2 Mind Maps Get into groups of 3-4 – use iPads to create a mindmap On iThoughtsHD create a mind map on thoughts, ideas, knowledge
3 Functions on the Urinary System Excretion of Metabolic WastesMaintenance of water – salt balanceMaintenance of acid – base balanceSecretion of hormones
4 Excretion of Metabolic Wastes Excrete nitrogenous wastesUrea is the primary nitrogenous wasteBy product of nucleic acid breakdownLiver releases ammonia (extremely toxic to cells)Forms with carbon dioxide to form ureaIf too much uric acid is present in the blood, can precipitate causing crystal = goutOthers wastes include methane
5 Maintenance of Water-Salt Balance Blood volume is closely associated with the salt balance of the bodyThe greater amount of salt in the blood, the greater the blood volume, the greater the blood pressureKidneys are responsible for filtering the blood of appropriate ions (Sodium, Potassium, Chloride etc…)
6 Maintenance of Acid-Base Balance Kidneys monitor and maintain a pH of 7.4Excretes hydrogen ionsReabsorbs bicarbonate ions
7 Secretion of HormonesAssist in the endocrine function of the human bodyReleases rennin which stimulates the release of aldosterone from the adrenal glandsPromotes the reabsorption of Na+ ions from the kidney
8 Organs of the Urinary System Consists of the kidneys, ureters, urinary bladder and urethraNumbered off into groups 1-4, learn the specific function of the specific organGroup 1: Kidney Group 2: Ureter Group 3: Urinary Bladder Group 4: Urethra1 person is nominated to write brief description onto the board
9 THE URINARY SYSTEM Wastes filtered from blood by kidneys. Wastes travel to bladder through ureters.Kidney cross section:Cortex: outer layer.Medulla: inner layer.Renal pelvis: hollow, central chamber.
10 Gross Anatomy of the Kidney Renal Cortex: outer granulated layer that dips downRenal Medulla: Consists of cone shaped tissuesRenal Pelvis: Is a central space or cavity that is continuous with the ureters
11 NEPHRONS Multiple small tubes. Functional unit of kidneys. Afferent arterioles supply blood.Branch into capillary bed or glomerulus.Blood leaves glomerulus through efferent arterioles.
12 NEPHRONS CONTINUED Glomerulus surrounded by Bowman’s capsule. Urine carried through proximal tubule (lined with microvili) to the loop of Henle (lined with simple squamous epithelium)Urine continues to distal tubule (cuboidal epithelial cells) and into collecting ducts.Collecting ducts merge in renal pelvis and expel urine into ureters.Cuboidal – not specialized for reabsorption
14 Glomerular Filtration Rate Occurs when the blood enters the afferent arteriole and the glomerulusDue to glomerular blood pressure, water and other small molecules move from blood into the filtrated urine
15 Glomerular Filtration Nephrons in kidney filter 180 liters of water per day ,including a small amount of molecules such as glucose and ionsSubstanceAmounted FilteredAmount ExcretedReabsorstion %Water180 L1.8 L99.0Sodium630g3.2g99.5Glucose180g0.0100Urea54g3044
16 FILTRATION Individual nephrons have own blood supply. Blood moves through afferent arteriole into glomerulus.Glomerulus under high pressure.Solutes diffuse across glomerulus walls into Bowman’s capsule.Materials move from high pressure to low pressure.
19 THE FILTRATE Not all blood components pass through capillary wall. Small molecules and ions pass through easily.E.g. Water, glucose, salts, amino acids.Large molecules and structures remain in blood.E.g. RBCs, platelets, proteins.
20 REABSORPTION Urine formation water intensive. Water and other important salts and molecules must be reabsorbed.Active and passive transport used.Na+ transported across nephron cell membrane.Excess salts excreted in urine when threshold level reached.
21 REABSORPTIONGlucose and amino acids actively transported back into blood.Some urea and uric acid is reabsorbed by this process.
22 SECRETION Movement of wastes into nephron. E.g. Nitrogenous wastes, surplus ions.Active transport.Mitochondria line distal tubule.
24 WATER BALANCE Increased water intake → increased urine production. Increased exercise, decreased water intake → reduced urine production and concentrated urine.
25 ANTIDIURETIC HORMONE (ADH) Increases water reabsorption.More concentrated urine results.Produced by nerve cells of hypothalamus and stored in pituitary gland.Pituitary gland releases ADH into blood.Osmoreceptors in hypothalamus detect changes in body osmotic pressure.Hypothalamus shrinks and sends nervous signals to pituitary gland.ADH released into blood.Thirst.
26 ADH ACTION ON NEPHRONAll parts of nephron not always permeable to water.ADH makes upper section of distal tubule and collecting duct permeable to water.High concentration of NaCl in interstitial fluid draws water back into interstitial space.
28 REGULATION OF BLOOD PRESSURE Kidneys regulate blood pressure by controlling blood volume.Aldosterone produced in adrenal glands increases causing water reabsorption and increased blood volume.
29 RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM Blood pressure receptors near glomerulus detect drop in blood pressure.Renin released.Converts angiotensinogen to angiotensin.Blood vessels constrict.Also stimulates release of more aldosterone.