Glands and hormones in homeostasis Flashcards
What is blood glucose?
The amount of sugar in the blood.
What happens if blood glucose levels are too high?
• Beta cells in the pancreas detect a rise in glucose levels and release insulin.
• Insulin causes glucose levels to fall by storing glucose as glycogen in the liver.
• There is now a normal blood glucose concentration.
• Insulin production is then inhibited.
(This continues as a constant cycle, as it is a negative feedback loop).
What happens if blood glucose levels are too low?
• Alpha cells in the pancreas detect a fall in glucose levels and release glucagon.
• Glucagon causes glucose levels to rise as it causes the liver to release stored glucose.
• A normal glucose concentration.
• Glucagon production is inhibited.
(This continues as a constant cycle, as it is a negative feedback loop).
What are the effects of a high blood glucose level?
• Thirst
• Fatigue
• Headaches
• Hunger
• Weight loss
• Poor healing
• Nausea
How does the hypothalamus control the amount of water lost in the urine?
This is done through the effect of the hormone (ADH) antidiuretic hormone.
• When water water potential is too LOW, the osmoreceptors in the hypothalamus detects this and the hypothalamus stimulates the release of ADH from the posterior pituitary gland. ADH causes more water to be reabsorbed by the kidney and the water potential rises to its normal level.
• When water potential is too HIGH, this is detected by osmoreceptors in the hypothalamus and causes the hypothalamus to inhibit the release of ADH and so less water is reabsorbed by the kidney, which reduces the water potential to its normal level.
(This is a cycle a negative feedback loop).
What is blood osmolarity?
The concentration of solutes in the blood.
If osmolality is high there is too little water in the blood.
What happens if body temperature is too high?
• Sweating to release heat via evaporation.
• Vasodilation: vessels dialyse to increase heat loss.
• Shivering is reduced to conserve energy and decrease heat production.
• Metabolic rate decreases to reduce heat.
What happens if body temperature is too low?
• Vasoconstriction: vessels constrict to minimise heat loss.
• Shivering: muscles generate heat through involuntary contractions.
• Metabolism increases causes metabolic processes to accelerate, to generate heat.
What can happen if someone is too hot?
• Heat strokes which can cause organ failure, CNS dysfunction, distribution of cellular function, dehydration and electrolyte imbalance.
What happens if blood osmolarity is too high?
• Dehydration
• Impaired cellular function
• kidney damage
• thirst
