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Eye and Endocrine System, Miranda Mancilla, Per. 2 (Hormones and their…
Eye and Endocrine System, Miranda Mancilla, Per. 2
Major Structures/Functions of the Eye
Structure:
Sclera
Function
: Tough outer covering of the eye which protects and gives the eye it's shape.
Pupil
Function
: allows a certain amount of light into the eye.
Cornea
Function
: Allows light to pass through. Provides assistance in focusing images onto the retina as well as gives protection to the iris.
Lens
Function
: Responsible for focusing images from the environment onto the retina of the eye.
Vitreous Humor
Function
: Helps maintain the shape of the eye.
Ciliary Body
Function
: Controls the size of the lens.
Retina
Function
: Houses the sight receptors that translate light impulses into neural inputs that the brain can interpret as images.
Aqueous Humor
Function
: A fluid that helps to retain the shape of the cornea.
Optic Disc
Function
: Connects the eye to the brain.
Blind Spot
Function
: Lacks any sight receptors.
Optic Nerve
Function
: Takes images received by the retina and transmits them to the brain in form of electrical impulses.
Choroid
Function
: Houses many blood vessels necessary to bring oxygen and nutrients to the back of the eye so that it can function.
Iris
Function
: Controls the amount of light that enters the eye. Identifies the color of the eye.
Major Glands/Organs and their Functions
Thyroid Gland
Function
: Produces hormones that regulate the body's metabolic rate as well as heart and digestive function, muscle control, brain development, mood and bone maintenance.
Parathyroid Gland
Function
: Control the body's calcium levels.
Anterior Pituitary
Function
: Regulates several physiological processes including stress, growth, reproduction, and lactation.
Pineal Gland
Function
: produces melatonin, which helps maintain circadian rhythm and regulate reproductive hormones.
Thymus
Function
: Generates mature T lymphocytes (white blood cells that help the immune system fight off illness).
Pancreas
Function
: Two of the main pancreatic hormones are insulin, which acts to lower blood sugar, and glucagon, which acts to raise blood sugar.
Adrenal Cortex
Function
: Produces hormones such as cortisol (which helps regulate metabolism and helps your body respond to stress) and aldosterone (which helps control blood pressure).
Ovaries
Function
: Produce the female hormones estrogen and progesterone.
Testes
Function
: Produce gametes, or sperm, and they secrete hormones, primarily testosterone.
Posterior Pituitary
Function
: Secretes the hormone oxytocin which increases uterine contractions and antidiuretic hormone (ADH) which increases reabsorption of water by the tubules of the kidney.
Adrenal Medulla
Function
: Controls hormones that initiate the "flight or fight" response.
Major Functions of the Endocrine System
Influences metabolic activity by means of hormones.
Hormones are chemical messengers secreted by cells into the extracellular fluids.
These messengers travel through the blood and regulate the metabolic function of other cells in the body.
Hormones and their Target Organs (functions)
Parathyroid Hormone (PTH)
Function
: Stimulates the osteoclasts to break down calcium-containing bone matrix to release free calcium ions into the bloodstream. Also triggers kidneys to return calcium ions.
Target
: Osteoclasts and kidneys.
Cortisol (glucocorticoids)
Function
: Breakdown of proteins and lipids to produce glucose. Reduces inflammation and immune response.
Target
: Proteins and lipids.
Calcitonin
Function
: Reduces the concentration of calcium ions in the blood by aiding the absorption of calcium into the matrix of bones.
Target
: Bones.
Aldosterone (mineralocorticoids)
Function
: Regulate the concentration of mineral ions in the body.
Target
: Kidneys.
Thyroid Hormone (Thyroxine and triiodothyronine) (TH)
Function
: T3 and T4 work together to regulate the body's metabolic rate. Increased levels lead to increased cellular activity and energy usage in the body.
Target
: All cells in the body.
Epinephrine/Norepinephrine
Function
: Helps increase blood flow to the brain and muscles to improve "fight-or-flight" response to stress. Increases heart rate, breathing rate, and blood pressure.
Target
: Brain.
Oxytocin
Function
: Triggers uterine contractions during childbirth and the release of milk during breastfeeding.
Target
: Uterine.
Insulin
Function
: Responsible for lowering blood glucose levels after a meal. Triggers absorption of glucose from the blood into the cells.
Target
: Blood.
Antidiuretic Hormone (Vasopressin) (ADH)
Function
: Prevents water loss in the body by increasing the re-uptake of water in the kidneys and reducing blood flow to sweat glands.
Target
: Kidneys.
Glucagon
Function
: Triggers muscle and liver cells to break down the polysaccharide glycogen to release glucose into the bloodstream.
Target
: Muscles and liver.
Luteinizing Hormone (LH)
Function
: Stimulates the gonads to produce the sex hormones.
Target
: Gonads.
Testosterone
Function
: Causes growth and increases in strength of the bones and muscles, including the accelerated growth of long bones. Controls growth and development of the sex organs and body hair.
Target
: Bones and muscles.
Follicle-stimulating Hormone (FSH)
Function
: Stimulates the follicle cells of the gonads to produce gametes.
Target
: Gonads.
Estrogen
Function
: Triggers the development of female secondary characteristics. Triggers the increased growth of bones during adolescence.
Target
: Sex organs.
Prolactin (PRL)
Function
: Stimulates the mammary glands of the breast to produce milk.
Target
: Mammary glands (breasts).
Progesterone
Function
: Maintains appropriate conditions in the human body to support a developing fetus.
Target
: Female human body.
Adrenocorticotropic Hormone (ACTH)
Function
: Stimulates the adrenal cortex, the outer part of the adrenal gland, to produce its hormones.
Target
: Adrenal cortex.
Melatonin
Function
: helps to regulate the human sleep-wake cycle known as the circadian rhythm. Increased melatonin production causes humans to feel drowsy.
Target
: Brain (hypothalamus).
Thyroid-Stimulating Hormone (TSH)
Function
: Responsible for the stimulation of the thyroid gland.
Target
: Thyroid.
Thymosin
Function
: Helps to train and develop T-lymphocytes during fetal development and childhood.
Target
: T-lymphocytes.
Growth Hormone (GH)
Function
: Affects many target cells throughout the body by stimulating their growth, repair, and reproduction.
Target
: Bones and muscles.
Diseases Associated with the Endocrine System
Diabetes insipidus
A syndrome marked by intense thirst and huge urine output.
Insulin deficiency causes large amounts of blood glucose to be lost in the uterine.
Grave's Disease
Most common hypothyroid condition.
A person makes antibodies directed against thyroid follicular cells.
Symptoms include rapid, irregular heartbeat; nervousness; and weight loss despite adequate food.
Cushing's Disease
Caused by an ACTH-releasing pituitary tumor.
Glucocorticoid excess.
Addison's Disease
The major hyposecretory disorder of the adrenal cortex, usually involves deficits in both glucocorticoids and mineralocorticoids.
Diabetes mellitus (DM)
Results from either hyposecretion or hypoactivity of insulin.
When insulin is absent, the result is type 1 diabetes mellitus. If insulin is present, but its effects are deficient, the result is type 2 diabetes mellitus.
Blood glucose levels remain high after a meal because glucose is unable to neter most tissue cells.