Ch 17 Learning Objectives

Endocrine System

17.1.1 Describe the general features of the endocrine system, including how hormones are transported between an endocrine gland and its target cells.

system of endocrine glands located throughout the body to secrete hormones

• hormones are released into interstitial fluid (endocrine glands have no ducts), then enter capillaries & travel through blood to issues

• target cell: cell that have specific receptors for a hormone

• once a hormone binds, it can activate/inhibit cellular activities

17.1.2 Compare and contrast the actions of the endocrine system and the nervous system to control body function.

Endocrine: secrete hormones & are transported in blood to target cells

• slower response time (minutes to hours)

• widespread effects

Nervous: neurotransmitter is released from a neuron into a synaptic cleft

• rapid response time (miliseconds/seconds)

• localized effects

17.1.3 Describe the general functions controlled by the endocrine system.

• regulating development, growth, & metabolism

• maintaining blood composition & volume

• controlling digestive processes

• controlling reproductive activities

17.2.4 List the major endocrine glands and their location within the body.

head: pituitary gland, pineal gland

neck: thyroid gland, parathyroid gland

torso: adrenal glands

17.2.5 Explain the three reflex mechanisms for regulating secretion of hormones.

hormonal stimulation: release of hormone triggering release of different hormone

• TSH binding to thyroid gland to release TH

humoral stimulation: changes in level of nutrients to release hormones

• blood glucose increase = release of insulin

nervous system stimulation: stimulation by the nervous system causing release of hormone

• release of epinephrine & norepinephrine due to autonomic nervous system

17.3.6 Name the three structural categories of circulating hormones, and give examples within each category

sterioids: lipid soluble made from cholestrol

• includes both hormones produced within gonads & adrenal cortex

• hormones that end with a “sterone” (testosterone, progesterone)

biogenic amines: modified amino acids

• includes the catecholamines (epinephrine, norepinephrine) released from adrenal medulla, TH from thyroid, melatonin from pineal gland

proteins: molecules composed of small chains of amino acids

• include small peptides, large polypeptides, & glycoproteins

• water soluable

17.3.7 Distinguish the hormones that are lipid-soluble from those that are water-soluble.

lipid soluble: steroids, calcitrol, thyroid hormone

• were nonpolar & didn’t dissolve well in blood

• must travel with transport proteins

water soluble: includes most biogenic amines & protein hormones

• dissolve easily in blood plasma

• don’t need transport protein

17.3.8 Describe the general structure, formation, and function of local hormones.

local hormones: large group of short lived signaling molecules that don’t circulate within blood

• act close to where they are made

• usually produced by many different tissues

elcosanoids: formed from fatty acid (released from membrane phospholipids)

• prostaglandins, thromboxanes, leukotrienes

17.3.9 Compare autocrine and paracrine signaling that occurs through local hormones.

utocrine stimulation: cells make & release these molecules which bind to the same cell that produced them

• signal feeds back to the original cell

paracrine stimulation: released molecule diffuses to nearby cells & affects them instead

17.4.10 Compare the transport of lipid-soluble hormones with that of water-soluble hormones.

Lipid-soluble: (steroids, calcitriol, thyroid hormone) nonpolar molecules

• don’t dissolve within aqueous environment of blood

• require transport protein

• protects hormone molecule (prevent destruction)

  • prolongs half life

• bound hormone: any hormone that is attached to a transport protein

• unbound (free) hormone: unattached hormone

Water-soluble: (biogenic amines & proteins) dissolve within blood

• don’t require transport proteins

• released directly into blood & transported to target cells

17.4.11 Describe the two primary factors that affect the concentration level of a circulating hormone.

hormone release: releases from an endocrine gland & hormone concentration within the blood are positively correclated

• increase in release of hormone results in higher hormone concentration in blood

• decrease in release of hormone results in lower hormone conc. in blood

hormone elimination:

1. through enzymatic degration (usually in liver cells)

2. removal of the hormone from the blood by excretion from the kidneys as a component of urine

3. uptake into target cells

• hormone elimination & conc. in blood are negatively correlated

• the faster the elimination, the lower hormone conc. in blood, vise versa

maintained through neg. feedback

17.4.12 Explain what is meant by the half-life of a hormone.

biological half life: amount of time necessary to reduce the hormone concentration within blood to half of what was the original

• water soluble hormones have shorter half life

• steroids have longest half life

the shorter the half life of a hormone, the more frequently it needs to be replaced to maintain its concent. in blood

17.5.13 Describe how lipid-soluble hormones reach their target cell receptors and the type of cellular change they initiate.

lipid soluble hormones (steroids, calcitriol) are small & nonpolar

• they can pass directly through the plasma membrane by simple diffusion

• once inside the target cell, they bind to receptors in cytosol/nucleus & form a hormone receptor complex

