1. Homeostasis – Endocrine System
Chapter 8

2. The Endocrine System – 8.1
Hormones  chemical regulators produced by cells in one part of the body that affect cells in another part of the body.
Endocrine hormones  produced in glands and secreted directly into blood.
The adrenal gland, on top of the kidneys secretes the hormone adrenaline

3. The Endocrine System – 8.1
Hormones  chemical regulators produced by cells in one part of the body that affect cells in another part of the body.
Exocrine glands  secrete substances through ducts onto the body surface or into cavity.
Mucous & sweat

4. The Endocrine System – 8.1 Hormone Classification
Nontarget hormones – affect many tissues throughout the body
Growth hormone
long bone growth
Increases calcium retention, and strengthens and increases the mineralization of bone
Increases muscle mass
Increases protein synthesis
Stimulates the growth of all internal organs excluding the brain
Reduces liver uptake of glucose
Stimulates the immune system
Target hormones – affect specific cells or tissues in the body
Gastrin stimulates cells of the stomach to produce digestive enzymes.

5. The Endocrine System Chemical Messengers – how we know what we know?
1889  von Mering and Minkowski with dog pancreases
If removed  slim and tired, ants
If present  normal, no ants
Pancreas controlled blood sugar
Radioactive tracers
Where hormones go and how they are broken down.

6. The Endocrine System Hormones do not affect all cells
Two types of hormones
Steroid Hormone  made from cholesterol, include sex hormones, rings of CHO
Blood  ECF  Joins with receptor molecule in cytoplasm  complex enters nucleus  Joins chromatin which activates gene to start making a specific protein

7. The Endocrine System
Protein Hormone  made of chains of AA, include insulin and growth hormone
Blood  ECF  Joins to receptor site on outside of cell  Activates adenylyl cyclase  This enzyme converts ATP to cAMP  cAMP acts as a messenger activating enzymes in the cytoplasm.

8. The Pituitary Gland
Gland at base of brain that, with hypothalamus, functions as a control centre coordinating the endocrine and nervous system.
Produces and stores hormones which are regulated by the hypothalamus
Posterior and Anterior lobes
Posterior  stores and releases hormones (ADH, oxytocin)
Anterior  produces its own hormones (GH, prolactin)

9. Hormones & Blood Sugar - 8.2
Pancreas contains two types of cells
Digestive enzyme producing cells
Hormone producing cells – islets of Langerhans:
produce insulin (beta)  released when blood sugar goes up and causes appropriate cells to become permeable to glucose.
produce glucagons (alpha)  released when blood sugar goes down and promotes the conversion of glycogen to glucose

11. Diabetes  Insufficient production or use of insulin
After a meal you would experience hyperglycemia
Kidneys  high concentration of glucose in nephron pulls water out of the body
Three types - mellitus
Type 1 (juvenile-onset)  early degeneration of beta cells, inject insulin to live, 10% of diabetics
Type 2 (adult-onset)  decrease in insulin production or efficiency, treated with sulfoamides which stimulate beta cells, 90%
Type 3 (gestational)  occurs in 2-4% of pregnancies, temporary yet increases risk
Banting and Best – isolated hormone (insulin)
Islet Cell Transplants

12. Adrenal Glands Made up of two glands
Adrenal Medulla – controlled by the nervous system, epinephrine and norepinephrine are produced (fight or flight response)
Increase blood sugar, heart rate
Adrenal Cortex – controlled by hormones
Glucocorticoids – associated with blood glucose levels and assist in dealing with stress (cortisol)
Mineralcorticoids – associated with regulation of salt-water balance, aldosterone increases sodium retention and therein water reabsorption.

