Renal Physiology Flashcards

1
Q

Kidney regulates the __________ of blood

A

Plasma

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2
Q

Renal (kidney) functions (5)

A
  1. Regulate our blood volume and pressure
  2. Maintain the acid-base balance
  3. Excrete waste products
  4. Synthesis of new glucose molecules to provide energy
  5. Secrete hormones
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3
Q

Primary function of renal(kidney)

A

Regulate our blood volume and pressure

  • Maintain the water concentration and fluid volume
  • Maintain the inorganic ion composition within a constant range
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4
Q

Example of waste products that the kidneys excrete

A
  • urea
  • uric acid
  • creatinine
  • bilirubin
  • foreign chemicals
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5
Q

Example of hormones the kidneys secrete

A
  • Erythropoietin (EPO): synthesized by fibroblasts in the kidney
  • Renin
  • 1,25- dihydroxyvitamin D: an active metabolite of Vitamin D
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6
Q

Kidneys regulate fluid volume, which affects ________________ and _______________

A

Blood volume and blood pressure

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7
Q

The function of the kidneys is to maintain the volume of the plasma within a very ______ range

A

narrow

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8
Q

Changes that occur where the plasma volume is affected happen due to the rapid movement of water form the plasma component by the process of __________

A

osmosis

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9
Q

Kidney regulates the extracellular fluid. What are the three extracellular fluid?

A
  • plasma
  • interstitial fluid
  • cerebrospinal fluid
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10
Q

These ions have higher concentration in the extracellular fluid compartment (3)

A
  • sodium
  • chloride
  • bicarbonate
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11
Q

These ions have higher concentration in the intracellular fluid compartment (2)

A
  • potassium
  • phosphate
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12
Q

__________ are specialized water-selective channels in the plasma membrane of cells. They are responsible for the rapid diffusion of water

A

Aquaporins

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13
Q

Water concentration does not just take into account the number of water molecules only but also the ___________________

A

solutes dissolved in the water

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14
Q

One _______ is equal to one mole of solute particle that is dissolved in water

Water concentration is always recorded in this

A

osmole

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15
Q

___________ is defined as the number of solutes per volume of solution expressed in moles per litre

A

Osmolarity

Pure water= high water concentration

The more solute, the more it will raise the osmolarity

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16
Q

A region of lower osmolarity has a _________ water concentration

A

higher

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17
Q

A region with higher osmolarity has a ______ water concentration as it contains more solute molecules

A

lower

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18
Q

In _________, solute molecules move from an area of higher concentration to an area of lower concentration due to random thermal motion

A

diffusion

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19
Q

This is the net diffusion of water across a selectively permeable membrane from a region of high water concentration to one with a lower water concentration

A

Osmosis

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20
Q

This is a membrane which is permeable to water but does not allow solutes to cross

A

Semi-permeable membrane

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21
Q

_____________ will push and prevent water from coming into the cell, to prevent them from taking on water and bursting.

Opposing pressure required to stop osmosis completely

A

Osmotic pressure

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22
Q

__________ is determined by the concentration of non-penetrating solutes of an extracellular solution.

A

Tonicity

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23
Q

3 classes of tonicity that one solution could have relative to another

A
  • Isotonic solution
  • Hypertonic solution
  • Hypotonic solution
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24
Q

In this class of tonicity, the inside of the cell and the extracellular environment have the same osmolarity.
The cell volume or shape does not change

A

Isotonic solution

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25
Q

In this class of tonicity, the extracellular medium has a higher osmolarity than inside the cell
A living cell in this medium will shrink

A

Hypertonic solution

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26
Q

In this class of tonicity, the extracellular medium has a lower osmolarity that inside the cell.
A living cell in this medium will swell up or bulge out

A

Hypotonic solution

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27
Q

Water always flows from a region of _________ osmolarity to a region of _______ osmolarity

A

lower, higher

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28
Q

Movement of water and solutes from the interstitial fluid compartment to the plasma is called __________

A

absorption

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29
Q

Movement of water and solutes from the plasma to the interstitial fluid is called ____________

A

filtration

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30
Q

How does fluid move between the plasma and the interstitial fluid compartments?

A
  • The capillary hydrostatic pressure pushes some of the fluid out of the capillary into the interstitial fluid
  • Interstitial fluid hydrostatic pressure pushes fluid into the capillaries
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31
Q

Hydrostatic pressure

A

the pressure exerted by a fluid; every fluid has this property (Pc)

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32
Q

What is the contribution of the plasma proteins to fluid movement?

