Endocrine Glands and Hormones: Functions, Disorders, and Musculoskeletal System

Endocrine Glands and Hormones

Endocrine glands respond to stimulations by producing hormones transported in blood through the body. Each hormone affects its target cell which contains specific receptors. Hormones are chemical messengers that activate or stop, accelerate or delay processes by organs. Hormone receptors cause chemical reactions inside the cell producing a response.

Hypothalamus produces nerve signals and hormones: releasing factors and inhibiting factors. These factors act on pituitary glands and control the release of hormones.

Pituitary (2 Lobes)

• Anterior: growth hormone/TSH-stimulates production of thyroid hormones/gonadotropes-follicle stimulating hormone (FSH) and (LH) act on ovaries and testes/ACTH-stimulates secretion of the adrenal glands/prolactin-breast growth and milk production
• Posterior: antidiuretic-prevent water loss in kidneys/oxytocin-uterine contractions and expulsion of milk after birth

Testes

• Testosterone-stimulates sperm production, secondary sex characteristics

Ovaries

• Oestrogens-secondary sex characteristics
• Progesterone-prepares uterus for pregnancy

Pancreas (Behind Stomach)

• Insulin-reduces glucose in blood, used as energy in tissues
• Glucagon-increases glucose in blood

Adrenal Glands (Over Kidneys)

• Cortex-cortisol synthesis of glucose and breakdown of fats and proteins
• Medulla-adrenaline

Parathyroid

• Four small dots at the back of thyroid
• Parathyroid hormone-increases amount of calcium in blood by stimulating release from bones

Thyroid (2 Lobes in Neck)

• T3 & T4-increase cell metabolic consumption, synthesis of proteins, use of glucose and growth
• Calcitonin-regulate level of calcium in blood, aids bone development

Diseases of the Endocrine System

• Hypofunction-insufficient hormone production
• Hyperfunction-excessive production of a hormone, dysfunction alteration in the receptors
• Diabetes mellitus-increase glucose in blood, problems affect cardiovascular system, liver, and retina. Type 1-deficiency in insulin production by the pancreas (Young). Type 2-pancreas produces insulin, cells don't respond to it (older)
• Hyperthyroidism-excess in thyroid hormone production, increase in metabolism
• Hypothyroidism-deficit in production of thyroid hormone, slowdown metabolism
• Dwarfism and gigantism-deficient or excessive production of growth hormone (pituitary)

Musculoskeletal System

When a muscle contracts, it thickens and reduces the distance between the tendons at both ends. The contracted muscle pulls on the bone that is connected to and moves it if it is part of a joint. The muscle relaxes, lengthens, and stops pulling on the bone. This allows the bone to return to its initial position.

Disorders:

• Osteoporosis-loss of bone mass, resulting in weakened bone
• Arthritis-inflammation joint
• Osteoarthritis-degeneration of joint cartilage
• Muscle contraction-involuntary, sustained contraction of a muscle
• Sprain-twisting of a joint, can cause breakage of fibers in ligaments
• Dislocation-two bones move from their normal position
• Fracture-break of a bone
• Slipped disc-displacement of an intervertebral disc, may compress the nerve, causing pain
• Torn cartilage-tearing of the meniscus in the knee

Musculoskeletal System

Skeletal System (bones, joints, and ligaments)-supports weight of the body, blood cells in bone marrow, stores calcium and phosphorus, protects internal organs

Muscle System (skeletal muscles)-attached to bone tendons. Musculoskeletal system acts as a system of levels. The active component (muscles) exerts force on the passive component (bones) causing the body to move. Continued involuntary contractions of muscles, muscle tone, keeps muscles firm.