1. Thyroid and Parathyroid Glands

2. Found at: Consists of: Produces two hormones 1. Thyroid hormone
the base of the throat
Consists of:
two lobes and a connecting isthmus
Produces two hormones
1. Thyroid hormone
2. Calcitonin

4. Thyroid Gland 1. Thyroid hormone Major metabolic hormone
Composed of two active iodine-containing hormones
Thyroxine (T4)—secreted by thyroid follicles
Triiodothyronine (T3)—conversion of T4 at target tissues

5. Thyroid Gland

6. Thyroid Hormone Disorders
Goiters
Thyroid gland enlarges
In U.S., rarely see goiters due to lack of iodine because we use “iodized” salt

7. Goiters

8. Thyroid Hormone Disorders
Cretinism
Caused by hyposecretion of thyroxine
Lack of iodine
Congenital lack of thyroid gland
Results in stunted physical and mental growth during childhood

9. Cretinism

10. Thyroid Hormone Disorders
Myxedema
Caused by hypothyroidism in adults
Results in physical and mental slugishness

11. Myxedema

12. Thyroid Hormone Disorders
Grave’s Disease
Caused by hyperthyroidism
Results in:
increased metabolism
heat intolerance
rapid heartbeat
weight loss
exophthalmos

13. Exophthalmos

14. Thyroid Gland 2. Calcitonin
Decreases blood calcium levels by causing its deposition on bone
Antagonistic to parathyroid hormone
Produced by parafollicular cells

15. Parathyroid Gland
Tiny masses (4) on the posterior of the thyroid

16. Parathyroid Gland Secrete parathyroid hormone (PTH)
Raise calcium levels in the blood
1. Stimulate osteoclasts to remove calcium from bone
2. Stimulate the kidneys and intestine to absorb more calcium

17. Calcium homeostasis of blood 9–11 mg/100 ml
Rising blood
Ca2+ levels
Imbalance

18. Calcium homeostasis of blood 9–11 mg/100 ml
Rising blood
Ca2+ levels
Thyroid gland
Imbalance

19. Calcium homeostasis of blood 9–11 mg/100 ml
Rising blood
Ca2+ levels
Thyroid gland releases calcitonin
Calcitonin
Thyroid gland
Imbalance

20. Calcium homeostasis of blood 9–11 mg/100 ml
Rising blood
Ca2+ levels
Thyroid gland releases calcitonin
Calcitonin
Calcitonin stimulates calcium salt deposit in bone
Thyroid gland
Imbalance

21. Calcium homeostasis of blood 9–11 mg/100 ml
Rising blood
Ca2+ levels
Thyroid gland releases calcitonin
Calcitonin
Calcitonin stimulates calcium salt deposit in bone
Thyroid gland

22. Calcium homeostasis of blood 9–11 mg/100 ml
Falling blood
Ca2+ levels
Imbalance

23. Calcium homeostasis of blood 9–11 mg/100 ml
Thyroid gland
Parathyroid glands
Falling blood
Ca2+ levels
Imbalance

24. Calcium homeostasis of blood 9–11 mg/100 ml
PTH
Parathyroid glands release parathyroid hormone (PTH)
Thyroid gland
Parathyroid glands
Falling blood
Ca2+ levels
Imbalance

25. Calcium homeostasis of blood 9–11 mg/100 ml
Osteoclasts
degrade bone matrix and release Ca2+ into blood
PTH
Parathyroid glands release parathyroid hormone (PTH)
Thyroid gland
Parathyroid glands
Falling blood
Ca2+ levels
Imbalance

26. Calcium homeostasis of blood 9–11 mg/100 ml
Osteoclasts
degrade bone matrix and release Ca2+ into blood
PTH
Parathyroid glands release parathyroid hormone (PTH)
Thyroid gland
Parathyroid glands

27. Calcium
Homeostasis

28. Adrenal Glands

29. Adrenal Glands Sit on top of the kidneys Two regions
1. Adrenal cortex—outer glandular region has three layers
A. Mineralocorticoids secreting area
B. Glucocorticoids secreting area
C. Sex hormones secreting area
2. Adrenal medulla—inner neural tissue region. When stimulated, it releases EPINEPHRINE and NOREPINEPHRINE

30. Adrenal Cortex

31. Adrenal Cortex Mineralocorticoid layer secretes ALDOSTERONE
Aldosterone is important for sodium (Na+) and potassium (K+) balance; works on kidneys
Glucocorticoid layer secretes CORTISOL and CORTISONE
Help resist long-term stressors
Released in response to increased blood levels of ACTH
Sex hormone layer secretes small amount of ANDROGENS and ESTROGENS

