Endocrine System Quiz

Endocrine System Overview

• The endocrine system is a collection of glands that produce hormones, chemical messengers that regulate various bodily functions.
• These hormones travel through the bloodstream to target organs, where they exert their effects.
• Includes glands such as the pituitary, thyroid, adrenal, pancreas, ovaries and testes.
• Exocrine glands differ from endocrine glands in that exocrine glands secrete products onto surfaces, whereas endocrine glands secrete hormones into the bloodstream.

Learning Outcomes

• Knowledge of endocrine glands is important
• Understanding of hormones and their roles is crucial
• Disorders arising from hormone imbalances are significant
• The intricate interplay between the nervous and endocrine systems regulating homeostasis is key
• A brief discussion on test anxiety is included

Endocrine Glands

• Endocrine glands release hormones into the bloodstream.
• Examples of these glands include the pituitary, thyroid, adrenals, and pancreas, these glands secrete hormones that regulate various bodily functions.  
• Exocrine glands secrete substances into a duct that leads to a surface or cavity, such as salivary and sweat glands.

Hormones

• Hormones are chemical messengers secreted by endocrine glands.
• They travel through the bloodstream and influence specific target organs or tissues. 
• Hormones exhibit diverse structures, categorized as steroid hormones, amine hormones, and peptide/protein hormones. 
• Examples of hormones include testosterone, estrogen, progesterone, adrenaline, insulin, and growth hormone.   
•  Each hormone has a unique receptor in target organs that binds with high specificity.

Functions of Hormones

• Stimulate secretions by exocrine glands. 
• Stimulate secretions by other endocrine glands.
• Regulate metabolic reactions and body biochemistry.
• Regulate muscle contraction and nervous stimulation.
• Regulate growth and development.
• Regulate reproduction.

Hypothalamus and Pituitary Gland

• The hypothalamus acts as the control center, regulating the pituitary gland.
• The hypothalamus targets the pituitary gland for controlling various hormones.
• The pituitary gland is divided into anterior and posterior lobes, which function differently.
• The hypothalamus uses different hormones on each lobe of the pituitary.
• Hormones released by the hypothalamus stimulate or inhibit release from the anterior pituitary.

Releasing Hormones of the Hypothalamus

• Adrenocorticotropic hormone releasing hormone (ACTHRH)
• Thyroid stimulating hormone releasing hormone (TSHRH)
• Gonadotropin releasing hormone (GnRH)
• Growth hormone releasing hormone (GHRH)
• Prolactin releasing hormone (PRH)

Hypothalamus and Anterior Pituitary

• The hypothalamus controls the release of hormones from the anterior pituitary.
• The hypophyseal portal system allows communication between them by way of blood vessels.

Hormones from the Posterior Pituitary

• Oxytocin: responsible for uterine contractions (childbirth) and milk ejection (lactation).
• Antidiuretic hormone (ADH): regulates water reabsorption in the kidneys, aiding in water balance.

When Things Go Wrong

• Over or under activity of endocrine glands can lead to imbalances in hormone levels.

Anterior Pituitary: Growth Hormone

• Stimulates physical growth, increases metabolism, and promotes cell size, bone, and muscle growth.
• Maintains bone and muscle mass in adults and promotes healing.

Growth Hormone Hyposecretion and Hypersecretion

• Childhood hyposecretion: pituitary dwarfism (short stature).
• Childhood hypersecretion: gigantism (abnormally tall).
• Adult hyposecretion: Simmond's disease (weakness, weight and body tissue loss).
• Adult hypersecretion: acromegaly (thickening of bones and other tissues).

Posterior Pituitary: Diabetes Insipidus

• Hyposecretion of ADH causes diabetes insipidus.
• Characterized by polyuria (excess urination) and polydipsia (extreme thirst).
• This is caused by damage to the posterior pituitary or the hypothalamus.

Hormones of the Thyroid

• Thyroid hormone (thyroxine):
  • Stimulated by Thyroid Stimulating Hormone (TSH).
  • Increases basal metabolic rate, affects protein metabolism.  
• Calcitonin: a hormone regulated by negative feedback of calcium ion levels preventing excessive calcium levels in the blood. Reduces calcium levels. 

Thyroid Disorders

• Cretinism (hypothyroid in children): impaired physical and mental development.
• Myxedema (hypothyroid in adults): decreased metabolism, tissue swelling, weight gain.
• Grave's disease (hyperthyroid): increased metabolic rate, nervousness, irritability, protruding eyes.
• Goiter (hyperthyroid in adults): enlarged thyroid gland, often due to iodine deficiency.

