Endocrine System and Hormones Review (copy)

How do the Endocrine and Nervous systems differ in speed and duration?

The nervous system is fast and short-acting via electrical impulses; the endocrine system is slower and longer-acting via hormones.

What are hormones?

Chemical messengers secreted into the blood that bind to specific target cell receptors to regulate physiological functions.

What is the difference between Peptide and Steroid hormones?

Peptides are water-soluble, bind to surface receptors, and use second messengers; Steroids are lipid-soluble, derive from cholesterol, and bind to intracellular receptors.

What is Signal Amplification?

The process where one hormone molecule triggers the activation of many enzymes, resulting in a large cellular effect.

Explain Up-regulation and Down-regulation of receptors.

Up-regulation increases receptor count due to low hormone levels; Down-regulation decreases receptor count due to high hormone levels.

What connects the Hypothalamus to the Anterior Pituitary?

The Hypophyseal Portal System, which is a network of blood vessels that transport releasing and inhibiting hormones.

What connects the Hypothalamus to the Posterior Pituitary?

The Hypothalamic-Hypophyseal Tract, consisting of nerve axons that transport ADH and Oxytocin.

List the hormones of the Anterior Pituitary.

GH, TSH, ACTH, FSH, LH, and Prolactin (PRL).

What hormones are released by the Posterior Pituitary?

Antidiuretic Hormone (ADH) for water retention and Oxytocin for contractions and milk ejection.

How is hormone secretion typically controlled?

Via Negative Feedback Mechanisms, where the rising level of a hormone inhibits further release of its stimulating hormone.

What are the primary functions of Thyroid Hormones (T{3} and T{4})?

They regulate the body's basal metabolic rate, promoting oxygen consumption and heat production.

Contrast Hypothyroidism and Hyperthyroidism.

Hypothyroidism (e.g., Iodine deficiency) causes weight gain and lethargy; Hyperthyroidism (e.g., Graves' disease) causes weight loss and anxiety.

What is the role of Parathyroid Hormone (PTH)?

It increases blood calcium levels by stimulating bone resorption (breakdown) and reducing calcium loss in urine.

How do Calcitonin and PTH interact?

They are antagonists; PTH raises blood calcium, while Calcitonin (from the thyroid) lowers it.

Name the three layers of the Adrenal Cortex and their products.

1. Zona Glomerulosa: Mineralocorticoids (Aldosterone).
2. Zona Fasciculata: Glucocorticoids (Cortisol).
3. Zona Reticularis: Androgens (DHEA).

What is the function of Aldosterone?

It promotes sodium and water retention by the kidneys to regulate blood pressure.

How does Cortisol help the body during stress?

It increases blood glucose levels through gluconeogenesis and has anti-inflammatory effects.

What hormones does the Adrenal Medulla secrete?

Epinephrine and Norepinephrine, which mediate the 'fight-or-flight' sympathetic response.

Contrast Cushing's Syndrome and Addison's Disease.

Cushing's is caused by hypersecretion of cortisol (weight gain, hyperglycemia); Addison's is adrenal insufficiency (hypoglycemia, low blood pressure).

What are the endocrine functions of the Pancreatic Alpha and Beta cells?

Alpha cells secrete Glucagon to raise blood sugar; Beta cells secrete Insulin to lower blood sugar.

What characterizes Type 1 Diabetes Mellitus?

Autoimmune destruction of beta cells leading to an absolute insulin deficiency.

What characterizes Type 2 Diabetes Mellitus?

Insulin resistance, where target cells fail to respond effectively to insulin.

What are the '3 Ps' of Diabetes Mellitus?

Polyuria (frequent urination), Polydipsia (excessive thirst), and Polyphagia (excessive hunger).

What is the function of the Pineal Gland?

It secretes Melatonin, which regulates circadian rhythms and sleep-wake cycles.

What is the role of the Thymus gland?

It secretes thymosin, which is essential for the maturation of T-lymphocytes (immune cells).

What are the effects of Growth Hormone (GH)?

It stimulates mitosis and cell differentiation, primarily affecting bone, cartilage, and muscle growth.

Contrast Acromegaly and Gigantism.

Gigantism is excess GH during childhood; Acromegaly is excess GH in adulthood (after growth plate closure).

What is the function of Atrial Natriuretic Peptide (ANP)?

Secreted by the heart to lower blood pressure by promoting sodium and water excretion.

What hormones are produced by the Kidneys?

Erythropoietin (EPO) for red blood cell production and Renin for blood pressure regulation.

Describe the three stages of General Adaptation Syndrome (GAS).

1. Alarm: Fight-or-flight.
2. Resistance: Adaptation to long-term stress.
3. Exhaustion: Resource depletion and potential organ failure.

What is Glycogenolysis?

The breakdown of glycogen into glucose, stimulated by glucagon.

What is Gluconeogenesis?

The synthesis of glucose from non-carbohydrate sources (e.g., amino acids), stimulated by cortisol.

What are Gonads and their primary hormones?

Testes (Testosterone) and Ovaries (Estrogen and Progesterone), regulating reproduction and secondary sex characteristics.

Define Synergistic, Permissive, and Antagonistic interactions.

Synergistic: Hormones work together for a larger effect. Permissive: One hormone requires another to work. Antagonistic: Hormones oppose each other.

What is the role of the hormone Leptin?

Produced by adipose tissue to signal satiety and inhibit appetite in the hypothalamus.

What is a Goiter and what causes it?

An enlargement of the thyroid gland, often caused by iodine deficiency leading to excessive TSH stimulation.

What is the function of Follicle-Stimulating Hormone (FSH)?

Stimulates the development of gametes (eggs and sperm).

What is the function of Luteinizing Hormone (LH)?

Triggers ovulation and stimulates the production of sex hormones.

What is Diabetes Insipidus?

A condition caused by a deficiency of ADH, resulting in the production of large volumes of dilute urine.

How does the liver clear hormones from the blood?

Through the Metabolic Clearance Rate (MCR), where hormones are chemically degraded and excreted in bile or urine.