copyright © 2010 pearson education, inc. figure 7-2 (1 of 2) anatomy summary: hormones

Copyright © 2010 Pearson Education, Inc. Figure 7-2 (1 of 2)

Anatomy Summary: Hormones

Copyright © 2010 Pearson Education, Inc. Figure 7-2 (2 of 2)

Anatomy Summary: Hormones

Copyright © 2010 Pearson Education, Inc.

Pituitary gland (Hypophysis)

• Pituitary gland – two-lobed organ that secretes nine major hormones

• Neurohypophysis – posterior lobe (neural tissue) and the infundibulum

• Receives, stores, and releases hormones from the hypothalamus

• Adenohypophysis – anterior lobe, made up of glandular tissue

• Synthesizes and secretes a number of hormones


Neurohypophysis hormones

Hormone Target Effect

Antidiuretic hormone (ADH)

Arginine vasopresin (AVP)

Kidneys Reabsorption of water,

elevation of blood volume and pressure (vasoconstriction)

Oxytocin (OT) Uterus, mammary glands (female)

Ductus deferens and prostate gland (male)

Labor contractions, milk ejection

Contractions of ductus deferens and prostate gland

Hormones that are produced in the hypothalamus and stored in the neurohypophysis

Copyright © 2010 Pearson Education, Inc. Figure 7-12, steps 1–4

HYPOTHALAMUS

Vein

POSTERIOR PITUITARY

Vesicles are transported down the cell.

Vesicles containing hormone are stored in posterior pituitary.

Hormones are releasedinto blood.

Hormone is made and packaged in cell body of neuron.

1

2

3

4


• Portal system - a system of blood vessels that begins and ends in capillaries. The blood, after passing through one capillary bed, is passing through a second capillary network.

• All blood entering the portal system will reach the target cells before returning to the general circulation

Question – why is such a system important in the communication between the hypothalamus and the

hypophysis?

Hypophyseal portal system


Pituitary-Hypothalamic Relationships: anterior Lobe

• The hypophyseal portal system, consisting of:

• The primary capillary plexus in the infundibulum

• The hypophyseal portal veins

• The secondary capillary plexus


The anterior lobe• There is no direct neural contact with the hypothalamus

• Hormone production is regulated by the hypothalamus

• Regulatory factors from the hypothalamus arrive directly to the

adenohypophysis through the hypophyseal portal system

• Releasing hormones stimulate the synthesis and release of hormones

• Inhibiting hormones shut off the synthesis and release of hormones

• The hormones of the anterior pituitary (7) are called tropic/trophic hormones because they “turn on” other glands or organs


Tropic Hormones of the Anterior Pituitary


The Pituitary Gland: Anterior

Figure 7-13

HYPOTHALAMIC HORMONES

ANTERIOR PITUITARYHORMONES

NONENDOCRINETARGETS

ENDOCRINE TARGETSAND THE HORMONESTHEY SECRETE

Somatostatin

GHRH* GnRH

Portal system

Anterior pituitary

FSH LH

Neurons in hypothalamussecreting trophic hormones

To target tissues

GH

Endocrine cellsof the gonads

Endocrinecells

Many tissues

Germ cellsof the gonads

Thyroid gland

Thyroid hormones

Adrenalcortex

Cortisol

Liver

IGFs AndrogensEstrogens,

progesterone

PRFs TRH CRH

TSH ACTHProlactin

Breast

Dopamine*

(Gonadotropins)


Anterior pituitary hormonesRegion

Hormone Target Effect Hypothalamic regulatory hormone

Follicle-stimulating hormone (FSH)

Follicle cells of the ovaries, sustentacular cells of testes

Secretion of estrogen, follicle development, stimulation of sperm maturation

Gonadotropin-releasing hormone (GnRH)

Luteinizing-Hormone (LH)

Follicle cells of ovary

Interstitial cell of testes

Ovulation, formation of corpus luteum, secretion of progesterone

Secretion of testosterone


Prolactin (PRL)

Mammary glands Production of milk Prolactin-releasing factor (PRF)

Prolactin-Inhibiting hormone (PIH)

Growth hormone (GH)

All cells Growth, protein synthesis, lipid mobilization and catabolism

Growth-hormone- releasing hormone (GH-RH)

Growth-hormone-inhibiting hormone (GH-IH)


Anterior pituitary hormones

Region Hormone Target Effect Hypothalamic regulatory hormone

Thyroid-stimulating hormone (TSH/ thyrotropin)

Thyroid gland Secretion of thyroid hormones (T3, T4)

Thyrotropin-releasing hormone (TRH)

Adrenocorticotropic hormone (ACTH)

Adrenal cortex (zona fasciculate)

Secretion of glucocorticoids (cortisole, corticosterone)

Corticotrophin-releasing hormone (CRH)


Anterior pituitary hormonesRegion

Hormone Target Effect Hypothalamic regulatory hormone

Follicle-stimulating hormone (FSH)

Follicle cells of the ovaries, sustentacular cells of testes

Secretion of estrogen, follicle development, stimulation of sperm maturation


Luteinizing-Hormone (LH)

Follicle cells of ovary

Interstitial cell of testes

Ovulation, formation of corpus luteum, secretion of progesterone

Secretion of testosterone


Prolactin (PRL)

Mammary glands Production of milk Prolactin-releasing factor (PRF)

