1. Biology 103 - Main points/Questions
Remember Plant Hormones?
What are the major human endocrine glands?
What hormones do you need to know?
How are hormones controlled?

2. In Summer plants need to balance root and shoot growth - too much of either is a waste of resources. Do you remember how they do this?

3. shoot tip
gradient of
auxin
plants need to balance root and shoot growth – use AUXIN & CYTOKININ amounts
(high)
(low)
Figure: 26-3
Title:
The role of auxin and cytokinin in lateral bud sprouting
Caption:
A simplified diagram of the interplay of auxin (blue dots) and cytokinin (red dots) in the control of sprouting of lateral buds. Auxin is produced by shoot tips and moves downward; cytokinin is produced by root tips and moves upward. Question What result would you expect if a plant's shoot tip were removed and auxin were applied to the cut surface?
(high)
gradient of
cytokinin

4. positive phototropism – controlled by …?
AUXIN!
Light!

5. In fall plants need to respond to changing environmental cues to trigger leaf senescence (death).

6. Figure 24.14 The effects of ethylene

7. Hormone Signals in Animals
Used for longer term signals than neurons
Different cells respond to different hormones
Hormones often key for homeostasis

8. 33.02 The Timescale over Which Chemical Messengers Work
CD33020.GIF

9. There are three big advantages to using chemical hormones as messengers rather than speedy electrical signals (nervous)
chemical molecules can spread to all tissues via the blood
chemical signals can persist much longer than electrical ones
many different kinds of chemicals can act as hormones

10. Balancing water concentration
The concentration of the urine is regulated to maintain homeostasis
Hormones are key signaling molecules in this process.

11. Negative feedback loops fight dehydration..
Page. 626

12. Your body also releases a hormone ADH that signals to the kidneys.
As you dehydrate you get thirsty (this is controlled by the nervous system)
Your body also releases a hormone ADH that signals to the kidneys.
Where does water get reabsorbed in the kidney?
Page. 626

13. The 5 steps of urine formation
Pressure Filtration
Reabsorption of water
Selective reabsorption
Secretion
More water reabsorption

14. Further reabsorption of water
Final step that balances water amounts
Water can be variably reabsorbed into blood from collecting duct
waters ability to be reabsorbed is controlled by a hormone called ADH – how?

15. Hormone signaling is a series of simple steps
issuing the command – release of the hormone from a gland

16. Issuing the command

17. Hormone signaling is a series of simple steps issuing the command
transporting the signal
most are transported through body by the blood

18. Transport

19. Hormone signaling is a series of simple steps issuing the command
transporting the signal
hitting the target
hormone binds to a receptor on the target cell

20. “hit the target”

21. Hormone signaling is a series of simple steps issuing the command
transporting the signal
hitting the target
having an effect
After binding the receptor protein changes shape and triggers a change in cell activity

23. Two basic categories of hormones
ADH is a peptide hormone (remember a peptide bond?
Built of amino acids
The other class of hormones are steroid based
Steroids are lipids so can pass through membranes!

24. Peptide based Steroid Bind to receptor on membrane
Transported attached to a protein
Bind to receptor inside the cell
Water-
soluble
hormone
Fat-soluble
hormone
Transport
protein
Signal receptor
TARGET
CELL
Signal
receptor
Figure 45.5 Receptor location varies with hormone type
(a)
NUCLEUS
(b)

25. Peptide based
Signals are often more transient (just in the cytoplasm)
May alter gene expression
Steroid
Mostly alter gene expression
Tend to be long lasting effects
Water-
soluble
hormone
Fat-soluble
hormone
Transport
protein
Signal receptor
TARGET
CELL OR
Signal
receptor
Figure 45.5 Receptor location varies with hormone type
Cytoplasmic
response
Gene
regulation
Cytoplasmic
response
Gene
regulation
(a)
NUCLEUS
(b)

26. Hormones are produced in glands throughout your body

27. Coordination of Endocrine and Nervous Systems in Vertebrates
The hypothalamus receives information from the nervous system and initiates responses through the endocrine system
Attached to the hypothalamus is the pituitary gland composed of the posterior pituitary and anterior pituitary

