Renal-Relates to the Kidney Kidney is part of the Urinary System Two sets of organs Urine forming organs (1) Organs that store or carry urine out of the body (3)

Kidneys Ureter, Bladder, Urethra

Outline of Topics 1. Nephrons and steps in Urine Formation 1. Glomerular Filtration - mechanism and _____ 2. Tubular Reabsorption - importance of ___ reabsorption 3. Tubular Secretion - __, ___, role for ______, Organic ____ 2. Hydration State and varying the concentration of urine 1. Medullary osmotic _____ 2. Anti____ Hormone 3. Variable ___ reabsorption at the distal tubule and CD 3. Long Term Control of Blood Pressure through the _____ System

1. Nephrons and steps in urine formation 1. control 2. Na+ reabsorption 3. H+, K+, Aldosterone, ions 2. Hydration state and varying concentration of urine 1. gradient 2. ADH 3. H20 3. Long term B control - RAAS system

Regional Differences Among Nephrons All nephrons originate in the _____ of the Kidney Differ in location of _____ within cortex (1) nephrons: glomeruli where? (1) nephrons: glomeruli where?

cortex glomeruli (Superficial) Cortical Nephrons: outer cortex Juxtamedullary Nephrons: inner cortex

Glomerular Filtration Renal Corpuscule = (3) Layers of Glomerular Membrane GF is a completely ______\ \ and nonselective process

Glomerulus + Bowman's Capsule 1. Wall of Glomerular Capillaries 2. Basement Membrane 3. Inner Layer of Bowman's Capsule passive\ \

Rate of Glomerular Filtration (Notes) GFR: volume of fluid filtered at glomerulus per ____, measure of renal ___ and ____ of kidneys SA = how many functional ____ you have Permeability - if membrane gets ____, perm will go down Filtration Coefficient Kf should be ____ in a normal healthy person -\> if it is then GFR is entirely dependent on (1) AKA capillary blood pressure

minute, function, health nephrons injured/scarred constant - net filtration pressure

Renal System Normal Function Flashcards by Felita Salim

Renal-Relates to the Kidney

Kidney is part of the Urinary System

Two sets of organs

Urine forming organs (1)
Organs that store or carry urine out of the body (3)

Kidneys
Ureter, Bladder, Urethra

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Outline of Topics

Nephrons and steps in Urine Formation
1. Glomerular Filtration - mechanism and _____
2. Tubular Reabsorption - importance of ___ reabsorption
3. Tubular Secretion - __, ___, role for ______, Organic ____
Hydration State and varying the concentration of urine
1. Medullary osmotic _____
2. Anti____ Hormone
3. Variable ___ reabsorption at the distal tubule and CD
Long Term Control of Blood Pressure through the _____ System

Nephrons and steps in urine formation
1. control
2. Na+ reabsorption
3. H+, K+, Aldosterone, ions
Hydration state and varying concentration of urine
1. gradient
2. ADH
3. H20
Long term B control - RAAS system

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Parts of the Urinary System

Kidneys: major filtering organ of our body

Filters _____ by taking blood and filter excess fluid, excess electrolytes to be removed from body
D____ elimination

Renal Blood Flow: (1) branches off abdominal aorta and supplies blood to kidneys -> kidney filters that blood then leaves through (1) -> drains to (1) back into heart

waste
drugs

Renal Artery -> Renal Vein -> Abdominal Vena Cava -> heart

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Parts of the Kidney

(1): outer, lighter region

(1): inner darker region

(1): set of tubules where urine collects and drains into renal pelvis

(1): center of kidneys where urine collects and exits through ureter

Renal Cortex

Renal Medulla

Renal Pyramid

Renal Pelvis

Urine is formed in cortex and medulla then drains into renal pelvis

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Structure of the Kidneys

Kidneys function as (3) types of organs

Each kidney is composed of about 1 million microscopic functional units called ______:

(2) components

Filtering, Endocrine, Metabolic

Nephrons

Vascular, Tubular Component

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Kidney Functions (notes)

We are going to focus on the kidneys filtering function however they also..

