Lecture 8: Urinary System Flashcards
(221 cards)
1
Q
What are the 5 functions of the urinary system?
A
Removal of wastes (toxins and medications) from the blood Formation/concentration of urine Storage of urine (in bladder) Excretion of urine Regulation of homeostasis (by kidneys)
2
Q
What are the 4 homeostatic functions of the urinary system?
A
Regulates blood volume and blood pressure
Regulates plasma ion concentrations
Helps stabilize blood pH
Conserves valuable nutrients
3
Q
What does an increase in blood volume result in?
A
Higher blood pressure
4
Q
How does the urinary system regulate blood volume and blood pressure?
A
Adjusting volume of water lost in urine
Releases renin
Releases erythropoietin
5
Q
What does erythropoietin do?
A
Increases O2 in blood
6
Q
What plasma ion concentrations get regulated by urinary system?
A
Sodium
Potassium
Chloride
Calcium Ion
7
Q
How are plasma ion concentrations regulated?
A
By controlling quantities lost in urine
8
Q
How are calcium ion levels regulated?
A
Through synthesis of calcitriol
9
Q
Calcitriol
A
Active form of vitamin D that helps absorb calcium from small intestine
10
Q
Calcitriol
A
Active form of vitamin D that helps absorb calcium from small intestine
11
Q
How is blood pH stabilized?
A
By controlling loss of hydrogen ions and bicarbonate ions in urine
12
Q
What is more acidic, venous vessels or arterial vessels?
A
Venous
13
Q
How does the urinary system conserve valuable nutrients?
A
By preventing excretion while excreting organic waste products
14
Q
What is part of the urinary system?
A
2 Kidneys
2 Ureters
Urinary bladder
Urethra
15
Q
Retroperitoneal
A
Posterior to peritoneum and closer to spine
16
Q
Peritoneum
A
Double layer membrane that surrounds most abdominal organs
17
Q
What are the kidneys held in place by? (3)
A
Overlying peritoneum
Contact with adjacent organs
Supporting connective tissues
18
Q
What are the supporting connective tissues that hold kidneys in place? (4)
A
Fibrous capsule
Perinephric fat capsule
Renal fascia
All 3 layers connected by collagen fibers and anchored to peritoneum and deep fascia posteriorly
19
Q
Hilum
A
Medial depression in kidneys
20
Q
What is the purpose of the hilum?
A
Entry and exit point for renal artery/vein/nerve and ureters
21
Q
Renal Sinus
A
Space/cavity within medial kidney
22
Q
What does the renal sinus contain?
A
Renal Pelvis
Passageways for transporting urine before it leaves the kidney
23
Q
Cortex of Kidney
A
Area closest to renal capsule laterally
24
Q
Medulla of Kidney
A
Inner layer (medial to cortex)
25
Renal Pelvis
Collection point for urine before it enters the ureter
26
Renal Pyramids
Triangular regions of medulla
27
Renal Columns
Tissue between pyramids
28
Renal Papillae
Tips of pyramids,
| Urine flows through to minor calyx
29
Minor Calyces (Calyx)
Urine flows through to major calyx
30
Major Calyces (Calyx)
Urine flows through to renal pelvis
31
Major Calyces (Calyx)
Urine flows through to renal pelvis
32
How much total cardiac output do the kidneys receive?
20-25%
33
How much blood flows through the kidneys each minute?
1200mL
34
What branches off the renal artery?
Segmental arteries in the renal sinus
35
Interlobar Arteries
Branch off of segmental arteries and travel through renal columns
36
What branches off of the interlobar arteries?
Arcuate arteries arc around the renal pyramids that divide the medulla and cortex
37
Cortical Radiate Arteries
Tiny arteries that branch off of arcuate arteries
| Also called interlobular arteries
38
Afferent Arterioles
Form capillary beds where blood filtration occurs
39
What type of veins are not the same as the arteries?
There are no such things as segmental veins
40
Glomerular Capsule
Collects filtrate that is modified and turned into urine
41
Glomerulus
Capillary bed formed by afferent and efferent arterioles
42
Efferent Arterioles
Carries filtered blood back out of kidney
43
Peritubular
Vessel exiting the glomerular capsule formed by converged capillaries
44
What does the nephron do?