28. The posterior pituitary stores and secretes hormones that are made in the hypothalamus
The anterior pituitary makes and releases hormones under regulation of the hypothalamus

29. The posterior pituitary contains cells that originate in the hypothalamus

30. The hypothalamus and the posterior pituitary are connected by a tract of neurons
hormones are made by cell bodies in the hypothalamus & moved to posterior pituitary
antidiuretic hormone (ADH) regulates the kidney’s retention of water
oxytocin initiates uterine contractions during childbirth and milk release in mothers

31. The anterior pituitary is a complete gland that produces the hormones that it secretes

32. The Hypothalamus and the Pituitary
The hypothalamus controls production and secretion of the anterior pituitary hormones by means of a family of special hormones
neurons in the hypothalamus secrete releasing hormones
they travel to the anterior pituitary through a special capillary system,

33. Portal system of the anterior pituitary gland and hypothalamus

34. The Anterior Pituitary
Secretes seven different hormones some you already know about…
LH & FSH
Some that are new to you…
TSH & GH

35. Pituitary hormones

36. Follicle-stimulating hormone (FSH)
in females, it triggers the maturation of egg cells and stimulates the release of estrogen
in males, it regulates sperm development
Luteinizing hormone (LH)
in females, it triggers ovulation of a mature egg
in males, it stimulates the gonads to produce testosterone

37. Degenerating corpus luteum
Control by hypothalamus
Inhibited by combination of estrogen and progesterone
Hypothalamus –
Stimulated by high levels of estrogen
Estrogen production feeds back on the signal that drives estrogen release
GnRH +
Anterior pituitary
Inhibited by low levels of estrogen –
FSH LH
(b)
Pituitary hormones in blood LH
FSH
FSH and LH stimulate follicle to grow
LH surge triggers ovulation
Figure The reproductive cycle of the human female
(c)
Ovarian cycle
Growing follicle
Corpus luteum
Degenerating corpus luteum
Maturing follicle
Follicular phase
Ovulation
Luteal phase
Days | | | | | | | | 5 10 14 15 20 25 28

38. growth hormone (GH) Thyroid stimulating hormone (TSH)
simulates the growth of muscle and bone throughout the body
Thyroid stimulating hormone (TSH)
Stimulates thyroid to produce thyroxin – a key control of metabolism

39. Negative feedback (feedback inhibition) controls how target gland hormones in the anterior pituitary are produced
when enough of the target hormone has been produced, the hormone then feeds back to the hypothalamus and inhibits the release of stimulating hormones from the hypothalamus and the anterior pituitary

40. What if you don’t have enough iodine?
Thyroxine
Modifies metabolic rate
Requires iodine
What if you don’t have enough iodine?

41. Fig b

42. Hormones are key players in maintaining homeostasis
Commonly used as signals in negative feedback loops
Remember Insulin & Glucagon?

43. Insulin and Glucagon: Control of Blood Glucose
Insulin and glucagon are antagonistic hormones that help maintain glucose homeostasis
The pancreas has clusters of cells that produce glucagon and insulin

44. Body cells
take up more
glucose.
Insulin
Beta cells of
pancreas
release insulin
into the blood.
Liver takes
up glucose
and stores it
as glycogen.
STIMULUS:
Blood glucose level
rises.
Blood glucose
level declines.
Homeostasis:
Blood glucose level
(about 90 mg/100 mL)
STIMULUS:
Blood glucose level
falls.
Blood glucose
level rises.
Figure Maintenance of glucose homeostasis by insulin and glucagon
Alpha cells of pancreas
release glucagon.
Liver breaks
down glycogen
and releases
glucose.
Glucagon

45. Control of Blood Calcium
Two antagonistic hormones regulate calcium (Ca2+) in the blood of mammals
Parathyroid hormone (PTH) causes blood calcium levels to increase
Calcitonin causes blood calcium levels to decrease.