Kidneys as Endocrine organs: (1) hormone that acts on bone marrow to stimulate RBC production

Kidneys as Metabolic organs: (1) produces new glucose from substrates such as lactic acid and amino acids (is a main function of liver but kidneys contribute to this)

Erythropoietin (EPO)

Gluconeogenesis

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Tubular Components

(1): yellow claw like structure that wraps around the Glomerulus

(1): tuft of capillairies where urine formation _____- plasma within capillaries filters across membrane into bowman’s capsule then down tubules

Flow of Urine

(1): first portion of tubule closest to glomerulus

(1): first down descending arm then up ascending arm

(1)

(1): physically attached to about 9-12 nephrons (located in renal pyramid) -> renal _____ -> _____

Bowman’s Capsule

Glomerulus

Proximal Tubule

Loop of Henle

Distal Tubule

Collecting Duct -> renal pelvis -> ureters

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Vascular Components

Flow of Blood

(1)
(1): blood moving into Glomerulus
(1): blood that doesn’t get filtered in glomerulus moves out through this
(1): network of capillaries (purple net) that surrounds the nephron
- Exchange of substances back and forth between capillaries and tubules adjusts _____ of urine
(1): then into vena cava

Renal Artery
Afferent Arteriole
Efferent Arteriole
Peritubular Capillaries
- composition
Renal Vein

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Juxtaglomerular Apparatus

**Importance** =

juxta-glomerular = right ____ to glomerulus
Portion of ____ tubule sits close and in between (2) -invaginate (form a V) -> regulates ____ of filtration

REGULATES KIDNEY FUNCTION

next to glomerulus
distal, sits between afferenta and efferent arteriole -> regulates rate of filtration

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Regional Differences Among Nephrons

All nephrons originate in the _____ of the Kidney
- Differ in location of _____ within cortex
  - (1) nephrons: glomeruli where?
  - (1) nephrons: glomeruli where?

cortex
- glomeruli
  - (Superficial) Cortical Nephrons: outer cortex
  - Juxtamedullary Nephrons: inner cortex

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3 Anatomical Differences of Nephrons

____ of glomeruli
_____ of loop of henle
Juxtamedullary has ___ ____

Juxtamedullary Nephron

Glomeruli near ____
____ loops of henle
(1): starts with single vessel that parallels the loop of henle and then exits medulla, peritubular capillaries only really wrap around tubular parts in the cortex

Cortical Nephron

Glomeruli sit near ____ edge of cortex
____ loops of henle
Peritubular capillaries wrap around _____ tubule

Location
Lengths
Vasa Recta

Juxtamedullary Nephron

medulla (outer cortex)
Long
Vasa Recta

Cortical Nephron

outer
Short
entire

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Functional Differences Between Nephrons

Juxtamedullary Nephrons important function =

High proportion of juxtamedullary nephrons in what type of animals?
High proportion of cortical nephrons in what type of animals?

Humans: ___% Juxtamedullary, __% Cortical

Important in kidney conservation of water by allowing kidneys at certain times produce very concentrated urine

dry climates
wet climates

20% juxta, 80% cortical

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Basic Renal Processes

(3)

What percent of plasma that enters glomerulus gets filtered into bowman’s capsule?

Glomerular Filtration (first stage of urine production)

Tubular Reabsorption (tubule -> capillary)

Tubular Secretion (capillary -> tubule)

20%

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Glomerular Filtration

Renal Corpuscule =

(3) Layers of Glomerular Membrane

GF is a completely ______** and nonselective process

Glomerulus + Bowman’s Capsule

Wall of Glomerular Capillaries
Basement Membrane
Inner Layer of Bowman’s Capsule

passive**

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Glomerular Membrane (Notes)

_____ cells compose the capillary wall
White outline = ______ membrane
(1) make up inner membrane of bowman’s capsule is the spaces in between these processes

Function of Glomerular membrane =

Fluid that enters Bowman’s capsule (filtrate) _____ in composition of plasma minus (2)

Endothelial cells
Basement Membrane
Podocytes: podo meaning feet, foot processes wrap around capillaries

Prevent plasma proteins and cells from getting out of capillaries

filtrate identical to plasma minus protein and cells

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Forces Involved in Glomerular Filtration

(3)

Which forces OPPOSE glomerular filtration?

Net Filtration Pressure =

Capillary Blood Pressure (55) pushing pressure

Plasma Colloid Osmotic Pressure (30) pulling pressure

Bowman’s Capsule Hydrostatic Pressure (15) pushing pressure from bowman’s

Plasma Colloid + Bowman’s Hydrostatic pressures OPPOSE -> only Cap BP promotes GF

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The Rate of Glomerular Filtration

Depends on (3)

Filtration Coefficient Kf = ___ x ___

GFR = ___ x ___

Net filtration pressure

Surface Area available

Permeability of Glomerular Membrane

SA x Permeability

Kf x net filtration pressure

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Rate of Glomerular Filtration (Notes)

GFR: volume of fluid filtered at glomerulus per ____, measure of renal ___ and ____ of kidneys
- SA = how many functional ____ you have
- Permeability - if membrane gets ____, perm will go down
Filtration Coefficient Kf should be ____ in a normal healthy person -> if it is then GFR is entirely dependent on (1) AKA capillary blood pressure

minute, function, health
- nephrons
- injured/scarred
constant - net filtration pressure

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Two Major Mechanisms Control GFR

(2)

Each with Different Goals/Priorities?

