hormone--> Bloodstream------> target organ/tissue"> hormone--> Bloodstream------> target organ/tissue">

Presentation is loading. Please wait.

Presentation is loading. Please wait.

Integration and Control:

Similar presentations

Presentation on theme: "Integration and Control:"— Presentation transcript:

1 Integration and Control:
THE ENDOCRINE SYSTEM Campbell & Reece Chapter 45

2 Endocrine Hormones: substances produced by particular tissues of the body carried by the bloodstream to "target cells," upon which they exert special effects *Hormones are secreted by glands, made mostly of epithelial tissue Exocrine glands: secrete into ducts (sweat glands, digestive glands) Endocrine glands: secrete hormones (into bloodstream) "ductless glands" Endocrine Gland--->hormone--> Bloodstream------> target organ/tissue

3 Active in very small quantities Controlled by:
Hormones may be: Steroids Peptides/proteins; Amino acids Active in very small quantities Controlled by: Negative Feedback Rapid degradation by the body Hormonal communication

4 Positive & Negative feedback

5 Mechanisms of Action of Hormones:
2 Main ways that Hormones Effect Target Cells: Intracellular receptor molecules- steroids, thyroid hormones Membrane receptor molecules- amino, peptide, protein hormones A.  Intracellular Receptors Steroid hormones and thyroid hormones are soluble in lipids and pass freely through cell membranes; must contact receptor site with in a cell This changes a cell’s actions (protein synthesis, etc.) B.  Membrane Receptors Combine with receptors on or in the membrane target cells Once combined, send a second messenger inside ? to the nucleus (cyclic AMP) May simply increase/decrease a cell’s permeability to substances Action of Steroid Hormones

6 The Hypothalamus-Pituitary Axis:
Pituitary was once considered the "master gland" until it was learned that it was under control of the hypothalamus (brain region) The hypothalamus makes several hormones which travel to and are released by the pituitary lobes. Target tissues are stimulated by (or inhibited by) release of these hormones into the bloodstream.

7 Hormone Major Target Organ(s) Effects Anterior Pituitary Growth hormone (GH) Liver, adipose tissue Promotes growth (indirectly), control of protein, lipid and carbohydrate metabolism Thyroid-stimulating hormone (TSH) Thyroid gland Stimulates secretion of thyroid hormones Adrenocorticotropic hormone (ACTH) Adrenal gland (cortex) Stimulates secretion of glucocorticoids Prolactin (PRL) Mammary gland Milk production Luteinizing hormone (LH) Ovary and testis Control of reproductive function Follicle-stimulating hormone (FSH) Posterior Pituitary Antidiuretic hormone (ADH) Kidney Conservation of body water Oxytocin Stimulates milk ejection and uterine contractions

8 The Hypothalamus-Pituitary Axis:
About the size of a kidney bean Divided into three lobes: Anterior, posterior, intermediate

9 Anterior Pituitary Somatotropin = growth hormone (GH), stimulates protein synthesis, growth of muscle and bone Deficit: midget Excess: giantism (acromegaly) Affects glucose metabolism; inhibits uptake and oxidation of glucose by cells, stimulates breakdown of fatty acid for energy (conserves glucose) Prolaction (PRL) –stimulates the secretion of milk in mammals controlled by inhibiting hormone in hypothalamus continued by nerve impulses from suckling; hypothalamus (supply upon demand)

10 Intermediate Pituitary Lobe
Melanocyte- stimulating Hormone (MSH) (Wikipedia)  ...stimulate the production and release of melanin (melanogenesis) by melanocytes in skin and hair. MSH is also produced by a subpopulation of neurons in the hypothalamus. MSH released into the brain by these neurons has effects on appetite and sexual arousal. More important for color change in reptiles, etc.

11 Posterior Pituitary Lobe
Hypothalamus releases Oxytocin and antidiuretic hormone (ADH) and stores it here, released by posterior pituitary Oxytocin- "milk let down" hormone, stimulates uterine contractions, smooth muscle contraction (BP regulation) Antidiuretic Hormone (ADH)- a.k.a. vasopression (increase BP) decreases excretion of water by kidneys. Increases permeability of water in nephrons

12 Regulation of The Other Glands:
Regulation: negative feedback system involving a gonadotropic (gonad-stimulating) hormone LH (luteinizing hormone): produced by ant. pituitary In males: LH is carried by blood to stimulate testes as blood level of testosterone increases, LH production decreases In females: rise in LH stimulates ovulation FSH (follicle-stimulating hormone): In males: acts upon the sertoli cells of the testes, important for spermatogenesis In females:  stimulates maturation of germ cells, sets mentrual cycle High concentrations of LH cause germ cells to produce an inhibitor, "inhibin", which will then lower LH levels

