1. Chapter 11
The Endocrine System

2. Objectives
Distinguish between endocrine and exocrine glands and define the terms hormone, hypersecretion, and hyposecretion.
Identify and locate the primary endocrine glands and list the major hormones produced by each gland.
Describe the mechanisms of steroid and nonsteroid hormone action.
Explain how negative and positive feedback mechanisms regulate the secretion of endocrine hormones.

3. Objectives Define and explain the importance of prostaglandins (PGs).
Identify the principal functions of each major endocrine gland and the hormones that each releases.
Describe the conditions that may result from hyposecretion or hypersecretion of endocrine hormones, including gigantism, diabetes insipidus, goiter, cretinism, diabetes mellitus, and glycosuria.

4. Glands: Endocrine vs. Exocrine

5. Endocrine and Exocrine Glands
All organs of the endocrine system are glands, but not all glands are organs of the endocrine system
Two types of glands in the body
Exocrine glands
Endocrine glands
Only endocrine glands belong to the endocrine system
Secrete chemicals known as hormones into intercellular spaces
Each hormone molecule then binds to a cell that has specific receptors for that hormone, triggering a reaction in the cell (target cell)
The endocrine system performs the same general functions as the nervous system: communication and control.
Main organs of the endocrine system are located in widely separated parts of the body.
Copyright © 2016 by Elsevier Inc. All rights reserved.

6. Introduction Function: Organs:
Communication with and control of organs through secretion of chemical messengers called hormones
Ductless organs secrete directly into blood
Organs:
Endocrine glands
Located throughout the body

8. Hormones
Chemicals used for communication and control of body systems and organs
Work slower than the nervous system
Have longer lasting effects than the nervous system
Affect specific target organs or cells that are usually distant from the secreting gland
Two types:
Non-Steroid
Steroid
Hormones cause changes in their target cells
Protein production
Secretion
Growth
Cell division
Metabolic changes

9. Hormones – Non-steroid
Made from proteins or amino acids
Water soluble and cannot pass pass through cell membranes
Work according to the second
messenger system
The hormone binds to the outside of the cell and triggers cAMP (cylic adenosine monophosphate – a second messenger) to cause changes inside the cell-like a relay race
Nonsteroid hormones are whole proteins, shorter chains of amino acids, or versions of single amino acids.
Nonsteroid hormones typically work according to the second messenger mechanism.

10. Non-Steroid Hormones
Water soluble and cannot pass through the cell membrane – require a second messenger system

11. Hormones - Steroid Made from cholesterol Lipid soluble
Pass directly into nucleus of the cells to affect changes
Primary effects – slower process produced by binding to receptors within the target cell nucleus and influence cell activity by acting on DNA
Secondary effects – may occur when steroid hormones bind to membrane receptors to rapidly trigger functional changes in the target cell
Steroid hormones pass through the cytoplasm and enter nucleus where they bind with a receptor (lock-and-key model).

12. Steroid Hormones

13. Regulation of Hormone Secretion
Hormone secretion is controlled by homeostatic feedback:
Negative feedback
High blood levels of the hormone causes secretion to stop
Low blood levels of the hormone causes secretion to begin
Positive feedback
Hormone secretion continues until homeostasis is regained (uncommon)
Figure 11-4: The secretion of most hormones is regulated by negative feedback mechanisms that tend to reverse any deviations from normal.
In this example, an increase in blood glucose triggers secretion of insulin. Because insulin promotes glucose uptake by cells, the blood glucose level is restored to its lower, normal level.

14. Prostaglandins Also known as “tissue hormones”
Produced in body tissue and diffuse only a short distance to act on cells in that tissue
Several classes of prostaglandins (PGs) include:
prostaglandin A (PGA)
prostaglandin E (PGE)
prostaglandin F (PGF)
Prostaglandins influence many body functions:
respiration
blood pressure
gastrointestinal secretion
reproduction

15. Pituitary Gland Located beneath the hypothalamus in the sella turcica
Two glands:
Anterior --
adenohypophysis
Posterior –
neurohypophysis

16. Anterior Pituitary Gland
Often called the master gland due to control over other endocrine glands
Four of the hormones are tropic hormones that stimulate other endocrine glands to grow and secrete its hormone
Metabolism:using food. Building up and tearing down.