46. PTH increases the level of blood Ca2+
It releases Ca2+ from bone and stimulates reabsorption of Ca2+ in the kidneys
It also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca2+ from food
Calcitonin decreases level of blood Ca2+
It stimulates Ca2+ deposition in bones and secretion by kidneys

47. Draw the two negative feedback loops that involve these two hormones
Increasing Blood Calcium level
Blood Calcium level (about 10mg/100ml)
Decreasing Blood Calcium level

48. Calcium Regulation What happens when calcium levels drop?
Parathyroid hormone (PTH) is secreted & causes bone cells to release calcium from the bones
PTH also stimulates calcium reabsorption by the kidneys and absorption by the gut
So dropping Ca++ leads to raising Ca++

49. Falling blood Ca2+ level Blood Ca2+ level (about 10 mg/100 mL)
PTH
Parathyroid gland (behind thyroid)
Figure The roles of parathyroid hormone (PTH) in regulating blood calcium levels in mammals
STIMULUS:
Falling blood Ca2+ level
Homeostasis:
Blood Ca2+ level (about 10 mg/100 mL)

50. Falling blood Ca2+ level Blood Ca2+ level (about 10 mg/100 mL)
Fig
Active vitamin D
Stimulates Ca2+ uptake in kidneys
Increases Ca2+ uptake in intestines
PTH
Parathyroid gland (behind thyroid)
Stimulates Ca2+ release from bones
Figure The roles of parathyroid hormone (PTH) in regulating blood calcium levels in mammals
STIMULUS:
Falling blood Ca2+ level
Blood Ca2+ level rises.
Homeostasis:
Blood Ca2+ level (about 10 mg/100 mL)

51. Calcium Regulation What happens when calcium levels rise?
Calcitonin is secreted & causes bone cells to sequester calcium in the bones
Calcitonin also slows calcium reabsorption by the kidneys
So raising Ca++ leads to falling Ca++

52. Hormonal control of calcium homeostasis in mammals

53. What do you need to know? Control Systems - Hormones:
List major plant hormones and their roles.
Explain how the two basic classes of animal hormones have their effects on a cell.
Describe antagonistic hormones and explain how they work together to maintain homeostasis.
List some major human hormones (certainly you should know ADH, insulin, glucagon, calcitonin & PTH and you should be familiar with FSH, LH, estrogen, and progesterone), where they are produced and their roles.

54. For the Discovery Video Endocrine System, go to Animation and Video Files.

55. Figure 45.1 What role do hormones play in transforming a caterpillar into a butterfly?
For the Discovery Video Endocrine System, go to Animation and Video Files.

56. Non-mammal Hormones
In insects, hormonal secretion influence both metamorphosis and molting
prior to molting, neurosecretory cells on the surface of the brain secrete brain hormone
brain hormone then stimulates a gland in the thorax to produce molting hormone (ecdysone)
juvenile hormone is produced in the brain and determines the result of a particular molt
when juvenile hormone levels are high, the molt produces another larva

57. Juvenile hormone promotes retention of larval characteristics
Ecdysone promotes molting (in the presence of juvenile hormone) and development (in the absence of juvenile hormone) of adult characteristics

58. Brain Neurosecretory cells Corpus cardiacum PTTH Corpus allatum
Prothoracic
gland
Ecdysone
Juvenile
hormone
(JH)
Figure Hormonal regulation of insect development
EARLY LARVA

59. Brain Neurosecretory cells Corpus cardiacum PTTH Corpus allatum
Prothoracic
gland
Ecdysone
Juvenile
hormone
(JH)
Figure Hormonal regulation of insect development
EARLY LARVA
LATER
LARVA

60. Brain Neurosecretory cells Corpus cardiacum PTTH Corpus allatum Low JH
Prothoracic
gland
Ecdysone
Juvenile
hormone
(JH)
Figure Hormonal regulation of insect development
EARLY LARVA
LATER
LARVA
PUPA
ADULT

61. The hormonal control of metamorphosis