Prolactin-Inhibiting hormone (PIH)

Growth hormone (GH)

All cells Growth, protein synthesis, lipid mobilization and catabolism

Growth-hormone- releasing hormone (GH-RH)

Growth-hormone-inhibiting hormone (GH-IH)


The thyroid gland on the anterior side of the neck. The thyroid gland has a right lobe and a left lobe connected by a narrow isthmus

http://webanatomy.net/histology/endocrine_histology.htm

Thyroid Gland


• Thyroid hormone – major metabolic hormone

• Consists of two related iodine-containing compounds

• T4 – thyroxine; has two tyrosine molecules plus four bound iodine atoms

• T3 – triiodothyronine; has two tyrosines with three bound iodine atoms

Thyroid Hormone


Functions of Thyroid Hormones

Elevates rates of oxygen consumption and energy consumption; in children, may cause a rise in body temperature

Increases heart rate and force of contraction; generally results in a rise in blood pressure

Increases sensitivity to sympathetic stimulation Stimulates red blood cell formation and thus enhances oxygen

delivery Activate genes that code for enzymes that are involved in

glycolysis (Glucose oxidation) increase rate of ATP production In the nucleus – activate genes that control the synthesis of

enzymes that involve with energy production and utilization (for example increase of production of sodium-potassim ATPase that uses ATP)


TSH

T4, T3

T4 T3

Hypothalamus

Anteriorpituitary

Thyroidgland

Systemicmetabolic

effects

Stimulus

Integrating center

Efferent pathway

Effector

Systemic response

TRH

Tonic release

KEY

Negative feed

back

Thyroid Hormone Control Pathway

Figure 23-11


Protein hormones that control calcium

Parathyroid gland – PTH

PTH—most important hormone in Ca2+ homeostasis

Thyroid gland – calcitonin

Liver and Kidney - Calcitriol – also known as vitamin D3


• Calcitonin targets the skeleton, where it:

• Inhibits osteoclast activity (and thus bone resorption) and release of calcium from the bone matrix

• Stimulates calcium uptake and incorporation into the bone matrix

• Regulated by a humoral (calcium ion concentration in the blood) negative feedback mechanism

Calcitonin


• PTH release increases Ca2+ in the blood:

• Stimulates osteoclasts to digest bone matrix

• Enhances the reabsorption of Ca2+ and the secretion of phosphate by the kidneys

• Increases absorption of Ca2+ by intestinal mucosal

• Rising Ca2+ in the blood inhibits PTH release

• The antagonist is the Calcitonin secreted by the thyroid gland

Effects of Parathyroid Hormone


Simple Endocrine Reflex: Parathyroid Hormone

Figure 7-10

Bone and

kidney

Low plasma

[Ca2+]

Plasma

[Ca2+]

Bone resorption

Kidneyreabsorption of

calcium

Parathyroid cell

Parathyroid hormone

Production of calcitriolleads to intestinalabsorption of Ca2+

Negative feedback


Pancreas structure

Exocrine pancreas (99% of volume)

Cells (pancreatic acini) forming glands and

ducts that secrete pancreatic fluid and enzymes

with digestive function

Endocrine pancreas (1%)

Small groups of cells scattered in clusters

(pancreatic islets) that secrete hormones


• Structurally and functionally, they are two glands in one

• Adrenal medulla – neural tissue; part of the sympathetic nervous system

• Adrenal cortex - three layers of glandular tissue that synthesize and secrete corticosteroids

Adrenal (Suprarenal) Glands


Adrenal Cortex

• Synthesizes and releases steroid hormones called corticosteroids

• Different corticosteroids are produced in each of the three layers

• Zona glomerulosa – glomerulus- little ball. Secretes mineralocorticoids – main one aldosterone

• Zona fasciculata – glucocorticoids (chiefly cortisol)

• Zona reticularis – gonadocorticoids (chiefly androgens)


Zona glomerulosa – Mineralocorticoids

• Aldosterone secretion is stimulated by:

• Rising blood levels of K+

• Low blood Na+

• Decreasing blood volume or pressure


Aldosterone and urine concentration

• Aldosterone is a steroid secreted by the adrenal cortex

• It is secreted when blood sodium falls or if blood potassium rises or when blood pressure decreased

• Aldosterone increases reabsorption of Na+ in the kidneys in exchange for secretion of K+ ions – water follow

• Net effect is that the body retains NaCl and water and urine volume reduced

• The retention of salt and water help to maintain blood pressure and volume


Zona fasciculata - Glucocorticoids (Cortisol/hydrocortisone)

• Main hormones secreted are the Cortisol/hydrocortisone and small amounts of corticosterone

• It protects against hypoglycemia by stimulating catabolism of energy stores.

• While adrenaline is responsible for rapid metabolic responses the glucocorticoids are responsible for long-term stress:

• Glucocorticoids accelerate the rates of glucose synthesis and glycogen formation – especially in the liver

• Promotes the utilization of fatty acids as source of energy - glucose-sparing effect

• Clucocorticoids also have anti-inflammatory effect – inhibit the activities of WBC (use?)

copyright © 2010 pearson education, inc. figure 7-2 (1 of 2) anatomy summary: hormones

Documents

release of hormones

tropic hormones

releases hormones

number of hormones

tropictrophic hormones

pearson education

anterior pituitary slide

prostate gland hormones