17. Anterior Pituitary Gland Hormones
Thyroid Stimulating Hormone (TSH)
To: Thyroid gland
Stimulates thyroid to secrete thyroid hormone
Stimulates cellular metabolism
Adrenocorticotropic Hormone (ACTH)
To: Adrenal cortex
Stimulates adrenal cortex to secrete hormones
Metabolic changes, stress hormones

18. Anterior Pituitary Gland Hormones
Follicle Stimulating Hormone (FSH)
To: Ovaries or testicles
In females: Secretion of estrogen. Development of follicle that cradles the egg.
In males stimulates sperm formation
Luteinizing Hormone (LH)
Ovulating hormone (egg released from follicle). Secretion of estrogen. Stimulates empty follicle to become the corpus luteum-secretes progesterone.
Secretion of testosterone

19. Anterior Pituitary Gland Hormones
Growth Hormone (GH)
To: Most body cells
Stimulates cell metabolism, protein formation
During deepest stage IV sleep, GH is secreted for production of new cells and collagen for healing and recovery.
Prolactin
To: Mammary glands
Stimulates breast development during pregnancy
Stimulates milk secretion
Increases blood glucose levels

20. Posterior Pituitary Gland Hormones
These hormones are made in hypothalamus and secreted by posterior pituitary.
Antidiuretic Hormone (ADH)
To: Kidneys
Causes retention of water, increase in bp
Decreases urine production
Diabetes insipidus if hyposecretion
Oxytocin
To: Uterus
Stimulates labor/birth contractions
Diabetes insipidus--polyuria. Polydipsia. Deficiency of ADH.
ADH accelerates the reabsorption of water from urine in kidney tubules back into the blood.

21. Pituitary Gland Review

22. Quick Check
What is the chemical messenger used by the endocrine system?
How do nonsteroid/steroid hormones alike/different?
What are tropic hormones?
What hormones are produced by the anterior pituitary?
What hormones are produced by the posterior pituitary?

23. Hypothalamus
A neuroendocrine organ - a gland influenced by the nervous system
Produces releasing (RHs) and inhibiting (IHs) hormones that travels to anterior pituitary
Produces ADH and oxytocin – hormones pass along axons into the pituitary gland
Controls many body functions related to homeostasis:
Temperature
Appetite
Thirst
Hypothalamus also produces releasing hormones (RHs) and inhibiting hormones (IHs).
The combined nervous and endocrine functions of the hypothalamus allow the nervous system to influence many endocrine functions.

24. Thyroid Gland Located in the anterior neck just below the larynx
Stores large amounts of hormones
Produces:
Thyroid hormones
Thyroxine (T4)
Triiodonthyrnine (T3)
Calcitonin (CT)
The thyroid gland lies in the neck just below the larynx.
Thyroid tissue is organized into many chambers called thyroid follicles.

25. Pg 234 Figure 11-6 shows the thyroid and parathyroid glands.
Note their relationship to each other and to the larynx (voice box) and trachea.

26. Thyroid Gland Thyroxine (T4) and Triiodothyronine (T3) - Calcitonin
To: all body cells
Increase cellular metabolism
Essential for growth and functioning
Both require iodine
Calcitonin
To: osteoclasts
Inhibits breakdown of bone
Decreases blood calcium levels
Works with parathyroid hormone to maintain calcium homeostasis

27. Parathyroid Glands Located on the thyroid gland (four) Secretion
Parathyroid Hormone (PTH)
To: Osteoclasts
Stimulates breakdown of bone
Increases blood calcium levels
Works with calcitonin to maintain
blood calcium homeostasis
PTH and calcitonin are antagonists
There are usually four parathyroid glands, and they are found on the posterior surfaces of the thyroid gland.

