urinary system Flashcards
What is homeostasis
refers to the maintenance of a relatively constant internal environment independent of changes in the external environment
Provide some examples of homeostasis?
- blood plasma levels of pH
- osmoregulation concentrations
- Glucose level consistency for cells especially brain and heart
- blood pressure
- hormone levels
- thermoregulation
- metabolic wastes can’t build up to toxic levels
What is thermoregulation
Bodies ability to maintain a consistent body temperature
Define osmoregulation
the maintenance of internal body fluids in terms of water and dissolved solutes, such as salt, relative to the surrounding environment
What is the role of the urinary system (kidneys)
- involved in osmoregulation
- excretion of metabolic wastes
- controls water and ion balance in body
What % of the adult body is composed of water?
55-60%
what are the sources of water within the body
- preformed water
- metabolic water
What is preformed water
water from ingested foods and liquids
What is metabolic water
water created by dehydration synthesis reactions
How is water lost in the body in descending order
- kidneys
- skin perspiration
- skin evaporation
- lungs
- GI tract
How do fluid levels remain constant?
usually water gain is equal to water loss
Describe the fluid compartments of the body
water in our bodies is found both inside cells and outside cells
- intracellular fluid (cytosol) - within cells
- extracellular fluid - fluid outside cells
What are the subdivisions of extracellular fluid?
- interstitial fluid - btwn cells in tissues
- blood plasma
- lymph
- cerebrospinal fluid
- others
Describe Fluid composition within urinary system
- fluids mainly consist of water but also have dissolved solutes
- dissolved solutes can be ions, proteins, sugars, hormones, other specialized molecules
What are the most prevalent ions in body fluids?
- sodium
- chloride
- potassium
- calcium
- bicarbonate
- phosphate
Define fluid balance
- refers to the correct amount of water in the correct places
- implies a balance of solutes including electrolytes
Describe how the kidneys excrete of metabolic wastes
- metabolic wastes are formed mainly in the liver, which converts amino acids into molecules to be used for cellular respiration
- Kidneys remove wastes from the blood
- nitrogenous wastes are produced which include ammonia, urea, and uric acid
- Liver must convert ammonia to uric acid or urea due to it being very toxic in the body
- uric acid is the most energetically costly for production (requires lots of ATP to make it)
What is a nitrogenous waste?
- a toxic byproduct containing nitrogen produced in the liver due to the breakdown of amino acids
- Very toxic in the body and must be converted.
What is the process of creating uric acid
- Amino acid
- Ammonia
- Urea
- Uric Acid
What does the urinary system consist of?
- paired kidneys
- paired ureters
- urinary bladder
- single urethra
What is the function of the ureters
Drain the kidneys
What is the function of the urinary bladder
stores urine
What is the function of the urethra
drains bladder
What is the role of the kidneys?
- filters approx. 2000 litres of blood / day
- monitors and regulates water, ion, sugar, and other molecules
- removes a variety of potentially harmful substances
Describe the structure of the kidney
- pair of kidney bean shaped organs with 2 regions
- outer called cortex
- inner called medulla
- Composed of tubules called Nephrons
What are nephrons
- tubules surrounded by interstitial fluid and blood capillaries
- over 1 million tiny nephrons / kidney
What is the role of nephrons?
- filter the urine (filtration)
- allow for water and important solutes to be reabsorbed back into the blood (reabsorption and secretion)
Describe the structure of a nephron
- coiled tubes that pack tightly together
- They have regions in order they are
- bowmans capsule
- proximal convoluted tubule
- loop of henle
- distal convoluted tubule
- collecting ducts
Describe the path of urine drainage
- converge at the renal pelvis
- empties in a single ureter
- ureter exits the kidneys and leads to the urinary bladder
- bladder is drained by the urethra
Describe renal physiology
- 3 processes (filtration, resorption, secretion) occur in the human kidney involved in osmoregulation and metabolic waste excretion resulting in the formation of urine
- Blood arrives at the kidney through renal artery which branches until single supplies the glomerulus or tuft of capillaries where the blood is filtered
Describe how the filtration function of the kidney works
- occurs at the renal corpuscle consists of bowman’s capsule of the nephron and the glomerulus
- high blood pressure forces almost everything out of the glomerulus and into the lumen of the bowman’s capsule with the exception of formed elements
- forms around 200 liters of filtrate each day
- only forms 1-2 liters of urine rest is reabsorbed
- Most of the filtrate will be reabsorbed by blood before urine is formed
What is blood pressure not able to force out of the glomerulus?
- formed elements
- medium and large proteins
What does filtrate consist of?
water, hydrogen ions Na+Cl, ammonia, urea, glucose, amino acids, vitamins
Describe the secretion process of the kidneys
- selective addition of solutes from the blood to filtrate occurring farther along the nephron
- waste products and excessive ions are eliminated in the urine this way
- important for regulating pH
Describe the reabsorption process of the kidneys
- selective removal of necessary substances from the filtrate across the nephron and back into the blood
- includes reabsorption of sugars, vitamins, amino acids, water, sodium chloride, bicarbonate ions
What hormone targets the kidneys and what is it’s function?
ADH acts on the nephron and alter urine volume and also blood volume and pressure
What is the composition of normal urine
- water
- metabolic wastes
- urea, ammonia, uric acid
- ions
- drugs, antibodies, water soluble vitamins
What should not be found in normal urine
- glucose
- more than a trace amount of protein
- red blood cells
- white blood cells
- bacteria or yeast
Why should glucose not be found in urine?
- indicator of diabetes mellitus
- blood glucose levels are abnormally high and the quantity filtered cannot be completely reabsorbed
Why should trace amounts of protein not be found in urine
high blood pressure, kidney disease, or infection
Why should red blood cells not be found in urine
sign of kidney disease (filter damage)
Why should white blood cells not be found in urine
indicator of infection
Why should bacteria or yeast not be found in urine
indicator of infection