Conduct, collect, and modify filtrate before it is urine
45
Nephron
The place of primary modification of filtrate
| Basic functional unit of the kidneys
46
What is the nephron made up of?
Renal corpuscle
PCT
Nephron loop
DCT
47
Renal Corpuscle
Glomerulus and glomerular capsule
48
PCT
Proximal convoluted tubule
| Closest to renal corpuscle
49
What is the nephron loop also called?
Loop of Henle
50
DCT
Distal convoluted tubule
51
What happens in the nephron?
Blood is filtered and the fluid (filtrate) removed is concentrated into urine
52
Cortical Nephron
85% of all types of nephrons in kidneys
| Nephron loop barely enters medulla of kidney
53
Juxtamedullary Nephron
Have long nephron loops that reach far into renal medulla where solute concentration is high in peritubular fluid
54
Why are juxtamedullary nephrons important?
They concentrate urine
55
Vasa Recta
Has the same function as the peritubular capillaries
56
Peritubular Capillaries
Efferent
| Surround the nephron to continue absorbing the good stuff filtered out of the filtrate from the peritubular fluid
57
Steps of Urine Formation (7)
1. Blood enters 'leaky' glomerulus
2. Fluid and some solutes leave the blood
3. Filtrate is caught by glomerular capsule and enters PCT
4. Water and solutes are reabsorbed back into blood as the filtrate passes through the PCT, loop and DCT
5. Flows into collecting duct after DCT to go through the final phases of alterations
6. Filtrate can be called urine once it leaves the collecting duct
7. Urine passes through papillae into minor calyx to major calyx to renal pelvis to ureter to urinary bladder
58
Steps of Urine Formation (7)
1. Blood enters 'leaky' glomerulus
2. Fluid and some solutes leave the blood
3. Filtrate is caught by glomerular capsule and enters PCT
4. Water and solutes are reabsorbed back into blood as the filtrate passes through the PCT, loop and DCT
5. Flows into collecting duct after DCT to go through the final phases of alterations
6. Filtrate can be called urine once it leaves the collecting duct
7. Urine passes through papillae into minor calyx to major calyx to renal pelvis to ureter to urinary bladder
59
What happens as you go deeper into the medulla?
It gets more salty, leading to osmosis
60
What is filtration?
Metabolic waste products being filtered out/removed by kidneys
61
Glomerular Capillaries
Single layer of endothelial cell plus basement membrane
62
Glomerular Capsule
Made up of simple squamous epithelium
| Encloses glomerulus
63
Podocytes
Cells that wrap around the glomerular capillaries
64
What do podocytes do?
Help keep small proteins in the bloodstream
65
Mesangial Cells
Cells that lie between capillaries and help regulate capillary blood flow
66
Glomerular Capillaries
Single layer of endothelial cell plus basement membrane
67
Mesangial Cells
Cells that lie between capillaries and help regulate capillary blood flow
68
What do the glomerular capillaries contain?
Holes/pores that allow fluid to leave
69
Fenestrated Endothelium
Large pores
70
Filtration slits in podocytes
Most selective of finest filters allow only small solutes to get through to enter capsular space and PCT
71
Glomerular Hydrostatic Pressure (GHP)
In glomerulus
| Blood pressure in glomerular capillaries
72
Capsular Hydrostatic Pressure (CsPP)
Pressure of filtrate in capsular space
73
Blood Colloid Osmotic Pressure (BCOP)
Force of solutes in blood that allows water back into glomerular capillaries
74
What is the GHP in glomerular capillaries?
50mmHg
75
Why is the GHP in the glomerular capillaries so high?
The efferent arteriole is smaller in diameter than the afferent arteriole
76
Decrease in diameter equals...
Increase in resistance
77
Decrease in diameter equals...
Increase in resistance
78
What is the capsular hydrostatic pressure?
15mmHg being pushed into PCT
79
How do you calculate net hydrostatic pressure (NHP)?
