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Home , Efferent arteriole, Peritubular capillaries

anatomy Renal Aids homeostasis by cortex removing cellular wastes and foreign compounds, and Cortex maintains salt and water Renal balance of plasma pelvis

Medulla

Nephrons Let’s make the filtrate... Each kidney has about one million Blood is filtered at the . Water Afferent arteriole brings and solutes leave the blood to glomerulus and blood and enter then forms efferent Bowman’s capsule. arteriole.

Efferent arteriole branches to peritubular

1 Glomerulus physiology Bowman’s capsule contains that encircle Glomerular filtration the glomerulus. Glomerular filtration Normally blood cells and plasma proteins are not is similar to filtered of 55 capillaries

Osmotic Hydrostatic 20% of plasma pressure 30 15 pressure becomes filtrate Glomerular filtration rate (GFR) determined by: Net filtration pressure and glomerulus permeability

Adjusting GFR Filtrate is adjusted along the Distal Blood pressure tubule Cortex region Bowman’s capsule Radius of afferent arteriole Juxtaglomerular apparatus - helps in Decreasing GFR helps retain adjustments to filtration rate fluid and salts Medulla region

2 Tubular and secretion 180 liters per day are filtered, most is reabsorbed

Reabsorption: filtered substances leave the nephron and enter

Secretion: some substances from the peritubular capillaries enter the nephron

So what is , then? Everything in the nephron that does not get Reabsorption physiology reabsorbed into the blood leaves as ….urine!!!

3 + Reabsorption of Na + (the key to it all…) Na reabsorption Na+ reabsorption (RA) drives the movement of many other substances in the tubule

Water will “follow” Na+ movement

Lumen Proximal tubular cell Control of sodium RA Page 533 When ECF volume is low, need to Na+ RA Osmosis Interstitial fluid Peritubular + Water capillary Na RA at distal and collection tubules with channel aldosterone. More Na+K+ pumps and Na+ Hydrostatic channels are made Osmosis pressure Renin is the trigger for eventual release of aldosterone, along a chain of events (renin- -aldosterone system or RAAS)

4 Jux.App. monitors NaCl and ECF levels

Efferent arteriole Distal tubule Bowman’s capsule Bowman’s capsule Juxtaglomerular Glomerular apparatus capillaries Distal Glomerular capillaries tubule Granular cells Juxtaglomerular apparatus Afferent arteriole

Glucose and amino acid reabsorption Hypertension can be due to increased renin leading to more plasma and thus high blood pressure  and AA’s are cotransported w/Na+ via carriers

 Actively RA substances have a “tubular maximum” (when all carriers are used)

5 Na+ movement allows passive RA of substances. Our old friend, cotransport 80% of water reabsorption occurs before distal tub. by following Na+

Glucose, amino acids are reabsorbed via cotransporters

If plasma levels get too high, renal threshold is reached (AAs or glucose leave in urine)

Tubular secretion H+ and K+, and organic anions are secreted to Adjusting the concentration of urine tubule Our body tissues and filtrate are 300 mosm (osmolarity)  K+ secretion is driven by the Na+K+ pump We can make urine as dilute as 100 or concentrated as 1200 mosm

Na+ gradient in renal medulla allows for control of urine osmolarity for water balance

6 Loop of Henle functions to set up high osmolarity along the collecting tubule (duct) Collecting tubule (duct)

Changing the permeability to H20 along the Distal collecting duct controls H O RA tubule 2 Cortex Vasopressin hormone controls permeability Medulla at distal and collecting tubules

Collecting Long loop Tubule or Duct of Henle

Collecting duct permeability Needing water Filtrate has concentration determines final amount of H2O RA of 100 mosm/liter 65 % of H20 RA is obligatory in the

proximal tubule, 15% at Loop of Henle. Cortex

Medulla 20% determined by vasopressin Collecting tubule

Concentration of urine may be up to 1,200

= passive diffusion of = portions of tubule impermeable to H O H2O 2 = of NaCl * = permeability to H2O increased by vasopressin

7 Too much water Why increased urination Filtrate has concentration of 100 mosm/liter from alcohol?  Alcohol inhibits vasopressin Cortex Medulla It can also temporarily reduce blood glucose (via liver effects) Collecting tubule

Concentration of urine may be as low as 100

= passive diffusion of = portions of tubule impermeable to H O H2O 2 = active transport of NaCl * = permeability to H2O increased by vasopressin

Medical problems Kidney stones – caused when hard deposits form in the kidney (usually calcium, sometimes uric acid).  They can enter the ureter and cause extreme pain. End of exam 4 material

Urinary tract infection – 2nd most common type of infection. Bacteria introduced to multiply and travel to bladder (cystitis) or further.

8 What goes on during Things I’m assuming you know: digestion… Know layers found throughout alimentary Motility - propulsion and mixing canal (mucosa, , muscular Secretion of digestive enzymes, bile, layers) and the term lumen mucus, water Chemical digestion Accessory structures (pancreas, liver, salivary glands, other exocrine glands) are Absorption a part of the digestive system Signaling

Intrinsic nerve plexus Down the chute…oral cavity Network of nerve fibers that controls digestive activity in gut. “Your 2nd brain” Physical digestion Mastication - mixes food with saliva

Saliva - amylase - digests starch mucus Tooth decay from lysozyme bacterial activity on food debris

9 Making saliva... Pressure and gustation promotes autonomic impulses to salivary glands PNS and SNS signals both influence salivary glands

Bolus touches receptors in the pharynx to stimulate swallowing

Peristaltic contractions push food Into the ....stomach through the esophagus.  Storage, physical and chemical digestion Distention will cause a second wave and saliva release  HCl

 Mixing in the antrum

 Bolus Chyme

10 Gastric emptying

Pyloric sphincter

Duodenum Peristaltic Peristaltic Movement contraction contraction of chyme

Mucosa Stomach mucosa of stomach Gastric juices!

Gastric Mucosa pH as low as 2 pits Gastric pit Mucosa cells

Gastric glands Chief cells (Pepsinogen) Submucosa Parietal cells (HCl)

11 autocatalysis Digestion Pepsinogen Pepsin Controlling gastric juices..  Cephalic (“head”) phase - stimuli from the Protein head stimulate chief and parietal cells via HCI Peptide fragments intrinsic plexus, gastrin released

Controlling gastric juices.. Protecting the stomach from itself…  Stomach lining is protected from Gastric phase – proteins, distension at stomach gastric secretions by mucus. H+ cannot also stimulate gastric secretions via intrinsic enter cells plexus  Cells are continually replaced

Low protein, low pH is inhibitory, decreasing flow of gastric juices

12 Stomach lining problems Leaving the stomach… Peptic ulcer - stomach wall injured by acid Emptying controlled by duodenum and and enzymes stomach Chyme volume promotes emptying Injured tissue releases histamine, which stimulates acid production (…not good) Acid and fats in duodenum prevent gastric emptying

Leaving the stomach... Pancreas

Gastroesophageal sphincter Stomach

Pyloric sphincter Islets of Langerhans Duodenum Duodenum

Movement Peristaltic Cells contraction of chyme secrete alkaline Cells secrete solution Gastric emptying digestive enzymes

13 Pancreas An endocrine and exocrine gland

Enzymes: protease, amylase, lipase

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