Physiology Block 4 Renal and Respiratory

What is the most abundant substance in the body that serves as a solvent for all dissolved constituents in the body?

Water

What is the volume of fluid within all cells of the body called?

Intracellular volume

What is the volume of fluid in the interstitial, intravascular, lymph, and transcellular spaces called?

Extracellular fluid

How much of the TBW is Intracellular fluid?

2/3

How much of the TBW is Extracellular fluid?

1/3

How much of the ECF is Interstitial fluid?

3/4

How much of the ECF is Plasma?

1/4

What fluid is within the cell membrane?

Intracellular fluid

What fluid is within the capillary membrane?

Plasma

What is the formula for calculating TBW?

TBW = 0.6 x Body Weight

What is the vital role of the kidneys?

Plasma purification and keeping the volume and composition of body fluids constant

What are the other, smaller roles of the kidneys?

Regulate water and inorganic ion balance, maintain acid-base balance, and eliminate metabolic waste products, eliminate foreign compounds, gluconeogenesis, and secrete hormones

What is the outer layer of the kidney called?

Cortex

What is the inner layer of the kidney called?

Medulla

What is the location of longer loops of Henle, & where drainage of collecting ducts into renal pelvis and ureter occur?

Medulla 

Where is the site of glomerular filtration and convoluted tubules

Cortex

What are the structural and functional units of the kidney called?

Nephrons

Each nephron is comprised of what?

A glomerulus and a renal tubule

A glomerulus is a collection of what?

Capillaries

The cup shape around the glomerulus that the tubule creates is called a glomerular capsule, better known as what?

Bowman’s capsule

What kind of nephrons are most nephrons that contain short loops of Henle?

Cortical

What kind of nephrons are involved in concentration of urine and contain long loops of Henle?

Juxtamedullary

What is a Renal Corpuscle made up of?

Glomerulus (glomerular capillaries) and Bowman’s capsule

Bowman’s Capsule is what layer of the Renal Corpuscle?

Parietal

What cells are located in the Afferent Arteriole as it enters the Renal Corpuscle?

JG

What layer of the Renal Corpuscle contains Glomerular capillaries and contains plasma, RBCs, WBCs, proteins, electrolytes, etc.?

Vascular

What space has Bowman’s space, contains ultrafiltrate of plasma, filtrate passes from vascular into tubule system, and is important in the 1st step of urine formation?

Urinary 

Which capillaries are specialized for filtration?

Glomerular

Which capillaries focus on reabsorption and secretion?

Peritubular

Which capillaries focus on concentration?

Vasa recta

What 3 sets of capillaries are nephrons associated with?

Glomerular, Peritubular, and Vasa recta

Most of filtrate reabsorbed by renal tubule cells is returned to blood through what capillaries?

Peritubular & Vasa recta

Few capillaries in the body are both fed and drained by arterioles. Drainage by arterioles instead of venules in glomerular capillaries allows what to be very high?

Glomerular capillary hydrostatic pressure

Glomerular capillary hydrostatic pressure being very high forces fluid and solute out of blood into Bowman’s capsule through what method?

Bulk flow

100% of plasma volume enters the kidneys via what?

Renal artery

80% of plasma travels in what structure of the kidney?

Efferent arterioles

What basic renal process occurs when fluid moves from the Glomerular capillary lumen to Bowman’s space through Bulk Flow?

Filtration

What basic renal process occurs when fluid moves from the Tubular lumen to the Peritubular capillary plasma?

Tubular reabsorption

What basic renal process occurs when fluid moves from the Peritubular plasma (capillary lumen) to the interstitial space, to tubular cell, to tubular lumen?

Tubular secretion

What is the equation for determining the amount of solute excreted?

Amount of solute excreted (E) = Amount filtered (F) - Amount reabsorbed (R) + Amount secreted (S)

What does the Glomerular Filtration Barrier consist of?

Glomerular capillary endothelium, basement membrane, and podocytes (Bowman’s capsule)

What component of the Glomerular filtration barrier is vascular?

Glomerular capillary endothelium

What component of the Glomerular filtration barrier is tubular?

Podocytes (Bowman’s capsule)

What component of the Glomerular filtration barrier is shared between tubular and vascular?

Basement membrane

What component of the Glomerular filtration barrier is produced by endothelial cells and podocytes?

Basement membrane

The Glomerular capillaries in the Glomerular filtration barrier are what type of capillaries, allowing for large amounts of solute-rich fluid to pass through?

Fenestrated

In the Glomerular Filtration Barrier, why is filtrate normally low in protein?

Proteins are too large to cross the capillary

What is the inner layer of the glomerular capsule that is highly modified branching epithelial cells?

Podocytes

What are podocyte terminations that surround basement membrane of glomerulus?

Foot processes

What are clefts between foot processes, where filtrate enters capsular space?

Filtration slits

Podocytes consist of what 2 main structures?

Foot processes and Filtration slits

What is pressure generated by large molecules (proteins) that are trapped in solutions (PULLING PRESSURE)?

Oncotic pressure

What is pressure exerted by liquids (PUSHING PRESSURE)?

