Renal Physiology Flashcards
(149 cards)
1
Q
Kidney regulates the __________ of blood
A
Plasma
2
Q
Renal (kidney) functions (5)
A
- Regulate our blood volume and pressure
- Maintain the acid-base balance
- Excrete waste products
- Synthesis of new glucose molecules to provide energy
- Secrete hormones
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
4
Q
Example of waste products that the kidneys excrete
A
- urea
- uric acid
- creatinine
- bilirubin
- foreign chemicals
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
6
Q
Kidneys regulate fluid volume, which affects ________________ and _______________
A
Blood volume and blood pressure
7
Q
The function of the kidneys is to maintain the volume of the plasma within a very ______ range
A
narrow
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
9
Q
Kidney regulates the extracellular fluid. What are the three extracellular fluid?
A
- plasma
- interstitial fluid
- cerebrospinal fluid
10
Q
These ions have higher concentration in the extracellular fluid compartment (3)
A
- sodium
- chloride
- bicarbonate
11
Q
These ions have higher concentration in the intracellular fluid compartment (2)
A
- potassium
- phosphate
12
Q
__________ are specialized water-selective channels in the plasma membrane of cells. They are responsible for the rapid diffusion of water
A
Aquaporins
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
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
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
16
Q
A region of lower osmolarity has a _________ water concentration
A
higher
17
Q
A region with higher osmolarity has a ______ water concentration as it contains more solute molecules
A
lower
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
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
20
Q
This is a membrane which is permeable to water but does not allow solutes to cross
A
Semi-permeable membrane
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
22
Q
__________ is determined by the concentration of non-penetrating solutes of an extracellular solution.
A
Tonicity
23
Q
3 classes of tonicity that one solution could have relative to another
A
- Isotonic solution
- Hypertonic solution
- Hypotonic solution
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
25
In this class of tonicity, the extracellular medium has a higher osmolarity than inside the cell
A living cell in this medium will shrink
Hypertonic solution
26
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
Hypotonic solution
27
Water always flows from a region of _________ osmolarity to a region of _______ osmolarity
lower, higher
28
Movement of water and solutes from the interstitial fluid compartment to the plasma is called __________
absorption
29
Movement of water and solutes from the plasma to the interstitial fluid is called ____________
filtration
30
How does fluid move between the plasma and the interstitial fluid compartments?
- 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
31
Hydrostatic pressure
the pressure exerted by a fluid; every fluid has this property (Pc)
32
What is the contribution of the plasma proteins to fluid movement?
- 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
33
Osmotic force due to plasma protein concentration
- 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
34
Osmotic force due to interstitial fluid protein concentration
- 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
35
The net pressure determines the direction of fluid movement. How do you determine the net pressure?
Sum the two outgoing forces and subtract the two ingoing forces
36
The four factors that determine the net filtration pressure are termed the __________________
Starling forces
37
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
out
38
At the venule end of the capillary, there's more absorption of fluid, as the net filtration pressure is negative; fluid moves _____ the capillary
into
39
Kidneys are ___________ in location (found behind the peritoneum)
retroperitoneal
40
What are the other structures associated with the urinary system? (3)
- ureters
- bladder
- urethra
41
This is the inner concave part of the kidney
Hilum
42
These drain the formed urine form the kidneys and empty into the bladder
Ureters
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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
Bladder
44
Bladder empties out of the body through the _________
urethra
45
Micturition
the process of releasing the urine outside the body, or urination
46
2 regions of the kidney
Outer portion: cortex
Inner portion: Medulla
47
Nephron
- functional units of the kidney
- where the urine is made
- contains renal corpuscle and renal tubule
48
Renal corpuscle
bulb-like structure
49
Attached to the renal corpuscle is a long tube called the ______________
renal tubule
50
Urine starts forming in the ___________ which fuse together and form collecting ducts
nephrons
51
Collecting ducts empty their contents into the ______________
renal pelvis
52
The formed urine enters into the ureter to be taken away to the ___________
bladder
53
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
Renal corpuscle
54
What are the renal tubule segments
- proximal convoluted tubule
- Loop of Henle (descending and ascending limbs)
- distal convoluted tubule
- collecting ducts
55
This segment of renal tubule is close to the renal corpuscle
proximal convoluted tubule
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The distal convoluted tubule drains its contents into a main tube called the ________________
collecting duct
57
This is the initial blood filtering component of a nephron
Renal corpuscle
58
_____________ are cells closest to which come in contact with the glomerular capillaries;
These cells have foot-like processes
Podocytes
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What is the ultimate outcome of the development of the renal corpuscle?