• this complex activates specific regions of DNA which leads to new proteins being made

17.5.14 Describe how water-soluble hormones induce cellular change in their target cells

water soluble hormones cannot pass through plasma membrane becasue they are polar

• they bind to receptors on cell surface

• this binding starts a signaling chain inside the cell: the hormone acts as the first messenger, activates G protein, & triggers formation of second messenger through enzyme cascade

  • this internal signal then changes cell activity such as enzyme action, secretion, ion movement, growth, or muscle contraction

17.6.15 Describe the conditions that influence the number of receptors available for a specific hormone

up- regulation: when hormone levels are low, target cells increase # of receptors to become more sensitive to the hormone

down- regulation: when hormone levels are high, target cells decrease # of receptors to reduce sensitivity

hormone exposure: long term exposure to a hormone can cause cells to reduce their #

17.6.16 Compare and contrast up-regulation and down-regulation.

ways for cells to adjust how strongly they respond to a hormone

up- regulation: when hormone levels are low, target cells increase # of receptors to become more sensitive to the hormone

down- regulation: when hormone levels are high, target cells decrease # of receptors to reduce sensitivity

17.6.17 Compare and contrast the three types of hormone interactions.

synergistic interaction: occurs when activity of one hormone reinforces the activity of another hormone

permissive interaction: takes place when the activity of one hormone requires a second hormone

antagonistic interaction: occurs when the activity of one hormone opposes the effects of another hormone

17.7.18 Explain the anatomic relationship between the hypothalamus and the pituitary gland.

hypothalamus sits above pituitary gland & connected by the infundibulum

• posterior pitituary gland is connected to hypothalamus by nerve fibers

  • it stores & releases hormones made by hypothalamus

• anterior pituitary is connected by a blood vessel system

  • carries hypothalamic hormones that control whether it releases or inhibits its own hormones

17.7.19 Describe the specific structures associated with the posterior pituitary and the anterior pituitary.

posterior pititiuary: neural part of gland,

• 10k neurons extend from hypothalamus to posterior pit.

  • contain supraoptic nulcleus & paraventricular nucleus

• releases antidiuretic hormone (ADH) & oxytocin

anterior pituitary: glandular part

• connects to hypothalamus by portal veins; primary plexus, secondary plexus; called the hypophyseal portal system

  • delivers hypothalamic signals to endocrine cells

17.7.20 Explain how the hypothalamus regulates the release of the two hormones from the posterior pituitary gland, and describe the general functions of each

hypothalamus controls posterior pit. by making hormones first

• supraoptic nucleus makes ADH

• paraventricular nucleus makes oxytocin

hormones are then sent down through hypothalamo hypophyseal tract to posterior pit.

ADH: helps conserve water by reducing urine output

Oxytocin: supports uterine contractions & milk ejection

17.7.21 List the hormones released from the hypothalamus that control the anterior pituitary.

TRH — Thyrotropin-releasing hormone → stimulates TSH

CRH — Corticotropin-releasing hormone → stimulates ACTH

GnRH — Gonadotropin-releasing hormone → stimulates FSH & LH

GHRH — Growth hormone-releasing hormone → stimulates GH

GHIH (somatostatin) — inhibits GH

PIH (dopamine) — inhibits prolactin

17.7.22 Explain how the hypothalamus controls the release of hormones from the anterior pituitary and the general function of each

hypothalamus controls anterior pit. by releasing hormones into to stimulate or inhibit hormone release

17.7.23 Explain how the release of growth hormone is regulated.

17.7.24 Describe the effects of growth hormone on its primary target organs.

17.8.25 Identify and describe thyroid gland location and anatomy.

17.8.26 List the two specific types of endocrine cells within the thyroid and the specific hormone produced by each.

17.8.27 Explain the homeostatic system involving thyroid hormone.

17.8.28 Explain the role of calcitonin in regulating blood calcium.

17.9.29 Describe the structure and location of the adrenal glands.

17.9.30 Name the three zones of the adrenal cortex and the hormones produced in each zone.

17.9.31 Describe the homeostatic system involving cortisol.

17.10.32 Identify and describe the gross anatomy and cellular structure of the pancreas.

17.10.33 Compare and contrast the primary types of pancreatic islet cells and the hormones they produce.

17.9.34 Describe the action of insulin in lowering blood glucose concentration.

17.9.35 Explain the action of glucagon in raising blood glucose concentration.

17.11.36 Describe the general structure, location, and function of the pineal gland.

17.11.37 Describe the general structure, location, and function of the parathyroid glands

17.11.38 Identify and provide a description of the general function of the hormone(s) released from each of the organs discussed in this section.

17.12.39 Describe how endocrine activity changes as people age.