Endocrine System Flashcards
How do the endocrine and nervous system interact?
The hypothalamus (nervous) sends neurotransmitters to the pituitary gland (endocrine) which can stimulate other endocrine glands to secrete hormones.
What is an endocrine gland?
They are ductless glands that secrete their hormones directly into the blood stream.
What are hormones?
They control the internal environment of the body from the cellular level
What are the three different types of hormones?
Modified amino acids
Protein
Steroid
Give an example of an amino acid hormone and where it is produced.
Adrenal medulla: epinephrine, norepinephrine.
Posterior pituitary: oxytocin & vasopressin.
Give an example of a protein hormone and where it is produced.
Anterior pituitary gland: gonad stimulating hormone, growth hormone.
Pancreatic islets: insulin
Give examples of steroid hormones and where they are produced.
Adrenal cortex: cortisol
Gonads: estrogen & testosterone.
What is the difference between amino acid, protein and steroid hormones bind?
Amino acid & protein hormones bind to the membrane-bound receptors sites on the cells of target organs. Where as a steroid hormone are soluble in lipids and therefore can cross the cell membrane and binds inside the cell
How do the hypothalamus and the pituitary link?
Via a funnel-shaped stalk called infundibulum.
What kind of chemical signals does the hypothalamus give to the pituitary?
It sends releasing hormones and releasing inhibitory hormones.
These stimulate or inhibit the release of particular hormones in the pituitary.
What are the endocrine glands?
Pituitary gland, pineal gland, thyroid gland, parathyroid gland, thymus, adrenal, islets of Langerhans of the pancreases, ovaries, testes
What is another name for the pituitary gland?
Hypophysis
What is another name for anterior/posterior pituitary?
Anterior =adenohypophysis
Posterior= neurohypophysis
Where is GH (Growth hormone) produced and what does it do?
GH is produced by the anterior pituitary lobe. It stimulates cell metabolism causes cells to divide and increase in size. It also increases protein synthesis, breakdown of fats and carbohydrates, stimulates growth of bone and muscle.
What happens if you don’t have enough GH when your growing?
Cause pituitary dwarfism. The person remains small but body portions are normal.
What happens if a person has to much GH?
In childhood can result in Gigantism.
If after childhood when bone has stopped growing results in acromegaly. Bones widen especially in the face, hands and feet.
What does TSH (thyroid stimulating hormone) do?
It stimulates the thyroid.
What regulates TSH (thyroid-stimulating hormone)
Hypothalamus (produces thyrotropin-releasing hormone (TRH) which stimulates the terror pituitary lobe to secrete TSH)
What does adrenocorticotrophic hormone (ACTH) stimulate?
It’s stimulates the adrenal cortex to secrete its hormone called cortisol.
What regulates Adrenocorticotropic (ACTH)
ACTH is regulated by corticotropin-releasing hormone (CRH) produced by the hypothalamus.
What is ACTH involved with?
ACTH is involved with the glucose-sparing effect and helps reduce inflammation as well as stimulating the adrenal cortex.
What does Melanocytes-stimulating hormone (MSH) do?
It increases the production of melanin in melanocytes in the skin, thus causing a deepening pigmentation/darkening of the skin.
What stimulates the ovaries in females to develope follicles?
Follicle-stimulating hormone.
What does FSH stimulate in males
Sperm production in the seminiferous tubules of the testes
What does Luteinizing hormone (LH) do?
It stimulates ovulation in the female ovary and production of the female sex hormone progesterone. It also helps maintain pregnancy.
What does LH do in males?
Stimulates the synthesis of testosterone in the testes to maintain sperm cell production.
What is another name for Lactogenic hormone (LTH)
Prolactin
What does LTH/prolactin do?
It stimulates milk production in the mammary glands following delivery in pregnant females.
It also helps to maintain progesterone levels following ovulation and during pregnancy.
What does Lactogenic hormone do in males?
It increases sensitivity to LH and may cause a decrease in male sex hormones
What is the posterior pituitary lobe composed of?
Nerve fibres and neuroglia cells that support the nerve fibres.
What is the anterior lobe of the pituitary made up of?
Glandular epithelial cells
What is another name for vasopressin?
Antidiuretic hormone (ADH)
What does ADH do?
Maintains the body’s water balance by promoting increase water reabsorption in the tubules of the nephrons of kidneys resulting in less water in the urine.
What happens if someone has a deficiency in ADH?
A condition called: diabetes insipidus. They produce 20-30L of urine daily.
What does oxytocin do?
OT stimulates contractions of smooth muscles in the wall of the uterus.
What stimulates OT?
Stretching of uterine and vaginal tissues in late pregnancy stimulates production of OT so that uterine contractions develop in the late stages of childbirth.
What else does oxytocin (OT)do?
It also causes contraction of cells in the mammary glands causing milk ejection or lactation forcing the milk from the glandular ducts into the nipple during breastfeeding.
Why would a women be given OT?
1) help to induce labor
2) give to women after childbirth to constrict blood vessels of the uterus to minimize the risk of hemorrhage.
Describe how the thyroid is made
It consist of two lobes connected by a smaller band called the isthmus. The loves are situated on the right and left sides of the trachea and thyroid cartilage just below the larynx
What covers the thyroid gland?
Covered with a capsule of connective tissue. It is made up of spheres of cells called follicles.
What are the follicles on the thyroid gland composed of?
They are composed of cuboidal epithelium. Which produces and secretes the thyroid horomones.
How is the thyroid gland regulated?
The hypothalamus signals the pituitary to release TSH to increase thyroid production.
What does the thyroid require to work properly?
Iodine
What happens if you don’t have enough iodine in you body?
The thyroid gland can enlarge to form a goiter.
What is another name for thyroxine?
Tetraiodothyronie
What does tetraiodothyronie (thyroxine) abbreviated to and why?
T4 b/c it contains four iodine atoms
What is the abbreviation for triiodothyronine?
Contains 3 iodine atoms = T3
What do T4 & T3 do?
They regulate the metabolism of carbohydrates, fats, proteins. They are necessary for normal growth and development and maturation of the nervous system.
What happens if you have low or lack thyroid hormones?
Hypothyroidism.
What happens in children if they are hypothyroidism?
They can develop a condition known as cretinism. = mentally retarded and does not grow to normal stature.
What happens in adults who are hypothyroid?
Lower metabolism, causing sluggishness, to tired to perform normal daily tasks.
What can accumulate in adults who are hypothyroid.
Can have an accumulation of fluid in subcutaneous tissues called myxedema
What is it called if you have to much thyroid hormone?
Hyperthyroidism. = extreme nervousness, fatigue, increased rate of body metabolism.
What is Graves’ disease?
A type of hyperthyroidism caused by overproduction of thyroid production. Associated with enlarged thyroid gland/goiter and bulging of eyeballs (exophthalmia)
What is exophthalmia?
Bulging of the eyeballs associated with Graves’ disease.
Where is calcitonin excreted from?
The extrafolliclar cells of the thyroid.
What does calcitonin do?
Lowers calcium/phosphate ion in blood by inhibiting it being released from bones and by increasing excretion of these ions by the kidneys.
What is thyroid secretion controlled by?
THS produced by the anterior pituitary gland
How is the thyroid regulated?
By an negative feedback loop that inhibits the anterior pituitary gland from releasing more TSH and the hypothalamus from secreting TSH releasing hormone.