Endocrine System - Hormones & Glands

Amino acid-based hormones

- Binds to a plasma membrane receptor - Acts through a second messenger such as cyclic AMP

What is involved in direct gene activation by a hormone?

1. The steroid hormone diffuses through the plasma membrane and binds to an intracellular receptor. 2. The receptor-hormone complex enters the nucleus. 3. Thus the receptor-hormone complex binds to a specific DNA region. 4. Binding initiates transcription of the gene to mRNA. 5. The mRNA directs protein synthesis.

What is a target cell?

A cell that has receptors for a particular hormone

infundibulum

A stalk that attaches the pituitary gland to the hypothalamus.

Hormones promote homeostasis by ________ of body cells rather than by _________.

Altering activity; stimulating new or unusual activity

Which hormones are produced by the hypothalamus?

Anterior Pituitary: · Thyrotropin-releasing hormone (TRH) · Gonadotropin-releasing hormone (GnRH) · Corticotropin-releasing hormone (CRH) · Growth hormone-releasing hormone (GHRH) · Prolactin-inhibiting hormone (PIH) Posterior Pituitary: · Oxytocin · Antidiuretic hormone (ADH)

The _________ is called the master endocrine gland because it regulates so many other endocrine organs. However, it is in turn controlled by _____________ secreted by the ___________. This structure identified as hypothalamus is also part of the brain, so it is appropriately called a _________ organ.

Anterior pituitary; Releasing hormones; hypothalamus; neuroendocrine

Choose the correct term. An endocrine/exocrine gland is a ductless gland that empties its hormone into the extracellular fluid.

Endocrine

Endocrine system vs Nervous Sytem

Endocrine System · Initiates responses slowly · Long-duration responses · Acts via hormones released into the blood · Acts at diffuse locations--targets can be anywhere blood reaches · Hormones act over long distances Nervous System · Initiates responses rapidly · Short-duration responses · Acts via action potentials & neurotransmitters · Acts at specific locations determined by axon pathways · Neurotransmitters act over very short distances

Aldosterone

Hormone that stimulates the kidney to retain sodium ions and water

The pituitary gland, also known as the ___________________, is located in the sella turcica of the sphenoid bone.

Hypophysis

A. Hypothalamus B. Pituitary gland C. Adrenal glands D. Ovary (female) E. Testes (male)

Label the human endocrine organs.

The secretion of most hormones is regulated by a ___________ system, in which incrasing levels of that particular hormone "turn off" its stimulus.

Negative feedback system

The various endocrine glands are prodded to release their hormones by nerve fibers (a ________ stimulus), by other hormones (a ________ stimulus), or by the presence of increased or decreased levels of various substances in the blood (a _______ stimulus).

Neural; hormonal; humoral

All cells do not respond to endocrine system stimulation. Only those that have the proper ___________ on their cell membranes are activated by the chemical messengers.

Receptors

Tropic Hormones (tropin) of Anterior Pituitary

TSH, ACTH, FSH, LH

These responsive cells are called the ___________ of the various endocrine glands.

Target cells

Steroid hormones

binds to a receptor in the cell's nucleus is lipid soluble activates a gene to transcribe messenger RNA

target cell

cells that have receptors for a particular hormone

Gonads: Ovaries

estrogen and progesterone

Norepinephrine

helps control alertness and arousal

Prehaps the reason for this is that the endocrine system uses chemical messengers, called ____________, instead of ______________. These chemical messengers enter the blood and are carried throughout the body by the activity of the _________________.

hormones; nerve impulses; cardiovascular system

sella turcica of sphenoid bone

houses the pituitary gland (hypophysis)

function of parathyroid gland

increases blood calcium level

Androgens

male sex hormones

found in the pelvic cavity of the female, concerned with ova and female hormone production

ovaries

a mixed gland, located close to the stomach and small intestine

pancreas

Choose the correct term. Pancreatic islets/ Acinar cells form the endocrine portion of the pancreas.

pancreatic islets

produces the hormones that are stored in the posterior pituitary

parathyroid gland

found in the roof of the 3rd ventricle of the brain

pineal gland

bilobed gland located in the sella turcica

pituitary gland

Major organs of the endocrine system

pituitary gland, thyroid gland, pancreas, adrenal glands, gonads, endocrine tissues in other systems

function of pituitary gland

produces hormones

Proclactin

promotes milk production

function of thyroid gland

regulates metabolism

The endocrine system is a major controlling system in the body. It means of control, however, is much ________________ than that of the _____________, the other major body system that acts to maintain homeostasis.

slower and more prolonged; nervous system

Most hormones are ________ molecules.

