1. Tyrosine derivatives
2. Peptides and proteins 
3. Steroids 
4. Eicosanoids

1. The hormone binds to receptor’s binding site on the extracellular side of the plasma membrane. 
2. The complex of receptor and hormone activates a G protein associated with the cytoplasmic side of the membrane. 
3. The G protein activates adenyl cyclase, also on the cytoplasmic face of the membrane. 
4. Adenyl cyclase converts a small fraction of the cell’s supply of ATP into cAMP. 
5. The cAMP diffuses throughout the cell, activating a specific family of cytoplasmic protein kinases. 
6. The activated protein kinases attach phosphate groups to intracellular enzymes, activating (or inhibiting) them—an example of allosteric regulation. 
• Changes in gene expression are the result of phosphorylation of a protein called CREB (cyclic AMP response element binding protein). 
• When phosphorylated, this protein can serve as an inducer for the transcription of specific genes. 
7. The second message is terminated as cAMP is converted to an inactive form (noncyclic AMP) by an enzyme called cAMP phosphodiesterase.

• Steroid hormones, being only poorly water soluble, typically travel in the blood as complexes with specific carrier proteins. 
• When the complex approaches the plasma membrane of a cell, the steroid may detach and dissolve in the lipid membrane. 
• The steroid enters the cell and is carried to the nucleus. 
• If the cell is a target cell, the steroid binds with a protein nuclear receptor. 

The posterior lobe (the neurohypophysis or pars nervosa), develops as an extension of the floor of the diencephalon, thus is neural tissue 

• The terminals that emanate from neurons in the paraventricular nucleus release the octapeptide hormone oxytocin. 
• The terminals that emanate from the supraoptic nucleus release a similar octapeptide hormone, antidiuretic hormone (ADH), also known as vasopressin. 

anterior lobe (adenohypophysis or pars distalis) begins as a pocket of ectoderm that forms in the roof of the primitive pharynx and ultimately becomes an island of cells cut off from the pharynx by the development of the sphenoid bone.

• secretions of the adenohypophesis
• Growth Hormone HGH
• Prolactin PRL
• adenocorticotropic hormone ACTH
• Thyroid-stimulating hormone TSH AKA thyrotropin
• Follicle-stimulating hormone FSH
• Luteinizing hormone LH 

1. Growth hormone (HGH; aka somatotropin)
2. Prolactin (PRL)
3. Adrenocorticotropic hormone (ACTH; aka corticotropin) 
4. Thyroid-stimulating hormone (TSH; aka thyrotropin) 
5. Follicle-stimulating hormone (FSH; a gonadotropin)
6. Luteinizing hormone (LH; a gonadotropin)

1. One group includes growth hormone and prolactin. These hormones possess substantial sequence homology—long stretches of their amino acid sequences are similar
2. TSH, FSH, and LH are glycoproteins related to each other and to chorionic gonadotropin. Each of these hormones is composed of two protein chains called alpha and beta subunits. he alpha subunits for all three hormones are the same; differences in the beta subunit alone account for the different effects of the different hormones. 
3. The cellular processes that lead to the hormone ACTH illustrate several general principles of gene expression. The gene that codes for ACTH also contains the code for additional peptide hormones, including beta-lipotrophin, a protein that can be processed into several members of the endorphin family of pain- and mood-modulating hormones. Different endocrine and neural tissues that express this gene secrete different mixes of these substances.

• Hormone secretion varies to oppose changes in a feedback-regulated variable. secretion of insulin is stimulated when plasma glucose levels rise and inhibited when they fall.
• Hormone secretion is regulated by plasma hormone levels.  
• For those hormones that must be secreted at steady rates to sustain long-term processes like growth and sexual differentiation, feedback from the target tissues is less important and direct feedback of the hormone on the secreting gland more important. 
• In this mechanism, high levels of the hormone secreted by a gland inhibit further secretion of the hormone, and low levels stimulate it. 
• Target cells regulate their sensitivity based on hormone levels. 
• In many endocrine systems, the target cells can down regulate receptor numbers in response to high levels of the corresponding hormone, decreasing their sensitivity to the hormone. A corresponding up regulation can occur when hormone levels are low.
•  A second possibility that has the same effect occurs with hormones that are secreted as prohormones and must be converted to another form to have their full effectiveness. 

