Endocrine System Notes

Cell Communication

• Cells communicate via hormones.
• Hormones act on target cells.
• Glands release hormones.

Endocrine System

• Consists of glands that secrete hormones.
• Gland: organ that secretes chemicals, specifically hormones.
• Hormone: chemical messenger secreted by a cell that travels through the blood to communicate with target cells.
• A hormone can only trigger a reaction in specific cells, which are called target cells.
• There are approximately 50 hormones in the human body.

Target Cell Example: Oxytocin

• Oxytocin stimulates the contraction of uterine muscles during childbirth.
• Uterine muscle cells have receptors that bind oxytocin.
• Oxytocin does not cause most other muscles in the body to contract because their cells lack the necessary receptors.

What Does the Endocrine System Regulate?

• Metabolism: chemical reactions in the body.
• Control of food intake and digestion: Hormones that give satiety and aid digestion/breakdown of food.
• Tissue development.
• Regulation of solute concentration of the blood (components of plasma).
• Water balance in the body: increasing or decreasing urine volume.
• Heart rate and blood pressure regulation.
• Control of blood glucose and other nutrients.
• Control of reproductive functions (LH / FSH).
• Uterine contractions and milk release.
• Immune system regulation.

Endocrine Glands

• Glands release hormones into the bloodstream.
• Some glands have mixed/extra functions:
  • Pancreas (enzymes).
  • Ovaries (production of oocytes).
  • Testis (production of sperm).

Endocrine System Disorders

Diabetes Mellitus Type 1 (Insulin Dependent)

• Pancreas cannot produce enough insulin, leading to increased glucose concentration in the blood.
• Cause: Autoimmune (unknown).
• Symptoms: Increased thirst, hunger, and fatigue.
• Early onset: Usually diagnosed before age 20.
• Less common.
• Treatment: Daily insulin shots.
• Recommended: Healthy diet and physical activity.

Diabetes Mellitus Type 2 (Insulin Resistant)

• Pancreas makes insulin, but body cells do not take glucose in, resulting in increased blood sugar.
• Causes: Genetics and lifestyle (lack of exercise, unhealthy diet).
• Symptoms: Increased thirst, hunger, and fatigue.
• Late onset: Usually diagnosed after age 40, but increasingly seen in children, teens, and young adults.
• More common.
• Treatment: Medication, healthy diet, and physical activity.

Pituitary Dwarfism

• Too little growth hormone (HGH) is secreted by the anterior pituitary.
• Causes: Genetic.
• Signs: Small stature but normal body proportions.
• Common complications: Bowing of the legs, hunching of the back, and crowded teeth.
• Treatments are aimed at reducing complications.

Gigantism

• Excess Growth Hormone is secreted by the anterior pituitary during childhood.
• Symptoms: Excessive growth in height and internal organs.
• Cause: Genetic or due to a very rare tumor causes the pituitary gland to release excess GH.
• Treatment: Surgery or radiation to remove the tumor and regulate production of GH.
• Early diagnosis is important.

Acromegaly

• Excess Growth Hormone is secreted by the anterior pituitary during adulthood.
• Symptoms: Enlarged bones in hands, feet, and face.
• Cause: Pituitary tumors (benign).
• Treatment: Surgery or radiation to remove the tumor, medication.