Hormones of the Parathyroid

• Parathyroid hormone (PTH): regulates calcium levels in the blood.
• Increases blood calcium levels by stimulating osteoclasts, breakdown bone releasing calcium, increasing calcium absorption in the gut.

Disorders of Parathyroid Hormone (PTH)

• Hyperparathyroidism (too much PTH): bone breakdown issues, weakening, deformations, and bone fractures.
• Hypoparathyroidism (too little PTH): insufficient calcium, depolarization, tetany (muscle spasms).

Adrenal Glands

• Two functional areas, the cortex and the medulla, secrete different hormones.

Adrenal Cortex Hormones

• Mineralocorticoids (e.g., aldosterone): regulate water and electrolyte balance.
• Glucocorticoids (e.g., cortisol): respond to stress, regulate glucose levels and muscle metabolism, and promote gluconeogenesis (production of glucose from non-carbohydrates).
• Androgens (e.g., androstenedione): involved in secondary sex characteristics, primarily released once puberty begins.

Adrenal Cortex Disorders

• Addison's disease (hyposecretion): muscle weakness, mental lethargy, weight loss, and hypoglycemia.
• Cushing's syndrome (hypersecretion): redistribution of fat, flushed facial skin, bruising, hyperglycemia, hypertension.

Adrenal Medulla Hormones

• Epinephrine (adrenaline) and norepinephrine (noradrenaline): response to stress, fear, excitement; increase blood pressure, blood flow to heart and muscles and dilation of the bronchi. Decreases blood flow to the other organs.

Hormones of the Pancreas

• Alpha cells produce glucagon: increases blood glucose levels.
• Beta cells produce insulin: decreases blood glucose levels 

Role of Insulin and Glucagon

• Counter-regulatory hormones regulate blood glucose to maintain homeostasis.  Insulin lowers glucose and glucagon raises it.

Role of Insulin in Glucose Homeostasis

• Insulin triggers body cells to absorb glucose from blood to utilization in cellular respiration.  - Inhibits glycogenolysis and gluconeogenesis

Role of Glucagon in Glucose Homeostasis

• Glucagon prevents cells from absorbing glucose from the blood and using it for energy (inhibits cell activity).  - Stimulates glycogenolysis and gluconeogenesis

Other Hormones

• Several other hormones also regulate blood glucose levels
• Examples include epinephrine, growth hormone and adrenocorticotropic hormones

Loss of Blood Glucose Level Control

• Diabetes mellitus: characterized by high blood sugar levels due to a loss of insulin or insulin resistance    - Type 1: immune system attacks beta cells preventing insulin production    - Type 2: cells do not respond to insulin.   - Hyperinsulinemia: causes hypoglycemia (low blood glucose)   - Symptoms: anxiety, sweating, tremors, increased heart rate, this leads to unconsciousness and coma. 

Blood Calcium Levels

• Bones store calcium, but some circulating calcium is necessary for blood clotting, neurotransmitter release, muscle contraction and heartbeat.
• Maintained by calcitonin and parathyroid hormone.  

Control of Blood Calcium Levels

• Calcitonin and parathyroid work in a counter-regulatory fashion by lowering or raising calcium levels, thus maintaining balance.

Loss of Blood Calcium Levels

• Hyperparathyroidism: too much parathyroid hormone leading to excessive bone breakdown, increasing calcium levels. This can result in bone weakness.
• Hypoparathyroidism: too little parathyroid hormone leading to a shortage of calcium causing muscle convulsions (tetany).

Overview of Glands and Hormones

• A checklist of numerous endocrine glands and the hormones they secrete, their functions, and interactions is provided  

Test Anxiety

•  A cycle of stages experienced before, during and after test taking.
  • Before: anticipation, procrastination, worry about the test
  • During: physiological symptoms, blank mind, nervousness
  • After: disappointment, feeling fear, impacts future tests. 

Dealing With Test Anxiety

• Ways to alleviate test anxiety include pacing studying, practice tests, positive self talk, and staying grounded during tests.

Undercover Endocrine Organs

• Some organs not primarily endocrine glands provide hormonal secretions include placenta, stomach and duodenum. 

Less Understood Endocrine Organs

• Thymus and pineal glands are identified as less understood glands
• Brief overview of their functions is also present

Homeostasis 

•  Homeostasis is the bodies tendency to maintain consistent physiological conditions.
• Stress is a trigger that disrupts homeostasis
• The endocrine and nervous systems work to regain balance in response to stress.

Test your knowledge of the endocrine system with this quiz covering key hormones, their functions, and the conditions associated with hormonal imbalances. Explore questions on growth hormone, insulin, and the distinctions between endocrine and exocrine glands.