Pathology 3500 Lecture Notes - Lecture 23: Pancreatic Islets, Thyroid, Parathyroid Gland
1 May 2018
School
Department
Course
Professor
Lecture 008: Endocrine Disease I
Objectives
● Describe the endocrine system in the broadest sense
● Know the difference between exocrine, endocrine, paracrine, and autocrine systems
○ Be able to give examples of each
● Draw a schematic diagram to show the relationships between the tertiary, secondary,
and primary levels of endocrine organs
○ i.e. hypothalamus, pituitary, and target organs
● Describe the structure and function of the pituitary gland and examples of excess and
deficient pituitary hormone production
○ Describe the effects on the body of increased glucocorticoids, mineralocorticoids,
and sex steroids.
○ Compare and contrast the common causes of Cushing’s syndrome in terms of
etiology and expected levels of ACTH.
○ Describe the effects on an individual of Addison’s Disease.
○ Describe the affected electrolytes and hormonal levels.
○ Describe the pathophysiology of congenital adrenal hyperplasia.
● Describe the structure and function of the thyroid gland and examples of excess and
deficient thyroid hormone production
○ Describe common autoimmune diseases of the thyroid gland
● Describe the cell types of the endocrine pancreas, and the hormones they produce
● Describe a broad classification of diabetes mellitus, as well as criteria for diagnosis of
this disease
○ Describe the pathogenesis of the major complications of diabetes mellitus
The Endocrine System
● A highly integrated and widely distributed group of organs
○ Provide system of communication and control
■ Positive and negative feedback system
● Turn on and shut off production of hormones
○ A group of glands that produce hormones
■ Functions to regulate metabolism, growth and development, specific
tissue functions, sexual function, reproduction, sleep and mood
● Use hormones to regulate and integrate body functions
Hormone Classes
● Steroid hormones
○ Glucocorticoids, estrogen, progesterone, testosterone, mineralocorticoid
○ Cholesterol backbone
■ Water insoluble due to lipid content
● Carried in the body by carrier protein
■ Able to cross cell membrane
● Bind to intracellular, steroid receptors in the cytoplasm
find more resources at oneclass.com
find more resources at oneclass.com
○ Move into the nucleus to elicit gene expression changes
● Protein
○ Anterior pituitary hormones (adrenocorticotropic hormone [ACTH])
○ Water soluble
■ Transported freely in the blood
■ Cannot traverse the plasma membrane
■ Bind to cell surface receptors (GPCR) on the plasma membrane
● Active second messenger systems
○ Ex. Hypothalamic releasing factors or releasing hormones
● Peptide
○ Antidiuretic hormone [ADH], growth hormone
● Amino acid
○ Thyroxine (T4), Triiodothyronine (T3), catecholamines (NE/E)
● Amine
○ Epinephrine
○ Modified amino acids
The Endocrine System Involves
● The hormone-producing organ
● The hormone (can have more than 1 target)
● The receptor or target organ
Major endocrine glands
● In the head
○ Hypothalamus
■ Major control of the endocrine system
■ Release peptide hormones that mainly act on the pituitary gland to elicit
hormone production from the pituitary gland
○ Pituitary gland
○ Pineal body
● In the throat:
○ Thyroid gland
○ Parathyroid gland
○ Thymus
● In the abdomen :
○ Adrenal glands
○ Pancreas
○ Gonads (testes and ovaries)
Endocrine System
find more resources at oneclass.com
find more resources at oneclass.com
● Release hormone into the bloodstream, that is transported via the blood to a target
organ
○ Has actions at a distant site
○ Requires transport by blood
● Ex. Hypothalamic-pituitary-adrenal pathway
Exocrine System
● Substances are secreted onto a surface by way of a duct
● Ex. Salivary glands, sweat glands, pancreas secrete enzymes into the small bowel
Paracrine System
● And endocrine gland secretes a hormone that will act locally on nearby cells
○ Doesn’t enter the bloodstream to be transported because the target is close
enough
● Estrogen secretion by the ovaries can affect cells in the ovary
Autocrine System
● A hormone that will act on the cell type it was produced from
○ Insulin will act on beta cells to shut off insulin production
Negative Feedback of the Endocrine System
● Product of the target organ turns off the control organ
● Key to regulation of the endocrine system
Hypothalamic-Pituitary Axis Regulation
● Example of a negative feedback loop
● Hypothalamus is in close proximity to the pituitary gland
● Hypothalamus
○ Tertiary endocrine organ
○ Produces CRH
■ CHR acts on the anterior pituitary gland
● Anterior pituitary gland
○ Secondary endocrine organ
○ Produces ACTH
■ ACTH travels via the bloodstream to the adrenal glands
● Adrenal glands
○ Primary endocrine organ
○ Produces cortisol
■ Cortisol regulates blood glucose levels, increasing fat stores, defends
against stress, helps in response against infectious organisms
● Cortisol also has inhibitory effect on the anterior pituitary gland (stops the production
of ACTH) and hypothalamus (stops the production of CRH)
○ Hormone is able to affect both the secondary and tertiary endocrine organs
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Describe the endocrine system in the broadest sense. Know the difference between exocrine, endocrine, paracrine, and autocrine systems. Be able to give examples of each. Draw a schematic diagram to show the relationships between the tertiary, secondary, and primary levels of endocrine organs i. e. hypothalamus, pituitary, and target organs. Describe the structure and function of the pituitary gland and examples of excess and deficient pituitary hormone production. Describe the effects on the body of increased glucocorticoids, mineralocorticoids, and sex steroids. Compare and contrast the common causes of cushing"s syndrome in terms of etiology and expected levels of acth. Describe the effects on an individual of addison"s disease. Describe the affected electrolytes and hormonal levels. Describe the pathophysiology of congenital adrenal hyperplasia. Describe the structure and function of the thyroid gland and examples of excess and deficient thyroid hormone production. Describe common autoimmune diseases of the thyroid gland. Describe the cell types of the endocrine pancreas, and the hormones they produce.
