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Physiology > 11-13 - The Renal System > Flashcards

11-13 - The Renal System Flashcards

1
Q

The majority of blood flow to the kidneys goes to the…

A

Renal cortex

(93%)

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2
Q

Which type of nephron is responsible for the production of concentrated urine?

A

Juxtamedullary nephrons

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3
Q

Name the 6 main parts of the nephron…

A
  • Bowman’s capsule
  • Proximal tubule
  • Loop of Henle
  • Distal tubule
  • Collecting tubules
  • Collecting duct
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4
Q

The vasa recta surround the…

A

Nephron

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5
Q

Describe the vasculation of the nephrons…

A
  1. Afferent arterioles
  2. Capillaries (at glomeruli)
  3. efferent arterioles
  4. peritubular capillaries (vasa recta)
  5. renal veins
  6. inferior vena cava
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6
Q

Outline the 3 functions of the kidneys…

A
  1. Homeostatic regulation of water/ion content of blood
  2. Excretion of metabolic waste (urea, creatinine, urobilinogen etc)
  3. Production of hormones
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7
Q

Name 4 hormones produced or activated in the kidneys…

A
  • erythropoietin
  • renin
  • prostaglandins and kinins
  • vitamin D (activated)
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8
Q

Which 3 processes occur at the nephron?

A
  • Glomerular filtration
  • Tubular reabsorption
  • Tubular secretion
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9
Q

All plasma constituents are filtered through the glomerulus, except…

A

Larger proteins

(>67kDa)

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10
Q

GFR stands for…

A

Glomerular filtration rate

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11
Q

The average GFR is…

A

180L/day

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12
Q

__% of cardiac output is recieved by the kidneys and __% of plasma filters into the nephron (this is known as the _______ ___________)

A

25% of cardiac output is recieved by the kidneys and 20% of plasma filters into the nephron (this is known as the filtration fraction)

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13
Q

Podocytes are cells in the Bowman’s capsule in the kidneys that wrap around the capillaries of the…

A

Glomerulus

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14
Q

The renal corpuscle is the bundle of ___________ ___________ within _____________ ___________

A

The renal corpuscle is the bundle of glomerular capillaries within Bowman’s capsule

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15
Q

Glomerular capillaries are ___________, allowing blood to be filtered out

A

Glomerular capillaries are fenestrated, allowing blood to be filtered out

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16
Q

The basement membrane between the fenestrated capillary and the podocyte feet forms the main…

A

Filtration barrier

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17
Q

99% of filtrate is…

a) Excreted
b) Reabsorbed
c) Secreted
d) Filtered

A

99% of filtrate is…

a) Excreted

b) Reabsorbed

c) Secreted
d) Filtered

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18
Q

1% of filtrate is…

a) Excreted
b) Reabsorbed
c) Secreted
d) Filtered

A

1% of filtrate is…

a) Excreted

b) Reabsorbed
c) Secreted
d) Filtered

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19
Q

A small amount of secretion contributes to the excreted urine, which mainly occurs at the…

A

Proximal convoluted tubule

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20
Q

Reabsorption involves the movement of solutes out of the __________ and back into capillaries via _________ ___________ mechanisms.

A

Reabsorption involves the movement of solutes out of the filtrate and back into capillaries via epitheleal transport mechanisms.

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21
Q

What is the difference between epithelial transcellular transport and paracellular transport…

A

Epipethelial transcellular transport = through cells/ across cell membranes

Paracellular transport = via cell-cell junctions (doesn’t cross cell membranes)

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22
Q

Summarise the cellular mechanisms by which solutes move from the filtrate across the epithelial cells to the peritubular capillary…

A
  • Co-transporters
  • Transporters
  • Membrane pumps
  • Membrane carriers
  • Membrane channels
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23
Q

Summarise the passive mechanisms by which solutes move from the filtrate across the epithelial cells to enter the peritubular capillaries…

A
  • Leak channels
  • Diffusion (if membrane permeable solute)
  • Paracellular transport (via cell-cell junctions)
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24
Q

The route taken by solutes to cross the epithelial cells depends on ____________ gradient and the ___________ of epitheleal junctions.

A

The route taken by solutes to cross the epithelial cells depends on electrochemical gradient and the permeability of epitheleal junctions.

