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Physiology Exam III Material > Micturition and glomerular filtration > Flashcards

Micturition and glomerular filtration Flashcards

1
Q

Superimposed micturition contractions begin to appear as

A

The bladder fills

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2
Q

During the micturition reflex sensory signals form bladder stretch receptors

A

Conduct sensory signals to sacral region of spinal cord via pelvic nerves
- conducted sensory signal then go reflexively back to bladder via the parasympathetic nerves

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3
Q

Once initiated, the micturition is

A

self-regenerative

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4
Q

Reflex contractions relax spontaneously when

A

bladder is only partially filled

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5
Q

The self-regenerative micturition reflex fatigues after

A

a few seconds and the bladder relaxes

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6
Q

As the bladder continues to fill, micturition reflexes occur

A

more often and are more powerful

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7
Q

When the micturition reflex is powerful enough it

A

causes a second reflex: passing through the pudenal nerves to inhibit the external sphincter

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8
Q

Higher bring center (in ____) keep micturition partially inhibited expect when micturition is desired

A

pons

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9
Q

When it is time to urinate, the cortical centers can facilitate the sacral micturition centers to help initiate a micturition reflex and at the same time inhibit ______ so that urination can occur

A

The external urinary sphincter

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10
Q

The sympathetics to the bladder originate from what spinal region

A

L2

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11
Q

The pelvic nerves to the bladder are connected with the spinal cord through the sacral plexus, mainly connecting with cord segments

A

S2 and S3

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12
Q

Explain the 3 steps in the single cycle of the micturition reflex

A
  1. ) Progressive and rapid increase of pressure
  2. ) a period of sustained pressure
  3. ) return of the pressure to the basal tone of the bladder
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13
Q

Functions of nephrons

A
  • Get rid of waste material (urea, creatinine, uric acid, bilirubin)
  • Regulate water and electrolyte balance
  • Regulate body fluid osmolarity
  • Regulate arterial pressure
  • Regulate acid-base balance
  • Secretion, metabolism, and exertion of hormones
  • Gluconeogenesis
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14
Q

What is the long term way that nephrons regulate arterial pressure

A

excrete variable amounts of sodium and water

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15
Q

What is the short term way that nephrons regulate arterial pressure

A

secrete hormones and vasoactive factors such as renin

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16
Q

How do Nephrons regulate acid-base balance

A
  • Excrete acids and regulate body fluid buffer stores

- Eliminate sulfuric and phosphoric acids (from protein metabolism)

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17
Q

What do nephrons secrete

A

Erythropoietin and Active form of Vitamin D

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18
Q

What are the three processes that determine the rates at which different substances are excreted in the urine

A
  • Filtration
  • Reabsorption
  • Secretion
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19
Q

Formula for urinary excretion rate

A

urinary excretion rate=Filtration rate - Reabsorption Rate + Secretion Rate

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20
Q

What is the first step in urine formation

A

Filtration

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21
Q

What are the components of the glomerular filtrate

A

Water
Ions
Glucose
Urea

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22
Q

Filtration rate=

A

GFR/Renal Plasma Flow

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23
Q

Urinary excretion rate=

A

Urinary excretion rate= Filtration rate - Reabsorption rate + Secretion Rate

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24
Q

Concentration for most substances except for ____ is the same in the filtrate and the plasma