Autoregulation

Goal = maintain GFR in the face of normal fluctuations in BP ie. diff positions, stress (intrinsic control, prevents spontaneous changes in GFR whenever arterial BP changes)

Extrinsic Sympathetic Control

Goal = alter GFR in an attempt to control blood volume and BP ie) if BP drops, GFR is going to drop to conserve fluid

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Autoregulation

(Goal = maintain GFR in face of normal fluctuations in BP)

Kidneys maintain steady Glomerular blood flow and a stable GFR by altering the _____ of the _____ _____ by constriction or dilation of ____ ____ lining of the vessels wall

What happens if arterial blood pressure increases?

What happens if arterial blood pressure decreases?

diameter, afferent arteriole, smooth muscle

Vasoconstriction of Afferent Arteriole to decrease blood flow into glomerulus

Vasodilation of Afferent Arteriole to increase blood flow into glomerulus

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What is the Mechanism for Autoregulation?

(1)

Tubuloglomerular Feedback Mechanism Involving the Juxtaglomerular Apparatus

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Cells Involved in Autoregulation

(1): located on afferent arteriole and constantly regulates ___

(1): located on distal tubule and constantly regulates ___

BOTH CELLS CAN RELEASE ______ and ______ ONTO AFFERENT ARTERIOLE

Granular Cells - BP

Macula Densa Cells - rate of fluid through distal tubule

VASOCONSTRICTORS, VASODILATORS

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Extrinsic (Sympathetic) Control of GFR

(Goal = alter GFR in an attempt to control blood volume and BP)

Sympathetic input can ______ the autoregulatory responses

The smooth muscle cells of the afferent and efferent arterioles contain many (1) receptors that are sensitive to (2)

Renal nerve releases norepinephrine - ______ arterioles
Glomerular capillary BP and GFR then ______

Override

alpha adrenergic receptors -> Epinephrine and norepinephrine

vasoconstricts
GFR decreases

Through innervation of smooth muscle cells of afferent and efferent arterioles by sympathetic nerves -> releases epi onto alpha adrenergic receptors to cause vasoconstriction -> decrease GFR

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Case of Hemorrhage

Example of where Extrinsic Control Kicks in

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Tubular Reabsorption and the Importance of Sodum Reabsorption ## Footnote **\_\_\_%** of plasma that enters glomerulus is filtered * Since GF is a ____ process, a lot filters out that we want to take back, Tubular reabsorption helps us do that * **Tubular Reabsorption**: can be a ____ or ____ process depending on the substance but it is **always \_\_\_\_\_**

**20%** * passive, we want to take alot back * passive OR active, but **always selective**

Tubular Reabsorption ## Footnote **\_\_% of water filtered is reabsorbed** **\_\_\_% of sugar filtered is reabsorbed** **\_\_\_% of salt filtered is reabsorbed** Pretty much we reabsorb \_\_\_\_\_

**99%** **100%** **99.5%** ALOT IS REABSORBED

Spaces that need to be crossed to be Reabsorbed ## Footnote * Tubular Lumen is made up of (2) 1. **\_\_\_\_\_\_ Membrane** 2. **\_\_\_\_\_ of Cell** 3. **\_\_\_\_\_\_ Membrane** 4. **\_\_\_\_\_\_ fluid space** 5. **\_\_\_\_\_\_ wall**

* epithelial cells and tight junctions 1. **Luminal** 2. **Interior of Cell** 3. **Basolateral** 4. **Interstitial** 5. **Capillary Wall**

Reabsorption of Na+ ## Footnote **\*Sodium is reabsorbed at any point in the nephron except?\*** * Na+ is _____ reabsorbed * 80% of energy requirement of the kidneys used for Na+ ____ (99.5% of Na+ filtered is reabsorbed) * Plays important role throughout tubule: not just an end, but also a \_\_\_\_

**Descending Loop of Henle** * actively * Transport * means (to transport many other substances- is why Na+ reabsorption takes up so many energy)

Reabsorption of Na+ ## Footnote Coupled with what other substances/roles in the 1. *Proximal Tubule* 2. *Ascending Limb of Loop of Henle* 3. *Distal tubule and Collecting Duct*

