15. physiology of Endocrine system [hormones]. ppt

endocrine

1. ENDOCRINE SYSTEM

2. Endocrine -General
•Major Control System of Homeostasis
•Negative Feedback
•Ductless Glands; Produce Hormones
•Diffuse into Blood
•SlowInitial Effects, but Effects Persist much
longer
•Hormones act on specific Targets

3. Mechanisms of Hormone Action
•Steroid Hormones (synthesized from
cholesterol)
–Hormone enters cell and binds to receptor
–Hormone/receptor complex enters nucleus
and binds to DNA
–Protein synthesis occurs
–Protein alters cell function
–Ie testosterone increasing sperm production

5. Mechanisms of Hormone Action
•Non-Steroid Hormones
(Proteins/Peptides/Amines)
–Hormone does not enter cell
–Hormone is 1st messenger; it binds to receptor
on cell membrane
–Triggers formation of 2
nd
messenger (cyclic
AMP) that alters cellular activities
–Ie. pituitary hormones

7. Endocrine Organs
•Pineal Gland
•Hypothalamus
•Pituitary
–Anterior
–Posterior
•Thyroid Gland
•Parathyroid Glands
•Thymus
•Adrenal Glands
–Cortex
–Medulla
•Pancreas
•Gonads
•Kidney/adipocytes/
small intestine

8. Hypothalamus/ Pituitary Gland

9. Regulation of Endocrine System
Figure 18–8a Feedback Control of Endocrine Secretion

10. Hypothalamus
•Communicates w/ anterior pituitary via hypothalamic-
hypophyseal portal vein
•Dumps protein hormones into portal veinant.
pituitary
•Releasing hormones stimulate hormone production in
anterior pituitary
•Inhibiting hormones prevent hormone production in
anterior pituitary

11. Hypothalamus/ Pituitary Gland

12. Anterior Pituitary
•Adenohypophysis
•Under hypothalamus rule via vein
•Releases six different hormones into the blood:
–Thyroid stimulating hormone (TSH)
–Adrenocorticotropic hormone (ACTH)
–Follicle stimulating hormone (FSH)
–Luteinizing hormone (LH)
–Prolactin (PRL)
–Growth hormone (GH)

13. Hypothalamus/ Pituitary Gland

14. Figure 18–9 Pituitary Hormones and Their Targets.

15. Posterior Pituitary
•Neurohypophysis
•Communicates with hypothalamus via nerve
axons from hypo to post. pit.
•Releases two different hormones into the blood:
–Antidiuretic hormone (ADH)
–Oxytocin

16. Hypothalamus/ Pituitary Gland

17. Figure 18–9 Pituitary Hormones and Their Targets.

18. Thyroid Gland
•Regulates basal metabolic rate via thyroxine
•Regulates blood [Ca
+2
] with the parathyroid gland by
releasing calcitonin when high blood [Ca
+2
]
Basal Metabolic Rate:
•Follicular cells release thyroid hormones T3
(Triiodothyronine) & T4 (Thyroxine)
•These hormones increases metabolic rate, regulates
body temperature

21. •Hypothyroidism(low thyroid hormone level)
leads to weight gain, lethargy, and potential
depression.
•Hyperthyroidism(oversecretion of thyroid
hormones), or Graves’disease, leads to
hyperactivity and insomnia; eyeballs tend to
bulge and a goiter (enlarged thyroid gland)
forms.
–Removal of a part of the thyroid is the usual
treatment
Thyroid Disorders

22. •Graves’disease
onset may be
associated with
severe stress.
Figure 16.12

23. Thyroid Gland
Blood Calcium Homeostasis
•Thyroid gland releases calcitonin when high blood
[Ca
+2
]
•Parathyroid gland releases parathyroid hormone
when low blood [Ca
+2
]
•Considered a humoralmediated response