28. Parathyroid Gland Regulation of blood calcium levels.
Calcitonin and parathyroid hormones have antagonistic (opposite) effects on calcium concentration in the blood .

29. Parathyroid Gland

30. Adrenal Glands Located on top of each kidney
Two layers secrete different hormones
Adrenal cortex
Outer layer
Secretions essential for survival
Adrenal medulla
Inner layer
“Fight or Flight” hormones
An adrenal gland curves over the superior surface of each kidney.
An adrenal gland is actually two separate endocrine glands: the adrenal cortex and the adrenal medulla.

32. Adrenal Cortex Produces corticoids: Mineralocorticoids Glucocorticoids
Sex hormones
The three cell layers of the adrenal cortex are shown in Figure 11-9.

33. Adrenal Cortex - Mineralocorticoids
Help control the amount of certain mineral salts (mainly sodium chloride) in the blood
Aldosterone – To: kidneys
Homeostasis of salts and electrolytes
Increases Na+ in the blood
K+ excreted in urine
Retains water
Increases blood pressure
Inc Na in the blood. Does this in the kidney tubules. Na+ are actively transported back into the blood from the tubular urine. Aldosterone affects the active transport pump.

34. Adrenal Cortex - Glucocorticoids
Important to maintaining normal:
Blood sugar levels
Cortisol (hydrocortisone) increases gluconeogenesis – the formation of “new” glucose from amino acids and the conversion of glucose from fatty acids
Blood pressure
Makes it possible for epinephrine and norepinephrine to maintain normal degree of vasoconstriction
Anti-immunity, anti-allergy effect
Acts with epinephrine and norepinephrine to produce anti- inflammatory and anti-allergy effect
Muscle cells in particular are broken down.
Works with adrenal medulla hormones to maintain B/P
Science daily: prolonged stress decreases tissue sensitivity to cortisol. The immune cells become insensitive to cortisol’s regulatory effect which causes runaway inflammation which leads to disease.
So….cortisol does dec inflam but longterm exposure causes problem in immune system. There are more inflammatory cytokines released.

35. Adrenal Cortex - Glucocorticoids
Secretion of glucocorticoids quickly increases when the body is stressed, leading to many other stress responses.
If constant stress, the HPA axis is activated
Long term stress leads to long term cortisol secretion. Cortisol is an anti- inflammatory but:
Immune cells become insensitive to cortisol’s regulating effect which causes runaway inflammation
Stress causes the hypothalamus to secrete vasopressin and corticotropic releasing hormone which the stimulates the HPA axis.
Cortisol blocks T-cells from proliferating-inc risk of infection.
Affects memory-hippocampus has cortisol receptors
decreases inflam
cortisol narrows arteries
has some influence in retaining fluids/inc b/p….yes! If dec inflam, that means vasoconstriction and inc b/p

36. Copyright © 2016 by Elsevier Inc. All rights reserved.
Stress Responses
Stress Responses
Figure shows stress responses in the body.
Stress may trigger elevated secretion of glucocorticoids (GCs) into the blood.
Copyright © 2016 by Elsevier Inc. All rights reserved.

37. Adrenal Glands - Androgens
Sex hormones
To: Sexual organs
Male hormones secreted in both genders
Stimulate female libido
Little effect on males

38. Adrenal Medulla Epinephrine and Norepinephrine
Adrenaline/noradrenaline
To: many body cells
Stimulated by sympathetic nervous system during short-term stress.
Maintains “fight or flight” response
Increases heart rate and blood pressure
Increases blood glucose
Diverts blood to skeletal muscles
Hypothalamus sends nerve impulses to adrenal medulla to secrete.