• Release of growth hormone (somatotropin) is stimulated by growth hormone-releasing factor (GHRF) and inhibited by a release-inhibiting factor called somatostatin. 
• Human growth hormone is designated by the abbreviation HGH and has a central role in the control of growth throughout the body. 
• Congenital failure to synthesize HGH leads to dwarfism. 
• Excess of HGH leads to giantism if it occurs early in life while long bone growth is still possible. 
• Excessive HGH that begins only after adulthood leads to a condition of deformed flat bones and phalanges called acromegaly. 
• HGH acts by inducing the liver (and some other tissues) to synthesize specific growth factors called somatomedins (also called insulin-like growth factors or IGFs). 
• Prolactin (PRL) has a critical role in sustaining milk production and in inhibiting reproductive cycling during lactation. 
• Prolactin secretion is increased during pregnancy, when, along with estrogen, progesterone, and chorionic somatomammotropin, it stimulates the growth of the ducts and alveoli of mammary glands. 
• Except during pregnancy and lactation, prolactin secretion is tonically suppressed by dopamine, a catecholamine that acts as PRL release inhibiting factor (PRLRIF).

• Each adrenal consists of two very dissimilar glands.
• The inner part is the adrenal medulla, a branch of the sympathetic nervous system that secretes catecholamines. 
• The outer part is the adrenal cortex, a gland that secretes steroid hormones. 

• Aldosterone regulates both Na+ content, and with ADH, extracellular fluid volume.
• Changes in aldosterone levels also have the potential to affect K+ and acid-base homeostasis. 
• Aldosterone participates in K+ regulation—an increase in plasma K+ stimulates its secretion by a direct effect on the adrenal cortex. 

• The two main hormones secreted by the thyroid are tetraiodothyronine (T4, also called thyroxine), and triiodothyronine (T3). 
• Thyroid hormones stimulate the metabolism of almost all tissues, including both catabolic and anabolic pathways. 
• They increase the rate of pumping of Na+ across plasma membranes and the ease with which Na+ leaks into cells. 
• This creates a futile cycle that increases the turnover of ATP in cells throughout the body. 
• Thus, thyroid secretion has a major effect on the basal metabolic rate. 
• As a result of this increase, the rate of heat production increases. 
• The thyroid is quite important for cold adaptation in infants and younger children.
• Thyroid hormones are essential for normal growth and development, particularly of the nervous system. 
• The thyroid secretes a third hormone, calcitonin, which stimulates bone calcification.

1. involves activation by a specific G protein of a membrane bound enzyme called phospholipase C
2. This enzyme splits a small fraction of the plasma membrane's phospholipid (phosphoinositol) into 2 signaling substances
1. inositol trisphosphate (ITP or IP3)
2. diacylglycerol
3. the signal pathway branches
4. IP3 is a water soluble substance that enters the cytoplasm and causes the release of Ca++ from intracellular stores in the ER
5. diacyglycerol is a hydrophobic molecule that diffuses freely within the plasma membrane and acts on a specific family of protein kinases (C kinases) distinct from that affected by cyclic nucleotides.
6. the C kinases can then phosphorylate specific proteins within the cell, affecting their function.

either or both:

Ca++ entry across the plasma membrane

or

Ca++ release from storage sites within the cell.

Ca++ calmodulin activates protein kinases in a way similar to _____A______. 

In skeletal and cardiac muscle, the Ca++ binding protein ______b_____ is attached to the thin filament and controls access of _____c_____ to active binding sites; the molecular structure of the Ca++ binding part of troponin closely resemles ____d_____.

A.   cAMP and ITP

B.    Troponin

C.     myosin heads

D.     calmodulin

dimerize 2 receptor monomers, bringing their cytoplasmic domains close to one another.

In a tyrosine-kinase coupled receptor,

 the cytoplasmic domains first ___A_____ one another, greatly increasing each other's _______B________.

They can then ______C_____ specific signal proteins that activate or inhibit ______D_____ and also exert specific genomic effects.

A.     phosphorylate

B.     tyrosine-kinase

C.     phosphorylate

D.     cytoplasmic enzymes

poorly water soluble

travel in the blood as complexes with specific carrier proteins.

and are carried to the nucleus. If the cell is a target cell, the steroid binds with a protein nuclear receptor.

