加拿大生物_渗透压调节以及内分泌系统

1、Osmoregulation and the Endocrine System Osmoregulation (water balance) is controlled by 2 hormones: Aldosterone (ALD) from the adrenal cortex Antidiuretic Hormone (ADH) from the posterior pituitary both of these hormones are controlled by regulators in the hypothalamus which control ion concentratio

2、n both combat DIURETICS (substances that make a person urinate such as alcohol, salt, blood pressure pills) and other losses of water from exercise, decreased water intake, fever, vomiting and diarrheaAntidiuretic Hormone (ADH) Specialized nerve cells, called OSMORECEPTORS, located in hypothalamus d

3、etect changes in osmotic pressure (concentration of solutes) the more solutes in the blood, the higher the osmotic pressure and the less water in the blood (the lower the blood pressure) when osmotic pressure increases (blood contains less water than normal) the osmoreceptors in the hypothalamus bec

4、ome dehydrated and this begins the negative feedback loopplumpshrunkADH Negative Feedback LoopStimulus: increased osmotic pressureHypothalamus releases a Releasing HormonePosterior Pituitary releases ADHADH reaches the kidneys and causes reabsorption of water into the bloodResult: osmotic pressure d

5、ecreases (blood pressure increases)(-)Aldosterone (ALD) The hypothalamus monitors the amount of K+ ion in the blood when K+ concentration on blood ( osmotic pressure, blood pressure) ALD is released ALD causes potassium to be taken up by the kidney and excreted in the urine this causes reabsorption

6、of sodium into the blood which in turn causes the reabsorption of water as well blood pressure and blood volume until normal levels are restoredALD Negative Feedback LoopStimulus: high potassium levels in blood (low blood pressure)Hypothalamus sends a message to the kidneysWithin the kidneys renin enzyme converts angiotensin I to angiotensin IIAdrenal Corte