Chapter 37: Endocrine System

What is the primary function of the endocrine system?

To produce hormones that help maintain homeostasis in multicellular animals.

What are some examples of peptide hormones?

Oxytocin, growth hormone, and follicle-stimulating hormone

How do the nervous and endocrine systems differ in their speed of response?

The nervous system responds in milliseconds via nerve impulses, while the endocrine system responds in seconds to days via hormones.

Up-regulation

An increase in the number of hormone receptors.

Down-regulation

A decrease in the number of hormone receptors in response to cellular activity.

Where do lipophilic (lipid-derived) hormones bind to their receptors?

They bind to intracellular receptors, often within the cytoplasm or nucleus.

Hormone response element (HRE)

A DNA sequence that the hormone-receptor complex binds to in the nucleus to trigger gene transcription.

Antidiuretic Hormone (ADH)

A hormone that regulates water excretion by the kidneys and helps maintain blood pressure.

Aldosterone

A steroid hormone that regulates water and electrolyte (sodium/potassium) balance.

Insulin (beta cells)

A hormone involved in blood glucose regulation that lowers blood sugar.

Glucagon (alpha cells)

A hormone involved in blood glucose regulation that raises blood sugar.

Where are insulin and glucagon found?

Pancreas

What are the primary hormones that determine basal metabolic rate?

Thyroxine (T4) and triiodothyronine (T3), released from the thyroid gland.

Which two hormones act as antagonists to regulate blood calcium levels?

Parathyroid hormone (PTH) increases blood calcium, while calcitonin decreases it.

Growth Hormone (GH)

This hormone stimulates growth, cell reproduction, regeneration, protein synthesis, and is glucose sparing.

What is the structural difference between the anterior and posterior pituitary?

The anterior pituitary is glandular tissue, while the posterior pituitary is neural tissue containing axons from the hypothalamus.

Which two hormones are stored and released by the posterior pituitary?

Antidiuretic hormone (ADH) and oxytocin.

What is the function of the second messenger system in hormone signaling?

It allows hydrophilic hormones (which cannot cross the plasma membrane) to initiate a signaling pathway inside the cell.

What is the role of cAMP in the second messenger system?

cAMP acts as a second messenger that mediates a cell-specific response after being activated by adenylyl cyclase.

What is the effect of oxytocin in the reproductive system?

It stimulates uterine contractions during childbirth.

What is the primary difference between diabetes insipidus and diabetes mellitus?

Diabetes insipidus is caused by an underproduction of ADH, whereas diabetes mellitus is related to insulin deficiency or resistance.

Follicle-stimulating hormone (FSH)

This stimulates the development of egg cells in ovarian follicles in females.

Luteinizing hormone (LH)

A surge in this causes ovulation in females

Hypothyroidism

The thyroid gland doesn't produce enough hormone, causing low metabolic rate, weight gain, sensitivity to cold, and lethargy.

Hyperthyroidism

The thyroid gland produces too many hormones, causing high metabolic rate, weight loss, irritability, and increased heart rate.

Why are amino acid-derived and peptide hormones unable to cross the plasma membrane?

They are hydrophilic and must bind to receptors on the outer surface of the plasma membrane.

Hormones

Regulatory chemicals secreted into extracellular fluid and carried by the blood

Lipid-derived hormones

Derived from the cholesterol molecule

Epinephrine

Amino acid-derived hormone that arises from tyrosine

Melatonin

Amino acid-derived hormone that arises from tryptophan

Nervous system

controls through nerve impulses conducted by axons

Endocrine system

controls through hormones transported in the blood

C cells (a.k.a. clear cells)

Made by the thyroid gland

Adrenal medulla

Epinephrine for "fight or flight" response is released from here

Adrenal cortex

Cortisol for long-term stress is produced from here

Hypothalamus

Creates and synthesizes hormones that it stores in the posterior pituitary gland

The Anterior Pituitary Gland

Produces essential hormones such as peptide hormones, protein hormones, prolactin, glycoprotein hormones, and thyroid-stimulating hormone.

The Posterior Pituitary Gland

Produces antidiuretic hormone and oxytocin.

Testosterone

Lipid-derived hormone, abundant in males

Estrogen

Lipid-derived hormone, abundant in females

True or false: the anterior and posterior pituitary glands synthesize their hormones on top of storing and releasing them.

False

2 multiple choice options