13 The Endocrine Glands

14 Testes Androgens- the "male sex hormones"
Testosterone (steroid) is one type.  Produced in the testes necessary for sperm production and secondary sex characteristics: genitals larnyx (voice change) skeletal enlargement muscle tissue acne

15 The Ovaries Estrogens- the "female sex hormones"
Different kinds of estrogen hormones:  estriol, estrone, and estradiol (most important) Produced by ovaries by stimulation of FSH from pituitary Stimulate development of secondary sex characteristics (breast development, genital development, distribution of body fat) Progesterone- maintenance of pregnancy, uterus (estrogen, progesterone interaction= menstrual cycle) estrus cycle diagram, showing hormone fluctuations in the mare

16 Prostaglandins Hormone-like chemicals differ from other hormones:
Fatty acids (formed by oxygenation of Arachidonic Acid) Produced by cell membranes of most organs (as opposed to specific glands) Often exert effects on the tissues that produce them The target tissue may be that of another person (e.g. in semen, for fertilization) More patent than hormones (needed in smaller amounts) Effects- stimulation of smooth muscle (uterus- menstruation labor); blood vessel dilation/constriction (BP down, up); inflammatory response by T-cells

17 Adrenal Glands Adrenal Cortex- outer layer of adrenal glands; major source of steroid hormones Adrenal glands lie on top of kidneys ("ad-renal") Humans: two major groups of adrenocortical steroids Glucocorticoids Mineralocorticoids

18 Adrenal Cortex: Glucocorticoids
Glucocorticoids- used to suppress inflammation (medical) Cortisol- (most important) mainly the formation of glucose from fats and proteins. Inhibit up take of glucose by most cells (except brain and heart). Release increases during excitement etc.; work with sympathetic nervous system. Secreted in response to Adrenocorticotropic Hormone (ACTH), secreted by Ant. Pituitary ("master gland") which is stimulated by hormone released from Hypothalamus

19 Adrenal Cortex: Mineralocorticoids
Affect the ion concentration in the blood; water loss/retention. Aldosterone- (example) regulation of ions (K+, Na+) Affect the transport of ions across membranes of the NEPHRONS Deficiency leads to Na+ ion loss (via urine) = loss of water = lowers blood pressure Since adrenal cortex is source of androgens (male and female) sex hormones, a tumor can increases male secondary sex characteristics (e.g. bearded ladies)

20 Adrenal Medulla Central portion of adrenal made up of neurosecretory cells (rather than epithelial) Adrenaline and Noradrenalin- increase rate and strength of heartbeat; raise BP; dilate resp. passages (act as enforcer of sympathetic N.S.)

21 Pancreatic Hormones: "Islets of Langerhans"
Insulin: secreted in response to rise in blood sugar or AA concentration. It lowers blood sugar by stimulating up take of glucose (conversion of glucose to glycogen by liver) Glucagon: increases blood sugar by breakdown of glycogen glucose in liver and breakdown of fats/proteins Somatostatin: synthesis of insulin Five different sugar-regulating hormones (growth hormone, cortisol, insulin, adrenalin, glucagon) Diabetes- insulin too low Hypoglycemia- insulin too high

22 Thyroid Gland: Located on top of Larynx
Controlled by "hypothalamus- pituitary axis" - TSH (thyroid-stimulating hormones a.k.a. "thyrotropin" A.  Thyroxine Accelerates rate of cellular respiration (metabolism) differs from androgens, estrogens, corticosteroids because it is an amino acid with 4 iodine atoms (T4), also T3 B.  Calcitonin: inhibits release of calcium ions [Ca2+ ions] from bones. Secretion is controlled by Ca ion conc. in fluid around thyroid cells.

23 Thyroid diseases Goiter is a swelling of the thyroid gland, results from low iodine in diet Hyperthyroidism: (overproduction) weight loss, nervousness, fatigue.  Most common cause in Grave's Disease. Hypothyroidism: (underproduction) dwarfism in infants (Cretinism) low energy, low brain cell development, can be caused by insufficient iodine in diet autoimmune disease of thyroid :  Hashimoto's thyroiditis

24 Parathyroid Glands: Located below thyroid, pea- size, smallest endocrine gland Parathormone: essential in mineral metabolism, regulation of Calcium and Phosphate ions in blood stimulates release of Ca?? ions from bones; secreted in response to low blood [Ca2+] (Calcium = blood coagulation, muscle contraction, nerve function)

25 The Pineal Gland Small lobe in forebrain, near center
Involved in "photoperiodism"- seasonal enlargement of ovaries etc. Secretes hormone: Melatonin (up/down, day/night) Melatonin: causes pigment cells to open/close "biological clock"

Download ppt "Integration and Control:"

Similar presentations

Ads by Google