1. Glucose, Amino acids, Water, Urea 2. Plays an important role in kidneys ability to _concentrate_ urine and _conserve_ water 3. Under _hormonal_ control and plays a role in regulating _ECF volume_ and _blood pressure_

General Pattern for Sodium Reabsorption ## Footnote Na+ travels across Luminal membrane either through (2) Na+ travels across Basolateral membrane through (1)

**Passive Channel** or **Secondary _Active_ Cotransporter** **Sodium Potassium ATP pumps** (this is what takes a lot of energy) and remember sodium has a huge driving force to get into cells (so very easy to do just through channels)

Na+ Reabsorption in the Proximal Tubule ## Footnote _In the Luminal Membrane_ * __Na+ diffuses through _____ (uses energy) with (3) _In the Basolateral Membrane_: * Na+ diffuses through (1) * Glucose, Amino Acids, Water soluble vitamins diffuses through (1)

* **Cotransporter** w glucose, amino acids, water soluble vitamins * **ATP pumps** * **Facilitated diffusion**

Tubular Maximum = * Ex) Glucose is 100% reabsorbed in proximal tubule, but for DM (hyperglycemia) - can start seeing glucose in urine -\> therefore there is a ____ to how much glucose can get reabsorbed dt limited ____ cotransporters

**Maximal rate of reabsorption limited by available cotransporters** * ****limit in available cotransporters

Sodium Reabsorption and Glucose (Proximal Tubule) ## Footnote * Normal (plasma) of glucose are \_\_\_\_/100ml of plasma * Amount of glucose filtered per min = (plasma) of glucose x \_\_\_ * 100mg/100ml x 125ml/min = \_\_\_mg/min * **Filtered Load =** * **Tubular Maximum (Tm) -** point of _____ (**is a \_\_\_)** * **Tm** for glucose is \_\_\_\_mg/min

* 100mg/100ml * GFR * 125mg/min * **amount of substance filtered by kidneys per minute** * **saturation (is a rate)** * ****375mg/min

Sodium Reabsorption and Glucose (Proximal Tubule) ## Footnote Usually \_\_\_% of glucose is reabsorbed in the proximal tubule and returned to the blood stream If the filtered load for glucose increased beyond 375mg/min, begin to find glucose excreted in \_\_\_\_ **Renal Threshold =** maximal _____ concentration any of these organic nutrients can reach before it starts to appear in \_\_\_\_\_ * Renal threshold for glucose = * RT (1) x GFR (1) = TM (1)

100% urine **RT =** maximal plasma concentration before appears in urine * 300mg/ml * 300mg/ml x 125ml/min = 375mg/min

Renal Threshold (Notes) ## Footnote * If our tubular maximum is 375mg/min, what amount of plasma is needed to reach that maximum? -\> this term is called **(1)** * **RT = \_\_\_\_\_/100ml plasma** * ****Anything above 300 -\> glucose will appear in urine -\> so you know that when you see glucose in urine their plasma glucose is at least ___ normal

* **Renal threshold** * **RT = 300mg** * ****3x normal before appearing in urine

Sodium Reabsorption in the Ascending Loop of Henle ## Footnote Same as in proximal tubule but cotransporter with what substances?

**K+, Cl-**

Sodium Reabsorption in the Distal Tubule ## Footnote Same as in proximal tubule and ascending loop but cotransporter with what substances?

Cl-

Sodium Reabsorption in the Collecting Duct =

Most simple ## Footnote **Na+ through passive channel then ATP pump**

Sodium Reabsorption Coupled to Passive Water Reabsorption ## Footnote Throughout the tubule, water is reabsorbed via _____ which requires (1) provided by \_\_\_ 80% is reabsorbed in (2) parts of the nephron **Two mechanisms (2)**

Osmosis, osmotic gradient, Na+ (water follows sodium) Proximal tubule and Loop of Henle **1) Paracellular Route** (in between epithelial cells) **2) Transcellular Route** (through epithelial cells)

Paracellular Route ## Footnote Explain how this mechanism works?

In certain areas the tight junctions between epithelial cells are leaky (mostly in proximal tubule) As Na+ gets pumped out of lateral membrane -\> **clumps in area creating high osmolarity** - that moves water into interstitial fluid and to capillary

Transcellular Route ## Footnote How does water move through this Route? **(1)** * Abundance of these channels on _____ membrane * Luminal Aquaporins only available in what areas? **Osmotic Gradient** in transcellular route is created by?

