Lesson 18-19 Flashcards
1
Q
what are the six principal organs of the urinary system
A
- two kidneys
- two ureters
- urinary bladder
- urethra
2
Q
what are the functions of the kidneys (7)
A
- filter blood and excrete toxic metabolic wastes
- regulate volume, pressure, and osmolarity
- regulate electrolytes and acid-base balance
- secrete erythropoietin
- help regulate calcium levels
- clear hormones from blood
- detoxify radicals
3
Q
the kidneys secrete erythropoietin. what does that do?
A
stimulates the production of red blood cells
4
Q
how do the kidneys regulate calcium levels?
A
participating in calcitriol synthesis
5
Q
what do the kidneys do in starvation?
A
synthesize glucose from amino acids
6
Q
waste
A
any substance that is useless to the body or present in excess of the body’s needs
7
Q
metabolic waste
A
waste substance produced by the body
8
Q
what type of metabolic waste is most toxic to the body?
A
nitrogenous waste
9
Q
urea
A
- from protein catabolism
- breakdown of macromolecules
10
Q
what is the normal concentration of blood urea?
A
10-20 mg/dL
11
Q
uric acid
A
product of nucleic acid catabolism
12
Q
creatinine
A
product of creatine phosphate catabolism
13
Q
blood urea nitrogen (BUN)
A
level of nitrogenous waste in blood
14
Q
azotemia
A
- elevated BUN
- may indicate renal insufficiency
15
Q
azotemia may progress to _____
A
uremia
16
Q
uremia
A
syndrome of diarrhea, vomiting, dyspnea, and cardiac arrhythmia stemming from the toxicity of nitrogenous waste
17
Q
excretion
A
separating wastes from body fluids and eliminating them
18
Q
what are the four body systems that carry out excretion
A
- respiratory
- integumentary
- digestive
- urinary
19
Q
what does the respiratory system excrete? (3)
A
- CO2
- small amounts of other gases
- water
20
Q
what does the integumentary system excrete? (4)
A
- water
- inorganic salts
- lactate
- urea in sweat
21
Q
what does the digestive system excrete? (7)
A
- water
- salts
- CO2
- lipids
- bile pigments
- cholesterol
- other metabolic wastes
22
Q
what does the urinary system excrete? (7)
A
- many metabolic wastes
- toxins
- drugs
- hormones
- salts
- H+
- water
23
Q
How much does each kidney weigh?
A
150g
24
Q
describe the surface structures of the kidneys
A
lateral surface is convex and medial is concave with a slit called the hilum
25
the hilum of the kidneys receives... (4)
- renal nerves
- blood vessels
- lymphatics
- ureter
26
describe the kidney position
- lie against posterior abdominal wall of T12 or L3
- retroperitoneal along with ureters, urinary bladder, renal artery and vein, and adrenal glands
27
why is the right kidney lower than the left?
the large right lobe of the liver
28
what are the three connective tissue coverings on the kidneys?
- renal fascia
- perirenal fat capsule
- fibrous capsule
29
renal fascia
- immediately deep to parietal peritoneum
- binds kidney to abdominal wall
30
perirenal fat capsule
cushions kidney and holds it into place
31
fibrous capsule
- encloses kidney protecting it from trauma and infection
- collagen fibers extend from fibrous capsule to renal fascia
32
renal parenchyma
glandular tissue that forms urine
33
renal sinus
medial cavity that contains blood and lymphatic vessels, nerves, and urine-collecting structures
34
what are the two zones of renal parenchyma?
- outer renal cortex
- inner renal medulla
35
what is the boundary between the renal cortex and medulla
corticomedullary junction
36
renal columns
extensions of the cortex that project inward toward sinus
37
renal pyramids
- triangular-shaped structures in the renal medulla
- base adjacent to the cortex while the apex of the pyramid projects into the renal sinus
38
lobe of kidney
one pyramid and its overlaying cortex separated by other lobes of the kidney by the renal column
39
urine produced in the renal parenchyma is drained by a series of structures. what are they in order? (4)
- minor calyx
- major calyx
- renal pelvis
- ureter
40
minor calyx
- little cup that surrounds the papilla of each pyramid
- collects its urine
41
major calyx
formed by convergence of 2 or 3 minor calyces
42
renal pelvis
formed by convergence of 2 or 3 major calyces
43
ureter
tubular continuation of the renal pelvis that drains down to the urinary bladder
44
each kidney has about ___ nephrons
1.2 million
45
what are the two principal parts of the nephron?
