1. Animal Coordination
Chemical Regulation

2. Endocrine vs Exocrine secretion

3. THE NATURE OF CHEMICAL REGULATION
Chemical signals coordinate activities in different parts of the body
Hormones are chemical signals, usually carried in the blood
Bind to receptors on / in target cells
Cause specific changes in target cells
Exert effects at very low concentrations

4. The Chemistry of Hormones
Amino acid-based hormones
Proteins
Peptides
Amines
Steroids – made from cholesterol
Prostaglandins – made from highly active lipids

6. Hormones are secreted by
Endocrine glands and neurosecretory cells
Secretory
vesicles
Endocrine cell
Hormone molecules
Blood
vessel
Target cell
Neurosecretory cell
Hormone molecules
Blood
vessel
Target cell

8. A few chemicals serve both as hormones in the endocrine system
And as chemical signals in the nervous system
Nerve cell
Nerve signals
Neurotransmitter molecules

9. Mechanisms of Hormone Action
Hormones affect only certain tissues or organs (target cells or organs)
Target cells must have specific protein receptors
Hormone binding influences the working of the cells
Slide 9.4

10. Effects Caused by Hormones
Changes in plasma membrane permeability or electrical state
Synthesis of proteins, such as enzymes
Activation or inactivation of enzymes
Stimulation of mitosis
Slide 9.5

11. Mechanisms of Hormone Action
Hormones affect target cells by two main signaling mechanisms depending on whether it can pass through the plasma membrane
Steroid hormones
( fat soluble)
Non-Steroid hormones
(water soluble)

12. Steroid Hormone Action
Lipid-soluble hormone (testosterone)
Target cell
Receptor
protein
Hormone-
receptor complex
Nucleus
DNA
mRNA
Transcription
New protein
Cellular response: activation
of a gene and synthesis of new protein
Steroid hormones, such as the sex hormones estrogen and testosterone:
Diffuse through the plasma membrane of target cells (how?)
Bind to intracellular receptors
Hormone receptor complex binds DNA in nucleus
Activate genes thus initiates transcription 1 2 3 4

13. Steroid Hormone Action
Diffuse through the plasma membrane of target cells (how?)
Enter the nucleus
Bind to a specific protein within the nucleus
Bind to specific sites on the cell’s DNA
Activate genes that result in synthesis of new proteins
Slide 9.6

14. Steroid Hormone Action
Figure 9.1a
Slide 9.7

15. Nonsteroid Hormone Action
Hormone binds to a membrane receptor
Hormone does not enter the cell
Sets off a series of reactions that activates an enzyme
Catalyzes a reaction that produces a second messenger molecule
Oversees additional intracellular changes to promote a specific response
Slide 9.8

16. Nonsteroid Hormone Action
Water-soluble hormones such as proteins and amines
Bind to plasma-membrane receptors on target cells
Figure 9.1b
Slide 9.9

17. Signal transduction pathway for non-steroid hormones
Hormone binds to a receptor protein on the plasma membrane
Receptor protein activates a signal-transduction pathway in the cell
Series of relay molecules transmits the signal to a protein that carries out the cell’s response

18. Control of Hormone Release
Hormone levels in the blood are maintained by negative feedback
A stimulus or low hormone levels in the blood triggers the release of more hormone
Hormone release stops once an appropriate level in the blood is reached
Slide 9.10

19. Hormonal Stimuli of Endocrine Glands
Endocrine glands are activated by other hormones
Figure 9.2a
Slide 9.11

20. Chemical Stimuli of Endocrine Glands
Changing blood levels of certain ions / metabolite stimulate hormone release
Figure 9.2b
Slide 9.12

21. Neural Stimuli of Endocrine Glands
Nerve impulses stimulate hormone release
Most are under control of the sympathetic nervous system
Figure 9.2c
Slide 9.13