A
  • Proteins are large and sometimes charged; cannot move in and out of capillaries easily
  • Inside the plasma there are many plasma proteins and these plasma proteins contribute to the osmolarity
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33
Q

Osmotic force due to plasma protein concentration

A
  • a lot pf plasma proteins means there are more plasma proteins in the plasma and less water concentration inside the capillary than outside the capillaries
  • water will try to move into the capillary as these plasma proteins tend to pull water into the capillary
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34
Q

Osmotic force due to interstitial fluid protein concentration

A
  • proteins do have a difficult time crossing the capillary, but some plasma proteins will escape and are found in the interstitial space
  • these plasma proteins will try to draw fluid out of the capillary into the interstitial space
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35
Q

The net pressure determines the direction of fluid movement. How do you determine the net pressure?

A

Sum the two outgoing forces and subtract the two ingoing forces

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36
Q

The four factors that determine the net filtration pressure are termed the __________________

A

Starling forces

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37
Q

At the arterial end of a capillary, there’s more filtration of fluid as the net filtration pressure is positive; fluid moves _______ of the capillary

A

out

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38
Q

At the venule end of the capillary, there’s more absorption of fluid, as the net filtration pressure is negative; fluid moves _____ the capillary

A

into

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39
Q

Kidneys are ___________ in location (found behind the peritoneum)

A

retroperitoneal

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40
Q

What are the other structures associated with the urinary system? (3)

A
  • ureters
  • bladder
  • urethra
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41
Q

This is the inner concave part of the kidney

A

Hilum

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42
Q

These drain the formed urine form the kidneys and empty into the bladder

A

Ureters

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43
Q

This is the storage organ or a sac for the formed urine.
This receives innervation from the autonomic nervous system; emptying of this is controlled by parasympathetic and sympathetic inputs

A

Bladder

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44
Q

Bladder empties out of the body through the _________

A

urethra

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45
Q

Micturition

A

the process of releasing the urine outside the body, or urination

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46
Q

2 regions of the kidney

A

Outer portion: cortex
Inner portion: Medulla

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47
Q

Nephron

A
  • functional units of the kidney
  • where the urine is made
  • contains renal corpuscle and renal tubule
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48
Q

Renal corpuscle

A

bulb-like structure

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49
Q

Attached to the renal corpuscle is a long tube called the ______________

A

renal tubule

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50
Q

Urine starts forming in the ___________ which fuse together and form collecting ducts

A

nephrons

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51
Q

Collecting ducts empty their contents into the ______________

A

renal pelvis

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52
Q

The formed urine enters into the ureter to be taken away to the ___________

A

bladder

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53
Q

This part of the nephron is a cup-like shaped structure with a tuft (loops) of capillaries.
The glomerulus and the Bowman’s capsule is known as this

A

Renal corpuscle

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54
Q

What are the renal tubule segments

A
  • proximal convoluted tubule
  • Loop of Henle (descending and ascending limbs)
  • distal convoluted tubule
  • collecting ducts
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55
Q

This segment of renal tubule is close to the renal corpuscle

A

proximal convoluted tubule

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56
Q

The distal convoluted tubule drains its contents into a main tube called the ________________

A

collecting duct

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57
Q

This is the initial blood filtering component of a nephron

A

Renal corpuscle

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58
Q

_____________ are cells closest to which come in contact with the glomerular capillaries;
These cells have foot-like processes

A

Podocytes

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59
Q

What is the ultimate outcome of the development of the renal corpuscle?

A

Development of a hollow tube which becomes the Bowman’s cup and continues on as the tubule

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60
Q

What is the first stage in the development of the renal corpuscle?

A

When the kidneys are forming during fetal life:
- a nephron will develop first as a blind-ended tube; there is no opening
- tube is lined by a layer of epithelial cells sitting on a basement membrane

61
Q

What is the second stage in the development of the renal corpuscle?

A
  • growing of tuft of capillaries penetrate the expanded end of tubules
  • tubule invaginates or indents
  • the capillaries continue to move closer to the epithelial cell layer
  • the basal lamina is trapped in between endothelial cells of capillaries and epithelial layer
  • epithelial cell layer differentiates into parietal (outer) and visceral (inner) layer
62
Q

What is the third stage in the development of the renal corpuscle?

