Endocrine System Flashcards
Comparison of Control by the Nervous and Endocrine Systems
- The nervous and endocrine systems act together to coordinate all systems of the body.
- The nervous system releases neurotransmitters; the endocrine system releases hormones.
- Most hormones circulate through the blood and bind to receptors on “target” cells.
- Neurotransmitters also bind to receptors on “target” cells.
is the nervous system or endocrine system faster to act?
nervous system is much faster to act
exocrine glands
- secrete products into ducts
- parotid gland - saliva through stensen’s duct
- pancreas - acini - secrete enzymes through the pancreatic duct to the duodenum
endocrine glands
- Secrete hormones
- They do not have ducts and secrete their hormones directly into the interstitial fluid that surrounds them
- The hormones diffuse into the blood stream through capillaries and are carried to target cells throughout the body
- Exclusive endocrine glands include the pituitary, thyroid, parathyroid, adrenal and pineal glands
what glands make up endocrine system but have additional functions?
- Hypothalamus
- Thymus
- Pancreas
- Ovaries/Testes
- Kidneys
- Stomach, Small Intestine
- Liver
- Skin
- Heart
Hormone activity
- hormones are mediator molecules - travel throughout the blood stream - only affect target cells
- target cells have specific protein receptors - hormones chemically bind to these specific receptors
2 classifications of hormones?
- soluble in lipids - bind to transport proteins to circulate in the blood
- soluble in water - travel freely in the blood
lipid soluble hormones
- steroid hormones - derived from cholesterol
- thyroid hormones
- nitric oxide
water-soluble hormones
- amine hormones
- peptide and protein hormones
- eicosanoid hormones
water-soluble hormones at the cellular level
- Water-soluble hormones bind to receptors on the exterior surface of the target cell
lipid-soluble hormones at the cellular level
- Lipid-soluble hormones pass through the cell membrane and bind to receptors within target cells.
- can get through cell membrane - bilipid layer
control of hormone secretion
- Most hormone regulation is achieved via negative feedback
- A few hormones operate via positive feedback
Hypothalamus and pituitary gland
- Work together to control other endocrine glands
- Connected by the infundibulum
hypothalamus
- Controls the ANS
- Coordinates both nervous and endocrine systems
- Secretes releasing and inhibiting hormones that control the release of hormones by the pituitary gland
pituitary
- Previously called “Master gland”
- Secretes hormones that control other endocrine glands
what are the lobes of the pituitary gland?
- adenohypophysis or anterior pituitary
- neurohypophysis or posterior pituitary
Adenohypophysis or Anterior Pituitary
- Anterior Lobe
- Larger (75%)
- Secretes 7 hormones
Neurohypophysis or Posterior Pituitary
- Posterior Lobe
- Releases 2 hormones made by the hypothalamus
Anterior lobe hormones
- Human Growth Hormone (hGH)
- Thyroid Stimulating Hormone (TSH)
- Follicle-Stimulating Hormone (FSH)
- Luteinizing Hormone (LH)
Prolactin (PRL) - Adrenocorticotropic Hormone (ACTH)
- Melanocyte-Stimulating 7. Hormone (MSH)
human growth hormone
- promotes growth, protein synthesis, tissue repair, lipolysis (break down fats)
Thyroid stimulating hormone
- Control metabolic rate – affect weight gain vs loss
- Control body temperature
- Brain development in infants
- Stimulate protein synthesis
- Increase the use of glucose and fatty acids for ATP production
- Work with hGH and insulin to accelerate body growth
- Hypothyroidism
Follicle stimulating hormone
- females - initiates development of eggs and induces ovarian secretion of estrogen
- males - stimulates testes to produce sperm
luteinizing hormone
females - stimulates secretion of estrogens and progesterone, ovulation and formation of corpus luteum
males - stimulates testes to produce testosterone
prolactin
together with other hormones, promotes milk production in mammary glands
adrenocorticotropic hormone
stimulates secretion of glucocorticoids (mainly cortisol) by adrenal cortex
Posterior gland hormones
- antidiuretic hormone
- oxytocin
Antidiuretic hormone
conserves body water by decreasing urine volume, decreases water loss through perspiration, raises blood pressure by constricting arterioles
oxytocin
stimulates contraction of smooth muscle cells of uterus during childbirth, stimulates contraction of myoepithelial cells in mammary glands to cause milk ejection
thyroid gland
- Butterfly shaped
- Right and Left Lateral lobes
- Inferior to larynx
- Anterior to trachea
thyroid gland hormones
Follicular cells are stimulated by TSH (from the anterior pituitary gland) to produce 2 thyroid hormones:
- Thyroxine (T4)
- Triiodothyronine (T3)
parafollicular cells of the thyroid gland
- secrete calcitonin
- decreases blood levels of calcium
hypothyroidism
- Fatigue, muscle weakness, delay in growth, memory problems
- called Myxedema in adults
parathyroid glands
- Posterior surface of the lateral lobes of the thyroid gland
- Each side has a superior and inferior gland
chief cells or principal cells of parathyroid glands
Release parathyroid hormone (PTH) or parathormone in response to low blood calcium levels - PTH increases calcium levels in the blood
diagram from slide 31
know it
Calcitonin (from the thyroid) decreases blood calcium levels, whereas Parathyroid hormone increases blood calcium levels. The 2 negative feedback systems work in unison to maintain homeostasis
adrenal glands
located on top of each kidney
- retroperitoneal
adrenal cortex zones
- outer zone
- middle zone
- inner zone
- steroid hormones are released from the adrenal cortex of the adrenal glands
Outer Zone
Aldosterone
- regulates blood pressure
Middle zone
Cortisone, Corticosterone
- controls inflammation
- dampens immune response
Inner Zone
Androgens
- supports sexual function and development
- promotes bone density and muscle strength
What stimulates the adrenal cortex to release these steroid hormones?
adrenalcorticotropic hormone (ACTH) that is released from the anterior lobe of the pituitary gland
adrenal medulla
- stimulated by the sympathetic division of the ANS
- chromaffin cells
- augment the fight or flight response
what do the chromatin cells secrete
- Epinephrine or adrenaline (80%)
- Norepinephrine or noradrenaline (20%)
Pancreas
- has both an exocrine and endocrine function
pancreas exocrine function
- acinar cells produce digestive enzymes
- digestive enzymes travel to the duodenum through the pancreatic duct
endocrine function of the pancreas
- pancreatic islets or islets of Langerhans
1. Alpha cells
2. Beta cells
alpha cells
secrete glucagon
- raises blood glucose levels
beta cells
secrete insulin
- lowers blood glucose levels
slide 40
know it
Insulin and glucagon work together to maintain blood sugar levels to maintain homeostasis. (Insulin decreases and glucagon increases blood sugar levels) Remember the brain does not store sugar. Therefore, hypoglycemia is a very serious issue clinically. Hyperglycemia is also very dangerous
ovaries hormones
- estrogen
- progesterone
- inhibin
- relaxin
estrogen
- Promotes secondary sex characteristics
- Stimulates uterine growth in preparation for pregnancy
progesterone
- important for fetal development
- if no pregnancy, progesterone decreases and triggers menstruation
Inhibin
inhibits secretion of follicle-stimulating hormone (FSH)
Relaxin
- increases flexibility of pubic symphysis during pregnancy
- helps dilate cervix during labor and delivery
testes hormones
- testosterone
- inhibin
testosterone
- Development of reproductive tissues during embryonic development
- Development of secondary sex characteristics (increase bone and muscle mass)
- Fertility
Inhibin
- inhibits secretion of follicle-stimulating hormone
