

What side of the heart does deoxygenated blood get pumped into pulmonary arteries?

right

What side of the heart does oxygenated blood get pumped into via pulmonary veins?

left

What is an artery?

A blood vessel that brings blood away from the heart

What is a vein?

A blood vessel that pumps blood into the heart

What does the systemic circuit do?

It delivers oxygenated blood to the rest of the body by systemic arteries

In the systemic circuit what side of the heart is oxygenated blood pumped?

left via systemic artieries

In the systemic circuit what side of the heart is deoxygenated blood pumped?

right via systemic veins

Where is the hypothalamus located?

Inferior to the thalamus.

What does the hypothalamus do?

Directs the pituitary gland.

What is another name for the pituitary gland?

Hypophysis.

What connects the pituitary gland to the hypothalamus?

The infundibular stalk also called the infundibulum.

Why is the pituitary called the master gland?

It controls other endocrine glands.

What are the two parts of the pituitary gland?

Anterior pituitary and posterior pituitary.

How big is the pituitary gland?

¾ AP and ¼ PP

What is another name for the anterior pituitary?

Adenohypophysis.

What is the anterior pituitary made of?

Glandular tissue.

How does the hypothalamus communicate with the anterior pituitary?

via the hypophysial portal system.

What is the hypophysial portal system?

Blood vessels that link the hypothalamus to the anterior pituitary.

What is another name for the posterior pituitary?

Neurohypophysis.

What is the posterior pituitary made of?

Nervous tissue.

How does the hypothalamus communicate with the posterior pituitary?

hormones travel through axons from the hypothalamus to the posterior pituitary where they are released.

Gonadotropin hormones: What does FSH stand for?

Follicle-Stimulating Hormone.

What does FSH do in females?

Stimulates ovarian follicle development.

What does FSH do in males?

Stimulates sperm production.

Gonadotropin hormone: What does LH stand for?

Luteinizing Hormone.

What does LH do in females?

Stimulates ovulation and formation of the corpus luteum.

What does LH do in males?

Stimulates testosterone secretion from the testes.

What does TSH stand for?

Thyroid-Stimulating Hormone.

What does TSH do?

Stimulates the thyroid to secrete thyroid hormone.

What does ACTH stand for?

Adrenocorticotropic Hormone.

What does ACTH do?

Stimulates the adrenal cortex to secrete glucocorticoids like cortisol.

What does PRL stand for?

Prolactin.

What does PRL do?

Stimulates the mammary glands to make milk.

What does GH stand for?

Growth Hormone.

What does GH do?

Causes growth in many tissues and organs and stimulates mitosis and cellular differentiation to make mature cells.

What does TRH stand for?

Thyrotropin-Releasing Hormone.

What does TRH do?

Causes the release of TSH and PRL.

What does CRH stand for?

Corticotrophin-Releasing Hormone.

What does CRH do?

Causes the release of ACTH.

What does GnRH stand for?

Gonadotropin-Releasing Hormone.

What does GnRH do?

Causes the release of FSH and LH.

What does GHRH stand for?

Growth Hormone-Releasing Hormone.

What does GHRH do?

Causes the release of growth hormone.

What does PIH stand for?

Prolactin-Inhibiting Hormone.

What does PIH do?

Inhibits the release of prolactin.

What does somatostatin do?

Inhibits the release of growth hormone.

What does OT stand for?

Oxytocin.

What does oxytocin do?

Promotes emotional bonding and stimulates uterine contractions during childbirth.

what is another name for OT (oxytocin)?

love or attachment hormone

True or false: oxytocin is not a positive feedback loop

False

What does ADH stand for?

Antidiuretic Hormone.

What is another name for ADH?

Vasopressin.