A
  • the outer layer does not fuse with the inner layer-there is a space between them
  • parietal layer eventually flattened to become wall of Bowman’s capsule; visceral layer becomes podocyte cell layer
63
Q

The outer layer of epithelial cells which forms the outer wall of the Bowman’s capsule is the _________ layer

A

parietal

64
Q

The layer closest to the glomerular capillaries is called the _________ layer. These cells are the podocytes

A

visceral

65
Q

Anatomy of the Renal Corpuscle:

Blood is brought in through the __________ arteriole and flows through the capillaries of the glomerulus. Capillaries are fenestrated

A

afferent

66
Q

Anatomy of the Renal Corpuscle:

Podocytes are arranged around the external surface of the ____________ capillaries. The podocytes are interlocked: the foot processes of one podocyte, which are cytoplasmic projections, interlock with those of another podocyte

A

glomerular

67
Q

In the anatomy of the renal corpuscle:

Between the interlocking foot processes of the podocytes are ________________

A

filtration slits

68
Q

3 layers of the glomerular capillary

A
  • Endothelial layer
  • Basement membrane
  • Podocytes
69
Q

This glomerular capillary layer is fenestrated to allow for filtration.

A

Endothelial layer

70
Q

The endothelial cells sit on a basement membrane. What is a basement membrane?

A

Gel-like mesh structure composed of collagen proteins and glycoproteins

71
Q

This glomerular capillary layer are found outside the basement membrane with filtration slits through which fluid moves

A

Podocytes

72
Q

Purpose of multiple foot processes of podocytes?

A

Magnify the surface area for filtration. It creates a large surface area

73
Q

Renal corpuscles are always found in the _______

A

cortex

74
Q

2 types of nephrons

A
  • Cortical
  • Juxtamedullary
75
Q

Cortical nephrons is the majority and comprised of _____%

A

85%

76
Q

The tubule segment, the collecting duct, the distal convoluted tubule, and the proximal tubule, are mostly located in the _________

A

cortex

77
Q

Juxtamedullary nephrons comprises of ______%

A

15%

78
Q

Renal corpuscles sit in the cortex but are closer to the __________ area

A

medullary

79
Q

The loop of Henle and the ascending limb are found in the _________________

A

renal medulla

80
Q

3 types of renal processes

A
  • filtration
  • reabsorption
  • secretion
81
Q

Juxtamedullary nephrons create __________________ in the interstitial space or outside the loop of Henle (in the medulla).

A

osmotic gradients

82
Q

Osmotic gradients help in _____________

A

water volume regulation

83
Q

Blood arrives at the renal corpuscle through the __________ arteriole

A

afferent

84
Q

This is a highly vascularized organ. It receives ~20% of the total cardiac output

A

Kidney

85
Q

Blood is brought into the kidneys through the ________________ which enters the kidney through a curved concave portion known as the ______________

A

renal artery;
hilum area

86
Q

This branches off from the renal artery and diverges into the capillaries of the glomerulus. This brings blood into the glomerular capillary.

A

Afferent arteriole

87
Q

Blood travels through the ______________ in the glomerulus or glomerular capillaries

A

Bowman’s capsule

88
Q

Blood exits the glomerulus through the ________________. This branches around to form a set of capillaries called the peritubular capillary network

A

Efferent arteriole

89
Q

____________ are found around the proximal convoluted tubules. These fuse together to form the renal vein

A

Peritubular capillaries

90
Q

____________ are capillaries that are found mostly associated with juxtamedullary nephrons in the medullary portion of the kidney

A

Vasa recta

91
Q

Both the loop of Henle and the vasa recta are important in forming the ______________

A

osmotic gradient

92
Q

3 types of capillaries that supply blood to the nephrons

A
  • Glomerular
  • Peritubular
  • Vasa recta
93
Q

How do the kidneys produce urine? (3 renal processes)

A
  • Glomerular filtration
  • Tubular reabsorption
  • Tubular secretion
94
Q

Glomerular filtration

A
  • fluid in the blood is filtered across the capillaries of the glomerulus and into Bowman’s space
  • blood is brought to the kidneys by the renal artery and then enters the glomeruli through the afferent arterioles, where it undergoes glomerular filtration
95
Q

Tubular reabsorption

A
  • the movement of a substance from inside the tubule into the blood
  • glucose is reabsorbed by the body as it is very important as an energy source
96
Q

Tubular secretion

A
  • movement of nonfiltered substances from the capillaries into the tubular lumen
  • waste products that did not undergo filtration can be removed form the blood by tubular secretion
97
Q

Formula for the amount excreted

A

Amount excreted= amount filtered + amount secreted - amount reabsorbed

98
Q

Urinary excretion

A
  • blood is filtered at the glomeruli, and then substances are added, or secreted, to the tubules, while other substances are reabsorbed; urine containing unwanted products is excreted from our body
99
Q