A

Proteins

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25
Some low-molecular weight substances are not freely filtered through the glomerulus because
they are partially bound to proteins
26
Endothelium of the glomerulus
Fenestrated with negative charge
27
Layers of the filtration barrier
Endothelium, Basement membrane, Podocytes
28
What is the basement membrane of the glomerulus (filtration barrier) composed of
collagen and proteoglycan fibers and strong negative charges
29
Do the Podocytes of the filtration barrier have a negative charge
yes
30
Glomerular filtration rate (GFR) is determined by
- Balance of hydrostatic and colloid osmotic forces acting across capillary membrane - Capillary filtration coefficient - Product of permeability and filtering surface area of capillaries (K1)
31
What is the GFR per min
125 mL/min
32
What is the GFR per day
180 L/day
33
Water has a filterability in the glomerulus of
1.0
34
Why does albumin not go through the glomerulus
Albumin molecule (6nm) are slightly smaller than the filtration pores (8nm) but have a negative charges
35
What are some of the diseases that lower glomerular capillary filtration coefficient
-Chronic uncontrolled hypertension and diabetes mellitus
36
Define minimal change nephropathy
Loss of negative charges on the basement membrane
37
Define hydronephrosis
Distension and dilation of renal pelvis and calyces
38
GFR=
K1 x net filtration pressure
39
net filtration pressure is equal to
glomerular hydrostatic pressure (60mm Hg) - Bowman's capsule hydrostatic pressure (18mm Hg) - glomerular capillary colloid osmotic pressure (32mm Hg) + colloid osmotic pressure of bowman's capsule (0 mm Hg)
40
What is K1
- capillary filtration coefficient | - product of permeability and filtering surface area of capillaries
41
increase in K1 has what effect on GFR
raises it
42
K1=
GFR/Net filtration pressure
43
What are two factors that influence glomerular capillary colloid osmotic pressure
- Arterial plasma colloid osmotic pressure | - Filtration fraction
44
Factors that increase glomerular colloid osmotic pressure
Increasing filtration fraction
45
Variables that determine glomerular hydrostatic pressure
- Arterial pressure - Afferent Arteriolar resistance - Efferent arteriolar resistance
46
increase in Arterial pressure has what effect on Glomerular hydrostatic pressure and GFR
Increase in glomerular hydrostatic pressure | increase in GFR
47
increase in Afferent arteriolar resistance has what effect on Glomerular hydrostatic pressure and GFR
- Decrease in glomerular hydrostatic pressure | - Decrease in GFR
48
increase in Efferent arteriolar pressure has what effect on Glomerular hydrostatic pressure and GFR
- increases in glomerular hydrostatic pressure | - slight increase in GFR
49
What is the fraction of renal plasma that is filtered
0.2 (about 20%)
50
The kidneys have ____x the blood flow of the brain but only ____ the oxygen consumption of the brain
7X, 2X
51
Most of the oxygen consumed by the kidneys is related to
the high rate of active sodium reabsorption
52
Tubular sodium reabsorption is closely related to _____ and ____
GFR and rate of sodium filtered
53
Renal blood flow equal
Renal blood flow= (Renal artery pressure - Renal vein pressure) / (total vascular resistance)
54
all blood vessels of the kidney are richly innervated by
The Sympathetic system
55
Strong activation of renal sympathetic nerves has what effects
- Constricts renal arterioles | - Decreases renal blood flow and GFR
56
Moderate sympathetic activation has _____ effect
little
57
Hormones that control GFR consistency
- Norepinephrine and epinephrine (from the adrenal medulla) - Endothelin - Angiotensin II - Endothelial-derived NO - Prostaglandins and Bradykinin
58
Mechanisms controlling GFR consistency include
- Sympathetic system | - Hormones
59
What is released by damaged vascular endothelial cells of the kidneys and other tissues
Endothelin
60
What is endothelin
-Hormone released by damaged vascular endothelial cells of the kidneys and other tissues
61
Endothelia may contribute to _______ leading to ____ in the kidneys
-Renal vasoconstriction leading to reduced GFR
62
Endothelin may contribute to ____ when a blood vessel is severed
hemostasis
63
When do Endothelin plasma levels increase in
in certain disease states associated with vascular injury: - Toxemia of pregnancy - Acute renal failure - Chronic Uremia
64
Effects of Angiotensin II on GFR
- Constricts efferent arterioles | - this leads to an increase in GFR
65
How do afferent arterioles protect themselves agains angiotensin II
- They release prostaglandins and Nitric oxide which are vasodilators
66
When is angiotensin II formed
in situations associated with decreased arterial pressure or volume depletion
67
Nitric oxide is derived from
endothelial cells
68
Basic levels of nitric oxide help maintain renal
vasodilation
69
Prostaglandins and bradykinin are _______ that may offset effects of ______ and ______ vasoconstrictor effects (especially on afferent arterioles)
Vasodilators, sympathetic and angiotensin II
70
_____ refers to the relative constancy of GFR and renal blood flow
Autoregulation
71
What is the primary function of autoregulation in the kidneys
- Maintain a relatively constant GFR - Allow precise control of renal excretion of water and solutes - Prevent relatively large changes in GFR and renal excretion that would otherwise occur with changes in blood pressure
72
What is Normal GFR/Day
180L/day
73
What is normal Tubular Reabsorption/Day
178.5 L/Day
74
What is normal daily fluid excretion
1.5 L/Day
75
Without auto regulation, a slight increase in blood pressure could increase GFR to
225 L/Day
76
An increase of GFR to 225 L/Day would increase urine flow to
46.5 L/Day
77
A filterability of 0.75 means what
That a substance is filtered only 75% as rapidly as water
78
Tubuloglomerular feedback mechanism for autoregulation has two components what are they
- An afferent arteriolar feedback mechanism | - An efferent arteriolar feedback mechanism
79
Components of the juxtaglomerular complex
- Macula densa in distal tubule | - Juxtaglomerular cells in the walls of afferent and efferent arterioles
80
Decrease GFR has what effect on the flow rate in the loop of hence and concentration of Sodium chloride at macula densa
Decrease in GFR leads to slow flow rate in loop of Henle, thus leading to increased reabsorption of sodium and chloride ions in ascending limb, this means decreased levels of sodium chloride at macula densa
81
A decrease in _____ results in a signal from the macula densa
NaCl
82
What signals does the macula densa send out when it has decreased levels of NaCl
- to decrease resistance to blood in afferent arterioles - increase renin release from juxtaglomerular cells, thus leading to an increase in angiotensin II, thus leading to increased efferent arteriolar resistance and increase GFR
83
What cells are a major storage site of renin
Juxtaglomerular cells
84
what is the definition of renal clearance of a substance
volume of plasma that is completely cleared of the substance by the kidneys per unit of time.
85
The clearance rate of a substance is equal to
( urine concentration X Urine flow rate) / (Plasma Concentration)

Physiology Exam III Material (13 decks)

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