GHP-CsHP=NHP
80
What is the value of net hydrostatic pressure usually?
35mmHg
81
What else opposes glomerular hydrostatic pressure?
Blood Colloid Osmotic Pressure
82
How do you calculate net filtration pressure (NFP)?
NHP-BCOP=NFP
83
How many liters of filtrate do the kidneys produce in a day?
180L
84
What happens to 99% of filtrate made?
It is reabsorbed by the nephron and collecting ducts
85
How many net liters of filtrate do we produce per day?
1.8L of urine in 24 hours
86
How many net liters of filtrate do we produce per day?
1.8L of urine in 24 hours
87
Glomerular Filtration Rate (GFR)
The amount of filtrate the kidneys produce in one minute
88
What does the GFR depend on?
Blood pressure entering the glomerulus
89
What happens when pressure is increased?
Filtrate is increased
90
Constriction of Afferent Arteriole
Exercise
Fight or flight
Decrease filtrate
91
Constriction of Efferent Arteriole
Raise blood pressure and urine production
Increase filtrate
Keeps blood in glomerulus and it keeps getting filtered
92
How is glomerular filtration rate regulated?
Autoregulation
Hormonal Regulation
Autonomic Regulation
93
How is autoregulation accomplished?
Myogenic mechanisms
94
How is autoregulation accomplished?
Myogenic mechanisms
95
What happens during a drop in systemic blood pressure?
Contraction of efferent arteriole
96
What happens during a rise in systemic blood pressure?
Contraction of afferent arteriole
97
What happens during a rise in systemic blood pressure?
Contraction of afferent arteriole
98
What is hormonal regulation?
Increase in glomerular filtration rate
99
What is hormonal regulation?
Increase in glomerular filtration rate
100
Where is renin secreted from?
Juxtaglomerular Complex
101
What is renin secretion caused by? (3)
Drop in blood pressure
Nervous stimulation
Decline in osmotic concentration of filtrate in DCT
102
Natriuretic Peptides
Decrease blood volume secreted by heart in response to high blood pressure
103
What causes natriuretic peptides to decrease blood volume? (3)
Vasodilation of afferent arterioles
Vasoconstriction of efferent arterioles
A decrease in Na+ reabsorption at nephron
104
Why is there a decrease in Na+ reabsorption at nephron?
More Na+ in urine (H2O follows salt)
| Lose H2O in urine from blood
105
Juxtaglomerular Complex
Made up of cells of the macula densa and juxtaglomerular cells
106
Where is the juxtaglomerular complex?
In and next to the DCT near the afferent arteriole
107
What does the JGC secrete? (2)
Erythropoietin
| Renin
108
Macula Densa
Cells in the wall of DCT
109
What does the macula densa do?
Stimulates juxtaglomerular cells in response to a drop in Na+ levels in filtrate
110
Juxtaglomerular Cells
Secrete renin and erythropoietin
111
Why do juxtaglomerular cells secrete renin and erythropoietin? (3)
Decline in blood pressure in afferent arteriole,
Nervous stimulation
Stimulated by cells of macula densa
112
Erythropoietin
Released in response to low blood oxygen levels
113
What does erythropoietin stimulate?
Red bone marrow to increase RBC production
114
What does the Renin-Angiotensin System increase?
Blood pressure
115
Renin
Not active form
| Release converts angiotensinogen to angiotensin 1
116
Angiotensin 1
Not active form
| Cleaved into angiotensin 2 in the lungs by the enzyme ACE
117
ACE
Angiotensin Converting Enzyme
118
Where is ACE produced?
Lungs
119
Angiotensin 2
Active form
120
What does angiotensin 2 cause? (5)
```
Constriction of efferent arteriole
Aldosterone release
Thirst
ADH release
Increase in heart rate and vasoconstriction in periphery
```
121
What does constriction of efferent arteriole cause?