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25
The structure of the **proximal convoluted tubule (PCT)** is adapted for 2 functions...
1. **Reabsorption** 2. **Secretion**
26
Describe the notable structural features of the **PCT**...
* The *apical* membrane has **microvilli** (maximise SA for reabsorption) * Presence of **ER, golgi, lysosomes and vacuoles** (synthesis of membrane proteins) * The *basolateral* membrane has **interdigitations** (reduce distance to mitochondria to provide energy for active transport)
27
Reabsorption at the PCT Name 5 types of substance **reabsorbed** at the PCT...
1. **Ions** (Chiefly sodium, but also chloride, potassium and calcium) 2. **Water** (Paracellular via osmosis) 3. **Glucose** (via co-transport and carriers) 4. **Urate** (also secreted) 5. **Low mW proteins and amino acids**
28
In diabetes mellitus the appearence of glucose in the urine is due to the...
**Saturation of transporters** by excessive glucose (plasma concentration exceeds *renal threshold*)
29
Sodium is reabsorbed at the PCT... a) actively b) passively c) both actively and passively d) sodium is not reabsorbed at the PCT
Sodium is reabsorbed at the PCT... a) actively b) passively **c) both actively and passively** d) sodium is not reabsorbed at the PCT
30
Describe the ways in which sodium can be **reabsorbed** at the PCT (and if they are active/passive)...
* *Actively* via **sodium/potassium ATPase pump** * *Passively* via * Leak channels * **Ion exchange** with H+ * **Cotransport** with **essential solutes** (glucose and amino acids)
31
The reabsorption of other ions (Cl-, K+, Ca2+) at the PCT can occur both...
Paracellularly or transcellularly (by diffusion)
32
Urate is reabsorbed into the PCT via...
* Organic anion transporters * Paracellularly * Transcellularly
33
Urate is secreted via...
Organic anion transporters
34
Secretion at the PCT is a(n) (passive / active) process which transfers molecules from the __________ \_\_\_\_\_\_\_\_\_\_ back into the tubule.
Secretion at the PCT is an **active** process which transfers molecules from the **peritubular capillary** back into the tubule.
35
List **anionic endogenous compounds** secreted from peritubular capillaries to tubules...
* Urate * cAMP * Bile salts * Prostaglandins
36
List examples of **anionic drugs** secreted from peritubular capillaries to tubules...
* Penicillin * Aspirin * Diuretics
37
List **cationic endogenous compounds** secreted from peritubular capillaries to tubules...
* Noradrenaline * Adrenaline * Dopamine * Creatinine
38
List examples of **cationic drugs** secreted from peritubular capillaries to tubules...
* Atropine * Morphine * Quinine * Amiloride
39
The composition of tubular fluid leaving the PCT... List the **reabsorption rates** for: * **Sodium ions, potassium ions and water** * **Urea and urate** * **Hydrogen carbonate ions** * **Glucose and amino acids**
* Sodium ions, potassium ions and water - **66%** * Urea and urate - **50%** * Hydrogen carbonate ions - **80%** * Glucose and amino acids - **100 %**
40
The tubular fluid leaving the PCT is... a) Isoosmotic with plasma (300mOsm) b) Hyperosmotic with plasma (\>300mOsm) c) Hypoosmotic with plasma (\<300mOsm)
The tubular fluid leaving the PCT is... **a) Isoosmotic with plasma (300mOsm)** b) Hyperosmotic with plasma (\>300mOsm) c) Hypoosmotic with plasma (\<300mOsm)
41
The descending limb of the loop of Henle is: a) permeable to water and solutes b) permeable to water not solutes c) permeable to solutes not water d) impermiable to water and solutes
The descending limb of the loop of Henle is: a) permeable to water and solutes **b) permeable to water not solutes** c) permeable to solutes not water d) impermiable to water and solutes
42
The ascending limb of the loop of Henle is: a) permeable to water and solutes b) permeable to water not solutes c) permeable to solutes not water d) impermiable to water and solutes
The ascending limb of the loop of Henle is: a) permeable to water and solutes b) permeable to water not solutes **c) permeable to solutes not water** d) impermiable to water and solutes
43
The collecting duct is: a) permeable to water and relatively impermiable to urea b) permeable to water and urea c) permeable to urea and relatively impermiable to water d) permeable to water not to solutes
The collecting duct is: a) permeable to water and relatively impermiable to urea b) permeable to water and urea **c) permeable to urea and relatively impermiable to water** d) permeable to water not to solutes
44
The osmolarity of the tubular fluid at the bottom of loop of Henle is... a) 300 b) 1200 c) 100 d) 75 (mOsM)
