Endocrine and Musculoskeletal Systems: Function & Health

The Endocrine System

Endocrine glands: are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct.

Hormones: are any member of a class of signaling molecules produced by glands in multicellular organisms that are transported by the circulatory system to target distant organs to regulate physiology and behaviour.

Blood vessels: are the part of the circulatory system, and microcirculation, that transports blood throughout the human body.

Target cell: are cells that respond to a hormone because they possess specific receptors for that hormone.

Receptor: A molecule, usually a protein, that binds to a specific hormone, initiating a cellular response.

Endocrine Signaling Pathway Example

Principal Endocrine Glands and Hormones

Pituitary Gland

It consists of two lobes located in the head. Each lobe secretes several hormones.

Anterior Pituitary Lobe

• Growth hormone
• Thyroid-stimulating hormone (TSH)
• Gonadotropins:
  • Follicle-stimulating hormone (FSH)
  • Luteinizing hormone (LH)
• Adrenocorticotropic hormone (ACTH)
• Prolactin

Posterior Pituitary Lobe

• Antidiuretic hormone (ADH)
• Oxytocin

Testes

Male glands.

• Testosterone

Thyroid Gland

It has two lobes and is located in the neck in front of the trachea.

• T3 (Triiodothyronine)
• T4 (Thyroxine)
• Calcitonin

Parathyroid Glands

Four small glands located at the back of the thyroid.

• Parathyroid hormone

Adrenal Glands

Two glands situated over the kidneys. There are two areas in each: cortex and medulla.

Pancreas

A flat, elongated gland located behind the stomach. It produces two hormones:

• Insulin
• Glucagon

Ovaries

Female glands.

• Estrogens
• Progesterone

Endocrine System Disorders

• Hypofunction
• Hyperfunction
• Diabetes mellitus
• Hyperthyroidism
• Hypothyroidism
• Dwarfism

Healthy Habits for Endocrine Health

• Maintain a balanced diet
• Do regular and moderate exercise
• Be responsible about consuming drugs

Bones and Joints

Joints are classified by their movement:

• Freely movable joints
• Slightly movable joints
• Immovable or fixed joints

Types of Muscle

Muscles can be described by shape or fiber arrangement:

• Triangular
• Parallel
• Orbicular

How the Musculoskeletal System Works

Muscles often work in pairs:

• Agonist: Muscle that works in the same direction (prime mover).
• Antagonist: Muscle that works in the opposite direction of the agonist.

Movement also involves mechanical principles:

• Effort
• Resistance
• Fulcrum

Musculoskeletal System Disorders

• Osteoporosis
• Arthritis
• Osteoarthritis
• Muscle contraction (e.g., cramp)
• Sprain
• Dislocation
• Fracture
• Slipped disc
• Torn cartilage

Healthy Habits for Musculoskeletal Health

• Maintain a healthy and balanced diet
• Practice correct posture
• Exercise regularly