Endocrine System

Pineal Gland

Pinealocytes secretes melatonin when stimulated by “darkness”

Importance of connection of hypothalamus to anterior pituitary gland

Hypothalamus releases hormones into portal system (ballsacks network of veins) and it carries them to the anterior pituitary gland —> rest of body

How did the pituitary gland develop an anterior and posterior lobe?

• Posterior develops by the hypothalamus projecting down modified nervous tissue

• Anterior forms when epithelium of oral cavity grows upward and meets the posterior side

Prolactin (anterior pituitary hormones)

Breast

LH (anterior pituitary hormones)

Growth hormone that goes to a lot of tissues

• Germ and endocrine cells of gonads

TSH (anterior pituitary hormones)

Thyroid gland

ACTH (anterior pituitary hormones)

Adrenal cortex

GH (anterior pituitary hormones)

Liver

FSH (anterior pituitary hormones)

Endocrine cells of gonads

Hormone release is regulated by ___

Feedback (it’s a loop!)

Connection of hypothalamus to posterior pituitary

Hypothalamo-hypophyseal tract

• Hypothalamus releases 2 hormones to posterior pituitary

1. Oxytocin: targets uterus, mammary glands

2. Antidiuretic hormone (ADH): targets kidney tubules (don’t pee!), blood vessels

Location and divisions of adrenal gland

Sits on top of kidney

Divided into:

1. outer cortex

   1. comes from mesoderm

2. inner medulla

   1. comes from neural crest cells (also makes sympathetic ganglion neurons)

Zona glomerulosa (Adrenal cortex)

Aldosterone regulates Na+

Stimulated by angiotensin II, increased K+, and a little bit by ACTH

Zona fasciculata (Adrenal cortex)

Cortisol affects carbohydrate metabolism and suppresses immune response

Stimulated by ACTH

Zona reticularis (Adrenal cortex)

DHEA is converted into testosterone

Stimulated by ACTH

What happens when you get too little cortisol?

Addison disease: no energy, weak immune system

What happens when you get too much cortisol?

Cushing disease: u turn into nikocadoavocado, DIABETES

How does the adrenal medulla release adrenaline?

Autonomic nervous system (ANS) uses the sympathetic system to act on the adrenal medulla to release epinephrine and norepinepherine (NE)

NE mostly gets converted into epinephrine (adrenaline)

2 important islet cells in pancreas?

alpha cells

• produces glucagon that works with insulin to regulate blood glucose levels

beta cells (majority)

• make, store, and release insulin to regulate blood glucose levels in body

Where is the thyroid gland?

anterior and lateral to larynx

What does the thyroid gland secrete?

Colloid

• stored in follicles that make up the gland

Calcitonin

• secreted from C cells to suppress bone resorption

Colloid

Follicular cells (that make up the thyroid gland) make and store colloid that utilizes iodine in your bloodstream to end up making T3 or T4 pre-thyroid hormone that is then released into capillaries

Hyperthyroidism

Elevated T3 and T4 in the blood when the feedback system for the thyroid is broken

Immunoglobins attach to receptor that produce T3 and T4 so it can’t be turned off so follicular cells keep making more thyroid hormone

Hypothyroidism

Thyroid stimulating hormones aren’t getting the thyroid to work; gland is damaged, does not produce thyroid hormones

Parathyroid gland

In the back of thyroid gland made up of chief cells to secrete PTH that promotes resorption of bone (opposite of calcitonin)

3 hormones that play a role in bone metabolism

1. Parathyroid hormone (PTH)

   1. Increase blood calcium levels

   2. Promote resorption

2. Calcitonin

   1. Decrease blood calcium levels

   2. Inhibits resorption

3. Vitamin D3

   1. Absorbs calcium in guts