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Renal System

Renal Artery – Comes In

contains

  1. Nutrients
  2. Oxygen
  3. Waste – Urea, Na+

Ureters –

Hilum

Con

  1. Renal Atery
  2. Renal Vein
  3. Ureter

Through which urine will go out of kidney

Renal Vein – Goes Out

  1. Nutrients
  2. O2

Kidney contains 2 capillary beds

  1. Vasa Recta(o2)
  2. Peritubular capillaries(nutrients)

Waste – Urea, Na+ will be passed through urine

Kidney

  1. Consists of Renal Cortex, Renal Medulla
  2. Filteration – Help us to excrete waste
  3. Maintain water
  4. Contains 22% of blood Supply of the entrie body at anytime
  5. 1.1 ltrs of blood flow through per minute. if a person has 5 litres of total body blood it will flow through kidny in 5 minutes
  6. Produces Harmones?
  7. Regulated Ph level in blood
  8. Maintains homeostasis(Blood Ph level, Pressure(Remove Hydrogen ions), Osmolality)

Nephron

  1. Functional unit of the kidney is the nephron
  2. Kidney has 1 million nephrons
  1. Does Filtration and Collection

Renal Cortex

Cortex just means the Shell

Renal MedullaMedulla just means the middle

Glomerulus

  1. First part of the nephron is called glomerulus
  2. It receives the branches that comes the renal artery
  3. Afferent (Going Towards) arteriole – Blood comes in through this – that is going towards the glomerulus
  4. Glomerulus is a loopy structure
  5. Glomerulus – Takes the blood that came out of renal artery
  6. Glomerulus is the filtrate and it let the rest of the blood flow on
  7. Glomerulus leaks out fluid. The fluid that leaks out will be caught in a capsule(Bowman)
  8. Efferent Arteriole (left the glomerulus)

Filtration Rate is proportional to the Diameter of Afferent arteriole and indirectly to Efferent Arterioles

  1. If we increase the diameter of afferent arterioles that run into the Glomerulus then the filtration rate will increase
  2. If we decrease the diameter of afferent arterioles that run into the Glomerulus then the filtration rate will decrease
  3. If we increase the diameter of efferent arterioles the run out from the  Glomerulus then the filtration rate will decrease

If we decrease the diameter of efferent arterioles that run out from the Glomerulus then the filtration rate will increase

Renal Artery Stenosis

Aterial system have higher blood pressure

Podocytes – Filters –  Are certain class of epithelial Cells

Bowman’s Capsule

Named after british doctor bowman. When artery meets the bowman’s capsule the leakage happens. Wall of these artery contains endothelial cells.

Endothelial CellsThese are fenestrated(contains holes). Through those holes small particles like Sodium, Amino Acids, Glucose can leak

Basement Membrane

Small things like sodium, Amino Acid, Glucose(at time) pass through. But not proteins Tubular cells – Epithelial cells

Glomerulus

  1. Afferent Arteriole
  2. Bowman’s Capsule – Is the beginning of a Nephron to collect fluid
  3. Filters 1/5th of the blood that flow in the artery
  4. Filter’s small molecules ex. sodium, glucose, amino acids
  5. Dont filter’s RBC(Red Blood Cells)

Efferent Arteriole – branches into capillaries- Peritubular capillaries and connects to the renal vein

Proximal Convoluted Tubule(Near Small Tube)

  1. Absorbs(about 65%) all good stuff(nutrients) – Glucose, Amino Acids, Sodium, Water

Proximal to the Glomerulus

Loop of Henle

  1. Most of the length of nephron is loop of henle
  2. Starts from cortex and goes through medula and come back to cortex
  3. Ascending par of loop of henle Make medulla salty by actively pumping out salts. Ex. Sodium, Potassium, Chlorine ions
  4. Has two limbs going in opposite directions
  5. Ascending Limb(part) – It is only permeable to the above ions(Sodium, Pottasium, Chloride)
  6. Ascending part – It is not permeable to water
  7. Descending Limb(Part) – It is permeable to water and impermeable to other ions. Water is reabsorbed passively. No energy is expanded to reabsorb water.
  8. Water will leaave through this descending part to balance the hypertonic region

Descending part – will gain back the water that is earlier filtered

Above Process is called Counter Current Multiplication

Descending limbs and ascending limbs go in opposite direction. Thats why it is called counter current multiplication.

