Endocrine System Flashcards
What is prolactin (PRL)?
acts on the mammary glands to stimulation milk production; sustains breast feeding
What body systems facilitate cellular communication? Describe how each works.
the nervous system and the endocrine system
NS vs ES:
- NS rapidly affects specific tissues to which neurons directly connect it
- ES uses chemical messengers, hormones, which circulate in the blood stream and have broad, long-lasting effects
What happens when the brain detects sustained danger (long term stress response)?
- the hypothalamus triggers the anterior pituitary to secrete ACTH
- this hormone targets the adrenal cortex (outer portion)
- Cortisol is released into the blood which raises blood glucose levels
What is dwarfism?
deficiency of the growth hormone (or even a genetic mutation)
- results in unusual, short stature
What is acromegaly?
overproduction of growth hormone which causes body tissues and bones to grow more quickly
- increase in thickness of bones in face hands, feet
How does glucose imbalance lead to diabetes mellitus? What is diabetes mellitus?
- diabetes mellitus: a serious chronic condition that results when the pancreas does not make enough insulin or the body does not respond properly to insulin
- levels of blood glucose tend to rise sharply after meals (hyperglycemia) and remain at significantly high levels
~ without insulin, cells remain relatively impermeable to glucose and cannot obtain enough from the blood - the body switches to protein and fat metabolism for energy (releases acetone as a toxic byproduct)
- kidneys cannot rebsorb all the glucose that is filtered through them from the blood, causing there to be glucose in urine
What happens after a meal?
- digestive system releases glucose into the blood stream, increasing blood sugar level
- this increase is detected by the islets of Langerhans
- the BETA cells of the pancreas release insulin into the blood
- it acts on two target cells: body cells to use glucose in respiration and liver cells that convert glucose into glycogen
- as glucose levels drop, insulin secretion slows
What are hormones?
chemical messengers distributed by the blood stream to target cells
What happens during fasting or skipping meals?
- blood glucose levels drop
- this drop is detected by the islets of Langerhans
- the alpha cells of the pancreas release glucagon into the blood
- it acts on the liver cells to convert glycogen back into glucose, which raises sugar levels in the blood and slows the release of glucagon
What are the two parts of the pituitary gland? What does each do?
the anterior pituitary - produces a variety of hormones
the posterior pituitary - stores and releases hormones produced by the HYPOTHALAMUS
What are most of the tropic hormones released by?
released by the hypothalamus & the anterior pituitary and are controlled by a negative feedback loop
What is antidiuretic hormones (ADH)?
acts on the kidney to increase WATER REABSORPTION into the blood
- decreases urine output when dehydrated
What is thyroid stimulating hormone (TSH)?
acts on the thyroid gland to produce thyroxine
- increases metabolism rate of fats, proteins, carbs for energy
- stimulates many cell types (heart, skeletal, kidney)
- assists growth and development in childhood by organizing cells into tissues and organs
What hormones are involved in LONG TERM STRESS RESPONSE?
- Glucocorticoids (Cortisol - increases metabolism)
- Mineralocorticoids (aldosterone - raises blood pressure
- Gonadocorticoids - supplement sex hormones
What is long term stress response?
- occurs in adrenal cortex (outer portion of adrenal glands)
produce stress hormones that trigger sustained physiological responses
What is oxytocin?
stimulate uterine contractions during child-birth & the mammary glands to produce milk for initial breastfeeding (positive feedback)
What is adrenocorticotropic hormone (ACTH)?
acts on the adrenal glands (outer cortex) and causes the release of stress hormone, cortisol
- cortisol raises blood glucose levels by breaking down muscle proteins into amino acids
- stimulates breakdown of fats
- chronic stress causes sustained high cortisol leading to high BP, heart damage, etc.
What is the role of the hypothalamus in the endocrine system?
- links the nervous system to the endocrine system
- produces hormones or electrical messages and sends them to pituitary gland through neurohormones via the pituitary stalk
What is hyperthyroidism?
high thyroxine levels
- symptoms: anxiety, insomnia, irregular heartbeat, weight loss
- severe state = Grave’s disease
What are the negative impacts of a sustained release of cortisol on the body?
can cause many health problems, can impair thinking, damage the heart, cause high BP, lead to diabetes, increase risk to infections and even cause early death
What is the thymus gland
gland between lungs in the chest (part of the immune system when young; produces thymosin which stimulates production & maturation of T lymphocytes
- disappears after puberty & regulated by the pituitary gland
what are neurosecretory cells?
cells in the hypothalamus that receive neural messages and convert them to hormone secretions
- secretions to the anterior pituitary = stimulate release or inhibit release of hormones
- secretions to the posterior pituitary = ADH, oxytocin
what happens in response to a stress for SHORT TERM STRESS RESPONSE?