- renal corpuscle
- renal tubule
46
renal corpuscle
filters the blood plasma
47
renal tubule
- long coiled tube that converts the filtrate into urine
- duct leading away from the glomerular capsule and ending at the tip of the medullary pyramid
48
the renal tubule consists of...(4)
- proximal convoluted tubule (PCT)
- loop of henle (nephron loop)
- distal convoluted tubule (DCT)
- collecting duct (CD)
49
the renal corpuscle consists of... (2)
- glomerulus
- two layers glomerular capsule
50
glomerular capsule
- encloses glomerulus
- parietal and visceral layers
51
parietal layer of the glomerular capsule
- outer layer
- simple squamous epithelium
52
visceral layer of the glomerular capsule
- inner layer
- consists of podocytes
53
podocytes in the visceral layer of the glomerular capsule
wrap around capillaries of the glomerulus
54
the capillaries in the visceral layer of the glomerular capsule are formed by what?
afferent arteriole
55
capsular space
separates the two layers of the glomerular capsule
56
mesangial cells
- pack the spaces among the glomerular capillaries
- regulate blood flow and phagocytize debris
57
proximal convolutes tubule
- arises from glomerular capsule
- longest and most coiled region
- simple cuboidal epithelium with prominent microvilli
58
where does the majority of absorption occur in the kidney?
proximal convoluted tubule
59
nephron loop (loop of henle)
- u-shaped portion of renal tubule with a descending and ascending limb
- thick and thin segment
60
descending limb of the loop of henle function
water reabsorption
61
ascending limb of loop of henle function
sodium and chlorine reabsorption
62
thick segments of the loop of henle
- simple cuboidal epithelium
- initial part of descending limb and part or all of the ascending limb
- nonpermeable to water
63
describe the thick segments of the loop of henle (2)
- heavily engaged in the active transport of salts and have many mitochondria
- pump salt and chloride out of tubular fluid
64
thin segments of the loop of henle
- simple squamous epithelium
- forms lower part of descending limb
- very permeable to water
65
distal convolutes tubule
- begins shortly after the ascending limb re-enters the cortex
- shorter and less coiled
- cuboidal epithelium within microvilli
- end of the nephron
66
collecting duct
receives fluid from the DCTs of several nephrons as it passes back into the medulla
67
numerous collecting ducts converge towards where?
the top of the medullary pyramid
68
papillary duct
formed by merger of several collecting ducts
69
how many papillary ducts end in the tip of each papilla
30
70
flow of fluid from the point where glomerular filtrate is formed to the point where urine leaves the body (12)
- glomerular capsule
- proximal convoluted tubule
- nephron loop
- distal convolutes tubule
- collecting duct
- papillary duct
- minor calyx
- major calyx
- renal pelvis
- ureter
- urinary bladder
- urethra
71
what are the two types of nephrons
- juxtamedullary nephrons
- cortical nephrons
72
juxtamedullary nephrons
- close to medulla
- very long nephron loops extend as far as apex of renal pyramid
73
what is the function of juxtamedullary nephrons
responsible for maintaining osmotic gradient in the medulla used to help conserve water and concentrate urine
74
about how many nephrons are juxtamedullary?
15%
75
cortical nephrons
- short nephron loops that dip a short way into medulla
- some have no nephron loop at all
76
about what percentage of nephrons are cortical nephrons
85%
77
renal plexus (3)
- nerve and ganglia wrapped around each renal artery
- issues nerve fibers to blood vessels and convoluted tubules of nephron
- carries sympathetic innervation from the abdominal aortic plexus
78
what does sympathetic stim do to the nephron
reduces glomerular blood flow and rate of urine production
79
when is there sympathetic stimulation to the nephron? what happens in this response?
- respond to falling BP
- stim kidney to secrete renin
80
renin
an enzyme that activates hormonal mechanisms to restore BP to trigger renin-angiotensin system
81
what are the four stages of urine formation?