**Aquaporins** = water channels on both membranes * abundance on basolateral membrane * luminal aquaporins only in proximal tubule, descending loop of henle Created by high osmolarity of Na+ in interstitial space

Water Reabsorption Takeaways (Notes) ## Footnote Only place where water reabsorption does not occur? _Things needed for water reabsorption_ 1. _____ \_\_\_\_\_ created by Na+ 2. Permeability through (2)

**Ascending Loop of Henle** (super tight junctions and no aquaporins) 1. Osmotic Gradient 2. Permeability through leaky tight junctions or luminal aquaporins

Sodium Reabsorption Coupled to Passive Chloride Reabsorption Following Water Reabsorption ## Footnote _Passive Reabsorption of Cl, Urea, K_ * Once Na and water move out, it increases concentration of everything left ___ (Cl, Urea, K) * _____ creates a concentration gradient for those substances to also move out through (1)

* behind * Natural osmotic gradient -\> leaky tight junctions

Regulated Reabsorption of PO43- and Ca2+ ## Footnote The reabsorption of some substances helps regulate ____ levels of those substances (1) for that substance equals normal plasma levels Our diets are normally rich in \_\_\_\_\_, it ___ gets filtered Renal threshold for phosphate reabsorption is set at ____ plasma phosphate, excess is ____ through urine

plasma Renal threshold = plasma lvls phosphate, all gets filtered RT set at normal plasma levels, excess excreted through urine

What does not get reabsorbed? ## Footnote * ____ products (2) except for \_\_\_\_ * Even though they do get concentrated, like chloride and urea, tubule is **\_\_\_\_\_\_ to these waste products**

We do not reabsorb waste products (phenols, creatinine) except for urea **Tubule is impermeable to waste products** We only reabsorb urea bc helps make amino acids

Summary of Reabsorption ## Footnote 1. **Proximal Tubule:** huge amount of (2) reabsorbed 2. **Loop of Henle** 1. \***Descending Loop of Henle:** 2. **\*Ascending Loop of Henle** 3. **Distal Tubule** and **Collecting Duct:** Na and Water reabsorption _____ and under _____ control

1. huge amount of Na and H20 2. Loop of Henle 1. Yes H20, No Na+ 2. Yes Na+, No H20 3. variable, hormonal

Tubular Secretion ## Footnote **Selective movement of substances from (1) into (1)** **(3)** important substances to be secreted

**Peritubular Capillaries -\> Tubular Lumen** 1. **Hydrogen ions** 2. **Potassium ions** 3. **Organic Cations and Anions** (usually foreign to the body-drugs, environmental pollutants)

Hydrogen ion secretion ## Footnote Plays an important role in \_\_\_/\_\_\_ balance in the body Occurs primarily in what parts of the nephron (2)...and minor amounts in (1)

acid/base proximal tubule and collecting duct, ascending loop of henle

Hydrogen Ion Secretion ## Footnote How does H+ cross the Basolateral membrane? How does H+ cross the Luminal membrane in the 1. Proximal Tubule = 2. Collecting Duct and Loop of Henle =

ATPase pump 1. Na/H+ antiporter (coupled with Na+ reabsorption) 2. Facilitated diffusion

Potassium Secretion ## Footnote Potassium undergoes both _____ and \_\_\_\_\_\_ * In the _proximal tubule_, potassium is _____ in via passive diffusion is much the same way as ___ and ___ following water reabsorption. * Potassium is also _____ secreted in the (2) parts of the nephron * Potassium reabsorption is \_\_\_\_\_, while potassium secretion is \_\_\_\_\_ * If plasma (K) is low -\> secretion is \_\_\_\_\_ * If plasma (K) is high -\> secretion/excretion is \_\_\_\_\_

Reabsorption AND Secretion * reabsorbed, Cl- and Urea * actively, distal tubule and collecting duct * unregulated, regulated * minimal * enhanced K reabsorption is passive and unregulated, K secretion is actively secreted and regulated

Mechanism for K+ Secretion ## Footnote Distal Tubule and Collecting Duct * K crosses basolateral membrane through (1) * K crosses luminal membrane through (1)

* Na/K ATP pump * Passive diffusion

Why isn't K secreted throughout the tubule when sodium is reabsorbed? ## Footnote Dt _____ of K+ channels * In proximal tubule and loop of henle, K+ channels on _____ membrane therefore? * In distal tubule and collecting duct, K+ channels on _____ membrane therefore?

