ENDOCRINOLOGY
(NWI-BB048B)
Radboud University 2020/2021
Sherissa Wirabuana (1067377)
,Table of Contents
Table of Contents ___________________________________________________________ 1
CHAPTER 1 | Histology of the endocrine glands __________________________________ 2
1.1. Pituitary gland ___________________________________________________________ 4
1.2. Adrenal gland ____________________________________________________________ 7
1.3. Thyroid and parathyroid glands ____________________________________________ 11
1.4. Pancreas ________________________________________________________________ 14
1.5. Ovaries _________________________________________________________________ 15
1.6. Testes __________________________________________________________________ 19
CHAPTER 2 | Mechanisms of hormone action ___________________________________ 23
CHAPTER 3 | The hypothalamus – pituitary axis _________________________________ 27
CHAPTER 4 | Endocrinology of the pancreas ____________________________________ 30
CHAPTER 5 | Hormones and reproduction ______________________________________ 33
5.1. Female sex hormones ____________________________________________________ 33
5.2. Male sex hormones_______________________________________________________ 36
CHAPTER 6 | Endocrinology of the thyroid gland ________________________________ 38
CHAPTER 7 | Endocrinology of the adrenal gland ________________________________ 42
7.1. The stress axis (HPA) _____________________________________________________ 42
7.2. Steroids of the adrenal cortex (RAAS) _______________________________________ 44
7.3. Catecholamines of the adrenal medulla _____________________________________ 45
7.4. Adrenogenital syndrome __________________________________________________ 47
CHAPTER 8 | Growth hormone _______________________________________________ 49
CHAPTER 9 | Calciotropic hormones and osteoporosis ____________________________ 51
CHAPTER 10 | Leptin and obesity _____________________________________________ 53
CHAPTER 11 | Endocrinology of the digestive tract _______________________________ 55
CHAPTER 12 | Hormones and tumors __________________________________________ 58
Appendices ________________________________________________________________ 60
Practical: A hormone and its receptor ______________________________________________ 60
Poster: Endocrinology of the pancreas _____________________________________________ 64
Peer feedback form _____________________________________________________________ 65
References ________________________________________________________________ 66
1
,CHAPTER 1 | Histology of the endocrine glands
Endocrinology is the study of the communication system of cells. Cells communicate with
each by secreting hormones.
Signaling mechanisms:
• Endocrine: signal molecules (hormones) are carried by blood; long distance
signaling
• Paracrine: signal molecules are secreted locally by cells; short distance signaling,
i.e. between cells of the same tissue
• Autocrine: signals secreted by a cell to be reused by the cell; self-signaling
• Neurocrine: signal molecules of the nervous system, i.e. neurotransmitters
• Neuroendocrine: signal molecules released by neurons into the blood
4 main classes of signaling molecules:
• Proteins/peptides
• Eicosanoids (paracrine/autocrine signaling agent)
• Steroids (mostly used in endocrine signaling, synthesized from cholesterols)
• Amines (e.g. adrenaline; synthesized from tyrosine/tryptophan)
Signaling molecules result in various effects depending on the type of molecule, target
tissue, and target receptor.
e.g. acetylcholine – neurotransmitter and neuromodulator in the brain, activates
skeletal muscles (voluntary movement) in the neuromuscular junction
Endocrine cells secrete hormones in response to changes from the environment.
Hormone-induced action process:
1. Formation of hormone-receptor complex, which may be on the membrane or
within the cytoplasm, depending on the receptor’s location.
2. The complex sets off a biochemical cascade that leads to the activation of gene
transcription.
3. Gene transcription produces a protein product that acts out the desired result
(effector).
See Figure 1-1 for the locations of all endocrine glands within the body and organs that
contain endocrine glands.
2
, Figure 1-1. Location of all endocrine glands and organs containing endocrine cells. Adipocytes are part of the endocrine system,
and are present in many tissues where paracrine signaling is important (Mescher, 2016; page 414).