- glomerular filtration
- tubular reabsorption
- tubular secretion
- water conservation
82
what are the three different names given to fluid as it passes through the nephron?
- glomerular filtrate
- tubular fluid
- urine
83
glomerular filtrate
- fluid in the capsular space of the glomerulus
- similar to blood plasma except that it has almost no proteins
84
why does glomerular filtrate have little to no proteins?
proteins are too big to be filtered into capsular space
85
tubular fluid
- fluid form the PCT through the DCT
- substances have been removed or added by tubular cells
86
urine
- fluid within the collecting duct and beyond
- undergoes little alteration beyond this point except for changes in water content
87
glomerular filtration
water and some solutes pass from blood within glomerulus into the capsular space of the nephron
88
filtration membrane
barrier through which filtered fluid passes
89
what are the three components of the filtration membrane used in glomerular filtration
- fenestrated endothelium of the capillary
- basement membrane
- filtration slits
90
fenestrated endothelium of the capillary in the filtration membrane
- contains large filtration pores
- highly permeable but small enough to exclude blood cells
91
what is the size of the filtration pores of the fenestrated endothelium of the capillary
70-90 nm
92
basement membrane of the filtration membrane used in glomerular filtration
- proteoglycan gel with negative charge
- excludes molecules greater than 8 nm
- smaller albumin repelled by negative charge
93
filtration slits of the filtration membrane used in glomerular filtration
- podocyte foot processes called pedicels wrap around the capillaries
- have negatively charged filtration slits between them
94
almost any molecule smaller than ___ can pass freely through the filtration membrane
3 nm
95
what can pass freely through the filtration membrane (7)
- water
- electrolytes
- glucose
- fatty acids
- amino acids
- nitrogenous wastes
- vitamins
96
what occurs in some substances that makes it to where they cant get through the filtration membrane
low molecular weight substances are bound to plasma proteins
97
what are the low molecular weight substances that can be bound to the plasma proteins so that they cant get through the filtration membrane?
- calcium
- iron
- through hormone
98
what two things can cause proteins and blood cells to filter through the filtration membrane?
- kidney infections
- trauma to the filtration membrane
99
proteinuria
- albuminuria
- albumin in urine
100
hematuria
blood in urine
101
glomerular filtration depends on what? (4)
- blood hydrostatic pressure
- hydrostatic pressure in capsular space
- colloid osmotic pressure of blood
- net filtration pressure
102
why is blood hydrostatic pressure higher in the afferent arteriole than the efferent when controlling glomerular filtration
afferent arteriole is larger than efferent arteriole
103
what is the standard blood hydrostatic pressure in glomerular filtration
60 mmHg
104
hydrostatic pressure in capsular space is due to what?
high filtration rate and accumulation of fluid in the capsule
105
what is the standard hydrostatic pressure in the capsular space during glomerular filtration
18 mmHg
106
what is the standard colloid osmotic pressure of blood during glomerular filtration
32 mmHg
107
why does filtrate have no significant ICOP?
because it is almost protein-free
108
what is the standard net filtration pressure
10 mmHg
109
what is the direction of fluid travel when it comes to net filtration pressure
outward from capillaries to capsular space
110
glomerular filtration rate
amount of filtrate formed per minute by the two kidneys combined
111
what is the GFR per minute in a normal male? per day?
- 125 ml/min
- 180 L/day
112
what is the GFR per minute of a normal female? per day?
- 105 ml/min
- 150 L/day
113
what does the filtration coefficient (Kf) depend on?
permeability and surface area of filtration barrier
114
about how much filtrate is reabsorbed?