Three filtration layers that substances move across from the lumen of the glomerular capillaries into Bowman’s space:

A
  1. Capillary endothelial layer
  2. Basement membrane
  3. Podocytes with filtration slits
100
Q

When blood is passing through the glomerulus, almost everything moves out of the glomerular capillaries into Bowman’s space except:

A

large proteins (albumin) and blood cells

101
Q

____________ have slits that remain covered with fine semiporous membranes

A

Podocytes

102
Q

Semiporous membranes are made up of proteins such as ___________ and __________

A

nephrins and podocins

103
Q

What substances are filtered through the glomerulus? (4)

A
  • water
  • electrolytes
  • glucose
  • waste products such as urea, uric acid, and creatinine
104
Q

What are non-filtered substances in the glomerulus? (retained in blood) (3)

A
  • plasma proteins and blood cells
  • large anions
  • anything bound to plasma proteins (ie. calcium)
105
Q

_____________ is the cell-free fluid that has come into Bowman’s space and, except for plasma proteins (and substances bound to them) and blood cells, contains mostly all the substances at the same concentrations as in the plasma

A

Ultrafiltrate

106
Q

The concentration of a substate filtered through the filtration layers is the same in the __________ and in the ________

A

plasma and filtrate

107
Q

This is a condition where some of the proteins that are not supposed to pass through the filtration barrier show up in the filtrate and ultimately in the urine.
Does not occur under normal healthy conditions

A

Proteinuria

108
Q

Glomerular capillary hydrostatic pressure (PGC)

A
  • hydrostatic pressure of the blood that is found in the glomerular capillaries
  • 60 mmHg
  • This pressure pushes fluid outward into Bowman’s space, or from the capillary side into Bowman’s space; favors filtration
109
Q

Bowman’s space hydrostatic pressure (PBS)

A
  • fluid pressure in Bowman’s space
  • 15 mmHg
  • Opposes filtration
110
Q

Osmotic force due to proteins in the plasma (ΠGC)

A
  • due to proteins that are present in the plasma
  • 29 mmHg
  • opposes filtration
111
Q

What is the net glomerular filtration pressure?

A

The sum of the 3 forces:

Glomerular capillary hydrostatic pressure - Bowman’s space hydrostatic pressure - Osmotic force due to proteins in the plasma

60 mmHg - 15 mmHg - 29 mmHg = 16 mmHg

112
Q

The __________ pressure pushes the protein-free filtrate from the plasma out of the glomerulus into Bowman’s space

A

positive

113
Q

In a healthy person, the filtrate in Bowman’s space does not contain ___________. There is therefore no osmotic force due to the presence of this in Bowman’s space

A

proteins

114
Q

In starling forces, the net filtration pressure is always __________ filtration

A

positive

115
Q

What factor would contribute to an increase in the glomerular filtration rate?

A

High blood pressure

Increase in blood pressure would increase glomerular filtration rate

116
Q

What factor would contribute to a decrease in the glomerular filtration rate?

A

An increase in the protein concentration in the plasma would increase the protein in the glomerular capillaries, decreasing the glomerular filtration rate

117
Q

Plasma volume entering the afferent arteriole is 100%. Only __% of the volume is filtered into Bowman’s space- this is the filtration fraction

A

20%

118
Q

What is the final volume of fluid (in percentage) that is excreted to the external environment?

A

1%

119
Q

__________ is the volume of fluid filtered from the glomerulus into the Bowman’s space per unit time

A

Glomerular filtration rate

120
Q

In a 70 kg man, what is the glomerular filtration rate?

A

~125 mL/minute or 180L/day

121
Q

4 factors that affect the glomerular filtration rate

A
  • Net glomerular filtration pressure (blood pressure)
  • Neural and endocrine control
  • Permeability of the corpuscular membrane
  • Surface area available for filtration
122
Q

Glomerular filtration rate (GFR) remains fairly constant despite large changes in arterial pressure or renal blood flow due to ___________

A

autoregulation

123
Q

Autoregulation is regulated by changes in the ______________ as well as by the __________________

A

myogenic reflex; tubuloglomerular effect

124
Q

_____________ changes in the renal arterioles alter renal blood flow and glomerular filtration rate

A

Resistance

125
Q

A change in resistance of ___________ arteriole will change how much blood is coming in, either increasing or decreasing the amount of blood

A

afferent

126
Q

Constriction of the afferent arteriole is due to the ____________ response

A

myogenic

127
Q

What happens during constriction of the afferent arteriole?

