Objectives Body Fluids Electrolytes The Kidney and formation of urine

Transcription

1 Objectives Body Fluids Outline the functions of water in the body. State how water content varies with age and sex. Differentiate between intracellular and extra-cellular fluid. Explain how water moves between fluid compartments. List the major sources of body water gains and losses. State the function and stimuli of thirst. Briefly explain how ADH regulates urine concentration. Briefly describe the role of aldosterone in fluid balance. Electrolytes Define the terms electrolyte, non electrolyte, ion, cation, anion List the body s major electrolytes State chemical symbols for the above Briefly outline the importance of electrolytes in body function State the main intra and extra cellular cations State normal ranges for Na+, K+, urea State key functions of Na+, K+, Ca++, PO4, HCO3- The Kidney and formation of urine State the main functions of the kidney Label a diagram to illustrate the location of the kidneys, ureters and bladder within the body Label a diagram of the kidney (to illustrate the renal cortex, renal medulla, renal pyramid, renal pelvis, major and minor calyces, renal artery and vein and the ureter) Label a diagram of a nephron (to illustrate the afferent and efferent arteriole, glomerulus, glomerular capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct) List and briefly explain the three stages in the process of urine formation State the main role of ADH and aldosterone in the formation of urine List the main constituents of normal urine State the minimum and average urine outputs/day Briefly discuss the importance of the kidney in relation to homeostasis

2 Body Fluids Functions of water Water is the used in the body: to transport... to remove to act as a transport vehicle for Water is also necessary.. * for body structure (e.g. * in temperature * as a medium for * as a * as a cushion and Body water and age and sex The volume of total body water in a healthy adult male is approximately 45 L (i.e. of their body is H2O) Variations in water content with age Infant Adult Older Adult % H2O % H2O Infants also ingest and excrete a greater volume of water in relation to their size. Why is this?? You need to know what is meant by ICF, ECF, interstitial fluid, plasma. Clinical relevance: Oedema define below

3 .. body H2O Inside cells Intra-Cellular Fluid (ICF) =.. Total Body Water About 65% of Body Weight.. body H2O Outside cells Extra-Cellular Fluid (ECF) =.. Interstitial fluid.. Plasma.. Also,.... Adult has.. litres of water in the body: Intracellular.. litres Extracellular...litres Tissue fluid.. Plasma.. Water gains and losses Gains Losses Water ml Urine ml Food ml Insensible losses Metabolism ml faeces ml lungs ml skin ml Total ml Total ml Alterations in homeostasis If the water gained = water lost each day the body will be in water.. If the water gained is less than water lost. What interventions may be necessary treatment of dehydration? Application to clinical practice: Dehydration What patients may be at risk of dehydration? Have you ever been dehydrated and how did you feel? What are the signs and symptoms of dehydration? What is minimum urine output/hr to maintain kidney function? Whose role is it to ensure that patients are adequately hydrated?

4 Regulation of Intake The sensation of ensures that water intake is adequate What patients may not be able to respond to the thirst sensation? The thirst centre is in the.. where there are nerve cells called Regulation of Fluid Volume DEHYDRATION Increased Osmotic Pressure (blood) Decreased Flow of Saliva Hypothalamus Dry Mouth & Throat THIRST INCREASED INTAKE INCREASED BLOOD VOLUME Regulation of Output Fluid output adjusted by... (both regulate urine production)

5 Anti Diuretic hormone (ADH). by the kidneys The hypothalamus synthesizes ADH which is transported to the posterior pituitary and stored there Inhibits release of ADH What effects have you noticed the day after consuming alcohol? Consider mucous membranes, urine output and urine appearance, bowel function, general discomfort etc. Control of ADH secretion Changes in extra-cellular.. Detected by in hypothalamus ADH production and release will be increased or decreased What will the effect be of increased ADH? What will the effect be of decreased ADH? Integration of concepts What is homeostasis and why is it so important? What is negative feedback? List three examples of negative feedback Aldosterone Aldosterone is a hormone (a mineralocorticoid) produced by the Aldosterone is a Mineralocorticoid produced by the Zona glomerulosa of the adrenal cortex Function of aldosterone is to: Stimulate kidneys to reabsorb. and secrete and water reabsorption Tissue Fluid production Draw diagrams and briefly explain the formation of tissue fluid.