Location of K+ channels * basolateral membrane -\> cannot enter tubular lumen (just diffuses right back through into interstital space) * luminal membrane -\> allowed to enter tubular lumen

Summarizing Reabsorption Events ## Footnote * Remember when summarizing reabsorption: Na+ and Cl- ____ in distal tubule and collecting duct through **\_\_\_\_\_ control** **(1)**

Variable **Hormonal control - Aldosterone** (mineralcorticoid that controls Na+ reabsorption and K loss) therefore aldosterone simultaneously controls **potassium secretion**

Aldosterone Control of Sodium Reabsorption and Potassium Secretion ## Footnote **Aldosterone functions (2)**

1) Opens Luminal Na+ Channels 2) Increases Na/K ATPase expression

Organic Anion and Cation Secretion ## Footnote Ways to secrete anion and cations in proximal tubule **(2) secretory pathways** * Involve anion and cation \_\_\_\_\_ * Includes blood born chemical messengers like \_\_\_\_\_\_ * Some are foregin compounds like ____ additives, environmental \_\_\_\_\_, and d\_\_\_ Reasons there must be a secretory pathway **(2)**

**Organic Anion pathway, Organic Cation pathway** * receptors * hormones * food additives, environmental pollutants, drugs **1) Some ions can be bound to plasma proteins and are never filtered by glomeruli** **2) Increases speed of elimination** 2 pathways both involve the use of energy and coupled with Na reabsorption

Ch 6 Urine Concentration: The Medullary Countercurrent System ## Footnote * Kidneys can produce urine that ranges in osmolarity (concentration) from \_\_\_\_mOsm to \_\_\_mOsm dependent on body's need to ____ water * Perfect balance of hydration = \_ml/min or _____ urine (\_\_\_mOsm) * Overhydrated = \_\_ml/min or ____ urine (\_\_\_mOsm) * Dehydrated = \_\_ml/min or _____ urine (\_\_\_mOsm)

* 100mOsm to 1200mOsm, conserve * 1ml/min, Isotonic Urine 300mOsm * 25ml/min, Hypotonic Urine 100mOsm * 0.3ml/min, Hypertonic Urine 1200mOsm

**Obligatory Water Loss** **=** Bc of this, the kidneys deal with persistent _____ way better than persistent \_\_\_\_\_

**Minimal water loss** bc we can't eliminate crystals so no matter how dehydrated we are we have to produce and excrete urine overhydration, dehydration

Medullary Countercurrent System ## Footnote The medullary osmotic gradient plays a key role in the kidneys ability to produce urine of varied \_\_\_\_\_\_ This osmotic gradient is created by a unique _____ arrangement **Medullary Countercurrent System =**

concentrations anatomical **Anatomical parts that create this gradient and the ones that use it to produce urine of varied concentration are collectively called this system**

Osmotic Gradient of the Renal Medulla ## Footnote Cortex = \_\_\_tonic Medulla interstitial space has an osmotic gradient -\> _____ as you get closer to the ____ \_\_\_\_ This gradient is what allows us to vary how water is reabsorbed and produce urine of varying \_\_\_\_\_

Isotonic increases closer to renal pelvis concentration

2 Parts of Countercurrent System**** ## Footnote **1)** **What part _creates the osmotic gradient?_** **2)** **What part _uses the gradient to vary concentration of urine?_**

1. **Long Loops of Henle of Juxtamedullary nephrons** 2. **Collecting ducts of all nephrons**

How Long Loops of Henle Create Osmotic Gradient ## Footnote Descending Loop = Ascending Loop =

Permeable to water, Impermeable to Na+ Permeable to Na+, Impermeable to water (ascending loop actively pumps sodium out)

ADH ## Footnote How does ADH determine how much water is reabsorbed in the distal tubule and collecting duct? Urine osmolarity that travels up ascending loop of henle gets ____ and exits with an osmolarity of \_\_\_\_mOsm * **100mOsm** = __ water reabsorption in distal tubule and collecting duct * **1200mOsm** = ___ water reabsorption in distal tubule and collecting duct * **300mOsm** = body is ______ hydrated

By determining **degree of permeability** of tubule/collecting duct smaller and smaller -\> exits with 100mOsm * NO * MAXIMAL * perfectly hydrated -\> which means 300 is the mOsm of distal tubule when normal

Vasopressin (ADH) ## Footnote = Hormone producted by (1) and released by (1) **How do we regulate ADH?**

Hypothalamus, Posterior Pituitary **Sensing plasma osmolarity changes in the brain**

Vasopressin (ADH) Function ## Footnote **Increases _____ of _____ membrane to H20 by inserting new water \_\_\_\_\_\_** * travels through bloodstream and binds to tubular _____ cells -\> acts through second messenger system and binds to its _____ -\> elevates _____ -\> increasing insertion of \_\_\_\_\_\_ Keep in mind: ADH just effects water, NOT sodium