A
  • Constriction increases resistance to flow through the afferent arteriole
  • Renal blood flow to the glomerulus has decreased due to an increase in the resistance in the afferent arteriole
  • A decrease in renal blood flow reduces the hydrostatic pressure of the glomerular capillary (PGC) resulting in a decrease in the glomerular filtration rate
128
Q

1 scenario that can alter the glomerular filtration rate is constrict afferent arteriole. What happens next?

A

Constrict afferent arteriole -> PGC, or the hydrostatic pressure of the glomerular capillary will decrease -> decrease GFR

129
Q

1 scenario that can alter the glomerular filtration rate is constrict efferent arteriole. What happens next?

A

Constrict efferent arteriole -> volume of blood builds up in the glomerular capillaries -> increase hydrostatic pressure in the glomerular capillaries -> increase GFR

130
Q

1 scenario that can alter the glomerular filtration rate is dilate efferent arteriole. What happens next?

A

Dilate efferent arteriole -> decreases resistance -> renal blood will drain rapidly -> decrease in the capillary hydrostatic pressure -> decrease GFR

131
Q

1 scenario that can alter the glomerular filtration rate is dilate afferent arteriole. What happens next?

A

Dilate afferent arteriole -> increase in blood flow into the afferent arteriole -> increase in the hydrostatic pressure -> increase GFR

132
Q

Mechanisms which change arteriolar resistance

A
  • Myogenic response
  • Hormones/neurotransmitters released from autonomic neurons may also act on arterioles and alter their resistance
  • Tubular glomerular feedback
133
Q

__________________ has a tubuloglomerular feedback. Depending on the volume that is flowing through, this apparatus will control the autoregulatory processes and affect the glomerular filtration rate

A

Juxtaglomerular apparatus

134
Q

The _______________ and ________________ play a role in autoregulation of the GFR

A

myogenic response and tubuloglomerular effect

135
Q

This is a specialized structure formed by the distal convolutes tubule and the glomerular afferent arteriole

A

Juxtaglomerular apparatus (JGA)

136
Q

3 cell types which control the glomerular filtration rate

A
  • Macula densa
  • Juxtaglomerular cells
  • Mesangial cells
137
Q

____________ are cells on wall of distal tubule at the junction where the ascending limb is beginning to form the distal tubule; in very close proximity to the glomerulus.
Secrete vasoactive compounds
Part of the JGA

A

Macula densa

138
Q

__________ is a paracrine factor which has an effect on arteriolar resistance by signalling JG cells

A

Adenosine

139
Q

__________________ are also called granular cells.
Sit on top of the afferent arteriole
Sit on top of the afferent arteriole
Innervated by sympathetic nerve fibers which can change the resistance of the afferent arteriole
Release renin which controls afferent arteriole resistance
Part of the JGA

A

Juxtaglomerular cells

140
Q

______________ are found in the triangular region between the afferent and efferent arterioles. Not considered part of the JGA

A

Mesangial cells

141
Q

______________ play a role in controlling the filtration surface area which affects the glomerular filtration rate. It shrinks the surface area of the glomerular filtration surface

A

Mesangial cells

142
Q

When the mesangial cells contract, they allow all the __________ to contract

A

podocytes

143
Q

When increased fluid volume flows through the distal tubule there is a feedback effect on the glomerular structure in controlling the GFR. What is the tubuloglomerular feedback?

A

Increase in the glomerular filtration rate -> Increase in flow to the tubule -> Flow past the macula densa increases -> Paracrine factors from the macula densa are secreted -> Paracrine factors act on the afferent arteriole -> Afferent arteriole constricts -> Resistance in the afferent arteriole increases -> Hydrostatic pressure drops in the glomerulus (PGC drops) -> GFR rate decreases

144
Q

What are substances filtered at the glomerulus?

A

Non-protein substances or non-protein bound substances

145
Q

______________ is the amount of a substance that is filtered by the kidneys per day or, how much of the load is filtered into Bowman’s space

A

Filtered load

146
Q

Formula to calculate filtered load

A

Filtered load= GFR x concentration of the substance in the plasma

147
Q

What does this indicate?:
Substance excreted in urine < filtered load

A

Reabsorption has occurred

148
Q

What does this indicate?:
Substance excreted in urine > filtered load

A

Secretion has occurred

149
Q

_____________ is the protein-free fluid formed as the plasma is filtered at the glomerulus; the concentration of substances in the filtrate and in the plasma, except for plasma proteins (and blood cells), should be the same

A

Ultrafiltrate