ch 9

Question 1

the endocrine system: function

Answer 1

system that works with nervous system to MAINTAIN HOMEOSTASIS by releasing chemical hormones from various glands
- composed of endocrine glands and hormones

Question 2

function of endocrine glands

Answer 2

secrete chemical messengers (HORMONES) directly into bloodstream

Question 3

there are over 200 hormones in the human body, with various functions that regulate

Answer 3

• growth and development
• metabolism
• blood pressure
• immune response
• blood glucose levels
• water-salt balance

Question 4

glands + tissues

Answer 4

some glands are exclusively endocrine glands:
- pituitary
- pineal
- thyroid
- parathyroid
- adrenal glands
some tissues/organs secrete hormones, but aren’t exclusively endocrine glands:
- hypothalamus
- thymus
- panreas
- testes
- ovaries

Question 5

endocrine hormones

define + types

Answer 5

chemicals secreted by endocrine glands directly into the blood
- classified according to their activation site
NON-TARGET HORMONES: affect many cells throughout body (ex. insulin, epinephrine)
TARGET HORMONES: affect specific cells/target tissues (parathyroid hormone, gastrin)

Question 6

chemical control systems: compared to the RAPID actions of the nervous system,

Answer 6

endocrine system has SLOWER and LONGER ACTING EFFECTS + affects a BROADER RANGE of CELL TYPES
- hypothalamus regulates PITUITARY GLAND through nerve stimulation, but pituitary gland is what stimulates the glands of the endocrine system to release hormones
- scientists discovered the hormones that are low concentration in the blood by trial and error (usually removing an organ and seeing what goes wrong lmao)

Question 7

types of hormones

Answer 7

1. steroid hormones
   made from cholesterol
   - complex CHO rings, fat soluble, easily diffuse DIRECTLY through lipid bilayer of target cell + activate specific genes to elicit response (1. diffuse into target cell 2. bind to receptor protein in cytoplasm 3. hormone-receptor complex activates specific genes to elicit response 4. affect gene expression)
2. peptide hormones
   made from a.a. chains
   - water soluble
   - can’t diffuse across membrane (1. bind to receptor on membrane surface, causing chain reaction inside target cell 2. peptide hormones affect metabolic enzyme activity- enzyme cascade)
   adenylyl cyclase catalyzes conversion of ATP to cyclic AMP
   - cAMP (cyclic AMP) = cyclic adenosine monophosphate = secondary chemical messenger that directs protein synthesis by ribosomes
   - production of cyclic AMP can be stopped by a 2nd type of G protein which inhibits the activity of adenylyl cyclase

Question 8

major glands of the endocrine system: pituitary gland

Answer 8

pea sized gland in bony cavity attached by thin stalk to hypothalamus at base of brain
- controls other endocrine glands + regulates body growth (coordinates endocrine and nervous)
- releases hormones important for metabolism, growth, development, reproduction, and other critical life functions
- composed of posterior pituitary/lobe and anterior pituitary/lobe

Question 9

major glands of the endocrine system: pituitary gland: posterior pituitary

Answer 9

• considered part of nervous system
• doesn’t produce any hormones- STORES AND RELEASES hormones ADH and oxytocin (childbirth) which are produced in the hypothalamus

Question 10

major glands of the endocrine system: pituitary gland: anterior pituitary

Answer 10

true hormone-synthesizizng gland
produces and releases 6 main hormones:
- TSH (thyroid-stimulating hormones)
- ACTH (adrenocorticotropic hormone)
- PRL (prolactin)
- hGH (human growth hormone)
- FSH (follicle-stimulating hormones)
- LH (luteinizing hormone)
hypothalamus controls secretions of anterior pituitary + hormones are secreted into bloodstream

Question 11

major glands of the endocrine system: thyroid gland

Answer 11

butterfly-shaped gland in front of neck that secretes a hormone that CONTROLS the SPEED at which the body cells work, e.g.
- bone growth
- mental development
- metabolic use of energy
- blood pressure and heart rate
- muscle tone
- digestion
- reproduction
secretion of thyroid hormones is under NEGATIVE CONTROL (feedback) from hypothalamus (via TSH)
- goiter: iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine (T4, which = tyrosine + iodine, which comes from seafood, milk, ionized salt)

Question 12

major glands of the endocrine system: parathyroid glands

Answer 12

four small glands in thyroid gland that regulate the CA2+ content in blood. Calcium’s functions:
- bone and teeth structure
- cell signaling
- nerve conduction
- muscle contraction
- blood clotting

Question 13

the adrenal glands

Answer 13

located above each kidney (tiny lil hats) (left vs right adrenal gland)
- regulate use of carbs and salts + prepares the body for emergency by producing epinephrine (adrenaline)
- two glands (each made of cortex + medulla encased in one shell): ADRENAL CORTEX (outer) and ADRENAL MEDULLA (inner)

