1. Anatomy Summary: Hormones
Figure 7-2 (1 of 2)

2. Anatomy Summary: Hormones
Figure 7-2 (2 of 2)

3. 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

5. Neurohypophysis hormones
Hormones that are produced in the hypothalamus and stored in the neurohypophysis
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

6. Figure 7-12, steps 1–4 1 Hormone is made and packaged in cell body
HYPOTHALAMUS 1
Hormone is made and
packaged in cell body
of neuron. 2
Vesicles are transported
down the cell. 3
Vesicles containing
hormone are stored in
posterior pituitary.
POSTERIOR PITUITARY
Vein 4
Hormones are released
into blood.
Figure 7-12, steps 1–4

7. Hypophyseal portal system
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?

8. 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

9. 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

10. Tropic Hormones of the Anterior Pituitary

11. The Pituitary Gland: Anterior
HYPOTHALAMIC
HORMONES
Neurons in hypothalamus
secreting trophic hormones
Dopamine*
TRH
CRH
PRFs
GHRH*
GnRH
Somatostatin
Portal system
Anterior pituitary
ANTERIOR
PITUITARY
HORMONES
Prolactin
TSH
ACTH GH
FSH LH
Endocrine
cells
(Gonadotropins)
To target
tissues
ENDOCRINE TARGETS
AND THE HORMONES
THEY SECRETE
Endocrine cells
of the gonads
Thyroid
gland
Adrenal
cortex
Liver
Thyroid
hormones
Estrogens,
progesterone
Cortisol
IGFs
Androgens
NONENDOCRINE
TARGETS
Many
tissues
Germ cells
of the gonads
Breast
Figure 7-13

12. Anterior pituitary hormones
Region
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)

13. Anterior pituitary hormones
Region
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)

14. 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)

15. Anterior pituitary hormones
Region
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)

16. Thyroid Gland
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

17. Thyroid Hormone 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

18. 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)

19. Thyroid Hormone Control Pathway
Tonic release
Hypothalamus
TRH
Anterior pituitary
TSH
Negative feedback
Thyroid gland
T4, T3 T4 T3
KEY
Stimulus
Integrating center
Efferent pathway
Systemic metabolic effects
Effector
Systemic response
Figure 23-11

20. 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

21. Calcitonin 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

22. Effects of Parathyroid Hormone
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

23. Simple Endocrine Reflex: Parathyroid Hormone
Low plasma
[Ca2+]
Negative feedback
Parathyroid
cell
Parathyroid
hormone
Bone
and
kidney
Bone
resorption
Kidney
reabsorption of
calcium
Production of calcitriol
leads to intestinal
absorption of Ca2+
Plasma
[Ca2+]
Figure 7-10

24. 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

25. Adrenal (Suprarenal) Glands
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

26. 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)

27. Zona glomerulosa – Mineralocorticoids
Aldosterone secretion is stimulated by:
Rising blood levels of K+
Low blood Na+
Decreasing blood volume or pressure

28. 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

29. 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?)