22. 26.3 Overview: The vertebrate endocrine system
Consists of more than a dozen glands secreting more than 50 hormones
Hypothalamus
Pineal gland
Pituitary gland
Thyroid gland
Parathyroid glands
Thymus
Adrenal glands (atop kidneys)
Pancreas
Ovary
(female)
Testes
(male)
Figure 26.3

23. Location of Major Endrocrine Organs
Figure 9.3
Slide 9.14

25. 26.4 The hypothalamus, closely tied to the pituitary, connects the nervous and endocrine systems
The hypothalamus exerts master control over the endocrine system
By using the pituitary gland to relay directives to other glands
Brain
Posterior pituitary
Anterior pituitary
Bone
Hypothalamus

26. Posterior pituitary Anterior pituitary Composed of nervous tissue
Stores and secretes hormones made in the hypothalamus
Anterior pituitary
Composed of glandular tissue
Hormone release controlled by releasing hormones – under control of the hypothalamus
Control the secretion of other hormones by producing trophic hormones.

27. The posterior pituitary
The posterior pituitary
Secretes oxytocin and antidiuretic hormone (ADH)
Hypothalamus transmits nerve signals that trigger release from posterior pituitary
Hypothalamus
Neurosecretory
cell
Hormone
Posterior
pituitary
Blood vessel
Oxytocin
ADH
Uterine muscles Mammary glands
Kidney tubules
Anterior

28. The posterior pituitary (neurohypo- physis) stores and secretes hormones produced by the hypothalamus.

29. The anterior pituitary
Releasing and inhibiting hormones secreted by the hypothalamus control the anterior pituitary
Portal system
The anterior pituitary
Secretes TSH, ACTH, FSH and LH, growth hormone, prolactin.

31. too little GH or defective receptors
Growth hormone disorder
Children
too little GH or defective receptors
dwarfism
too much GH
gigantism

32. ACROMEGALY

37. Table 45.1 (continued)

38. Secretion of thyroxine by the thyroid gland
Hypothalamus
Inhibition
TRH
Anterior pituitary
Thyroid
TSH
Thyroxine
Secretion of thyroxine by the thyroid gland
Is controlled by a negative-feedback mechanism

40. HORMONES AND HOMEOSTASIS
The thyroid regulates development and metabolism
Two hormones from the thyroid gland, T4 and T3
Regulate an animal’s development and metabolism

42. Thyroid imbalance
Can cause cretinism, metabolic disorders and goiter

43. Maintains homeostatic levels of T4 and T3 in the blood
Negative feedback
Maintains homeostatic levels of T4 and T3 in the blood
Hypothalamus
Anterior pituitary
Thyroid
No inhibition
No iodine
Insufficient T4 and T3
produced
Thyroid grows to form goiter
TRH
TSH

44. Pancreatic hormones Pancreatic hormones regulate blood glucose levels
Pancreatic hormones regulate blood glucose levels
The pancreas secretes two hormones
Insulin
Signals cells to use and store glucose
Glucagon
Signals cells to release stored glucose into the blood

46. The islets are composed of three cell types: alpha cells, beta cells, and delta cells. These cells cannot be readily distinguished without special stains. Delta cells (not visibly stained in this slide) are found throughout the islet and secrete somatostatin.
The insulin producing cells are called  cells and make up about 70% of the islet cells.
The glucagon producing cells are called  cells and make up about % of the islet cells.

47.  cells of islets of Langerhans
SECRETORY ROLE
CELL CHARACTERISTICS
 cells of islets of Langerhans
Glucagon
% of the islet cells; generally more peripherally located in the islet; more uniform in size; cytoplasm appears to be more densely packed than the  cells
 cells of islets of Langerhans
Insulin
70% of the islet cells; generally more centrally located in the islet
 cells of islets of Langerhans
Somatostatin
approximately 5 – 10% of the islets
Acinus cells
Digestive enzymes
Usually oriented in a circular pattern