99%
115
why is 99% of filtrate reabsorbed?
only 1-2 L of urine is excreted per day
116
if GFR is too high what happens? (2)
- fluid flows through renal tubules too rapidly for them to reabsorb the usual amount of water and solutes
- urine output rises increasing chance of dehydration and electrolyte depletion
117
if GFR is too low what happens?
wastes are reabsorbed and azotemia may occur
118
what is the only way to adjust GFR?
adjust glomerular blood pressure
119
what are the three mechanisms that change glomerular blood pressure
- renal autoregulation
- sympathetic control
- hormonal control
120
renal autoregulation
the ability of the nephrons to adjust their own blood flow and GFR without external control
121
renal autoregulation enables the kidneys to do what?
to maintain a relatively stable GFR in spite of changes in arterial BP
122
what are the two mechanisms of renal autoregulation
- myogenic mechanism
- tubuloglomerular feedback
123
myogenic mechanism as renal autoregulation
if arterial BP increases afferent arteriole is stretched which leads to afferent arteriole constriction which reduces blood flow into the glomerulus
124
tubuloglomerular feedback as renal autoregulation (2)
- when GFR is high macula densa secretes ATP which ultimately stims nearby granular cells to constrict afferent arterioles to reduce GFR
- granular cells secrete renin if BP is low to trigger the renin-angiotensin-aldosterone system
125
tubuloglomerular feedback involves what?
juxtaglomerular apparatus
126
the juxtaglomerular apparatus consists of what two structures?
- macula densa
- granular/juxtaglomerular cells
127
what kind of nerve fibers richly innervate the renal blood vessels?
sympathetic nerve fibers
128
what two things constrict the afferent arterioles
- sympathetic nervous system
- adrenal epinephrine
129
when does the sympathetic nervous system and adrenal epinephrine constrict the afferent arterioles
- strenuous exercise
- acute conditions like circulatory shock
130
what is the effect of sympathetic control on the renal system?
- reduces GFR and urine output
- redirects blood from the kidneys to the heart, brain, and skeletal muscles
- GFR may be as low as a few millimeters per minute
131
the renin-angiotensin-aldosterone mechanism
system of hormones that controls blood pressure and GFR
132
what is the mechanism of the renin-angiotensin-aldosterone mechanism (5)
- when there is a drop in BP baroreceptors in carotid and aorta stim the sympathetic nervous system
- sympathetic fibers trigger release of renin by kidneys' granular cells
- renin converts angiotensinogen to angiotensin 1
- lungs and kidneys have angiotensin-converting enzyme that converts angiotensin 1 to angiotensin 2
-BP/fluid volume is restored
133
effects of angiotensin 2 (6)
- raise BP throughout body
- constrict efferent arterioles in kidneys raising GFR despite low BP
- stims adrenal cortex to secrete aldosterone which promotes NA and H2O reabsorption in the DCT and collecting duct
- directly stims Na and H2O reabsorption in PCT
- stims posterior pituitary to secrete ADH
- stims thirst and encourages water intake
134
what does the constriction of the efferent arteriole do int he body?
lowers BP in peritubular capillaries enhancing reabsorption of NaCl and H2O
135
what does ADH do?
promotes water reabsorption by collecting duct
136
what is the function of the PCT?
- reabsorbs about 65% of glomerular filtrate
- removes substances from blood and secretes them into tubular fluid for disposal in urine
137
how is secretion reflected in the structure and energy consumption of the PCT
- long length
- prominent microvilli
- abundant mitochondria provide ATP for active transport
138
the PCT alone account for about ___ of one's resting ATP and calorie consumption
6%
139
reabsorption of what molecules occurs in the PCT
- glucose
- amino acids
- water
- potassium
- sodium
bicarbonate
140
what happens if blood glucose if greater than 180 mg/dl
not all will be reabsorbed in the PCT and will be found in the urine
141
glycosuria
the presence of glucose in the urine
142
when are amino acids commonly found in the urine?
after a protein-rich meal
143
aminoaciduria
the presence of amino acids in the urine
144
tubular reabsorption
process of reclaiming water and solutes from tubular fluid and returning them to the blood
145
what ions are reabsorbed during tubular reabsorption
- Na
- K
- Cl
146
sodium-glucose transporters
glucose is cotransported with sodium during reabsorption
147
reabsorbed fluid is ultimately taken up by
peritubular capillaries
148
if there is glucose in urine that could indicate what disease
diabetes mellitus
149
tubular reabsorption of nitrogenous wastes
- urea reabsorbed with water
- nephron reabsorbs about half of urea in tubular fluid
- PCT reabsorbs nearly all uric acid
150
what happens to uric acid in later portions of the nephron
it is secreted back into the renal tubule
151
why is there such an intense reduction of urine output (180 L to 1-2 L) a day?