32. Short term
Stress
Hypothalamus

33. Short term
Stress
Hypothalamus
Nerve impulses
Spinal cord

34. Short term
Stress
Hypothalamus
Nerve impulses
Spinal cord
Adrenal medulla
Preganglionic sympathetic fibers

35. Short term
Stress
Hypothalamus
Nerve impulses
Short-term stress response
Spinal cord
Adrenal medulla
Preganglionic sympathetic fibers
Catecholamines (epinephrine and norepinephrine)

36. More prolonged
Stress
Hypothalamus

37. More prolonged
Stress
Hypothalamus
Adrenal cortex
Releasing hormone
Corticotropic cells of anterior pituitary
ACTH

38. More prolonged
Stress
Hypothalamus
Adrenal cortex
Releasing hormone
Corticotropic cells of anterior pituitary
ACTH
Mineralocorticoids
Glucocorticoids
Long-term stress response

39. Adrenal cortex disorders
Addison’s disease
Results from hyposecretion of all adrenal cortex hormones
Bronze skin tone, muscles are weak, burnout, susceptibility to infection

40. Adrenal cortex disorders

41. Adrenal cortex disorders
Cushing’s syndrome
Results from a tumor in the middle cortical area of the adrenal cortex
Characterized by:
“Moon face”
“Buffalo hump” on the upper back
High blood pressure
Increased blood sugar
Depression

42. Cushing’s Syndrome

43. Pancreas

44. Pancreas
The pancreas is a mixed gland and has both endocrine and exocrine functions

46. Pancreatic Islets: 2 Hormones
1. Insulin (beta cells): allows glucose to cross plasma membranes into cells
2. Glucagon (alpha cells): allows glucose stored in cells to be released into the blood

47. Homeostasis: Normal blood glucose levels (90 mg/100ml)

48. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Stimulus: rising blood glucose levels (e.g., after eating four jelly doughnuts)
Imbalance
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance

49. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Elevated blood sugar levels
Stimulus: rising blood glucose levels (e.g., after eating four jelly doughnuts)
Imbalance
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance

50. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Insulin-secreting cells of the pancreas activated; release insulin into the blood
Elevated blood sugar levels
Stimulus: rising blood glucose levels (e.g., after eating four jelly doughnuts)
Imbalance
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance

51. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Insulin-secreting cells of the pancreas activated; release insulin into the blood
Uptake of glucose from blood is en- hanced in most body cells
Elevated blood sugar levels
Stimulus: rising blood glucose levels (e.g., after eating four jelly doughnuts)
Imbalance
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance

52. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Insulin-secreting cells of the pancreas activated; release insulin into the blood
Uptake of glucose from blood is en- hanced in most body cells
Elevated blood sugar levels
Liver takes up glucose and stores it as glycogen
Stimulus: rising blood glucose levels (e.g., after eating four jelly doughnuts)
Imbalance
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance

53. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Insulin-secreting cells of the pancreas activated; release insulin into the blood
Uptake of glucose from blood is en- hanced in most body cells
Blood glucose levels decline to set point; stimulus for insulin release diminishes
Elevated blood sugar levels
Liver takes up glucose and stores it as glycogen
Stimulus: rising blood glucose levels (e.g., after eating four jelly doughnuts)
Homeostasis: Normal blood glucose levels (90 mg/100ml)

54. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance
Stimulus: declining blood glucose levels (e.g., after skipping a meal)
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance

55. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance
Stimulus: declining blood glucose levels (e.g., after skipping a meal)
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance
Low blood sugar levels

56. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance
Stimulus: declining blood glucose levels (e.g., after skipping a meal)
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance
Low blood sugar levels
Glucagon-releasing cells of pancreas activated; release glucagon into blood; target is the liver

57. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance
Stimulus: declining blood glucose levels (e.g., after skipping a meal)
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Imbalance
Low blood sugar levels
Glucagon-releasing cells of pancreas activated; release glucagon into blood; target is the liver
Liver breaks down glycogen stores and releases glucose to the blood

58. Homeostasis: Normal blood glucose levels (90 mg/100ml)
Stimulus: declining blood glucose levels (e.g., after skipping a meal)
Homeostasis: Normal blood glucose levels (90 mg/100ml)
Low blood sugar levels
Rising blood glucose levels return blood sugar to homeostatic set point; stimulus for glucagon release diminishes
Glucagon-releasing cells of pancreas activated; release glucagon into blood; target is the liver
Liver breaks down glycogen stores and releases glucose to the blood

59. Pineal Gland

60. Pineal Gland
Found on the third ventricle of the brain

61. Pineal Gland
Called the “third eye” because it receives visual information from the retina regarding light and dark
Secretes melatonin
Helps establish the body’s wake and sleep cycles