25. http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/thyroid/pth.html

26. Adrenal Gland
Two separate portions with different functions:
•Adrenal cortex
•Adrenal medulla

27. Adrenal Gland
Adrenal Cortex (outer/glandular)
–Glucocorticoids (cortisol)
•Released from zona fasciculata when under stress (
ACTH)
•Causes tissues to increase blood glucose, liver storage
of glucose (glycogen) and decrease inflammation/
immune response
–Mineralcorticoids (aldosterone)
•Released from zona glomerulosa when blood volume
is low
•Increases blood volume by increasing Na
+
/ H
2O
reabsorption & K
+
excretion from kidneys
–Androgens (zona reticularis)
•Sex hormones

28. •Cushing’s syndrome-hypercortisolism
–Cushing’s patients have very high
glucocorticoid levels caused by adrenal or
pituitary disease or an excess of
glucocorticoid drugs.
–Cushing’s patients store fat in cells (face and
midsection) that only respond to high levels of
insulin, and they have a high risk of type-2
diabetes.
Stress Response

30. Aldosterone
30
Regulates blood volume
-Secretion by the adrenal cortex triggered by angiotensin II
-Promotes sodium reabsorption by the kidney tubules
-Na
+
moves back into the blood
-H
2O follows by osmosis

31. Adrenal Medulla

32. Adrenal Gland
•Adrenal Medulla (inner/nervous)
–CNS synapses directly with adrenal medulla
(neural response)
–Adrenal medulla releases Epinephrine (adrenalin)
& NorEpinephrine (noradrenalin) during your fight
or flight mechanism
–Stimulates use of glucose and glycogen and release
of lipids from adipocytes
–Increases HR, BP and vasoconstricts blood vessels
–Stress and low blood glucose can increase Epi and
NE

33. Figure 18–9 Pituitary Hormones and Their Targets.

34. Posterior Pituitary and ADH
•Posterior pituitary will release antidiuretic
hormone (ADH; vasopressin) into the blood
when blood osmolarity is high
–Is this when you are hydrated or dehydrated?
•ADH target is kidney
–Reabsorb H
2O back into body to decrease blood
osmolarity (~ 300 mOsM)
–Less urine is formed

35. Regulation
of Blood
Osmolarity

36. Diabetes Insipidus
•Less water reabsorption and excessive urination
•Decrease in ADH due to damage to hypothalamus
or post. pituitary (brain trauma; tumor)
•OR damage to kidney so water reabsorption is
inhibited (inherited genetic mutation in males,
drugs, infection, and hypercalcemia)

37. Pancreas***
•Digestive and endocrine functions
•Endocrine portion is the Islet of Langerhans
•alphacells release glucagon
•betacells release insulin
•Regulates blood glucose levels

38. Blood Glucose Regulation
•Low blood glucose
–When blood glc is low (when you wake up) glucagon
is release into the blood
–increases blood glucose by causing the liver to break
down glycogen
•High blood glucose
–When blood glc is high (after a meal) insulin is
released into the blood
–Decreases blood glucose by causing glucose to go into
body cells
–Liver cells store glucose as glycogen

39. blood glucose (120 mg/dl)
Pancreatic Beta cells
Liver and Skeletal Muscle
Liver and skeletal muscle uptake
glucoseglycogen
Blood Glucose Homeostasis
insulin
blood glucose (110 mg/dl)
www.histol.chuvashia.com/imag
es

40. Stimulus
Sensor
Integrator
Effector
Response
Result
Blood Glucose Homeostasis
Disturbance
(i.e. Diabetes
melitus)

41. Blood glucose homeostasis is disrupted by both types
of Diabetes mellitus (type 1 and type 2)
http://www.theholisticcare.com/cure%20diseases/Imag
es/Pancreas.jpg
insulin

42. Blood glucose homeostasis is disrupted by both types
of Diabetes mellitus (type 1 and type 2)
http://www.theholisticcare.com/cure%20diseases/Imag
es/Pancreas.jpg
insulin
Blood glucose

43. Pineal & Thymus Glands
•Pineal Gland (Endocrine & CNS)
–Melatonin
•Target: Hypothalamus
•Action: Sets Diurnal Clock/Circadian rhythm
& promotes sleep
•Thymus (atrophies at puberty)
–Thymosins
•Target: T cells of immune system
•Action: T cell maturation
(immunocompetence)

44. Figure 16.13