water reabsorbtion in the PCT
152
____ of water in filtrate is reabsorbed in PCT
2/3
153
reabsorption of solutes makes the tubule cells and tissue fluid ___ to tubular fluid
hypotonic
154
obligatory water reabsorption
in pCT water is reabsorbed independent of hormones and at a constant rate
155
peritubular capillaries reabsorb water and solutes form where?
that leave the basal surface of the tubular epithelium
156
how does reabsorption occur in the peritubular capillaries?
osmosis and solvent drag
157
what are the 7 steps of the effect of angiotensin 2 on tubular reabsorption
- angiotensin 2 secreted
- constricts afferent and esp efferent arterioles
- maintains glomerular blood pressure and glomerular filtration
- reduces BP in peritubular capillary
- reduces resistance to tubular reabsorption
- tubular absorption increases
- urine volume is less but concentration is high
158
tubular secretion
process in which renal tubule extracts chemicals from capillary blood and secretes them into the tubular fluid
159
what are the three purposes of secretion in PCT and nephron loop?
- acid-base balance
- waste removal
- clearance of drugs and contaminants
160
purposes of secretion in PCT and nephron loop: acid-base balance
secretion of varying proportions of hydrogen and bicarbonate ions help regulate pH of body fluids
161
purposes of secretion in PCT and nephron loop: waste removal
urea, uric acid, bile acids, ammonia, excess ions, and a little creatinine are secreted into the tubule
162
purposes of secretion in PCT and nephron loop: clearance of drugs and contaminants
some drugs must be taken multiple times per day to keep up with renal clearance
163
what drugs are excreted in the urine via secretion in PCT and nephron loop
- morphine
- penicillin
- aspirin
164
nephron loop primary function is to do what?
generate osmotic gradient that enables collecting duct to concentrate the urine and conserve water
165
the thick segment of the nephron loop reabsorbs what
25% of Na, K, and Cl in filtrate
166
ion reabsorption in the nephron loop occurs mostly in
the ascending limb
167
water reabsorption in the nephron loop occurs mostly in
the descending limb
168
ions of the nephron loop leave cells by
active transport and diffusion
169
what happens to NaCl in the kidneys
it remains in the tissue fluid of renal medulla
170
why can water not follow ions in the thick segment of the nephron loop
the thick segment is impermeable to water
171
what is still in fluid as it arrives to DCT?
- about 20% of water
- 7% of salts from glomerular filtrate
172
what would happen if all the fluid in the DCT passes to urine?
it would result in 36 L/day of urine
173
what hormones regulate the reabsorption of water and salts in the DCT and collecting ducts? (4)
- aldosterone
- atrial natriuretic peptide
- ADH
- parathyroid hormone
174
aldosterone
- steroid hormone that stims reabsorption of sodium and secretion of potassium
- secreted by adrenal cortex
175
when is aldosterone secreted?
- blood Na concentration falls or K concentration rises
- drop in BP stims renin release resulting in aldosterone release
176
where does aldosterone act?
acts on thick segment of ascending nephron loop, on the DCT, and cortical portion of collecting duct
177
what happens when aldosterone acts?
- stims reabsorption of Na and secretion of K
- water and Cl follow Na
- body retains NaCl and water as net effect
- urine is reduced
- urine has elevated K concentration
178
what is the purpose of the body retaining NaCl
helps maintain blood volume and pressure
179
antidiuretic hormone (ADH)
- stims water retention by kidney
- released by posterior pituitary
180
when is ADH released?
- dehydration
- loss of blood volume
- rising blood osmolarity
181
what happens when ADH is released?
stims the arterial baroreceptors and hypothalamic osmoreceptors
182
what does ADH do in the kidney?
