B13 Homeostasis Flashcards
Homeostasis
the maintenance of a constant internal environment. The conditions inside the body must be controlled within narrow limits. The conditions that need to be maintained include water content, ion content, body temperature and blood glucose concentration
The internal environment
the surroundings of the individual cells of our body
Factor to be kept constant in the pancreas
Glucose- which is converted into glycagon
Factor to be kept constant in the skin
Temperature
Factor to be kept constant in the liver
Temperature
Factor to be kept constant in the kidney
Water/ Osmoregulation/ pH/ Urea
Factor to be kept constant in the lungs
Oxygen and carbon dioxide
Reasons for pH to be kept constant
So that a optimal pH for enzymes for metabolic reactions such as cellular respiration is provided, and to maintain the acidity of the blood
Reasons for water content to be kept constant
So that a stable concentration of all water soluble substances in the blood and fluids in the body is provided. It is also to maintain the concentration gradient and avoid dehydration of cells. It is also a medium for many chemical reactions
Reasons for oxygen content to be kept constant
To ensure sufficient provision for the blood to from oxyhaemoglobin and to load oxygen to cells for cellular respiration for growth, metabolic activities and to release energy
Reasons for carbon dioxide levels to be kept constant
To maintain the constant acidity of the blood. Carbon dioxide combines with water to form carbonate acid and will release hydrogen and bicarbonate
Reasons for temperature to be kept constant
Temperature has to be kept constant in order to maintain a stable metabolic rate and to provide the optimum temperature for enzymes
Negative feedback
Ensures that in any controlled system, changes are reversed and returned back to the set level. It is the body correcting/ reversing and changes
Hypothalamus
The area of the brain that monitors blood temperature and information sent from receptors in the skin
What happens when we get too hot?
1) the erector muscles of the hair relax, allowing more heat out
2) Sweat glands produce sweat to cool down the body, as it evaporates and takes up energy and heat
3) Vasodilation- Arterioles near the surface of the skin dilate (get wider) to allow more blood to flow in the capillaries near the surface of the skin. This allows for more heat to be lost through radiation.
4) Metabolic rate will decrease/ respiration slows- as these reactions produce heat
What happens when it gets too cold?
1) erector muscles of the hair contract, causing the hairs to stand up and trap a layer of air that acts as an insulator.
2) the sweat glands stop producing sweat
3) Vasoconstriction- The arterioles near the surface of the skin contract (get narrower), so less blood flows in the capillaries near the surface of the skin. This allows less heat loss through radiation.
4) Metabolic rate/ respiration increases- as these reactions produce more heat and muscular activity including shivering produces heat
Why do blood sugar levels need to be kept constant?
So that complications and diabetes doesn’t occur
What happens when blood sugar levels are too high?
The pancreatic beta cells secrete insulin, which travels via the bloodstream to the liver. The insulin causes the conversion of the excess soluble glucose into glycogen (insoluble) for storage in the liver and muscle cells
What happens when blood sugar levels are too low?
The pancreatic alpha cells secrete glucagon, which travels to the liver and causes glycogen to be converted back into glucose
