Chapter 14: The Endocrine System and Hormonal Functions

What is homeostasis?

The process to keep the human body within certain limits for many physiological variables.

What are some examples of physiological variables that are regulated by homeostasis?

Blood pH, Blood CO2 concentration, Blood glucose concentration, Body temperature, Water balance within tissues.

What is a negative feedback mechanism?

Physiological processes that bring a value back towards a set point, similar to a thermostat.

How do the nervous and endocrine systems work together to ensure homeostasis?

The nervous system controls homeostasis under the autonomic nervous system, while the endocrine system consists of glands that produce hormones.

What are hormones?

Chemical messengers transported by the bloodstream from the gland where they are produced to specific cell types that are influenced.

What is a target tissue?

Cells that are influenced by a particular hormone.

What distinguishes steroid hormones from peptide hormones?

Steroid hormones are made from cholesterol and can easily pass through cell membranes, while peptide hormones are composed of amino acids and bind to receptors on the outer surface of target cells.

What is the role of the receptor-hormone complex in steroid hormone action?

The steroid binds with a receptor protein, which then enters the nucleus and binds to a specific gene, potentially inhibiting or promoting transcription.

What are examples of steroid hormones?

Estrogen and testosterone.

How do peptide hormones initiate a response in target cells?

They bind to a receptor on the outer surface of the target cell, triggering a secondary messenger that starts a cascade of reactions inside the cell.

What is thyroid hormone (TH) and where is it produced?

Thyroid hormone is produced by the thyroid gland in the neck and is created from an amino acid and iodine.

What is the effect of thyroid hormone on metabolism?

It increases the metabolism of the cell, leading to a greater need for oxygen and other indicators of an increased metabolic rate.

What is hyperthyroidism?

A condition where someone secretes too much thyroid hormone (TH).

What is the significance of the presence or absence of hormone receptors on target cells?

It determines whether or not a cell is a target cell for a particular hormone.

How do hormones influence target cells?

They alter the biochemistry of target cells, leading to changes in function or activity.

What is hypothyroidism?

A condition where someone secretes too little thyroid hormone (TH).

What is melatonin and where is it produced?

Melatonin is produced in the pineal gland and helps regulate the circadian rhythm.

What hormones regulate blood glucose levels?

Insulin and glucagon, produced and secreted by the pancreas.

What effect does insulin have on blood glucose levels?

Insulin lowers blood glucose levels by facilitating glucose uptake into cells.

What is the role of glucagon in blood glucose regulation?

Glucagon increases blood glucose levels by stimulating the hydrolysis of glycogen in the liver and muscle cells.

What is diabetes characterized by?

Hyperglycemia, which is high blood glucose levels.

What causes Type I diabetes?

Insufficient insulin production due to the destruction of beta (ß) cells in the pancreas.

What is Type II diabetes?

A condition where body cell receptors do not respond properly to insulin, leading to insulin resistance.

What are some common factors associated with Type II diabetes?

Genetic history, obesity, lack of exercise, age, and certain ethnic groups.

What is the function of adrenal gland hormones?

They help the body cope with stressful situations and are steroid hormones.

Where are the adrenal glands located?

They are paired pyramid-shaped organs located on top of each kidney.

What is the function of aldosterone?

Targets kidneys to regulate sodium and potassium levels.

What role does cortisol play in the body?

Influences energy metabolism of cells and helps resist stressors, affecting glucose levels and blood pressure.

What are gonadocorticoids?

Weak male sex hormones that are converted to stronger male hormones and some are converted to estrogens in females.

What hormones are released during short-term stress by the adrenal glands?

Epinephrine and norepinephrine, which target the sympathetic nervous system.

What is leptin and where is it produced?

Produced by adipose (fat) tissue and targets the hypothalamus to lower appetite.

What is the function of erythropoietin?

Produced by the kidneys to signal the bone marrow to increase production of red blood cells.

What is osteocalcin and its role?

Produced in bones to signal the pancreas to secrete more insulin.

What is cholecalciferol and how is it activated?

Produced in skin as an inactive form of Vitamin D, activated in the kidneys into calcitriol.

What is the function of calcitriol?

Targets the intestines to transport calcium from food to the blood.

What is the role of the hypothalamus in relation to the pituitary gland?

Controls the actions of the pituitary gland and communicates with its two lobes differently.

What is the growth hormone-releasing hormone (GHRH)?

Stimulates the release of growth hormone, secreted on a daily cycle with highest levels during sleep.

What does growth hormone-inhibiting hormone (GHIH) do?

Inhibits growth hormone release, triggered by feedback of GH.

What hormones are produced in the posterior pituitary gland?

Oxytocin and antidiuretic hormone (ADH).

What is the function of oxytocin?

Targets the uterus for contractions during labor and mammary glands for milk ejection.

What is the role of antidiuretic hormone (ADH)?

Targets the kidneys' collecting ducts to reabsorb water from urine.

What is the function of growth hormone (GH)?

Targets liver, muscle, bone, and other tissues for growth.

What does thyroid-stimulating hormone (TSH) do?

Targets the thyroid gland and causes the release of thyroid hormones.

What is the function of adrenocorticotropic hormone (ACTH)?

Targets the adrenal gland and causes the release of adrenal gland hormones.

What is the role of follicle-stimulating hormone (FSH)?

Targets ovaries and testes for egg and sperm production.

What does luteinizing hormone (LH) target?

Targets ovaries and testes for hormone production.

What is the function of prolactin (PRL)?

Targets mammary glands for milk production during lactation.

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