1. Chemical signals in animals

2. Keywords Reading Ch. 45 Endocrine system Hormone Target cell
Neurosecretory cell
Steroid
Amino acid derived hormone
Surface receptors
Internal receptors
Action of steroids
Glucose homeostasis
Insulin
Glucagon
Epinephrine
Norepinephrine
ACTH

3. Chemical signals outside of organisms
Pheromones
Prey tracking by rattlesnakes

4. Pheromone
A small volatile chemical signal that functions in communication between animals
Often in mate attraction

5. Rattlesnakes (research of Dr. Ken Kardong Zoology WSU)
Bite prey, inject venom, prey runs away, snake can track down the prey
Follows a scent trail left by bitten prey.
Doesn’t matter if venom glands have been ligated
Don’t know what the signal is.

6. Will focus on chemical signals inside organisms
Two regulatory systems coordinate internal body functions
Nervous system (will deal with in a later lecture)
Endocrine system (focus of today’s lecture)

7. Endocrine system definition
The internal chemical communication system involving hormones
Hormone
Chemical signal secreted into body fluids (usually blood)
Effective in minute amounts

8. Types of signaling in endocrine system

9. Hormones act on specific target cells in two ways
Surface receptors
Within target cells (internal receptor)

10. Surface receptor - often amino acid derived hormone

11. Internal receptor - often steroid hormones

12. Action of steroids

13. Two specific examples of hormone action
Glucose homeostasis
Stress and the adrenal gland

14. Glucose homeostasis
Homeostasis = The steady-state physiological condition of the body
Glucose = major fuel of cellular respiration
Normal blood glucose level = 900 mg/L
How is this regulated?
First look at when glucose levels are too high

15. P. 906

16. High blood glucose causes beta cells to release insulin

19. Summary Beta cells release insulin
Insulin causes body cells and liver to take up glucose
Glucose levels restored

20. What happens if you need to increase blood glucose?

21. Low blood glucose causes alpha cells to release the hormone glucagon

22. Glucogon stimulates the liver to break down glycogen releasing glucose

23. Summary
Low blood glucose causes alpha cells to release the hormone glucagon
Glucogon stimulates the liver to break down glycogen releasing glucose

24. Glucose homeostasis
Example of use of amino-acid derived hormones: insulin and glucagon are peptides
Surface receptors on target cells

25. Diabetes mellitus Greek = copious urine, honey
Type I - autoimmune disorder - cells of pancreas are targeted - no ability to produce insulin - usually occurs during childhood
Type II (90%) - reduced responsiveness of target cells or insulin deficiency-usually occurs after age 40

26. Stress and the adrenal gland
Short-term response - Epinephrine (adrenaline) and norepinephrine
Long-term response - ACTH and corticosteroids

27. P. 909

28. Short-term stress: medulla of the adrenal gland

30. Some effects of epinephrine and norepinephrine
Glycogen broken down to glucose
Increased blood pressure, breathing, metabolic rate

31. Example of:
Use of neurosecretory cells
Amino acid-derived hormones

32. Long-term stress: cortex of the adrenal gland

34. Corticosteroids (mineral- and gluco- corticoids) released by adrenal cortex
Some effects: increased blood volume and blood pressure, breakdown of protein and fats

35. Example of: Interaction between nervous and endocrine systems
Use of steroid hormones