39. Pancreatic Islets
Islets of Langerhans - Scattered throughout the pancreas
Glucagon – secreted by alpha cells
Insulin – secreted by beta cells
Maintain homeostasis of blood glucose
Glucagon increases blood glucose level by accelerating conversion of glycogen to glucose
Insulin decreases blood glucose level by accelerating the movement of glucose out of the blood into the cells, which increases glucose metabolism by cell
Figure 11-11, A: The location and structure of the pancreas (shown partially cut open.)
Figure 11-11, B: A pancreatic islet (of Langerhans) in enlarged cross section, showing the glucagon-producing alpha cells and insulin-producing beta cells.

40. Insulin Function and Diabetes

41. Female Sex Glands
Ovaries contain two structures that secrete hormones:
Ovarian follicles
Estrogen (feminizing hormone)
Development and maturation of breasts and external genitals
Development of adult female body contours
Initiation of menstrual cycle
Corpus luteum (ch. 20)
Progesterone mainly
Estrogen
A woman’s primary sex organs are her two ovaries.
Ovarian follicles are little pockets in which egg cells (ova) develop; they also secrete estrogen.
The corpus luteum secretes progesterone and also some estrogen.

42. Male - Sex Glands Interstitial cells Effects of testosterone:
Located in the testes
Effects of testosterone:
Maturation of external genitalia
Beard growth
Voice changes at puberty
Development of musculature and body contours typical of a male
Some of the cells of the testes produce the male sex cells (sperm).
Testosterone is responsible for the maturation of the external genitals, beard growth, changes in voice at puberty, and for the muscular development and body contours typical of the male.

43. Thymus Located in the mediastinum between the sternum and heart
Thymosin
Plays an important role in the development and function of the body’s immune system
The thymus is located in the mediastinum.
In infants, the thymus may extend up into the neck as far as the lower edge of the thyroid gland.
Small structure (weighs less than a gram).

44. Placenta Temporary endocrine gland during pregnancy that produces:
Chorionic gonadotropins
Estrogen
Progesterone
Maintains pregnancy
The placenta functions as a temporary endocrine gland.
During earliest weeks of pregnancy, the kidneys excrete large amounts of chorionic gonadotropins in the urine.

45. Pineal Gland
Called the third eye because its influence on secretory activity is related to the amount of light entering the eyes
Secretes melatonin, which:
Inhibits ovarian activity
Regulates the body’s internal clock
Produces a number of hormones in very small quantity.
Melatonin inhibits the tropic hormone that affect the ovaries.
Melatonin levels increase during the night and decrease during the day.

46. Pineal Gland
A small gland near the roof of the third ventricle of the brain
Glandular tissue predominates in children and young adults
Becomes fibrous and calcified with age
Produces a number of hormones in very small quantity.
Melatonin inhibits the tropic hormone that affect the ovaries.
Melatonin levels increase during the night and decrease during the day.

47. Tissues Prostaglandins “tissue hormones” “local hormones”
To: nearby tissues
Act on cells close to the secreting cells
Often in the same organ
Increases Inflammation, increases pain, uterine contractions.
Looks like it has a role in injury.

48. Endocrine Functions Throughout the Body.
Endocrine Functions Throughout the Body
Many organs (e.g., the stomach, intestines, and kidney) produce endocrine hormones
Stomach lining produces ghrelin, which affects appetite and metabolism
The atrial wall of the heart secretes atrial natriuretic hormone (ANH), which stimulates sodium loss from the kidneys
Fat-storing cells secrete leptin, which controls how full or hungry one feels
Hormone actions are important regulators of homeostasis throughout the body.
As you move forward, always be on the lookout for the regulatory and coordinating roles of hormones.

49. Card Sort Review
Work with a partner to sort the hormones according to:
There are 3 groups of hormones to sort.
Baggies are labeled 1,2,3. Share among your groups.
Check by referring to Table 11-1 on pg. 240.
GLAND
HORMONE
FUNCTION

50. Test Prep
You will label page 135 in the Study Guide without a word bank.
Make sure you know the glands, hormones and functions from table Most of this test will be about what hormones are produced by what gland and what the hormones do.