**Permeability, luminal, channels** * epithelial, receptors, cAMP -\> increased insertion of aquaporins

Control of Sodium and Water Excretion: Regulation of Plasma Volume and Osmolarity ## Footnote * There are two separate but closely ______ control systems that regulate ECF ____ and ECF \_\_\_\_\_ * ECF volume and ECF Osmolarity have different effects on \_\_\_\_\_\_ * Regulation of **ECF Volume maintains (1)** therefore blood supply to \_\_\_\_\_ * Regulation of **ECF Osmolarity helps maintain (1)** * The _____ play a major role in both of these control systems

* interrelated, volume, osmolarity * homeostasis * **blood pressure -\>** blood supply to tissue * **cell volume** * ****kidneys

Sodium Balance and ECF Volume ## Footnote * The body regulates ECF volume by regulating what? * Sodium is the main ______ constituent of the ECF volume * ECF osmolarity is tightly maintained so when _____ moves, _____ must move with it - Sodium _____ in the kidney is always followed by water _____ (wherever permeable) * So any sodium gains or losses in the body are asctd with a corresponding gain or loss in \_\_\_\_

* total body salt content * osmotic * sodium moves, water moves -\> sodium reabsorption, water reabsorption * water

Sodium Balance ## Footnote Balance between gains and losses What sources 1. Gains = 2. Losses = Sodium balance if: ____ NaCl intake = ____ NaCl output + ____ NaCl output

1. Ingested Sodium absorbed through GI tract 2. Renal Excretion, Nonrenal loss (sweat, feces) usually low except for cases like diarrhea and profuse sweating Oral = Renal + Nonrenal loss

How are Changes in ECF Volume Sensed? ## Footnote Body actually monitors\_\_\_\_\_ volume, not total ECF volume Changes in plasma volume are sensed by monitoring ___ \_\_\_\_ Specialized sensory receptors called **\_\_\_\_\_\_\_\_** **(3)** **Unlike the first two =**

plasma blood pressure **baroreceptors** 1. **Aortica Arch baroreceptors** 2. **Carotid Sinus barorecetors** 3. **Renal baroreceptors** **Renal Baroreceptors** unlike first two do not change by momentary changes in BP, responsible for **long term regulation of BP**

Renal Baroreceptors Location =

**Renal Baroreceptors ARE the Glomerular Cells in the Glomerular Apparatus** ## Footnote Can sense arterial pressure in afferent arteriole-but DOES NOT adapt

Baroreceptors and RAAS ## Footnote Decrease in Plasma Volume -\> Decrease in Blood Pressure -\> Sensed by JGA Granular Cell Baroreceptors stimulates release of enzyme * **(1)** into bloodstream and converts peptide prohormone * **(1)** found in bloodstream and produced by liver into * **(1)** which enters organs like the lungs that have * **(1)** which is an enzyme that interacts with it to form active hormone * **(1)** : strong hormone that increases plasma volume and BP

* **Renin** * **Angiotensinogen** * **Angiotensin I** * **ACE** * **Angiotensin II**

Actions of Angiotensin II (5) _Increases Sodium reabsorption (and water reabsorption)_ _Decreasing GFR_ _Increased Water consumption and reabsorption_

_Increase Sodium Reabsorption (and Water Reabsorption)_ 1. **Aldosterone Release** 2. **Na/H+ exchanger** in proximal tubule _Decreasing GFR_ 1. **Direct vasoconstriction of afferent arterioles** 2. **Enhancing Tubuloglomerular feedback system** _Increased Water consumption and Reabsorption_ 1. **Stimulates thirst and ADH secretion**

Angiotensin II Action #1 ## Footnote **Angiotensin II** acts on (1) to stimulate release of (1) -\> that acts on (2) parts of the nephron to increase (1)

Adrenal Cortex -\> Aldosterone -\> Distal tubule, collecting duct -\> sodium reabsorption

Angiotensin II Action #2 ## Footnote Ang II stimulates the **(1)** in the _____ tubule to increase **(1)** (water follows sodium) * Directly stimulates sodium reabsorption through mechanism thats coupled with (1) -\> so ang II directly and indirectly through \_\_\_\_

**Na/H exchangers** -\> proximal tubule -\> **sodium reabsorption** * H+ secretion (so simultaneusly secretes H+) -\> so ang II directly and indirectly stimulates sodium reabsorption through aldosterone

Angiotensin II Action #3 **(1)** Reduces capillary blood flow and GFR -\> limit urine production -\> minimize fluid loss

**Vasoconstriction of Afferent Arteriole and Systemic Blood Vessels**

Angiotensin II Action #4 (1) Tricks this system into thinking that GFR has gotten too high -\> enhances sensitivity and net effect is drop in GFR

**Tricks Tubuloglomerular Feedback System** -\> **macula densa cells respond more quickly -\> vasoconstrict afferent arteriole -\> decrease GFR**

Angiotensin II Action #5 (1) All acts on the hypothalamus to increase the sensation of?