Development of a hollow tube which becomes the Bowman's cup and continues on as the tubule
60
What is the first stage in the development of the renal corpuscle?
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
What is the second stage in the development of the renal corpuscle?
- 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
What is the third stage in the development of the renal corpuscle?
- 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
The outer layer of epithelial cells which forms the outer wall of the Bowman's capsule is the _________ layer
parietal
64
The layer closest to the glomerular capillaries is called the _________ layer. These cells are the podocytes
visceral
65
Anatomy of the Renal Corpuscle:
Blood is brought in through the __________ arteriole and flows through the capillaries of the glomerulus. Capillaries are fenestrated
afferent
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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
glomerular
67
In the anatomy of the renal corpuscle:
Between the interlocking foot processes of the podocytes are ________________
filtration slits
68
3 layers of the glomerular capillary
- Endothelial layer
- Basement membrane
- Podocytes
69
This glomerular capillary layer is fenestrated to allow for filtration.
Endothelial layer
70
The endothelial cells sit on a basement membrane. What is a basement membrane?
Gel-like mesh structure composed of collagen proteins and glycoproteins
71
This glomerular capillary layer are found outside the basement membrane with filtration slits through which fluid moves
Podocytes
72
Purpose of multiple foot processes of podocytes?
Magnify the surface area for filtration. It creates a large surface area
73
Renal corpuscles are always found in the _______
cortex
74
2 types of nephrons
- Cortical
- Juxtamedullary
75
Cortical nephrons is the majority and comprised of _____%
85%
76
The tubule segment, the collecting duct, the distal convoluted tubule, and the proximal tubule, are mostly located in the _________
cortex
77
Juxtamedullary nephrons comprises of ______%
15%
78
Renal corpuscles sit in the cortex but are closer to the __________ area
medullary
79
The loop of Henle and the ascending limb are found in the _________________
renal medulla
80
3 types of renal processes
- filtration
- reabsorption
- secretion
81
Juxtamedullary nephrons create __________________ in the interstitial space or outside the loop of Henle (in the medulla).
osmotic gradients
82
Osmotic gradients help in _____________
water volume regulation
83
Blood arrives at the renal corpuscle through the __________ arteriole
afferent
84
This is a highly vascularized organ. It receives ~20% of the total cardiac output
Kidney
85
Blood is brought into the kidneys through the ________________ which enters the kidney through a curved concave portion known as the ______________
renal artery;
hilum area
86
This branches off from the renal artery and diverges into the capillaries of the glomerulus. This brings blood into the glomerular capillary.
Afferent arteriole
87
Blood travels through the ______________ in the glomerulus or glomerular capillaries
Bowman's capsule
88
Blood exits the glomerulus through the ________________. This branches around to form a set of capillaries called the peritubular capillary network
Efferent arteriole
89
____________ are found around the proximal convoluted tubules. These fuse together to form the renal vein
Peritubular capillaries
90
____________ are capillaries that are found mostly associated with juxtamedullary nephrons in the medullary portion of the kidney
Vasa recta
91
Both the loop of Henle and the vasa recta are important in forming the ______________
osmotic gradient
92
3 types of capillaries that supply blood to the nephrons
- Glomerular
- Peritubular
- Vasa recta
93
How do the kidneys produce urine? (3 renal processes)
- Glomerular filtration
- Tubular reabsorption
- Tubular secretion
94
Glomerular filtration
- 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
Tubular reabsorption
- 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
Tubular secretion
- 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
Formula for the amount excreted
Amount excreted= amount filtered + amount secreted - amount reabsorbed
98
Urinary excretion
- 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
Three filtration layers that substances move across from the lumen of the glomerular capillaries into Bowman's space:
1. Capillary endothelial layer
2. Basement membrane
3. Podocytes with filtration slits
100
When blood is passing through the glomerulus, almost everything moves out of the glomerular capillaries into Bowman's space except:
large proteins (albumin) and blood cells
101
____________ have slits that remain covered with fine semiporous membranes
Podocytes
102
Semiporous membranes are made up of proteins such as ___________ and __________
nephrins and podocins
103
What substances are filtered through the glomerulus? (4)
- water
- electrolytes
- glucose
- waste products such as urea, uric acid, and creatinine
104
What are non-filtered substances in the glomerulus? (retained in blood) (3)
- plasma proteins and blood cells
- large anions
- anything bound to plasma proteins (ie. calcium)
105
_____________ 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
Ultrafiltrate
106
The concentration of a substate filtered through the filtration layers is the same in the __________ and in the ________
plasma and filtrate
107
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
Proteinuria
108
Glomerular capillary hydrostatic pressure (PGC)
- 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
Bowman's space hydrostatic pressure (PBS)
- fluid pressure in Bowman's space
- 15 mmHg
- Opposes filtration
110
Osmotic force due to proteins in the plasma (ΠGC)
- due to proteins that are present in the plasma
- 29 mmHg
- opposes filtration
111
What is the net glomerular filtration pressure?
