Regulation of body fluids HBS 3A

Body fluids Body fluids consist of Body fluids have different names in different locations. Intracellular fluid (c_______________) is found Extracellular fluid is found and includes: intercellular (interstitial or tissue) fluid plasma lymph ___________________________________

Body fluids Body fluids consist of Body fluids have different names in different locations. Intracellular fluid (cytoplasm) is found Extracellular fluid is found and includes: intercellular (interstitial or tissue) fluid plasma lymph cerebrospinal fluid synovial fluid pericardial fluid pleural fluid perilymph endolymph

Movement of fluids Fluid moves from one location to the other, taking dissolved substances with it. Movement of fluid and dissolved substances is by the processes of d________, o________ and a______________

Movement of fluids Fluid moves from one location to the other, taking dissolved substances with it. Movement of fluid and dissolved substances is by the processes of diffusion, osmosis and active transport

Diffusion through membranes Membranes are differentially permeable Permeable substances (eg small particles) move through Impermeable substances (eg large particles) can’t move through Movement is from areas of high concentration to areas of low concentration Energy is not needed

Facilitated diffusion Allows larger or less permeable substances to cross Involves channel proteins Energy is not needed

Osmosis Movement of water This occurs from areas of high water concentration (low concentration of solute) to areas of low water concentration (high concentration of solute) Energy is not needed

Active transport Movement against a concentration gradient. Energy is needed

Forces affecting water movement Concentration gradient refers to Osmotic pressure is Other factors influencing fluid movement include

Forces affecting water movement Concentration gradient refers to the difference between concentrations either side of a membrane – the greater the difference in concentration, the larger the gradient. Diffusion and osmosis are more rapid when the gradient is high (there is a larger difference in concentrations) Osmotic pressure is the force acting to move water across membranes, due to concentration differences (the greater the difference in concentration, the higher the osmotic pressure). Generally, high osmotic pressure refers to fluids with high salt concentration, low osmotic pressure refers to fluids with low salt concentration Other factors influencing fluid movement include surface area of the membrane, permeability (leakiness) of membrane, size of particles, fluid pressure (eg blood pressure), rate of flow

Regulation of fluids The body needs to regulate the composition of fluid by monitoring and changing: either the levels of w______ or the _____________________ found in the water eg This is necessary because

Regulation of fluids The body needs to regulate the composition of fluid by monitoring and changing: either the levels of water or the substances found in the water eg ions, wastes This is necessary because: if the water concentration is higher in the cells than the surrounding fluids, water will leave and the cells will shrivel and die if the water concentration is higher in the surrounding fluids than the cells, water will enter and the cells will swell and burst

Triggering water control Osmoreceptors are They are located The thirst reflex refers to It can be triggered by d______________________ or high salt intake.

Triggering water control Osmoreceptors are receptors than detect concentrations of ions and water They are located in the hypothalamus The thirst reflex refers to the reflex triggered by the hypothalamus when water concentration is low (high osmotic pressure). The hypothalamus sends a message to the cerebral cortex so you feel thirsty and you will take a drink It can be triggered by dehydration or high salt intake.

Dehydration Dehydration refers to Symptoms include Causes include

Dehydration Dehydration refers to high osmotic pressure due to low water concentration or high salt concentration. Symptoms include severe thirst, low blood pressure, dizziness, headache. If untreated – delirium, loss of consciousness and death Causes include sweating, vomiting or diarrhoea

Water intoxication Water intoxication refers to Symptoms include Causes include

Water intoxication Water intoxication refers to low osmotic pressure due to high water concentration or low salt concentration. Symptoms include light-headedness. If untreated – headache, vomiting and collapse Causes include loss of salts and water by sweating which are replaced by plain water

ADH ADH (______________________________) is secreted by the _______________ lobe of the ___________ gland in response to It acts on the n_____________ in the k___________ to

ADH ADH (antidiuretic hormone) is secreted by the posterior lobe of the pituitary gland in response to nerve impulses from the hypothalamus It acts on the nephrons in the kidneys to increase water re-absorption and return water to the blood

Feedback control of water Stimulus Negative feedbackReceptor ResponseModulator Effector Increased osmotic pressure

Feedback control of water Stimulus Negative feedbackReceptor ResponseModulator Effector Increased osmotic pressure Osmoreceptors in the hypothalamus Hypothalamus triggers thirst reflex and release of ADH from posterior pituitary Muscles of arms and throat Nephrons of kidney Drinking Increased water reabsorption – less urine produced Decreased osmotic pressure High salt Low water

Feedback control of water 2 Stimulus Negative feedbackReceptor ResponseModulator Effector Decreased osmotic pressure

Feedback control of water 2 Stimulus Negative feedbackReceptor ResponseModulator Effector Decreased osmotic pressure Osmoreceptors in the hypothalamus Increased osmotic pressure Hypothalamus triggers less release of ADH from posterior pituitary Nephron in kidney Decreased water reabsorption – more urine produced Low salt High water