Chapter 18 Endocrine System

What three zones make up the adrenal cortex, and what kind of hormones does each zone produce?

-Zona glomerulosa: mineralocorticoid----zona fasciculata: glucocorticoids ----------zona reticularis: androgens

The Exhaustion Phase

1. Homeostatic regulations break down 2. Without immediate corrective action, failure of one or more organ systems; will be fatal 3. Mineral imbalances contribute to problems with major systems 4.Inability to sustain the endocrine & metabolic adjustments of the resistance phase will cause death

Characteristics of The Alarm Phase:

1. increased mental alertness 2. increased energy consumption 3. mobilization of energy reserves (glycogen and lipids) 4. changes in circulation: increased blood flow to skeletal muscles, decreased blood flow to the skin, kidneys, and digestive organs 5. drastic reduction in digestion and urine production 6. increased sweat gland secretion 7. increases in blood pressure, heart rate, and respiratory rate

How do hormones work?

Coordinate cell, tissue, and organ activities on a long term basis; they circulate in the extracellular fluid and bind to specific receptors on or in target cells; they then modify cellular activities by altering membrane permeability, activating or inactivating key enzymes, or changing genetic activity.

In what ways can a hormone modify the activities of its target cells?

Direct the synthesis of an enzyme (or other protein) not already present in the cytoplasm; run an existing enzyme "on" or "off"; and increase the rate of systhess of a particular enzyme of other portion.

Which two hormones are released by the kidneys, and what is the importance of each hormone?

Erythropoietin, which stimulates the production of RBCs by the red bone marrow, and calcitriol which stimulates calcium and phosphate absorption along the digestive tract.

The Resistance Phase

If a stress lasts longer than a few hours, the individual enters the resistance phase of the GAS. Making energy demands higher; The body's lipid reserves are sufficient to maintain the in this phase for weeks or even months. •Glucocorticoids (cortisol) are the dominant hormones.

What is an endocrine reflex? Compare endocrine reflexes and neural reflexes.

In endocrine reflexes-the functional counterpart of neural reflexes;a stimulus triggers the production of hormone both neural and endocrine reflexes are typically controlled by neg feedback mechanisms.

How would blocking the activity of phosphodiesterase (POE) affect a cell that responds to hormonal stimulation by the cAMP second-messenger system?

Inactivation of phosphodiesterase PDE which converts cAMP to AMP, would prolong the effect of the hormone.

What five primary effects result form the action of thyroid hormones?

Increased rate of energy consumption and utilization in cells; accelerated production of sodium-potassium ATPase; activation of genes coding for the synthesis of enzymes involved in glycolysis and energy production; accelerated ATP production by mitochondria and in growing children, normal development of skeletal, muscular and nervous system.

All of the following are true of the endocrine system, except that it

Produces rapid, local brief-duration responses to specific stimuli.

What are the four opposing effects of natriuretic peptides and angiotensin II?

Promote the loss of sodium ions and water at the kidneys; inhibit the secretion of water-conserving hormones such as ADH and aldosterone; suppress thirst; and blocks the effects of angiotensin II and norepinephrine on arterioles. Angiotensin II opposes these actions by stimulating aldosterone secretion but eh adrenal cortex and ADH by the posterior lob of the pit. gland and further by retain sal and water by the kidneys. Also stimulates thirst and elevates blood pressure.

What three higher-level mechanisms are involved in integrating the activities of the nervous and endocrine systems?

They hypothalamus produces regulatory hormones that control secretion by endocrine cells in the anterior lobe of the pituitary gland; contains autonomic centers that exert direct neural control over the endocrine cells of the adrenal medullae; releases ADH and oxytocin in the blood stream at the posterior lobe of the pituitary gland. These mechanisms are adjusted through neg feedback loops involving hormones related by peripheral endocrine tissues and organs.

Which seven hormones are relased by the anterior lobe of the pituitary gland?

Thyroid-stiumlatin hormone TSH; adrenocortcortrophic hormone ACTH; follicle stimulating hormone FSH; luteinizing hormone LH; prolactin PRL; growth hormone GH; melanocyte stimulating hormone MSH

Paracrine Communication

Transmission: Through extracellular fluid, Chemical mediators: Paracrine factor, Distribution of Effects: primarily limited to a local area, where paracrine factor concentrations are relatively high Target cells must have appropriate receptors.

Direct Communication

Transmission: Through gap Junctions, Chemical Mediators: Ions, small solutes, lipid-soluble materials, Distribution of Effects: Usually limited to adjacent cells of the same type that are interconnected by connexons.

