The document summarizes the major endocrine glands and their hormones. It describes the hypothalamus and pituitary gland which secretes six important peptide hormones. It also discusses the thyroid gland which produces thyroxine and triiodothyronine, regulating cellular metabolism. The parathyroid glands contain four glands which secrete parathyroid hormone to regulate calcium levels. The pancreas has endocrine functions secreting insulin and glucagon to regulate blood sugar. The adrenal glands are composed of an outer cortex secreting glucocorticoids and mineralocorticoids, and an inner medulla secreting epinephrine and norepinephrine. The gonads are the testes and ovaries which se

1. Dr. Maria Idrees; PT
MS (RIU)
DPT(TUF)

2.  The endocrine system helps to maintain internal
homeostasis through the use of endogenous chemicals
known as hormones.
 A hormone is typically regarded as a chemical
messenger that is released into the bloodstream to
exert an effect on target cells located some distance
from the hormonal release site.
 Drugs can be used as replacement therapy during
hormonal deficiency—for example, insulin
administration in diabetes mellitus.

3. Primary Endocrine Glands
and Their Hormones
 Hypothalamus and Pituitary Gland
 The pituitary gland is a small, pea-shaped structure.
 The pituitary can be subdivided into an anterior, an
intermediate, and a posterior lobe.
 Anterior Lobe:
 Secrets six important peptide hormones
1) growth hormone (GH),
2) luteinizing hormone (LH),
3) follicle-stimulating hormone (FSH),
4) thyroid-stimulating hormone (TSH),
5) adrenocorticotropic hormone (ACTH), and
6) Prolactin (Pr).

5.  Intermediate Lobe.
 In mammals, there is a small intermediate lobe of the
pituitary (pars intermedia) that may secrete
melanocyte-stimulating hormone (MSH).
 Although it can influence skin pigmentation in lower
vertebrates, the intermediate lobe does not produce
MSH in meaningful amounts in humans.
 Humans can, however, produce MSH from a precursor
protein (proopiomelacortin) that is synthesized in
central tissues (anterior pituitary, hypothalamus) and
the periphery (skin, lymphoid tissues)

6.  Posterior Lobe
 Secretes two hormones:
1) Antidiuretic hormone (ADH) (Exerts its effect
primarily on the kidneys, where it increases the
reabsorption of water from the distal renal tubules.
2) Oxytocin (important in parturition and stimulates
the uterus to contract. It also promotes lactation by
stimulating the ejection of milk from the mammary
glands.

8. Thyroid Gland
 The thyroid gland is located in the anterior neck
region, approximately at the level of the fifth cervical
to first thoracic vertebrae.
 The thyroid synthesizes and secretes two hormones:
 Thyroxine (T4) and
 Triiodothyronine (T3)
 The primary effect of the thyroid hormones is to
increase cellular metabolism in most body tissues

9. Parathyroid Gland
 Parathyroid glands are small, egg-shaped structures
embedded in the posterior surface of the thyroid
gland.
 There are usually four parathyroid glands
 The parathyroids synthesize and release parathyroid
hormone (PTH).
 PTH is essential in maintaining normal calcium
homeostasis in the body; the primary effect of PTH is
to increase the concentration of calcium in the
bloodstream.

10. Pancreas
 The pancreas is located behind the stomach in the
lower left area of the abdomen.
 This gland is unique in that it serves both endocrine
and exocrine functions.
 The exocrine aspect of this gland involves digestive
enzymes that are excreted into the duodenum.
 As an endocrine gland, the pancreas primarily secretes
two peptide hormones:
1) Insulin (Alpha cells) and
2) Glucagon (Beta cells)

11. Adrenal Gland
 Adrenal glands are located at the superior poles of
each kidney.
 Each adrenal gland is composed of an outer cortex and
an inner medulla.

12.  Hormones of the Adrenal Cortex
 Synthesizes and secretes two primary groups of steroidal
hormones:
1) Glucocorticoids
2) Mineralocorticoids (controlling electrolyte and fluid
levels)
3) Small amounts of sex steroids (estrogens, androgens,
progesterone) are also produced.
 Glucocorticoids are involved in the regulation of glucose
metabolism and are important in enhancing the body’s
ability to handle stress.
 Anti-inflammatory
 Immunosuppressive properties

13.  Hormones of the Adrenal Medulla
 synthesizes and secretes
 Epinephrine and
 Norepinephrine
 To prepare the body for sudden physical activity.
 By the fight-or-flight reaction

14. Gonads
 In men, the testes produce testosterone and similar
androgens that are responsible for spermatogenesis
and the secondary sexual characteristics of adult
males.
 In women, sexual maturation and reproductive
function are governed by the production of estrogens
and progestins from the ovaries

15. Hormone Chemistry
 Steroid hormones share a common chemical
framework that is derived from lipids such as
cholesterol. (e.g sex hormones, glucocorticoids,
mineralocorticoids)
 Peptide hormones consist of amino acids linked
together in a specific sequence (3-180 amino acids, e.g
T3 and T4)

16. Feedback Control Mechanisms
in Endocrine Function

17. Hormone Transport
 Hormones are usually carried from their site of origin
to the target cell via the systemic circulation.
 During transport in the bloodstream, certain
hormones such as steroids are bound to specific
plasma proteins.
 These protein carriers appear to help prolong the half-
life of the hormone and prevent premature
degradation.

18. Hormone Effects on the Target Cell

19. Assignment
 Steroid hormone Mechanism of action??????????
 Due date: 4-11-2022