If the cell is not a target cell, there is no effect.

cell-surface-acting hormones typically turn on or off enzymes that are already in place within the cell

steroid hormones must await the transcription of new mRNA, the synthesis of new proteins, and their integration into cellular machinery.

posterior lobe (neurohypophesis or pars nervosa) develops as an extension of the floor of the diencephalon and is nueral tissue.

anterior lobe (adenohypophesis or pars distalis) begins as a pocket of ectoderm that forms in the roof of the primitive pharynx

oxytocin release: 2 specific roles in femal reproduction

potenitiates uterine contractions during labor

promotes contraction of mammary ducts leading to milk ejection during lactation

internal body conditions:

body temp

energy supplies

fluid volume regulation

reproductive cycling

hunger

thirst

sexual interest

a special variety of blood circulation that involves 2 sets of capillaries connected by one or more portal veins.

In this system, blood first flows through capillaries in the hypothalamus where it collects the secreted releasing factors.

It then passes to the 2nd set of capillaries in the adenohypohphysis where the releasing factors are delivered to the endocrine cells

1. hormones possessing substantial sequence homology - long stretches of their amino acids are simila
1. HGH
2. PRL
2. glycoproteins related to each other and to chorionic gonadotropin. composed of 2 protein chains called alpha and beta subunits. alpha subunits for all three hormones are the same.
1. TSH
2. FSH
3. LH
3. cellular processes that lead to ACTH illustrate several general principles of gene expression. The gene that codes for ACTH also contains codes for peptide hormones including beta-lipotrophin

ACTH Production

1. primary transcript of the gene is translatd into a protein sequence called proopiomelanocortin (POMC) that serves as a ____a_____.
2. Posttranslational processing snips the prohormone's sequence to yield _______b_____.
3. The ______c______ of the adenohypophysis snip POMC at 2 points in the middle of the sequence to yield ACTH, discarding the 2 scraps.

A. prohormone

B. shorter sequences of the various hormones

C. corticotrophs

• Cortisol favors resistance to several specific stressors: 
• Survival of food deprivation and recovery from injury. 
• Within a few hours after a meal, the body enters a state called the postabsorptive state in which it is no longer receiving nutrients from food in the intestine and must begin to draw upon its reserves of stored energy. 
• Cortisol is an important hormone of the postabsorptive state, the other main hormones being epinephrine from the adrenal medulla and glucagon from the pancreas. 
• This combination of hormones has three main effects: 
• an increase in the breakdown of glycogen stores in the liver and muscle
• an increase in fat breakdown
• an increase in the rate of breakdown of nonessential proteins, making their amino acids available for synthesis of essential proteins and/or for metabolism for energy.
•  Resistance to infection. Appropriate levels of cortisol are necessary for vigorous immune responses. 
• Paradoxically, high levels of cortisol suppress some aspects of immune function, and cortisol can be used as a drug for this purpose.

rises significantly after every meal

largest part of daily secretion occurs as a pulse or series of pulses after the person falls asleep at night.

• is stimulated by growth hormone-releasing factor and inhibited by a release-inhibiting factor called somatostatin

• is an example of a single chemical mediator with multiple roles in different tissues:
• hormone-releasing factor GHRF
• serves as a GI tract hormone

inducing the liver to synthesize specific growth factors called somatomedins (aka insulin-like growth factors IGFs)

2 IGFs are identified

IGF-I

IGF-II

• sit on kidneys
• each consists of 2 very dissimilar glands
• adrenal medulla
• inner portion
• branch of the sympathetic nervous system that secretes catecholamines
• adrenal cortex
• outer part
• secretes steroid hormones

• a collection of chromaffin cells - sympathetic postganglionic neurons that lack axons and are modified to serve as a neurosecretory organ, releasing the catecholamines epinephrine and norepinephrine into the bloodstream.
• preganglionic cells that control adrenal medullary secretion are located in spinal segments T6-T11.
• the axons of these neurons course in the thoracic splanchnic nerves, pass through the celiac plexus and terminate in the adrenal medulla.

• mineralocorticoids
• glucocorticoids
• gonadocorticoids

• major form is aldosterone
• have their major effect on the body's homeostatic mechanisms for Na+ and K+

• major form is cortisol
• major effects are on energy production during fasting and on immune system function.
• are released during a variety of stressful life situations, including starvation, exhaustive exercise, intense emotion, and injury (including surgery)

• sex hormones
• adrenal cortex secretes both adrongenic and estrogenic steroids.