Increased glomerular filtration rate
122
What does the release of aldosterone do? (3)
Reabsorb more sodium, keeps it in the body
Water leaves the filtrate, keeping it in body
Raises blood volume and blood pressure
123
What happens when ADH is released? (3)
More water is held onto
Increase blood volume
Increased blood pressure
124
ACE Inhibitors
Prevents angiotensin 1 from cleaving angiotensin 2
| Decrease blood pressure by inhibiting the ACE enzyme
125
Autonomic Regulation
Regulates glomerular filtration rate
| Sympathetic nervous system stimulation causes vasoconstriction in afferent arteriole
126
Autonomic Regulation
Regulates glomerular filtration rate
| Sympathetic nervous system stimulation causes vasoconstriction in afferent arteriole
127
What happens after GFR autonomic regulation?
Decreases GFR and filtrate production during sympathetic activation during fight or flight response or strenuous exercise
128
Summary of GFR Control
Hormonal Control regulates GFR by the products of renin-angiotensin system and natriuretic peptides
Autoregulation changes the tone of smooth muscle in walls of afferent and efferent arterioles and a local level
Autonomic (Sympathetic) Control occurs during strenuous exercise or fight/flight response by a powerful constriction of afferent arterioles
129
Reabsorption
Certain substances are reabsorbed (removed) from the filtrate into the interstitial fluid (peritubular fluid) of kidneys
Glomerulus to capsule
Filtrate to peritubular fluid
130
Secretion
Certain substances are added to the filtrate from the interstitial fluid (peritubular fluid) of the kidneys
Capsule to glomerulus
Peritubular fluid to filtrate
131
Where is filtrate contained?
Nephron
132
Where is peritubular fluid?
Extracellular fluid outside of the nephron
133
What happens to peritubular fluid?
It is taken up by peritubular capillaries and vasa recta
134
What is the peritubular fluid solute concentration near the cortex?
300mOsm/L
135
What is the peritubular fluid solute concentration deep in the medulla?
1200mOsm/L
136
What solutes are in the peritubular fluid?
Na+
Cl-
Urea
137
What is one reason the peritubular fluid is important?
Helps absorb water
138
What is one reason the peritubular fluid is important?
Helps absorb water
139
Microvilli
Line the cells forming the wall of the PCT to increase surface area
140
What is PCT?
Proximal Convoluted Tubule
141
How much of the filtrate does the PCT reabsorb?
60-70%
142
What does the PCT reabsorb?
Glucose
Amino Acids
Ions (Na+, HCO3, etc)
Osmosis of water
143
How does the PCT reabsorb solutes?
ATP
| Cotransport via help of Na+
144
Where do the reabsorb solutes go?
Peritubular fluid
145
How much water does the nephron loop reabsorb?
50% of what is left
146
How much Na+ and Cl- does the nephron loop reabsorb?
66%
147
Descending Limb of Nephron Loop
Thin
| Filtrate flows toward the medulla
148
Ascending Limb of Nephron Loop
Thick
| Filtrate flows toward the cortex
149
What is able to permeate the descending limb of the nephron loop?
```
Water (because of the very Na+ concentrated fluid in medulla and osmosis pulls water out)
Not solutes (because they're too big)
```
150
What is able to permeate the ascending limb of the nephron loop?
Not permeable to water or solutes freely, but has active transport mechanisms for removal of solutes
151
What is able to permeate the ascending limb of the nephron loop?
Not permeable to water or solutes freely, but has active transport mechanisms for removal of solutes
152
What does the ascending limb actively transport out?
Na+
K+
Cl-
153
Where do the solutes from the ascending limb go to?
Apical surface of cell
154
What does the cell do with the solutes from the ascending limb?
Actively transports Cl- and K+ out the basal surface into the peritubular fluid
155
What happens to K+?
Cells use the Na+/K+ ATPase pump to return K+ into cells and pump the Na+ out into peritubular fluid
K+ then diffuses back into filtrate through passive channels
156
What do the different permeabilities of the nephron loop limbs do?
Helps create osmotic gradient in medulla
| Facilitates reabsorption of water and solutes
157
Countercurrent Multiplication
Positive feedback loop between the two limbs in the nephron loop
158
How does countercurrent multiplication work?