13. Hormones & Metabolism - 8.3
Thyroid Gland
Thyroxine (T4) and triiodothyronine (T3) regulate body metabolism and the growth and differentiation of tissues. T4
Regulates metabolic rates
Sugars get oxidized faster by people with a “faster” rate of metabolism

14. Thyroid Gland
Control of the hormones is accomplished by negative feedback
Metabolic rate decreases
hypothalamus gets signal
thyroid releasing hormone (TRH) is released
pituitary gland releases thyroid stimulating hormone (TSH)
blood transports TSH to thyroid and thyroxine is released
blood sugar goes up due to thyroxine stimulating increased sugar utilization.
The process gets shut off when thyroxine levels get high as it inhibits the release of TRH

15. Parathyroid Gland
Responds to immediate surroundings to help maintain homeostasis…a little different then other endocrine glands which are regulated by hormones.
Low Ca2+ levels in blood cause parathyroid hormone (PTH) to be released which corrects that issue (absorb more from intestines and kidneys and break down bones)

16. Pituitary Gland Adrenocorticotropic hormone
Melanocyte-stimulating hormone

17. Anterior Pituitary Gland
Produces growth hormone (somatotropin)
Increases growth of bones and cartilage, if growth plates have fused, other bones will respond  acromegaly
Increases muscle cell size and connective tissue by promoting protein synthesis and inhibiting protein breakdown.
Relationship between aging and GH.
As you get older production of growth hormone decreases. Growth hormone is responsible for stimulating ribosomes to follow genetic information for protein synthesis.
Cellular repair and protein replacement is compromised…protein is often replaced by fat as we age.

18. Stress – 8.4
Connection between long-term stress from a noxious stimulus.
A general adaptation syndrome results from exposure to prolonged stress
Stress Hormones  (p.388, table 1).
More energy required so hormones make more glucose available in blood
Increase in blood pressure and an elevated metabolic rate
Problems with Long-Term Stress (p.389, table 2)
Steroids – what do you think?
p. 391, table 3

19. Stress – 8.4

20. Reproductive Hormones – 8.5
Male Reproductive System
Sex hormones – androsterone & testosterone produced in the interstitial cells (between seminiferous cells) of the testes.
Androsterone (ADT) is a steroid hormone with weak androgenic activity. It is made in the liver from the metabolism of testosterone
Testosterone stimulates spermatogenesis (spermatogonia divide and mature); influences development of male secondary characteristics at puberty
Hypothalamus and pituitary gland control the production of sperm and male sex hormones

21. Male Reproductive System
Negative feedback ensures adequate numbers of sperm cells and testosterone are maintained.
Pituitary produces and stores gonadotropic hormones which regulate functions of testes:
Follicle stimulating (FSH)  promotes production of sperm cells
Luteinizing (LH)  promotes production of testosterone
Gonadotropin-releasing (GnRH)  hypothalamus secretes GnRH to the pituitary to release FSH and LH
Once high levels of testosterone are detected by the hypothalamus, negative feedback is activated in that GnRH stops being released.

22. Female Reproductive System
Oogenesis & Ovulation
Ovaries contain fibrous connective tissue and small groups of cells called follicles
Follicles are made up of two types of cells
Primary oocyte - contain 46 chromosomes, undergoes meiosis, ovum
Granulosa cell – nutrient production for oocyte
total follicles in each ovary  approximately 400 will mature in a woman’s life
birth defects and older follicles?

23. Menstrual Cycle Flow phase – shedding of endometrium (5 days)
Follicular phase – development of follicles within ovary, estrogen secreted (day 6-13)
Ovulatory phase – egg bursts from ovary, estrogen and progesterone released (endometrium development). Progesterone inhibits further ovulation and prevents contractions (day 14).
Luteal phase – preparation of uterus for fertilized egg. No fertilization means estrogen and progesterone decrease  weak contractions which cause endometrium to pull away from uterus.

24. Hormonal Control of the Female Reproductive System
Hypothalamus-pituitary complex regulates estrogen and progesterone via gonadotropins
FSH and LH
GnRH signals puberty and allows release of FSH and LH
Negative feedback  as estrogen levels increase the pituitary gland picks this up and turns off FSH
Positive feedback  as estrogen levels increase the pituitary gland picks this up and releases more LH