The osmolarity of the tubular fluid at the bottom of loop of Henle is... a) 300 **b) 1200** (hypertonic to the plasma) c) 100 d) 75 (mOsM)
45
The osmolarity of the tubular fluid at the distal tubule (after loop of Henle) is: a) 300 b) 1200 c) 100 d) 75 (mOsM)
The osmolarity of the tubular fluid at the distal tubule (after loop of Henle) is: a) 300 b) 1200 **c) 100** (hypotonic to the plasma) d) 75 (mOsM)
46
( Increased / decreased ) water reabsorption leads to the formation of concentrated urine.
**Increased** water reabsorption leads to the formation of concentrated urine.
47
Which hormone enables the production of concentrated urine (and by what mechanism)?
Anti-diuretic hormone (**ADH**/ vasopressin) increases the **permeability of the collecting duct to H2O**. More H2O is then reabsorbed, increasing the OsM
48
What maintains the osmotic gradient in the **medullary interstitium**?
**Counter-current systems**
49
Describe the 3 properties of **countercurrent systems**...
1. **2 flows in opposing directions** 2. **2 vessels in close proximity** 3. **passive transfer of molecules between vessels**
50
A countercurrent multiplier system is the use of _______________ to enhance countercurrent flow
A countercurrent multiplier system is the use of **active transport (of solutes)** to enhance countercurrent flow
51
Name the two types of nephron found in the kidneys...
* **Cortical** * **Juxtamedullary**
52
(In the presence of ADH/vasopressin) water is reabsorbed from the collecting duct and removed from the medulla by the...
**Ascending vasa recta**
53
In the absence of ADH/vasopressin, the wall of the collecting duct is...
**Impermiable** to water
54
Concentrated urine has ( high / low ) osmolarity
Concentrated urine has **high** osmolarity
55
Dilute urine has ( high / low ) osmolarity
Dilute urine has **low** osmolarity *(osmolarity is concentration expressed as the total number of solute particles per litre. Less concentrated urine has fewer solute particles per litres, so the osmolarity is lower)*
56
Plasma pH is tightly regulated between a normal range of...
pH 7.38 - 7.42
57
Name **4 buffers** present in the plasma which help to regulate pH...
* **Cellular proteins** * **Haemoglobin** * **HPO42- **(hydrogen phosphate) * **HCO3-** (hydrogen carbonate)
58
Other than buffers present in the plasma, which 2 other mecanisms contribute to the maintainence of plasma pH?
* **Respiratory adjustment** (via CO2) * **Renal adjustment** (via H+, HCO3- secretion/absorption)
59
In response to low pH (**Acidosis**), Type A **intercalated cells** in the **collecting duct** excrete: a) H+ and absorb HCO3- b) HCO3- and absob H+ c) HPO42- and absorb HCO3- d) urea and absorb H2O
In response to low pH (Acidosis Type A), intercalated cells in the collecting duct excrete: **a) H+ and absorb HCO3** Thus increasing the pH of the plasma
60
In response to high pH (**Alkalosis**), **type B intercalated cells** in the collecting duct excrete: a) H+ and absorb HCO3- b) HCO3- and absob H+ c) HPO42- and absorb HCO3- d) urea and absorb H2O
In response to high pH (**Alkalosis**), **type B intercalated cells** in the collecting duct excrete: **b) HCO3- and absob H+** Thus increasing H+ in plasma and lowering the pH
61
**Diuretics** are drugs that promote...
Urine excretion (formation of urine)
62
ADH/vasopressin increases the permeability of the ____________ to _____ resulting in ____________ \_\_\_\_\_\_\_
ADH/vasopressin increases the permeability of the **collecting duct** to **H2O** resulting in **concentrated** **urine**
63
Describe the cellular action of ADH in 3 steps...
1. ADH binds to **V2 receptors** 2. **Adenyl cyclase** generates **cAMP** and activates **protein kinases** 3. **More** **aquaporin 2 channels** inserted into apical membrane (which increases water permeability)
64
Name 3 inputs which control the release of ADH...
1. Hypothalamic *osmoreceptors* 2. Atrial *stretch* receptors 3. Carotid and aortic *baroreceptors*
65
Signals from the hypothalamic neurones trigger release of ADH/vasopressin from the a) anterior pituitary b) thalamic neuclei c) posterior pituitary d) vasa recta
Signals from the hypothalamic neurones trigger release of ADH/vasopressin from the a) anterior pituitary b) thalamic neuclei **c) posterior pituitary** d) vasa recta
66
Name the two types of control over ADH/vasopressin secretion...
* Plasma **osmolarity** (via *hypothalamic osmoreceptors*) - this is **osmolar control** * **Set point 280mOsM** * Blood **volume**/pressure (via *atrial stretch receptors* and *carotid & aortic baroreceptors*) - this is **non-osmolar control** * Responsible for **MUCH LARGER output of ADH** * 10% decrease in BV = activated!