Interstitium

Space around tubules is called intertitium

Juxtaglomerular apparatus – Controls Blood Pressure – The area where Distal Convoluted Tubule and Glomerulus comes near

ATP is used for actively pumping out

Biological systems are good at using ATP to pump out ions but it can’t pump out water. Water is hard thing for proteins to operate on

Distal Convoluted Tubule

  1. Reabsorption happens Calcium, Sodium, water
  2. Connects to the collecting duct – Mutiple nephrons to connect to this

Collecting Tubule or Duct

  1. Many Distal Convoluted Tubules connect to Collecting Tubule to dump waste
  2. Reabsorbs water
  3. Nephrons connect to this to dump wastes
  4. It goes to the medulla again (Salty Part)
  5. part of Urea reabsorbed to maintain osmolarity in medulla to drive the water reabsorption in the loop of henle
  6. This first part of urine will be sent to renal calyces

Anti Diarrhetic Harmones

Dictates how porous this collecting tube is and make it more pores. Allows more water to leave, if this is pores

Renal Calyx(Renal Calyces)

Renal Pelvis

Where all Renal Calyx collect together

Ureter

Conducts our urine to the Bladder

Urine will only flow towards your feet(Valves prevent back flow)

Bladder

Transitional Epithelium – Allows to expand

Internal Urethral Sphincter

Male Urinary Tract

  1. Prostatic Urethra
  2. External Urethral Sphincter
  3. Membranous Urethra – Skeletal Muscle
  4. Spongy Urethra
  5. out

Female Urinary Tract

  1. External Urethral Sphincter – Skeletal Muscle
  2. Membranous

Final part of urinary tract is called Urethra

Mictuirtion(Pee)

Body’s way of controlling Blood Pressure

RAA System

Renin – Angiotensin – Aldosterone System

  1. Key cell in the RAAS is JuxtaGlomerular Cells is available in the kidney Blood Vessels
  2. JuxtaGlomerular cell is a smooth muscle cell
  3. JuxtaGlomerular cells release a hormone called Renin
  4. Renin Help us raise Blood Pressure

Triggers for JuxtaGomerular Cells to release Renin

  1. Low Blood Pressure – JuxtaGlomerular cells observe low blood pressure in afferent arteriole
  2. Neighbour Sympathetic Nerves Cell – Whenever something big is going on
  3. Low Salt in Distal Convoluted Tubule – Macula Densa Cells – Available in Distal Convoluted Tubule in the nephron – samples sodium comes through. If sodium is quite low. It could be a reflection of low blood pressure in glomerulus

Macula Densa Cells

  1. Their interesting ability is to sense the sodium. When they don’t find much salt then they will say there is a low blood pressure.
  2. They will produce Prostaglandin. Paracrine hormone and it will be sent to JuxtaGlomerular cells(Message – we sense low sodium and we think it is due to the low pressure, why dont you go and do something about it)

Renin It is Protein Hormone. It lets one cell talks to other cell of at a distance away

Liver Cells

Liver Cells will produce Angiotensinogen. It meets renin and chop of big hunk of angiostensinogen and produce

  1. Angiotensin I

Angiotensin I floats through blood vessels where endothelial cell converts Angiotensin I to Angiotensin II. Angiotensin II is also a hormone

Angiotensin II will go to different places of the body

  1. Smooth Muscle Cells in the blood Vessels all over the body. Those contract and increase resistance
  2. It helps kidney cells to hold on to more water. It is going to increase the stroke volume
  3. Pituitary Gland – Produces ADH(Anti Diarhetic) Hormone. ADH increases the resistance of the blood vessels. Also increased the volume to let kidney hold on more water

Adrenal Gland – Produces Aldosterone Hormone going to act on kidney cells

Angiotensin II

  1. 8 amino acids
  2. Angio means blood Vessel
  3. Tensin means tense.
  4. Vasoconstriction – Angiotension II make smooth blood vessels to constrict
  5. Angiotensin II acts on Smooth Blood Vessels is a rapid response
  6. Angiotensin II acts on Kidney is a slow response – Sodium Reabsorption which increases Stroke Volume
  7. Angiotensin II acts on Pituitary Gland and it produces ADH and sends to Smooth Blood Vessels. Also sends H20 reabsorption(This area of Nephron is not permeable to water) in kidney which increases Stroke Volume
  8. Angiotensin II acts on Adrenal Gland and it produces Aldosterone and sends to the kidney to reabsorb Salts.Sodium reabsorption(This area of nephron are permeable to water) which increases water reabsorption and which in turn increases Stroke Volume