6 Electrolytes Electrolytes form.....when in H2O (ions are electrically charged particles) (Non electrolytes are substances which do not split into ions, e.g. glucose) E.g. NaCl = Positively charged particles (e.g. Na+, K+, Ca++)... = Negatively charged particles (e.g. HCO3- Cl-) Major body electrolytes What are the body s major electrolytes? Sodium ( ) Potassium ( ) Chloride ( ) Calcium ( ) Magnesium ( ) Bicarbonate ( ) Phosphate ( ) Sulphate ( ) (Urea and Creatinine are not electrolytes) You should be familiar with the chemical symbols: Na+, K+, Cl-, Ca++, Mg++, HCO3- Importance of electrolyte balance Electrolytes are critical for.. They are found in all. Essential in:.... co-ordination..... function.... absorption and excretion.... function Sodium (Na+) Na+ is the main -cellular fluid Cation Normal range for Na+ = mmol/l The hormone that regulates Na+ levels is. Adrenal Cortex Aldosterone Nephron reabsorption of Na+ reabsorption of H20 Functions of Na+ Maintaining volume and concentration of.. cellular fluid * Involved in.conduction Qu: When is a sodium test requested? (* Part of a routine laboratory evaluation)

7 What is Hyponatraemia? Low blood sodium levels (less than 135mmol/L) May occur in: Symptoms of Hyponatraemia Muscle cramps & Weakness, Fatigue & Nausea, Apathy & Headache, Confusion Seizures Treatment = What is Hypernatraemia? High sodium in the blood (more than 145mmol/L) Normally occurs because of Signs and symptoms include Intense thirst, Decreased urine output, Confusion Seizures Treatment = IV or oral Potassium (K+) Primary...-cellular cation Necessary to maintain.. conduction. Necessary for normal... function Normal range for Potassium (K+) =.. mmol/l What type of muscle is particularly sensitive to K+ levels?. E.g.... Potassium testing * Routinely measured * Also specifically measured in diuretic therapy Hypokalaemia = An abnormally low level of blood potassium (less than 3.5mmol/L) Causes: Inadequate intake, Loss of K + from the body (e.g. diuretics or gastric losses) Signs and symptoms: Skeletal muscle changes Treatment = Replacement: foods (e.g. bananas, spinach) or K+ supplements Hyperkalaemia = serum potassium concentration greater than 5.5mmol/L Caused by: Decreased excretion of K + Movement of K + out of the cells in IV potassium infusion Signs of hyperkalaemia: Include ECG changes Treatment - Depends on the blood K + level

8 Calcium (Ca++). is stored in the skeleton and teeth (huge reserve). of blood calcium is ionized, the rest is protein bound * Only the ionized calcium is used in functions such as: Phosphate (PO4)... of body s total phosphorus is contained in the.. The remainder is in the cells Phosphate is required for: Generation of bony tissue, Metabolism, Maintenance of acid base balance Bicarbonate (HCO3-) What is the normal range for Bicarbonate (HCO3-). What is the job of bicarbonate? Prevents body getting too acidic (i.e. ) Urea Nitrogen containing waste product from metabolism (...) Excreted through the kidneys Good indicator of Serum urea =.. mmol/l Creatinine A metabolic waste product produced by breakdown of.. (creatine). Why is creatinine measured? To determine. Serum Creatinine concentration is a more accurate indicator of renal function than urea Normal ranges: common electrolytes Na mmol/l K mmol/l Mg mmol/l Ca mmol/l ( mmol/L) PO mmol/l ( mmol/l) Cl mmol/l ( mmol/l) Urea mmol/l Creatinine mcmol/l ( mmol/l) (40-90mcmol/L) HCO mmol/l (22-32 mmol/l) Haslet et al (2002) p1216 (figures in brackets children Davis and Hassell (2001) p142)

9 The Kidney and formation of urine The main function of the urinary system is:.. Each day the kidneys of fluid from the blood plasma Most of this fluid (containing vital constituents such as electrolytes, nutrients and water) is recovered by the kidneys and.. This leaves only.. of fluid (containing water soluble waste) to be excreted as... There are 2 kidneys, situated at the back of the abdomen The kidneys and homeostasis The kidneys are regulatory organs that function to maintain a normal body state under variations in the environment (homeostasis) Which of the above graphs best represents homeostasis?

