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Unit 8: Eye and Endocrine System (Hormones and glands (Growth hormone:…
Unit 8: Eye and Endocrine System
Major structures and
functions of the eye
The accessory structures of the eye include the eyebrows, eyelids, conjunctiva, lacrimal apparatus, and extrinsic eye muscles.
The eyebrows help shade the eyes from sunlight and prevent perspiration trickling down the forehead from reaching the eyes.
The conjunctiva is a transparent mucous membrane.
The lacrimal apparatus consists of the lacrimal gland and the ducts that drain lacrimal secretions into the nasal cavity. The lacrimal gland lies in the orbit above the lateral end of the eye and is visible through the conjunctiva when the lid is everted.
The sclera forms the posterior portion and the bulk of the fibrous layer, it is the white part of the eye.
The cornea bulges anteriorly from its junction with the sclera.
The choroid is a blood vessel–rich, dark brown membrane that forms the posterior five-sixths of the vascular layer.
The iris, the colored part of the eye.
Rods are our dim-light and peripheral vision receptors.
Cones are our vision receptors for bright light and provide high-resolution color vision.
Diseases associated with the eye
Refractive errors are vision problems that happen when the shape of the eye keeps you from focusing well.
A cataract is a clouding of the lens in your eye. It affects your vision. Cataracts are very common in older people.
Glaucoma is a group of diseases that are the leading cause of blindness.Glaucoma usually happens when the fluid pressure inside the eyes slowly rises and damages the optic nerve.
Optic neuritis is an inflammation of the optic nerve.
Optic nerve atrophy is damage to the optic nerve. Causes include poor blood flow to the eye, disease, trauma, or exposure to toxic substances.
Macular degeneration is a disease that destroys your sharp, central vision
Retinoblastoma is cancer of the retina. It is most common in young children.
Diabetic retinopathy is If you have diabetes, your blood glucose, or blood sugar, levels are too high, over time, this can damage your eyes
Major functions of the endocrine system
Endocrine glands produce hormones and lack ducts. They release their hormones into the surrounding tissue fluid and typically have a rich vascular and lymphatic drainage that receives their hormones.
The endocrine system is made up of glands that produce and secrete hormones, chemical substances produced in the body that regulate the activity of cells or organs.
Hormones are chemical messengers created by the body. They transfer information from one set of cells to another to coordinate the functions of different parts of the body.
The hypothalamus is located in the lower central part of the brain. This part of the brain is important in regulation of satiety, metabolism, and body temperature
The pituitary gland is located at the base of the brain beneath the hypothalamus, it produces hormones that control many functions of other endocrine glands.
Hormones and glands
Growth hormone: Stimulates growth of bone and tissue
Thyroid-stimulating hormone (TSH): Stimulates the thyroid gland to produce thyroid hormones
Adrenocorticotropin hormone (ACTH): Stimulates the adrenal gland to produce several related steroid hormones
Luteinizing hormone and follicle-stimulating hormone : Hormones that control sexual function and production of the sex steroids, estrogen and progesterone in females or testosterone in males
Prolactin: Hormone that stimulates milk production in females
Antidiuretic hormone: Controls water loss by the kidneys
Oxytocin: Contracts the uterus during childbirth and stimulates milk production
The thyroid gland is located in the lower front part of the neck. It produces thyroid hormones that regulate the body's metabolism.
The parathyroid glands are two pairs of small glands embedded in the surface of the thyroid gland, one pair on each side.
The two adrenal glands are triangular-shaped glands located on top of each kidney. The adrenal glands are made up of two parts. The outer part is called the adrenal cortex, and the inner part is called the adrenal medulla.
The pineal body, or pineal gland, is located in the middle of the brain. It secretes a hormone called melatonin, which may help regulate the wake-sleep cycle of the body.
The reproductive glands are the main source of sex hormones
The pancreas is an elongated organ located toward the back of the abdomen behind the stomach. The pancreas has digestive and hormonal functions.
Diseases associated with the endocrine system
Adrenal insufficiency. The adrenal gland releases too little of the hormone cortisol and sometimes, aldosterone. Symptoms include fatigue, stomach upset, dehydration, and skin changes. Addison's disease is a type of adrenal insufficiency.
Cushing's disease. Overproduction of a pituitary gland hormone leads to an overactive adrenal gland.
Gigantism and other growth hormone problems. If the pituitary gland produces too much growth hormone, a child's bones and body parts may grow abnormally fast
Hyperthyroidism. The thyroid gland produces too much thyroid hormone, leading to weight loss, fast heart rate, sweating, and nervousness.
In type 1 diabetes, the body isn’t able to produce enough insulin and so blood glucose becomes too high unless insulin is injected.
In type 2 diabetes, the body is unable to respond effectively to insulin, which can also result in higher than normal blood glucose levels.