48. Homeostasis: Normal blood glucose level
Glucose balance
Body
cells
take up more glucose
Insulin
Blood glucose level declines to a set point; stimulus for insulin release diminishes
Stimulus:
Declining blood glucose level (e.g., after skipping a meal)
Alpha cells of pancreas stimulated to release glucagon into the blood
Glucagon
Liver breaks down glycogen and releases glucose to the blood
Blood glucose level rises to set point; stimulus for glucagon release diminishes
Rising blood glucose level (e.g., after eating a carbohydrate-rich meal)
Homeostasis: Normal blood glucose level
(about 90 mg/100mL)
Beta cells
of pancreas stimulated to release insulin into the blood
Liver takes up glucose and stores it as glycogen
High blood
glucose level

51. Hours after glucose ingestion
Diabetes can be detected
By a test called a glucose tolerance test
400
350
300
Diabetic
Blood glucose (mg/100mL)
250
200
150
100
Normal 50 1 2 1 2 3 4 5
Hours after glucose ingestion

52. Diabetes is a common endocrine disorder Diabetes mellitus
Results from a lack of insulin or a failure of cells to respond to it
2 types of diabetes
Type I (insulin-dependent)
Autoimmune disease
Beta cells destroyed, no insulin made
Type II
Body cells fail to respond to insulin

53. Diabetes type I and type II
Type II - due to aging, lifestyle, heredity and other lifestyle (diet) factors decreased responsiveness by cells of target organs to insulin
Type I - autoimmune disorder (destroys ability to produce insulin)

56. Complications related to Diabetes

57. Insulin Pump

60. Interaction between Hormones
synergism occurs when more than one hormone produces the same effects in a target cell, and their combined effects are amplified
both glucagon and epinephrine cause the liver to release glucose into the bloodstream
2. antagonism occurs when one hormone opposes the action of another hormone
insulin lowers blood sugar, and glucagon raises blood sugar

62. Adrenal glands consists of adrenal cortex and adrenal medulla

63. The adrenal glands mobilize responses to stress
The adrenal glands mobilize responses to stress
Hormones from the adrenal glands
Help maintain homeostasis when the body is stressed
Adrenal medulla
Nervous signals from hypothalamus stimulate secretion of epinephrine
Trigger fight or flight response

64. Boost blood pressure and energy in response to long-term stress
Adrenal cortex
ACTH from the pituitary causes the adrenal cortex to secrete glucocorticoids and mineralocorticoids
Boost blood pressure and energy in response to long-term stress

65. How the adrenal glands control our responses to stress
Figure 26.9

66. Glucocorticoids offer relief from pain, but not without serious risks
Glucocorticoids relieve inflammation and pain
But they can mask injury and suppress immunity
Figure 26.10

67. The gonads secrete sex hormones
Estrogens, progestins, and androgens are steroid sex hormones
Produced by the gonads in response to signals from the hypothalamus and pituitary
Estrogen and progestins
Maintain female reproductive system
Development of female characteristics

68. Androgens, such as testosterone
Androgens, such as testosterone
Trigger the development of male characteristics

69. Other Hormone-Producing Structures
a. Gastrointestinal tract
contains enteroendocrine cells throughout the mucosa
secrete hormones to regulate digestive functions
b. Placenta
secretes estrogens, progesterone, and human chorionic gonadotropin
act on the uterus to influence pregnancy

70. Other Hormone-Producing Structures
c. Kidneys
produce erythropoietin--signals the bone marrow to make RBCs
d. Skin
produces cholecalciferol--inactive form of vitamin D3
e. Adipose tissue
produces leptin---acts on the hypothalamus to produce a feeling of satiety

71. Hypothalamic feeding center
Neuropeptide Y
Hypothalamic feeding center
Negative feedback
 Food intake
 Fat stores   
 Leptin secretion   

72. Hypothalamic feeding center
Neuropeptide Y
Hypothalamic feeding center X
Negative feedback
 Food intake
 Fat stores    X
 Leptin secretion