3
(NWI-BB048B)
Radboud University 2020/2021
Sherissa Wirabuana (1067377)
,Table of Contents
Table of Contents ___________________________________________________________ 1
CHAPTER 1 | Histology of the endocrine glands __________________________________ 2
1.1. Pituitary gland ___________________________________________________________ 4
1.2. Adrenal gland ____________________________________________________________ 7
1.3. Thyroid and parathyroid glands ____________________________________________ 11
1.4. Pancreas ________________________________________________________________ 14
1.5. Ovaries _________________________________________________________________ 15
1.6. Testes __________________________________________________________________ 19
CHAPTER 2 | Mechanisms of hormone action ___________________________________ 23
CHAPTER 3 | The hypothalamus – pituitary axis _________________________________ 27
CHAPTER 4 | Endocrinology of the pancreas ____________________________________ 30
CHAPTER 5 | Hormones and reproduction ______________________________________ 33
5.1. Female sex hormones ____________________________________________________ 33
5.2. Male sex hormones_______________________________________________________ 36
CHAPTER 6 | Endocrinology of the thyroid gland ________________________________ 38
CHAPTER 7 | Endocrinology of the adrenal gland ________________________________ 42
7.1. The stress axis (HPA) _____________________________________________________ 42
7.2. Steroids of the adrenal cortex (RAAS) _______________________________________ 44
7.3. Catecholamines of the adrenal medulla _____________________________________ 45
7.4. Adrenogenital syndrome __________________________________________________ 47
CHAPTER 8 | Growth hormone _______________________________________________ 49
CHAPTER 9 | Calciotropic hormones and osteoporosis ____________________________ 51
CHAPTER 10 | Leptin and obesity _____________________________________________ 53
CHAPTER 11 | Endocrinology of the digestive tract _______________________________ 55
CHAPTER 12 | Hormones and tumors __________________________________________ 58
Appendices ________________________________________________________________ 60
Practical: A hormone and its receptor ______________________________________________ 60
Poster: Endocrinology of the pancreas _____________________________________________ 64
Peer feedback form _____________________________________________________________ 65
References ________________________________________________________________ 66
1
,CHAPTER 1 | Histology of the endocrine glands
Endocrinology is the study of the communication system of cells. Cells communicate with
each by secreting hormones.
Signaling mechanisms:
• Endocrine: signal molecules (hormones) are carried by blood; long distance
signaling
• Paracrine: signal molecules are secreted locally by cells; short distance signaling,
i.e. between cells of the same tissue
• Autocrine: signals secreted by a cell to be reused by the cell; self-signaling
• Neurocrine: signal molecules of the nervous system, i.e. neurotransmitters
• Neuroendocrine: signal molecules released by neurons into the blood
4 main classes of signaling molecules:
• Proteins/peptides
• Eicosanoids (paracrine/autocrine signaling agent)
• Steroids (mostly used in endocrine signaling, synthesized from cholesterols)
• Amines (e.g. adrenaline; synthesized from tyrosine/tryptophan)
Signaling molecules result in various effects depending on the type of molecule, target
tissue, and target receptor.
e.g. acetylcholine – neurotransmitter and neuromodulator in the brain, activates
skeletal muscles (voluntary movement) in the neuromuscular junction
Endocrine cells secrete hormones in response to changes from the environment.
Hormone-induced action process:
1. Formation of hormone-receptor complex, which may be on the membrane or
within the cytoplasm, depending on the receptor’s location.
2. The complex sets off a biochemical cascade that leads to the activation of gene
transcription.
3. Gene transcription produces a protein product that acts out the desired result
(effector).
See Figure 1-1 for the locations of all endocrine glands within the body and organs that
contain endocrine glands.
2
, Figure 1-1. Location of all endocrine glands and organs containing endocrine cells. Adipocytes are part of the endocrine system,
and are present in many tissues where paracrine signaling is important (Mescher, 2016; page 414).
3