• chronically low levels of cortisol cause elevated levels of ACTH in 21-hydroxylase deficiency 
• which stimulates the adrenal cortex to the rate of conversion of cholesterol into the early intermediates of all three pathways
• the intermediates in the pathways leading to cortisol and aldosterone simply pile up at the blocked steps in their pathways and then spill into the pathway of androgen synthesis.
• excess androgen can masculinize the female fetuses if the mother has the defect causing a condition known as androgenital syndrome

1. decrease in the Na+ concentration of blood (hyponatremia), an indicaotr of a need to conserve more Na+
2. A decrease in the rate of blood flow to the kidney, an indicator of hypovolemia, a need to form additional extracellular fluid

1. renin is a protease that acts on a plasma protein called angiotensinogen to split off angiotensin I
2. angiotensin I is then converted to angiotensin II by angiotensin-converting enzyme (ACE)
3. angiotensin II acts on the adrenal cortex to increase aldosterone secretion

• in the distal tubule, the part of the renal tubule that responds to aldosterone, the recovery of Na+ from the tubular fluid must be matched by secretion of K+ and H+ to maintain electric charge neutrality.
• changes in aldosterone levels also have the potential to affect K+ and acid-base homeostasis.
• aldosterone participates in K+ regluation - an increase in plasma K+ stimulates its secretion by a direct effect on the adrenal cortex.
• an excess of aldosterone, which occurs in some disorders of the adrenal cortex, causes a syndrome of elevated blood pressure (hypertension), depressed plasma K+ (hypokalemia), and excessive plasma alkalinity (alkalosis)

• supply of adrenal steroids is inadequate
• characteristics (J F Kennedy)
• Muscle weakness and fatigue
• Weight loss and decreased appetite
• Darkening of your skin (hyperpigmentation)
• Low blood pressure, even fainting
• Salt craving
• Low blood sugar (hypoglycemia)
• Nausea, diarrhea or vomiting
• Muscle or joint pains
• Irritability
• Depression

• excess mineralocorticoid causes a condition of hypervolemic hypertension.
• excess glucocorticoid cuases mobilization of fat, particularly from the lower body, leaving excess fat deposits in the face and upper body
• protein is also mobilized with the effect that muscle mass diminishes and tissues become more delicate
• anti-insulin effects of glucocorticoid cause a decrease in tissue glycogen stores and an elevation of plasma glucose levels

• millions of thyroid follicles
• each follicle consists of a single layer of cuboidal epithelial cells currounding a center space filled with a protein matrix called colloid
• the colloid acts as a reservoir for iodine accumulated in the thyroid from the blood
• the iodine combines with tyrosine residues of the colloid
• to support thyroid secretion, colloid is taken up by follicle cells and the iodinated tyrosines are removed and converted into T4 and T3

T3.

This gives these tissues some control over the effectiveness of the hormone.

• Thyroid hormones stimulate the metabolism of almost all tissues including both catabolic and anabolic pathways.
• They increase the rate of pumping of Na+ across plasma membranes and the ease with which Na+ leaks into cells.
• this creates a cycle which increases turnover of ATP in cells throughout the body
• Thyroid secretion has a major effect on the basal metabolic rate

BMR is measured by

devleopment of an enlarged gland (goiter)

Which hormones are key mediators in the control of blood flow and inflammation?

1. peptides
2. prostaglandins
3. steroids
4. tyrosine derivatives

To affet the synthesis of particular proteins, the complex of steroid hormone and its nuclear receptor must be able to interact with particular _____ in the nucleaus

1. carrier proteins
2. genes
3. receptors
4. target cells

What type of tissue is the posterior lobe of the pituitary gland composed of?

1. adipose
2. connective
3. epithelial
4. neural

Which one of the following is not a hormone secreted by adenohypophesis?

1. carotidtropin
2. growth hormone
3. prolactin
4. thyrotropin

Which of the following is composed of two protein chains called alpha and beta subunits?

1. ACTH
2. FSH
3. Growth hormone
4. Prolactin

Prolactin is incorrect

fsh?

The control of ______ release by the hypothalamus does not fit the pattern of other adenohypophyseal hormone, in which small peptide act as releasing factors of release-inhibiting factors.

1. CRF
2. GnRF
3. HGH
4. PRL

The adrenal medulla is a branch of the sympathetic nervous system that secretes

1. catecholamines
2. gonadocorticoids
3. glucocorticoids
4. mineralocorticoids

Which steroid plays an important role in regulating Na+ and extracellular fluid volume?

1. Aldosterone
2. Cholesterol
3. Cortisol
4. Progesterone

Which one of the following is not affected - directly or indirectly - by PTH?

1. bone
2. intestine
3. kidney
4. pancreas

The day-night cycle of the ______ gland is set by light delivered to the eyes, so there are neural connections between the retina and this gland

1. adrenal
2. endocrine
3. pineal
4. pituitary