- the hypothalamus triggers the adrenal medulla to secrete two related hormones: epinephrine and norepinephrine
- these trigger an increase in breathing rate, heart rate, blood pressure, and conversion of glycogen to glucose
~ pupils also dilate & blood flow to extremities is decreased
What is prolactinoma?
tumor causing the pituitary gland to overproduce prolactin
- symptoms: infertility, irregular periods, breast tenderness
What does the stress response involve?
- many interacting hormone pathways, including those that regulate metabolism, heart rate, and breathing
- includes the adrenal glands (located at the top of the kidneys) which mainly initiate the stress response
What is hypothyrodism?
low thyroxine levels
- symptoms include fatigue, slow heart rate, hair loss, weight gain
- if thyroid fails to develop, it can lead to short stature (cretinism)
what is luteinizing hormone (LH)?
in males –> acts on testes to stimulate the release of sex hormone, testosterone to promote sexual maturity
in females –> acts on ovaries to trigger ovulation (release of ovum/egg)
- occurs around day 14 of menstrual cycle; the remainder of the follicle forms a corpus luteum
- corpus luteum releases progesterone to thicken uterine lining in prep for a fertilized egg to implant
- if fertilization does not occur, corpus luteum degenerates, breaking down the uterine lining and causing your period
What do target cells have in response to hormones?
have specific receptors for the hormone & when the hormone binds, a reaction is triggered in the target cell
What is gigantism?
overproduction of a growth hormone
- growth continues during adolescence when bones should stop growing
What is called the master gland and why is it called this?
pituitary gland; releases many hormones that stimulate other endocrine glands & initially controls activity of all other endocrine glands
~ these main hormones are involved in metabolism, growth, reproduction and other life functions
What is short term stress response
hormones associated with the ADRENAL medulla (inner part of adrenal gland) work with the sympathetic nervous system to prepare the body for flight or fight
What type of feedback loop regulates the level of glucose in the blood? What is the normal glucose level?
negative feedback; about 100 mg/dL (4-6 mmol/L)
What hormones are produced by the Anterior Pituitary?
- TSH - thyroid stimulating hormone
- ACTH - adrenocorticotropic hormone
- PRL - prolactin
- hGH - human growth hormone
- FSH - follicle stimulating hormone
- LH - luteinizing hormone
What drives the endocrine stress response?
HPA: the hypothalamic-pituitary-adrenal axis
What is Cushing’s Disease?
tumor causes too much cortisol production (prolonged exposure of body to cortisol)
- causes muscle weakness, weight gain, memory loss
- caused by drugs, cured by drugs
- symptoms: high BP, high blood glucose, muscle weakness, fluid retention
what is follicle stimulating hormone (FSH)?
in males –> acts on testes to stimulate sperm production
in females –> acts on ovaries to produce estrogen and progesterone
- FSH stimulates follicles (containing egg cells) to mature inside the ovary
- as it matures, estrogen and progesterone are released (causing menstrual cycle)
What are islets of Langerhans?
cluster of endocrine cells in the pancreas that secrete two hormones:
1. glucagon (increases blood glucose)
2. insulin (decreases blood glucose
~ both controlled by NEGATIVE FEEDBACK LOOPS
What is calcium balance?
- regulated by two hormones: calcitonin & parathyroid hormone
HIGH BLOOD CALCIUM: stimulates the thyroid gland to release calcitonin which acts on the bones to absorb more calcium to lower blood conc.
LOW BLOOD CALCIUM: stimulates the parathyroid glands attached to the thyroid to release parathyroid hormone (PTH) which causes the bones to break down material & release calcium to raise blood conc
How does the hypothalamus control secretions of the pituitary gland?
by releasing or regulating TROPIC hormones
- these hormones act on other endocrine glands to secrete a target hormone to cause a specific action by a certain tissue, muscle or bone
What is the pineal gland
small gland in the brain that produces melatonin (involved in sleep, mood disorders, depression)
high at night, low in day
what is human growth hormone (hGH)?
acts on almost every body tissue
- stimulates liver to release growth factors to increase protein synthesis and mitosis, which causes growth of muscles, bones and connective tissue
What are the hormones released by the posterior pituitary?
- Antidiuretic Hormone (ADH)
- oxytocin