steroid or amino acid-based

Chemically, hormones belong chiefly to two molecular groups, the ____ and the _____

steroids and amino acids

function of posterior pituitary (neurohypophysis)

stores and releases ADH and oxytocin

Cortisol

stress hormone

paired glands suspended in the scrotum

testes

Gonads: Testes

testosterone

This gland is rather large in an infant, begins to atrophy at puberty, and is relatively inconspicuous by old age. It produces hormones that direct the maturation of T cells. It is the __________ gland.

thymus

found in the upper thorax overlying the heart; large during youth

thymus

The ______________ gland is composed of two lobes and located in the throat, just inferior to the larynx.

thyroid

located in the anterior neck; produces key hormones for metabolism

thyroid gland

What is the difference between a water soluble hormone and a lipid soluble hormone?

· A water-soluble hormone-- such as amino acids, peptides, and proteins-- cannot cross the plasma membrane. · A lipid-soluble hormone-- such as steroids--can cross the plasma membrane.

These hormones function to regulate the functions of another endocrine gland (tropic)

· ACTH · LH · FSH · ADH

Identify the 3 types of stimuli that cause hormone release and give an example for each.

· Altered levels of specific critical ions or nutrients cause humoral stimulus. Example: Cells of the PTH glands monitor the body's crucial blood Ca^2+ levels and release PTH hormone as needed. · Hormone release is caused by neural input as a result of Neural Stimulus. Example: Stress, in which the sympathetic nervous system stimulates the adrenal medulla to release norepinephrine and epinephrine. · Hormone release is caused by another hormone (a tropic hormone) = hormonal stimulus. For example, hormones released and inhibited by the hypothalamus regulate the secretion of most anterior pituitary hormones and stimulate another endocrine organ to release their hormones.

Identify 3 factors the degree of target cell activation depends on and give specific examples of each.

· Blood levels of the hormone · example: · Affinity (strength) of the binding between the hormone & the receptor · example: having a large number of high-affinity receptors produced a noticeable hormonal effect and having a small number of low-affinity receptors reduces the target cell response or causes outright endocrine dysfunction. · Relative numbers of receptors for that hormone on or in the target cells · example: progesterone down-regulates estrogen receptors in the uterus, thus antagonizing estrogens' actions. p. 608

Explain the importance of the hypothalamus to the secretions of the pituitary gland.

· By alerting the pituitary gland to release certain hormones to the rest of the endocrine system, the hypothalamus ensures that the internal processes of your body are balanced and working as they should.

Non-Tropic Hormones of the Anterior Pituitary

· Growth hormone (GH) · Prolactin (PRL)

What is the difference between a hyposecretion of a hormone and a hypersecretion of a hormone?

· Hyposecretion is the understimulated thyroid hormone · Hypersecretion is the overstimulated thyroid hormone

Pancreas

· Location: behind the stomach and close to the small intestine · function: as both endocrine and exocrine glands; produces enzymes that are important with the regulation of blood sugar levels such as insulin and glucagon

If hormones travel in the bloodstream, why don't all tissues respond to all hormones?

· Only a hormone's "target" cells, which have receptors for that hormone, will respond to its signal. · When the hormone binds to its receptor, it causes a biological response within the cell.

Epinephrine (adrenaline)

· Secreted by the adrenal medulla; · Increases heart rate and blood pressure and dilates airways (sympathomimetic). · It is part of the body's "fight or flight" reaction.

What is stress? Which part of the brain coordinates a short or long-term response to stress?

· Stress is a potential threat to homeostasis-- the body's response to nonspecific stressors. · Short-term stress = the hypothalamus activates the adrenal medulla via neural stimuli. · Example: running from a fire · Long-term stress = the hypothalamus activates the adrenal cortex via hormonal stimuli, thus continuing short-term stress response. · Example: starvation that may lead to muscle loss, altered immunity, and high blood pressure.

These hormones function to control the rate of body metabolism and cellular oxidation

· T3/T4

What is a hormone?

· a regulatory substance produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action.

What is a second messenger?

· a substance whose release within a cell is promoted by a hormone and that brings about a response by the cell.

These hormones function to maintain salt and water balance in the extracellular fluid

· aldosterone · cortisol

What macromolecules make up the structure of hormones?

