Chapter 5.4 Flashcards
aldosterone’s
Aldosterone increases sodium and water reabsorption in the distal convoluted tubule of and the collecting duct of the nephron. It also decreases the reabsorption of potassium and hydrogen ions in these same segments of the nephron.
How are the effects of Aldosterone and ADH different and similar?
ADH only increases reabsorption of water in the collecting duct, which increases the amount of water in the blood without any respect for solutes. This causes the blood to become more dilute.
Aldosterone on the other hadn increases the reabsorption of sodium and water, which means the blood has more water and solutes, maintaining its initial concentration.
Both increase blood volume and pressure
How are mineralcorticoids signalled to be released?
Mineralcorticoids (aldosterone) are signalled to be released by the renin-angiotensin-aldosterone system.
Briefly describe the steps of the renin-angiotensin-aldosterone system
- Decrease in blood pressure activates the juxtaglomerular cells of the kidney to secrete renin.
- Renin cleaves Angiotensinogen into Angiotensin I, its active form.
- Angiotensin I is converted into Angiotensin II by Angiotensin Converting Enzyme (ACE). This happens in the lungs!
- Angiotensin II stimulates the adrenal cortex to secrete aldosterone.
- Blood pressure increases
What are the three main functions of the corticosteroids?
MNEMONIC: The 3 S’s
1. Salt (Mineralcorticoids)
2. Sugar (Glucocorticoids)
3. Sex (Cortical Sex Hormones)
What are the cortical sex hormones?
The cortical sex hormones are androgens and estrogens that are synthesized outside of the gonads by the adrenal cortex.
What are the hormones secreted by the Adrenal Medulla?
Epinephrine and Norepinephrine
How does cortisol compare to Epinephrine and Norepinpephrine in terms of stress response?
Cortisol is considered to be a long term stress hormone, where as epinephrine and norepinephrine are meant to deal with immediate stressful situations.
What is the pancreas?
The pancreas is a endocrine gland that controls the level of blood sugar.
What are the three types of cells found in the pancreas?
- Alpha cells
- Beta cells
- Delta cells
What is the function of the alpha cells?
To secrete glucagon
What is the function of the beta cells?
To secrete insulin
What is the function of the delta cells?
To secrete somatostatin
What is the function of Glucagon?
Glucagon increases the level of glucose in the blood.
MNEMONIC: GlucaGON levels are high when glucose is GONE
What are the 3 ways Glucagon increases blood glucose?
- Glucagon stimulates degradation of protein and fat into glucose.
- Glucagon stimulates conversion of Glycogen to Glucose
- Glucagon stimulates production of new glucose via Gluconeogenesis.
What is the function of Insulin?
Insulin decreases the level of glucose in the blood.
How does Insulin decrease glucose levels in the blood?
Insulin decreases blood sugar by stimulating the uptake of glucose by muscle and liver cells to store as glycogen. Insulin also stimulates the synthesis of proteins and fats, which uses up glucose.
What is hypoglycemia?
Low blood sugar
What is hyperglycemia?
High blood sugar (diabetes)
What is the difference between the two types of diabetes?
In type 1 Diabetics, the body’s immune system has erroneously destroyed the Beta Cells, making endogenous insulin production impossible.
In type 2 Diabetics, Insulin is produced, but the insulin receptors on the cells are insensitive to it.
What is the function of Somatostatin and when is it released?
Somatostatin inhibits the secretion of both insulin and glucagon. High blood glucose and amino acid concentrations stimulate its secretion.
Its also produced by hypothalamus where it decreases growth hormone secretion
What is the pineal gland?
The pineal gland is an organ deep in the brain that secretes melatonin.
What is the function of melatonin?
The precise function of melatonin is still unclear, but levels of melatonin in the blood are correlated with feelings of sleepiness. Melatonin has also been shown to affect circadian rhythm.
What is erythropoeitin’s function and what organ secretes it?
Erythropoeitin stimulates bone marrow to increase the production of blood cells. This hormone is secreted by the kidneys in response to low oxygen levels in the blood.
What is Atrial Natriuretic Peptide (ANP) and what organ secretes it?
ANP is a hormone that promotes the excretion of sodium and therefore water, which increases the volume of urine and lowers blood volume/pressure. Antagonistic to aldosterone (because no change in osmolarity) This hormone is secreted by the heart.
What is thymosin and what organ secretes it?
Thymosin is a hormone involved in the proper development and differentiation of T-Cells. This hormone is produced by the Thymus.
Does the posterior pituitary synthesize its own hormones?
No. Both Oxytocin and ADH are synthesized by the hypothalamus, but released by the posterior pituitary.