Delta of Pressure = Q * R

PA – PV = SV * HRPressure in Arteriole – Pressure in Venous = (Stroke Volume * Heart Rate) * R

Renin Production in the Kidneys

JuxtaGlomerular Complex or Apparatus

Goal of the JuxtaGomerular Apparatus is to release the Renin. JuxtaGlomerular cells release renin in afferent arteriole and it will pass through glomerulus and to efferent arteriole

Efferent Arteriole Has many layers

  1. Tnuica Intima is the Endothelial Cells
  2. Tunica Media is the Smoothe muscle cells
  3. JuxtaGlomerular Cells(Granular Cells)
  4. Mesangial Cells – are for the structure

Tunica Externa layer – Nerves can end at tunica external layer Ex. Sympathetic Nerve Endings that makes JuxtaGlomerular to release renin

Liver

  1. Liver cells produces Angiotensionogen and sends them to the blood vessels
  2. Angiotensinogen has 452 amino acids
  3. Its not truly active. It meets with Renin and produces Angiotensin I of 10 amino acids
  4. Blood capillaries endothelial cells contain Angiotensin converting enzymes (ACE)
  5. Angiostensin I meets ACE and produces Angiotensin II of 8 amino acids
  6. It is very active

Blood Pressure Maintaining Hormones

  1. Renin
  2. Angiotensin
  3. Aldosterone

Aldosterone

  1. Aldosterone comes from a Adrenal Gland
  2. Cholestrol in adrenal gland produces Aldosterone
  3. Works in the principal cell of collecting duct or distal convoluted tubule

Triggers for Aldosterone

  1. When angiotensin II comes around
  2. Potassium ions start creeping up

Effects of aldosterone

  1. Works in Principal Cell to use ATP to push Sodium ions receive Potassium Ions
  2. Pushes potassium ions to collecting duct and Distal convoluted tubule
  3. Receives Sodium ions from collecting duct and Distal Convoluted Tubule
  4. Acid component (Proton) from Blood vessel will move from blood to Alpha Intercalated cells and Aldosterone move it to the collecting duct using ATP

Aldosterone moves proton from Alpha intercalated cells to collecting duct and takes back sodium ions to Alpha intercalated cells from Collecting Duct

Effects of Aldosteron in Blood

  1. Lowers Pottasium levels
  2. Increases Sodium Levels which inturn increases water
  3. Increases Stroke Volume
  4. Increases Blood Pressure

Adrenal Gland

  1. Cortex of the adrenal gland is made up of cholestrol
  2. Cholestrol helps the cells to make aldosterone
  3. Medulla

Basolateral Surface

Surface between principal cells of nephron and pertitubular capillary

Apical Surface

Surface between late distal convoluted tubule or collecting duct and principal cells

Principal Cells

contains Potattium k+

Blood Vessels

contains sodiu Na+ATP drives a pump and push 3 Sodium ions to the blood vessel and in take 2 Potassium ions

ADH – Anti Diuretic Hormone (Vasopressin)

  1. Is actually a small protein

9 amino acids long

Meaning squeezing(pressin) blood vessels(vaso)

Pituitary Gland

  1. Hypothalamus
  2. Supra optic nucleus – Collection of nerve cell bodies – ADH is actually made in these nerve cells
  3. Optic chiasm
  4. Infundibulum
  5. pituitary
    1. Anterior Pituitary
    2. Posterior Pituitary – ADH will be sent to the blood vessels of this pituitary

ADH Triggers

  1. High Blood Concentration(osmolarity) Osmolarity = Osms per Litre. Blood Concentration =  Osmolarity in the range of 300 -320 will trigger ADH. It will be notified by osmoreceptors
  2. Low Blood Volume (Identified through nerves connection with Superior Vena Cava, Inferior vena cava etc)
  3. Low Blood Pressure ( Identified through Baroreceptors in arotic arch, carotid sinuses)
  4. Presence of Angiotensin II

ADH Goal

Increase Blood Pressure

ADH Path

  1. Posterior Pituitary Blood Vessel
  2. All of arteriole smooth blood vessels of the body(vaso constriction). Intrun increases Resistance
  3. It will be sent to kidney to increase the reabsorption of water which will also increase the Stroke Volume using aquaporin
  4.  

Delta Pressure = Q * RAretirole Pressure – Venous Pressure = (Stroke Volume * Heart Rate) * Resistance

AquaPorin

  1. Available in Collecting Duct cells
  2. Water cannot flow through

ADH make it to allow water to go to collecing duct and to blood stream.

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