Synaptic Communication

Transmission: across synapses, Chemical mediators: Neurotransmitters, Distribution of Effects: Limited to very specific area-tarot cells must have appropriate receptors.

Endocrine Communication

Transmission: through the blood stream, Chemical mediators: hormones, Distribution of Effects: Target cells are primarily in other tissues and organs and must have appropriate receptors.

A researcher observes the stimulation by a particular hormone induces a marked increase in the activity of G proteins in the target plasma membrane. The hormone being studied is probably______

a peptide

Characteristics of The Resistance Phase

1. mobilization of remaining lipid and protein reserves 2. conservation of glucose for neural tissues 3. elevation and stabilization of blood glucose concentrations 4. conservation of salts and water, and the loss of K+ and H+.

Side effects of Resistance Phase

1.Glucocorticoids (cortisol)-anti-inflammatory (slow would healing, increased susceptibility to infection) 2.ADH & Aldosterone-conserve fluids (over time increase of BP & Blood volume) 3.Adrenal Cortex my become unable to produce glucocorticoids

The two hormones released by the posterior lobe of the pituitary gland are

ADH and oxytocin

Summarize the mechanisms for intercellular communication used by the cells.

Both systems rely on the reals of chemicals that bind to specific receptors on their target cells; share many chemical messengers. (hormones in blood, neurotransmitters in synapses); both are regulated mainly by negative feedback control mechanisms; share a common goal: to preserve homeostasis by coordinating activities of other class, tissues, organs and systems.

What effects do calcitonin and parathyroid hormone have on blood calcium levels?

Calcitonin decreases the concentration of calcium ions in body fluids and parathyroid hormone causes an increase in the concentration of calcium ions in body fluids.

Increased blood calcium levels would result in increased_______

secretion of calcitonin

Neural Stimuli:

the arrival of neurotransmitters at neuroglandular junctions.

Hormonal Stimuli:

the arrival or removal of a specific hormone.

In Type 2 diabetes, insulin levels are frequently normal, yet the target cells are less sensitive to the effects of insulin. This suggests that the target cells____

may lack enough insulin receptors

What four cell populations make up the endocrine pancreas? Which hormone does each type of cell produce?

Alpha cells: glucagon; beta cells: insulin; delta cells: growth hormone-inhibiting hormone and Fcells: pancreatic polypeptide.

The Alarm phase

An immediate response to the stress occurs, directed by the autonomic nervous system. 1. energy reserves are mobilized, mainly in the form of glucose 2. the body prepares to deal with the stress by "fight or flight" responses •Epinephrine is the dominant hormone.

What are the phases of the stress response.

Any condition that threatens homeostasis is a stress; Our bodies respond to a variety of stress-causing factors through the general adaptation syndrome (GAS), or stress response. 1. the alarm phase 2. the resistance phase 3. the exhaustion phase

Cyclic AMP functions as a second messenger to________

Open ion channels and activate key enzymes in the cytoplasm

The use of chemical messenger to transfer information from cell to cell within a single tissue is referred to as ______ communication.

Paracrine

What factors can cause the Resistance Phase to end, and progression into the Exhaustion Phase?

Poor nutrition, emotional or physical trauma, chronic illness, and damage to key organs.

A cell's hormonal sensitivities are determined by the

Presence of the absence of an appropriate receptors.

What is the primary difference in the way the nervous and endocrine systems communicate with their target cells?

Speed and duration. In the nervous system the source and destination of communication are quite specific and the effects are extremely quick and short lived. In the endocrine communication the effects are slow to appear con commonly persist for days. A single e hormone can alter the metabolic activities of multiple tissues and organs simultaneously.

Adrenocorticotropic hormone (ACTH) stimulates the release of_________

Steroid hormones by the adrenal glands

How does control of the adrenal medulla differ from control of the adrenal cortex?

The adrenal medulla is controlled by the sympathetic nervous system wears the adrenal cortex is stimulated by the release of ACTH forms he anterior lobe of the pituitary gland.

Describe how the hypothalamus influences the action of the pituitary gland.

The pituitary gland, or hypophysis, lies within the sella turcica. It hangs inferior to the hypothalamus, connected by the infundibulum. The diaphragma sellae locks the pituitary gland in position and isolates it from the cranial cavity.

Humoral Stimuli:

changes in the composition of the extracellular fluid.

What six hormones primary affect growth?

growth hormone, thyroid hormones, insulin, parathyroid hormone, calcitriol and the reproductive hormones.

FSH production in males supports

the maturation of sperm by stimulating nurse cells.