10 Functional unit of the kidney is the... (about.. nephrons in each kidney Formation of Urine Three Phases: 1. Glomerular Filtration 2. Reabsorption 3. Secretion Glomerular Filtration What you think will happen to water and other small (water soluble) molecules such as glucose, water, salts, urea? Answer: What will happen to large molecules (such as blood cells and plasma proteins)? Answer:

11 Glomerular Filtration Outline the properties of capillary walls and state what factors are needed to maintain capillary pressure. List examples of small molecules and state the site of plasma protein synthesis

12 Reabsorption An extensive. around the renal tubules provides a for contact Follow the blood vessels from the afferent arteriole to the interlobular vein. How essential substances are recovered by the body (and not lost in the urine) = Reabsorption This will be achieved by re-absorption (or not) of constituents from the..... in the tubules to the.... in the peri-tubular capillaries Purpose of re-absorption is to: reabsorb filtrate constituents needed by the body to. Complete reabsorption Some constituents of the filtrate are completely reabsorbed (actively) unless present in excessive quantities This is because they are needed by the body e.g... absorbed

13 Partial Reabsorption The re-absorption of some substances varies according to the need e.g..... Anti Diuretic Hormone (ADH) regulates the amount of... reabsorbed by the kidney.. blood concentration Detected by Secretion of. ADH released by the. water reabsorbed.. urine output and.. blood concentration The hormone..increases re-absorption of sodium by the kidney (water follows) This will also lead to a.. urine output No reabsorption Waste products are absorbed only to a slight extent (e.g.....) or not at all (e.g.... ).. is the chief nitrogenous waste of mammals... is a break-down product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body. The urea cycle Breakdown of amino acids (deamination) Ammonia is extremely toxic! The.....contains enzymes which quickly converts the ammonia into... (less toxic than ammonia) Urea is removed efficiently by the... Recap Filtration and Reabsorption

14 Secretion How excess waste (and / or toxic substances) is removed from the blood and added to the urine = Secretion Addition of substances from the blood stream to the filtrate e.g. and Functions of secretion are to eliminate.... and maintain blood. Normal amounts and constituents of urine H2O L/day - average mls/day - minimum mls/hr - minimum Urea Creatinine Uric acid Na+, K+, Mg++ Briefly discuss the general rationale for testing urine (urinalysis)....

15 Case Study 1 Callum is 12 months old and has been having very loose stools for a couple of days. What effect is this likely to have on his fluid balance? What mechanisms should enable homeostasis to be maintained? What advice would you give his mother? Case Study 2 Stephen is 21 years old and has been drinking excessive amounts of alcohol! How does alcohol effect his fluid balance? What advice would you give him to maintain homeostasis and health? What problems might you encounter in giving such advice? What strategies are in place to reduce the amount of alcohol consumed by young people? Case Study 3 Sarah has been taking Clozapine to control the symptoms of her schizophrenia. Her CPN visits her and she confides in him that her housemates are stealing her possessions during the night and have also been trying to poison her. She has started locking her door and is refusing to eat anything unless it is sealed and she has bought it herself from the local shop. The CPN suspects that Sarah has been taking cannabis (she has a history of drug abuse). How might the mental health team establish if Sarah is experiencing drug induced psychosis? What other possible explanations are there for this situation? Case Study 4 Caroline is 29 and expecting twins. She is 30 weeks into her pregnancy. She visits the clinic for a routine assessment. The nurse does a urine tests and finds that there is protein present in Caroline s sample. Should there be protein in Caroline s urine? If not, why not? Does this indicate a problem with Caroline s kidneys? Where else might the protein have come from? Case Study 5 Mrs Evans (who is 65 years of age) has Non Insulin Dependent Diabetes Mellitus (NIDDM). She regularly tests her blood glucose levels. This morning, after breakfast, it was 9mmol/L. Would you expect her urine to contain glucose? (explain your answer) After lunch it was 12mmol/L. Now would you expect her urine to contain glucose? (explain your answer). What are the implications in terms of urine testing for people with diabetes?