· amino acids · steroids

These hormones function to regulate blood calcium levels

· calcitonin (thyroid gland) · PTH (parathyroid gland)

These hormones function in which are released in response to stressors

· epinephrine (adrenal medulla) · cortisol (adrenal cortex)

These hormones function in which are directly responsible for regulation of the menstrual cycle

· estrogens · progesterone

Glucagon

· function: accelerates the breakdown of glycogen to glucose, stimulates the conversion of lactic acid into glucose, releases glucose into the blood from the liver · target: liver and adipose

Insulin

· function: accelerates the transport of glucose into body cells; promotes glycogen, fat, and protein synthesis · target: most cells of the body

T4 (thyroxine) and T3 (triiodothyronine)

· function: increases basal metabolic rate (BMR); regulates tissue growth and development · target: most cells in the body

parathyroid hormone (PTH)

· function: increases blood calcium levels by stimulating osteoclasts and by stimulating the kidneys to convert vitamin D to calcitriol, which is required for the absorption of calcium in the intestines · target: bones and kidneys

Calcitonin

· function: lower blood calicum levels by bone resorption · target: bones

Glucorticoids

· function: regulate glucose metabolism

adrenal medulla

· function: secretes epinephrine 80% and norepinephrine 20%; mimics the sympathetic nervous system; "fight or flight" response · target: most body cells

TSH (thyroid stimulating hormone)

· function: secretion of thyroid hormone T3 and T4 (anterior pituitary) · target: thyroid gland

Growth Hormone (GH)

· function: stimulates body growth and protein synthesis, mobilizes fat, and conserves glucose · target: liver, muscle, bone, and cartilage

Prolactin (PRL)

· function: stimulates milk production · target: mammary glands in breasts

Oxytocin

· function: stimulates powerful uterine contractions during birth and milk ejection in lactating mothers · target: the uterus and mammary glands

antidiuretic hormone (ADH)

· function: stimulates the kidneys to reabsorb more water, reducing urine output and conserving body water · target: kidneys

FSH (follicle stimulating hormone)

· function: stimulates the secretion of ovarian sex hormones, development of ovarian follicles, and sperm production (anterior pituitary) · target: ovaries and testes (gonads)

LH (luteinizing hormone)

· function: triggers ovulation and stimulates ovarian production of estrogen and progesterone, stimulates testosterone production (anterior pituitary) · target: ovaries and testes (gonads)

These hormones function to regulate blood glucose levels; produced by the same "mixed" gland

· glucagon · insulin

pineal gland

· located in the roof of the 3rd ventricle of the brain · endocrine product is melatonin

adrenal glands (suprarenal glands)

· location: above kidneys · function: produce hormones that help the body control blood sugar, burn protein and fat, react to stressors like a major illness or injury, and regulate blood pressure.

Thymus

· location: superior thorax, posterior to the sternum, and overlying the heart · function: produces peptide hormones such as thymulin, thymosins, and thymopoietins; which are involved in the development of T lymphocytes and the immune response

adrenal cortex

· location: the outer section of each adrenal gland; · function: secretes cortisol, aldosterone, and sex hormones

What are two systems of control for the human body?

· nervous system · endocrine system

The synthesizing gland corresponding to estrogen and progesterone is:

· ovaries

These hormones function directly involved in milk production and ejection

· oxytocin (hypothalamus) · prolactin (anterior pituitary)

The synthesizing gland corresponding to glucagon and insulin is:

· pancreas

Exocrine gland

· produce hormones · lack ducts · release hormones into tissue fluid · vascular & lymphatic drainage input

Although the pituitary gland is sometimes referred to as the master gland of the body, the hypothalamus exerts control over the pituitary gland. How does the hypothalamus control both anterior and posterior pituitary functioning?

· produces "releasing and inhibiting hormones" which control the production and release of anterior pituitary hormones; · form hormones ADH and oxytocin that are transported to the posterior pituitary and later released on nervous stimulation from the hypothalamus

function of anterior pituitary (adenohypophysis)

· produces and secretes tropic hormones: FSH, LH, ACTH, TSH, prolactin, GH, melanotropin (MSH). · "master endocrine gland" due to control of activity of many endocrine glands

Endocrine gland

· produces hormones · have ducts to carry to the surface · release their hormones directly into an extracellular fluid such as the bloodstream or lymph · example: sweat/saliva

melatonin (pineal gland)

· regulates sleep/wake cycles

Give examples of the major functions of hormones.

· reproduction = the ability to produce offspring · growth and development = produce most body's cells · maintenance of electrolyte, water, and nutrient balance of the blood = · regulation of cellular metabolism and energy balance = · mobilization of body defenses = immunity against viruses and bacteria

Hormones

· steroids or amino acid-based molecules are used to arouse the body's tissues and cells via stimulation in metabolic activity · changes lead to growth and development, homeostasis

ACTH (adrenocorticotropic hormone)

· stimulates the release of glucorticoids and androgens (anterior pituitary) · target: adernal cortex

The synthesizing gland corresponding to testosterone is:

· testes

These hormones function to drive development of secondary sex characteristics in males

· testosterone

secretion

· the substance produced by a gland