ch 6/13 physio, endocrine

Which part of the endocrine system is also part of the central nervous system?

Hypothalamus

How does hypothalamus control thyroid gland?

• Once the hypothalamus senses a disruption in homeostasis

• The hypothalamus creates and sends releasing hormone (RH) to the anterior pituitary gland ONLY via hypothalamohypophyseal portal system

• The anterior pituitary then sends stimulating hormones (SH) to the endocrine glands that have the target cells which have receptors for the hormones

• Homeostasis comes back which stops hypothalamus from signalling by negative feedback

Pituitary gland location

under hypothalamus

Adrenal gland location

on top of kidneys

Thyroid gland location

on top of trachea

Parathyroid gland location

 in thyroid gland

Pancreas location

behind stomach

Neurohypophysis

posterior pituitary

Adenohypophysis

anterior pituitary

Target cells

whatever cells have a protein receptor for that hormone

• Protein receptor determines where hormone will have its effect 

Eg. target cell of thyroid hormone has a protein receptor for thyroid hormone

Target organ

specific organ that has target cells/receptors for certain hormone

Metabolic rate controlled by

thyroid gland

Blood calcium controlled by

 thyroid and parathyroid

Blood sugar controlled by

pancreas

Stress hormones controlled by

adrenal glands

Glucagon

raises blood glucose

• Made by alpha islet

• Tells liver to cut apart glycogen for more glucose (glycogenolysis)

Insulin

decreases blood glucose

• Made by B(eta) blood sugar

• Stimulates protein and fat synthesis and glucose intake

• Stimulates liver to connect glucose to make glycogen

Which organ secretes ADH and oxytocin?

Posterior pituitary gland

ADH

• Secreted to sustain water 

• Released when blood pressure is hypertonic or low

• Target cells in kidneys/blood vessels

Oxytocin

For labor contractions/lactation

ADH and Oxytocin

• made/produced and secreted by the hypothalamus

• most alike hormone

• released signaled by electrical signal from hypothalamus

Which part of the endocrine system is a modified sympathetic ganglion?

Adrenal Medulla

Adrenal Medulla makes

epinephrine

Adrenal cortex makes

cortisol

How does the endocrine system release thyroid hormone?

1. Hypothalamus TRH ->

2. Anterior pituitary TSH ->

3. Thyroid gland -> thyroid hormone

How does the endocrine system release cortisol?

1. Hypothalamus CRH ->

2. Anterior pituitary ACTH ->

3. Adrenal cortex -> cortisol

 action of hydrophobic hormones

1. Need to travel on water soluble transport protein to travel through blood to get to target cell

2. Goes straight through cell membrane to nucleus without second messenger

action of hydrophilic hormones

1. Dissolve in water part of blood and travels to target cell easy

2. Require cell-surface receptor protein to get through cell membrane

3. Need 2nd messenger to get to nucleus

Hydrophobic hormones

non-polar, lipid soluble hormones

• Steroid hormones

• Thyroid hormone

• Vitamin D

Hydrophilic hormones

polar, water soluble hormones

• Peptides, proteins, insulin, etc.

1. Dissolve in water part of blood and travels to target cell easy

2. Require cell-surface receptor protein to get through cell membrane

3. Need 2nd messenger to get to nucleus

Steroid hormones

• Cholesterol

• Progesterone

• Testosterone

• Cortisol (what is mostly used as steroids)

• Aldosterone

• Estrogen

What is the molecule the cell uses as the starting point for making steroid hormones?

Cholesterol

Name the hydrophobic hormone that is NOT a steroid hormone.

Thyroid hormone and vitamin D

When a patient has elevated thyroid hormone levels due to a thyroid tumor, what will happen to that patient’s TSH and TRH levels?

Levels become extremely low/cease as TSH and TRH stop being secreted altogether

GLUTS

glucose transporters

• Transport glucose into cell through cell membrane for usage

• Found in cell membrane

• Insulin activates insulin receptor to move GLUT into cell membrane to use

When there is not enough insulin, what happens to glucose levels inside cells? What happens to glucose levels in the blood?

Glucose levels inside cells decrease as there are no GLUTS, glucose blood levels increase in blood as cells cannot use glucose

What are the causes and symptoms of diabetes mellitus?

• High blood sugar (hyper glycemia)

• Excessive thirst (polydipsia)

• Excessive urination (polyurea)

• Glucose cannot enter muscle and other cells

Type I diabetes

• Autoimmune destruction of B islet cells (that make insulin)

• Not enough insulin in body

• Usually before 12 yrs old

Type II diabetes

• Insulin resistance (insulin receptors not working)

• GLUTS not being put into cell membrane, causing glucose blood levels to rise

• Obesity, lack of exercise, diet, genetic tendency