Bio 30- endocrine system

the endocrine system

works in conjunction with the nervous system to maintain homeostasis. Glands are ductless and secrete their hormones (chemical messages) directly into the blood and have prolonged effects.

classification of hormones: non target

Affect many cells or tissues. Ex growth hormones

classification of hormones: target

tissue specific

classification of hormones: tropic

activate glands to produce hormones. dont have immediate response.

non tropic

have direct results

chemical structure: steroid

Lipids. Can enter the cell. Lasts longer in blood. Hydrophobic

non steroid

Protein. cant go inside the cell.

antagonistic hormones

work against each other. Ex. blood sugar (insulin vs glucagon)

positive feedback

reinforcement increases further results. Ex. oxytocin

negative feedback

non tropic inhibits tropic hormone production. Ex. metabolism (TSH and thyroxine)

hypothalamus

located in the brain. Physical link between nervous and endocrine systems. Produces oxytocin and ADH which are stored in the posterior pituitary. Stimulates the pituitary via releasing hormones. (GnRH)

Pituitary gland

Located in the brain below the hypothalamus. Anterior: FSH, LH, hGH, PRL,ACTH, TSH. Posterior: OCT, ADH

Antidiuretic Hormone (ADH)

released when the osmoreceptors (check how much water is in the body) shrinks (dehydrates) Directly affects water balance. Makes the nephron more permeable to water so that water can be reabsorbed back into the body.

Hyposecretion of ADH

diabetes insipidus.

Thyroid stimulating hormone (TSH)

stimulates the thyroid gland to release its hormones

Adrenocorticotropic hormone (ACTH)

stimulates the adrenal cortex to release hormones (cortisol, aldosterone, testosterone, estrogen)

Human growth hormone (hGH)

stimulates the growth of bones, muscles, and organs by increasing the uptake of amino acids, the metabolism of fats, and rate of cell division.

hyposecretion of hGH

dwarfism

hypersecretion of hGH

gigantism, acromegaly

prolactin (PRL)

causes milk production

oxytocin (OCT)

causes uterine and mammary muscle contraction

follicle stimulating hormone (FSH)

stimulates gametogenesis. stimulates estrogen production

luteinizing hormone (LH)

Females: stimulates ovulation and progesterone production. Males: testosterone production.

the thyroid gland

located in the neck below the larynx. Controlled by TSH which is secreted by the pituitary. Affected by levels of iodine the body. produces thyroxine and calcitonin.

Thyroxin (T4)

regulates metabolic rate by speeding up the rate of cell resp and utilization of glucose and oxygen. Increases the uptake of carbohydrates from small intestine.

Calcitonin

lowers blood calcium levels by stimulating calcium deposition of bones, reduced calcium uptake in intestines and kidneys. Calcium is needed for proper bone, muscle, and nerve functioning as well as blood clotting.

hyperthyroidism

too much thyroid hormones, results in Graves Disease. Weight loss, rapid heartbeat, fatigue, heat intolerance

Hypothyroidism

not enough thyroid hormones produced. Cretinism and goitre.

The parathyroid glands

produces parathyroid hormone (PTH). Antagonistic to calcitonin. Raises blood calcium levels by stimulating the release of Ca from bones, and the reabsorption of Ca in the GI tract and in the kidneys.

the adrenal glands

located on top of each kidney. Outer layer is the cortex which produces aldosterone, cortisol and sex hormones in response to ACTH from the pituitary. Inner layer is the medulla which produces epinephrine in response to the sympathetic nervous system.

aldosterone

increases the movement of Na+ out of the kidney (urine) back into the blood creating an osmotic pull. Increases blood pressure by increasing water retention.

Difference between ADH and Aldosterone

ADH: Makes the nephron more permeable to water so it can be reabsorbed into the body. Regulated by osmotic pressure.

Aldosterone: Increases the movement of sodium out of the kidney, water follows. Regulated by blood pressure.

Cortisol

responds to long term stress. Reduces inflammation and increases the levels of amino acids in the blood which are converted to glucose. (negative feedback)

Epinephrine (adrenaline)

responds to short term stress (flight or fight). Targets the muscles and liver to convert glycogen into glucose. Increases blood to muscles.

Sex hormones

Males: also from testes. Spermatogenesis in testes and 2nd degree sex traits in the body.

Females: estrogen grows endometrium in uterus and 2nd degree sex traits in body. Progesterone: maintain endometrium and inhibits uterine contractions.

pancreas

located below the stomach. Endocrine and exocrine gland because it produces enzymes to digest food, and contains specialized cells known as islets of Langerhans which secrete insulin and glucagon.

insulin

decreases blood glucose levels. makes the cells more permeable to glucose. Increases the conversion of glucose into glycogen in the liver. non target

hyposecretion of insulin

diabetes mellitus (hyperglycemia)

glucagon

antagonistic to insulin. Increases blood glucose levels. Stimulates the breakdown of glycogen to glucose in the liver.

hyposecretion of glucagon

hypoglycemia

hypersecretion of glucagon

hyperglycemia

Type 1 Diabetes

insulin dependant due to the inability to produce insulin. Treatments include insulin injections/pump, pancreas transplantation, Islet transplantation

Type 2 Diabetes (adult onset)

non insulin dependant. Results from the receptors not responding to insulin. Risk factors are diabetes and lack of exercise. Treatment is diet, exercise and drugs.