- makes the collecting duct more permeable to water to cause more water reabsorption
- water in the tubular fluid reenters the tissue fluid and blood stream rather than being lost in urine
183
what are the steps of the CD creating hypertonic urine (4)
- CD begins in the cortex where it receives tubular fluid from several nephrons
- CD runs through medulla and reabsorbs water making urine up to four times more concentrated
- medullary portion of CD is more permeable to water than to NaCl
- as urine passes through the increasingly salty medulla water leaves CD by osmosis concentrating urine
184
urine concentration depends on what
the body's state of hydration
185
how does dehydration lead to production of hypertonic urine (2)
- ADH stims increase in aquaporin channels in the CD to cause more water reabsorption
- results in urine volume decrease since more concentrated
186
how does hydration cause less concentrated urine (3)
- ADH secretion falls and tubule cells remove aquaporins
- CD are less permeable to water so more water remains in CD
- results in more urine with less concentration
187
ureters
- retroperitoneal
- muscular tubes that extend from each kidney to urinary bladder
- 25 cm long
188
where do the ureters enter the urinary bladder?
pass posterior to bladder and enter it from below
189
____ acts as valve into bladder
flap of mucosa at entrance of each ureter
190
what is the purpose of the valve at the entrance of each ureter
keeps urine from backing up into ureter when bladder contracts
191
what is the con of the ureter lumen being very narrow
easily obstructed by kidneys stones
192
urinary bladder
- muscular sac located on floor of the pelvic cavity
- inferior to peritoneum and posterior to pubic symphysis
193
wall of urinary bladder consists of
- muscularis called the detrusor
- mucosa lined with urothelium
194
detrusor
three layers of smooth muscle in the urinary bladder
195
trigone
smooth triangular area marked by openings of the two ureters and the urethra
196
rugae in the urinary bladder
conspicuous wrinkles in empty bladder
197
urethra
tube that conveys urine out of body
198
female urethra
- 3-4cm long
- bound to anterior wall of vagina
199
external urethral orifice is located where
between vaginal orifice and clitoris
200
male urethra
- 18 cm long
- three regions
201
what are the three regions of the urethra?
- prostatic urethra
- membranous urethra
- spongy urethra
202
prostatic urethra
- 2.5 cm
- passes through prostate
203
membranous urethra
- 0.5 cm
- passes through penis in the corpus spongiosum
204
spongy urethra
- penile urethra
- 15 cm
- passes through the penis in the corpus spongiosum
205
describe how the tissue of the mucosa in the urethra changes as it gets closer to the external orifice
- urothelium near the bladder
- pseudostratified epithelium for most of its length
- stratified squamous near external orifice
206
mucous ____ are on the walls of the urethra
urethral glands
207
what are the two urethral sphincters?
internal and external
208
internal urethral sphincter
- thickened collar of muscle around the neck of the urinary bladder and nearby urethra
- composed with smooth muscle
209
external urethral sphincter
- where urethra passes through the pelvic floor
- composed of skeletal muscle
210
what happens to the detrusor when the urinary bladder fills
remains relaxed and urethral sphincters are closed
211
micturition
the act of urinating
212
what does micturition require?
relaxation of both the internal and external urethral sphincters
213
contraction of ___ compresses urinary bladder to expel urine
detrusor muscle
214
what controls the internal urethral sphincter?
the pons
215
what controls the external urethral sphincter
voluntary control of skeletal muscle
216
what are the four steps of the involuntary micturition reflex
- stretch receptors detect filling of bladder and transmit afferent signals to spinal cord
- signals return to bladder from spinal cord segments S2 and S3 via parasym fibers in pelvic nerve
- efferent signals excite detrusor muscle
- efferent signals relax internal urethral spincter
217
urine is involuntarily voided when the efferent signals of the bladder relax unless what happens
inhibited by the brain
218
what are the four steps of voluntary micturition reflex
- micturition center in pons receives signals from stretch receptors
- if timely to urinate, urination occurs
- if untimely to urinate, urination does not occur
219
if it is timely to urinate, which of what two things could happen in the voluntary micturition reflex
- pons returns signals to spinal interneurons that excite detrusor and relax internal urethral sphincter
- signals from cerebrum inhibit sacral neurons that keep external sphincter closed relaxing the external urethral sphincter and urine is voided
220
if it is untimely to urinate what happens to inhibit micturition in the voluntary micturition reflex
signals from cerebrum excite spinal interneurons that keep urethral sphincter contracted so urine is retained in the bladder