Question 14

adrenal glands: adrenal cortex (outer)

Answer 14

• involved in long-term stress response
• produces glutocorticoids and mineralocorticoids
  cortisol: glucocorticoid (adrenal cortex) that raises blood glucose by promoting breakdown of muscles to a.a., prompts breakdown of fat cells
• chronic stress => impaired thinking, heart damage, high blood pressure, infection, death
• natural anti-inflammatory + supresses immune system + inhibits regeneration of connection tissue
  aldosteron: mineralocorticoid (adrenal cortex) that increases the absorption of sodium into the blood (inc. ion sodium concentration in blood, more osmosis, inc. blood pressure) (water always follows sodium) (increases volume)

Question 15

adrenal glands: adrenal medulla (inner)

Answer 15

• produces epinephrine and norepinephrine (adrenaline and noradrenaline)
• regulates the short-term stress response (fight/flight)
• hormonal effects similar to sympathetic system, but influence lasts about 10 times longer

Question 16

pancreas + hormones

Answer 16

pancreas located behind stomach + connected to small intestine
- much of the tissue secretes digestive enzymes into the small int, but also functions as an endocrine gland
ISLETS OF LANGERHANS: scattered throughout pancreas: 2000+ clusters of endocrine cells
- secrete INSULIN and GLUCAGON (antagonistic hormones: have opposite effects)
- 2 types of cells in islets of langerhans: beta cells (secrete insulin, decrease blood glucose level) + alpha cells (secrete glucagon, increase blood glucose level)
- insulin and glucagon regulated by NEGATIVE FEEDBACK

Question 17

insulin and glucagon: blood glucose homeostasis

Answer 17

regulated by negative feedback
- when blood glucose levels rise, beta cells secrete insulin (which makes cells more permeable to glucose, therefore blood glucose decreases)
- especially after muscle cells, which use a large amount of glucose in cellular respiration, and liver cells, where glucose is converted into glycogen for temporary storage
- exercise/fasting causes blood glucose levels to drop
- low blood sugar stimulates the alpha cells to release glucagon
- glucagon stimulates the liver to convert glycogen back into glucose, which is released into blood

Question 18

effects of glucose imbalance

Answer 18

• diabates mellitus
• hyperglycemia/high blood sugar (levels of blood glucose rise sharply after meals + remain significantly elevated)
• kidney disease

Question 19

effects of glucose imbalance: diabetes mellitus

Answer 19

serious chronic condition with no known cure: diabetes results when the body does not produce enough insulin/doesn’t respond properly to insulin
- w/o insulin, cells remain relatively impermeable to glucose and cannot obtain enough enough from the blood
- individuals experience fatigue (cells starved for glucose)
- body compensates by switching to protein and fat metabolism for energy
- fats + proteins less accessible and harder to break down
- kidneys cannot reabsorb all the blood glucose that is filtered through them, so glucose ends up in the urine
- as there is a lot of glucose in the urine, quite a bit of water follows it
- make diabetics very thirsty and usually produce large volumes of glucose-rich urine
- continued high levels of blood glucose can lead to blindness, kidney failure, nerve damage, and gangrene in the limbs
type 1 + type 2

Question 20

effects of glucose imbalance: diabetes mellitus: type 1

Answer 20

• Juvenile diabetes/insulin-dependent diabetes
• Immune system produces antibodies that attack and destroy beta cells in the islets of Langerhands
• Beta cells degenerate and can’t produce insulin
• Condition is usually diagnosed in childhood
• Patients must have daily injections of insulin to live

Question 21

effects of glucose imbalance: diabetes mellitus: type 1

Answer 21

Adult-onset diabetes/non-insulin-dependent diabetes
- Tends to develop gradually as insulin receptors on body’s cells stop responding to insulin
- In some cases, beta cells produce less and less insulin over time
- Usually diagnosed in adulthood and can often be controlled with diet, exercise and oral drugs that stimulate the islets of Langerhans
- People who are overweight have a higher risk of developing type 2 diabetes
- About 90% of people with diabetes have type 2
- Without proper care, type 2 diabetes can develop into type 1, which is insulin-dependent
Type 2 diabetes is increasing worldwide at an alarming rate
- Type 2 diabetes is linked closely to unhealthy diet and weight gain

Question 22

effects of glucose imbalance: kidney disease

Answer 22

condition in which kidney’s don’t concentrate urine very well
- symptoms: frequent urination, strong thirst response
- causes: inadequate production of ADH by hypothalamus (kidneys don’t reabsorb enough water), may be caused after head/brain injury, brain tumours, medication containing lithium
- treatment: drinking large volumes of water to replace what has not been reabsorbed