**Release of ADH to increase sensation of Thirst** ## Footnote Thirst increases water consumption, ADH increases water reabsorption in distal tubule and collecting ducts

Short Term Plasma/BP Regulation = These receptors sense drops in BP when it first happens and then stimulates what?

Aortic Arch and Carotid Sinus Baroreceptors **Increases Sympathetic Actiity** to body including kidneys

Increased Sympathetic Nerve Activity Actions (3)

1. Sympathetic Nerve innervates **Afferent Arteriole to vasoconstrict** and decrease GFR 2. Sympathetic Nerve innervates **Juxtaglomerular Apparatus to stimulate Granular cells to release Renin** 3. **Stimulates ADH secretion**

Summary of Control of Plasma Volume and Total Body Sodium ## Footnote All in all =

Aortic and Carotid baroreceptors adapt after a few minutes so only a few minutes of sympathetic nerve activity but is enough to get the ball rolling bc renal baroreceptros will take over

Ch 7: Control of Fluid Osmolarity by ADH Thirst System ## Footnote Water balance and ECF osmolarity * ECF osmolarity is regulated by maintaining _____ balance * Total body osmolarity is defined as the ratio of (1):(1) * Total body osmoles is primarily determined by ECF ____ content * Water balance depends on equality between total body water ____ and total body water \_\_\_\_

* water * total body osmoles: total body water * sodium * gains, loss We want to control osmolarity to control **cell volume** -\> hypotonic ECF -\> cell swelling -\> impaired function/injury to cells Regulated by maintaining water balance to match whatever concentration of solues we have to make it isotonic

Water Balance ## Footnote Body water is **gained** from two primary sources = Body water is primarily **lost** through three routes =

Consumed alone or in food or liberated from metabolic processes Lost through Urine, Feces, Sweat

Water Balance and ECF osmolarity ## Footnote Two elements that control total body water and therefore osmolarity 1. the ____ control water excretion 2. the _____ mechanism that controls oral intake of water Both effector mechanisms are part of a _____ feedback loop that starts in the _____ of the brain Regulation of ECF osmolarity involves the detection of ____ osmolarity

1. kidneys 2. thirst negative feedback loop, hypothalamus plasma

Central Osmoreceptors = (2) Increased plasma osmolarity sensed by these and stimulate _____ -\> ______ -\> \_\_\_\_\_\_\_

**Circumventricular Organs** that sense changes in osmolarity of plasma **SFO** **OVLT** Hypothalamus -\> Posterior Pituitary -\> release of ADH

Sensitivity of ADH release ## Footnote OVC's very \_\_\_\_ In healthy individuals, plasma osmolarity is about 290mOsm * The threshold for AVP (arginine vasopressin) release is actually a bit lower about _____ mOsm * Increases by as little as \_% in plasma osmolarity can produce a large increase in plasma \_\_\_ * ADH then acts on the (2) to increase water reabsorption

sensitive * 280 * 1%, ADH * distal tubule and collecting duct

Central Osmoreceptors: Functions of SFO/OVLT ## Footnote When SFO and OVLT sense increased osmolarity and release ADH, also stimulates what?

**Thirst**

Where does the system that controls plasma osmolarity intersect with the system that controls plasma volume?

Ang II receptors on SFO and OLVT -\> stimulate thirst and hypothalmic release of vasopressin Part of brainstem that controls SNS activity also stimulates thirst and hypothalmic release of vasopressin + ang II also stimulates SFO/OVLT to sitmulate thirst Thirst and ADH release stimulated under conditions where plasma osmolarity rises OR when plasma volume and BP drop -\> goals are both fluid consumption and water retention

Other Factors Affecting Plasma (ADH) and Plasma Osmolarity ## Footnote and how? 1. Rate of ADH _____ by \_\_\_\_\_ 2. P\_\_\_, F\_\_\_, and T\_\_\_\_ 3. A\_\_\_\_\_

1. ADH breakdown by Liver * liver impairment -\> decreased breakdown -\> increased plasma 2. Pain, Fear, Trauma * increased sympathetic activation increases plasma ADH (ie post surgical SIADH, temporary) 3. Alcohol * Alcohol suppreses ADH secretion -\> inappropriate water loss (why we pee so much when we're drunk) -\> more vulnerable to dehydration