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
The __________ pressure pushes the protein-free filtrate from the plasma out of the glomerulus into Bowman's space
positive
113
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
proteins
114
In starling forces, the net filtration pressure is always __________ filtration
positive
115
What factor would contribute to an increase in the glomerular filtration rate?
High blood pressure
Increase in blood pressure would increase glomerular filtration rate
116
What factor would contribute to a decrease in the glomerular filtration rate?
An increase in the protein concentration in the plasma would increase the protein in the glomerular capillaries, decreasing the glomerular filtration rate
117
Plasma volume entering the afferent arteriole is 100%. Only __% of the volume is filtered into Bowman's space- this is the filtration fraction
20%
118
What is the final volume of fluid (in percentage) that is excreted to the external environment?
1%
119
__________ is the volume of fluid filtered from the glomerulus into the Bowman's space per unit time
Glomerular filtration rate
120
In a 70 kg man, what is the glomerular filtration rate?
~125 mL/minute or 180L/day
121
4 factors that affect the glomerular filtration rate
- Net glomerular filtration pressure (blood pressure)
- Neural and endocrine control
- Permeability of the corpuscular membrane
- Surface area available for filtration
122
Glomerular filtration rate (GFR) remains fairly constant despite large changes in arterial pressure or renal blood flow due to ___________
autoregulation
123
Autoregulation is regulated by changes in the ______________ as well as by the __________________
myogenic reflex; tubuloglomerular effect
124
_____________ changes in the renal arterioles alter renal blood flow and glomerular filtration rate
Resistance
125
A change in resistance of ___________ arteriole will change how much blood is coming in, either increasing or decreasing the amount of blood
afferent
126
Constriction of the afferent arteriole is due to the ____________ response
myogenic
127
What happens during constriction of the afferent arteriole?
- 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
1 scenario that can alter the glomerular filtration rate is constrict afferent arteriole. What happens next?
Constrict afferent arteriole -> PGC, or the hydrostatic pressure of the glomerular capillary will decrease -> decrease GFR
129
1 scenario that can alter the glomerular filtration rate is constrict efferent arteriole. What happens next?
Constrict efferent arteriole -> volume of blood builds up in the glomerular capillaries -> increase hydrostatic pressure in the glomerular capillaries -> increase GFR
130
1 scenario that can alter the glomerular filtration rate is dilate efferent arteriole. What happens next?
Dilate efferent arteriole -> decreases resistance -> renal blood will drain rapidly -> decrease in the capillary hydrostatic pressure -> decrease GFR
131
1 scenario that can alter the glomerular filtration rate is dilate afferent arteriole. What happens next?
Dilate afferent arteriole -> increase in blood flow into the afferent arteriole -> increase in the hydrostatic pressure -> increase GFR
132
Mechanisms which change arteriolar resistance
- Myogenic response
- Hormones/neurotransmitters released from autonomic neurons may also act on arterioles and alter their resistance
- Tubular glomerular feedback
133
__________________ 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
Juxtaglomerular apparatus
134
The _______________ and ________________ play a role in autoregulation of the GFR
myogenic response and tubuloglomerular effect
135
This is a specialized structure formed by the distal convolutes tubule and the glomerular afferent arteriole
Juxtaglomerular apparatus (JGA)
136
3 cell types which control the glomerular filtration rate
- Macula densa
- Juxtaglomerular cells
- Mesangial cells
137
____________ 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
Macula densa
138
__________ is a paracrine factor which has an effect on arteriolar resistance by signalling JG cells
Adenosine
139
__________________ 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
Juxtaglomerular cells
140
______________ are found in the triangular region between the afferent and efferent arterioles. Not considered part of the JGA
Mesangial cells
141
______________ 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
Mesangial cells
142
When the mesangial cells contract, they allow all the __________ to contract
podocytes
143
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?
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
What are substances filtered at the glomerulus?
Non-protein substances or non-protein bound substances
145
______________ 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
Filtered load
146
Formula to calculate filtered load
Filtered load= GFR x concentration of the substance in the plasma
147
What does this indicate?:
Substance excreted in urine < filtered load
Reabsorption has occurred
148
What does this indicate?:
Substance excreted in urine > filtered load
Secretion has occurred
149
_____________ 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
Ultrafiltrate
