Water regulation Flashcards
Excretion
Removal from the body of waste products (mostly toxic) of metabolism (waste produced by cells)
Excretory organs (4)
Lungs, sweat glands, alimentary canal (bile pigments) and kidneys
Elimination
Defaecation (faeces is not waste products produced by the cells, is undigested material)
Intracellular fluid
Inside the cell
Extracellular fluid
Outside the cell
Interstitial extracellular fluid
Plasma or lymph
How is osmotic pressure maintained
Equal fluid input and output (around 2.5L)
Fluid inputs (3)
Mostly drinking water, water in foods, metabolic water (smallest input)
Water intoxication
Water intake exceeds water loss
Fluid outputs (4)
Mainly urine (96% water, 2% urea, 1.5% ions), sweat, breathing, faeces (smallest output)
Dehydration
Water loss exceeds water intake
Lymphoedema
Lymph building up, More common around limbs as the heart is further away meaning there is less pressure to push the lymph around (lack of vascular activity)
Decreasing osmotic pressure feedback loop
Stimulus- increased osmotic pressure caused by dehydration/decreased water concentration due to (water output), Receptor- osmoreceptors in the hypothalamus, Modulator- Hypothalamus, Hypothalamus sends nerve impulses to the posterior pituitary to secrete ADH and the blood stream carries ADH to the kidneys, Effector- kidneys, drinking centre in the hypothalamus and skeletal muscles, Kidneys cells lining the tubules in the nephron become more permeable to water, Response- distal convoluted tubules and collecting ducts increase water reabsorption by osmosis causing urine to become more concentrated and decreasing volume of urine, become thirsty and drink more water, Feedback- decreased osmotic pressure and increased water concentration in the plasma