67
Alcohol ( stimulates / inhibits ) ADH release
Alcohol **inhibits** ADH release
68
Name some normal and inappropriate stimuli that may lead to ADH release...
* **Physiological stimuli** * High temp, exercise, pain, stress * **Inappropriate stimuli** * Tumours, opiates, nicotine MDMA
69
Outline how MDMA can result in **hyponatremia** (low blood sodium)
* MDMA stimulates **ADH secretion,** *reducing fluid out* * MDMA stimulates **thirst refle**x, *increasing fluid in*
70
Diabetes insipidus is the result of...
ADH deficiency
71
Diabetes insipidus can be either **central** or **nephrogenic**, differentiate between these two types...
* **Central** - deficiency of ADH secretion * **Nephrogenic** - nephron is insensitive to secreted ADH
72
_Summary of sodium ion handling by the nephron_ Most Na+ is reabsorbed by the \_\_\_\_\_\_\_\_\_\_\_\_\_(67%). No reabsorption occurs at the \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_. Some reabsorption occurs at the ___________________ (25%). A further 5% is reabsorbed at the distal convoluted tubule and finally 3% at the \_\_\_\_\_\_\_\_\_\_\_\_\_\_. 0.4% of Na+ is excreted in ________ urine.
_Summary of sodium ion handling by the nephron_ Most Na+ is reabsorbed by the **proximal convoluted tubule** (67%). No reabsorption occurs at the **loop of Henle**. Some reabsorption occurs at the **thick ascending limb** (25%). A further 5% is reabsorbed at the distal convoluted tubule and finally 3% at the **collecting duct**. 0.4% of Na+ is excreted in **dilute** urine.
73
The Renin-Angiotensin-Aldosterone axis is responsible for maintaining ____________ by increasing reabsorption of \_\_\_\_\_\_\_\_\_\_
The Renin-Angiotensin-Aldosterone axis is responsible for maintaining **blood volume** by increasing reabsorption of **sodium ions**
74
**Renin** is released by juxtaglomerular (JG) cells in response to 3 stimuli...
* Decreased **blood pressure** (afferent arteriole stretch receptors) * Decreased **central blood pressure** (renal sympathetic nerve stimulation) * Decreased **sodium chloride** (in **macula densa\*** cells) *\*Macula densa cells line the wall of the distal tubule in the area where it meets the collecting duct.*
75
**Renin** released by the JG cells goes on to catalyse the conversion of...
**Angiotensiongen** to **Angiotensin I** (in the plasma)
76
**Angiotensis I** is converted to **Angiotensin** **II** by...
**Angiotensin-converting enzyme (ACE)** (in the plasma)
77
**Angiotensin II** is converted to...
**Aldosterone** | (in the **adrenal cortex**)
78
**Aldosterone** increases the **reabsorption of sodium ions in the kidneys**, which subsequently increases the volume of...
the **ECF**
79
On a cellular level how does **aldosterone** promote the reabsorption of Na+?
* Aldosterone binds to a cytoplasmic receptor * This increases: * ENaC channels on apical surface * Na+/K+ pumps on basolateral surface
80
How does the increased reabsorption of Na+ triggered by aldosterone result in increased blood volume?
Increased Na+ reabsorption (Cl- follows) -\> water follows
81
**Angiotensin II** has a variety of effects, including...
* Stimulation of **aldosteron release** * **thirst** sensation * **vasoconstriction** * increases **noradrenaline** release * inhibits **baroreceptor reflex**
82
The formation of renal caculi (kidney stones) is known as ______________ and is due to the supersaturation of filtrate.
The formation of renal caculi (kidney stones) is known as **nephrolithiasis** and is due to the supersaturation of filtrate. (nephro - kidney, lithiasis - formation of calculi. Gall bladder stones are *chole*lithiasis)
83
_Micturition (peeing)_ The **internal sphincter** is (smooth muscle / skeletal muscle) contracted passively. The **external sphincter** is (smooth muslce / skeletal muscle) contracted by **tonic stimulation**.
_Micturition (peeing)_ The **internal sphincter** is ***smooth** **muscle*** contracted passively. The **external sphincter** is ***skeletal** **muscle*** contracted by **tonic stimulation**.
84
**ANP** stands for...
**Atrial Naturetic Peptide**
85
The release of **ANP** is triggered by the **increase in atrial stretch** resulting from **increased blood volume**. Name 3 impacts of **ANP**...
* *Hypothalamus* **decreases ADH** release * *Kidneys* **decrease renin release**, **increased GFR** and **decreased NaCl/H2O reabsorption** * *Adrenal* *cortex* **inhibits** **aldosterone** release

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