Hydrostatic pressure

What regarding the heart pump prevents absorption of fluid into glomerular capillaries?

Hydrostatic pressure

What 2 forces favor fluid filtration?

Glomerular capillary hydrostatic pressure (P_GC) and Bowman’s space oncotic pressure (π_BS)

What 2 forces oppose fluid filtration?

Bowman’s space hydrostatic pressure (P_BS) and Glomerular capillary oncotic pressure (π_GC)

What are hollow tubes with filtered plasma in the lumen and capillary at the epithelial base?

Nephrons

Transport across membranes is dependent upon what?

Transport proteins in luminal and basolateral membranes of nephron epithelial cells

All water movement is passive. (T/F)

True

What section of the plasma membrane of tubule epithelial cells faces filtrate?

Luminal

What section of the plasma membrane of tubule epithelial cells is in close proximity to peritubular capillary (blood side)?

Basolateral membrane

What kind of transport is between cells and involves mostly ions?

Paracellular

What kind of transport is across luminal and basolateral plasma membranes?

Transcellular

What kind of transport is from tubular fluid (inside lumen of nephron) into the capillary?

Reabsorption

What percent of oxygen do the kidneys consume?

10%

Water reabsorption can be achieved through reabsorption of what ion?

Sodium (Na+)

What drives water to follow movement of sodium ions?

Osmosis

How do we move Na+ from the filtrate into the interstitium?

Reabsorption

When Na+ and K+ are pumped against their concentration gradients, what is this method of transport called?

Primary active transport

What kind of transporter allows for the “driven” solute to move in the same direction as the “driving” ion?

Cotransporter/Symporter

What kind of transporter allows for the “driven” solute to move in the opposite direction as the “driving” ion?

Exchangers/Countertransporters

Where is the ATP ion pump on collecting duct cells that facilitates movement of Na+ into the interstitial fluid and eventually into the blood, achieving reabsorption into the peritubular capillary?

On the basolateral plasma membrane

The ATP ion pump on the basolateral membrane of collecting duct cells aids in producing what that facilitates Na+ movement from the tubular lumen across the luminal (apical) plasma membrane and into the cell?

Electro-chemical gradient

What kind of transport of Na+ takes place across the luminal (apical) plasma membrane of collecting duct cells?

Diffusion

What kind of transport of Na+ takes place across the basolateral plasma membrane of collecting duct cells, moving Na+ out of the collecting duct cell and into the interstitial fluid?

Primary Active Transport (ATP pump)

How does water travel through from the lumen directly into the blood?

Through tight junctions

How does water travel through a proximal tubule epithelial cell from the lumen into the blood?

Through AQP1 (aquaporin 1)

In a proximal tubule cell, what ion is countertransported with Na+, facilitating Na+ movement into the cell?

H+

In a proximal tubule cell, what is the role of organic molecules like glucose and amino acids?

To allow for cotransport of Na+

What is the movement of molecules from the peritubular capillary into the tubular fluid of the lumen of the nephron?

Secretion

What mechanism facilitates the disposal of drugs and drug metabolites?

Secretion

Hydrogen ions, potassium, and organic anions move in what direction?

From peritubular capillaries into tubular lumen (added to fluid that may become urine)

Elimination of undesired substances or end-products of metabolism, removal of excess K+, and control of blood pH all occur through what mechanism?

Secretion

How is K+ moved from the interstitium into the filtrate?

Secretion

What kind of transport moves K+ into the collecting duct cells from the interstitial fluid on the basolateral plasma membrane?

Primary active transport (ATP pump)

What renal processes does water go through?

Filtration and reabsorption

What renal processes does glucose go through?

Filtration and COMPLETE reasborption

TRUE OR FALSE: There is tight regulation of rates of reabsorption and/or secretion of many substances

TRUE

What do membrane channels and transporters respond to?

Hormones and paracrine/autocrine factors

What about transport proteins in the plasma membrane can be regulated?

Activity and/or number

What order of structures would a water drop traveling in the renal artery that is filtered encounter?

Afferent arteriole → Glomerulus → Bowman’s capsule → Proximal tubule → Loop of Henle → Distal tubule → Collecting duct → Renal pelvis → Ureter → Bladder → Urethra

What is movement of fluid and solutes from glomerular capillaries across barrier into Bowman’s space?

Glomerular filtration

What is movement of fluid and solutes from glomerular capillaries across barrier into Bowman’s space due to?

Starling Forces

What initiates urine formation?

Net glomerular filtration pressure

Urine is a ____-free and _______-free filtrate of plasma

cell, protein

Urine travels down the proximal tubule into _____ ______

renal pelvis

Glomerular filtration is a passive process, with ___________ pressures forcing fluids and solute through the membrane

hydrostatic

What is the most efficient filter, more so than any other capillary bed in the body?

Glomerular capillaries in the kidney

Glomerular filtration membrane has a very _____ (small/large) surface area and is ____ (not/very) permeable to water and solutes

large, very

Glomerular capillary pressure is very ____ (low/high)

high