The more water that leaves, the more Na+ is reabsorbed, which makes more water diffuse out and the cycle keeps repeating
159
How is homeostasis regulated in the fluid outside of the nephron loop?
Capillaries and vasa recta reabsorb the excess water and Na+ to maintain a constant level in medulla
160
How is homeostasis regulated in the fluid outside of the nephron loop?
Capillaries and vasa recta reabsorb the excess water and Na+ to maintain a constant level in medulla
161
How much of the original filtrate reaches the DCT?
15-20%
162
What is the DCT?
Distal Convoluted Tubule
163
What is reabsorbed in the DCT?
Na+ and Cl- through active transport
| Water
164
What is secreted in the DCT?
K+ and H+ from peritubular fluid into filtrate
165
DCT Reabsorption Under Hormonal Control
Aldosterone
| ADH
166
What does aldosterone do in the DCT?
Increases Na+ reabsorption with more Na+ channels and pumps
167
What does ADH do in the DCT?
Increases water reabsorption
168
What opposes aldosterone and ADH?
Natriuretic peptides
169
What is the collecting duct reabsorption regulated by?
ADH and aldosterone
170
What does the collecting duct reabsorb?
Bicarbonate ions
Hydrogen
Urea
171
What does reabsorption of urea do?
Helps contribute to high osmotic gradient in medulla and therefore helps concentrate the urine
172
Where is urea reabsorbed?
Near the renal papillae
173
Where is urea reabsorbed?
Near the renal papillae
174
What is ADH?
Anti-Diuretic Hormone
175
What does ADH allow?
The DCT and collecting duct to be permeable to water
176
What does ADH stimulate?
Water channels to be produced and embedded in the apical surface of the DCT and collecting duct cells
177
How much does the ADH mechanism reabsorb per day?
26L
178
Peritubular Capillaries and Vasa Recta
Take up peritubular fluid and carry away both water and solutes and returns them to the circulation
179
What makes normal urine a light yellow?
Urobilinogen
180
Why is urine sterile?
It inhibits bacterial growth because of its acidic pH of 6
181
Why is there no protein or blood in the urine?
They are too big to enter the nephron, they never leave he glomerular capsule
182
Why is there no glucose in urine?
It is reabsorbed in the PCT
183
What does it mean if there is proteins and blood in urine?
Intense workouts can sometimes create bigger pores the nephron which allows RBCs and proteins to fit through
184
Why might one have glucose in their urine?
People with diabetes mellitus could if their blood glucose levels are too high
185
Ureters
Muscular tubes that extend from the kidneys to the urinary bladder
186
What tissue layers make up the ureters?
Inner transitional epithelium
Middle smooth muscle
Superficial connective tissue
187
What is inner transitional epithelium?
It can stretch without damage
188
Peristaltic Contractions
Smooth muscle contraction that starts at kidneys and moves down the ureter very slowly
189
How often do peristaltic contractions occur?
About every 30 seconds to move urine along toward bladder
190
Where is the urinary bladder located?
Within pelvic cavity,
| Posterior to pubic symphysis
191
Where do ureters enter the bladder?
Posterior/inferior portion
192
Urinary Trigone
Acts as a funnel in the bladder
| Triangle between ureter openings and urethra
193
What are the 4 tissue layers of the bladder?
Inner transitional epithelium (mucosa)
Submucosa
Musclaris layer (detrusor muscle)
Superficial connective tissue layer
194
What makes up the musclaris layer of the bladder?
3 layers of smooth muscle
| Expels urine from bladder during urination
195
Urethra
Tubular structure that extends from urinary bladder to exterior
196
What types of tissues line the urethra?
Transitional epithelium near bladder and stratified squamous epithelium near external environment
197
How long is the urethra in males?
18-20 cm
198
How long is the urethra in females?
3-5 cm
199
Internal Urethral Sphincter
Circular band of smooth muscle where the urethra exits the bladder
200
What does the internal urethral sphincter do?
Provides involuntary control over discharge of urine
201
External Urethral Sphincter
Circular band of skeletal muscle where the urethra passes through the pelvic floor masculature
202
What does the external urethral sphincter do?
Provides voluntary control over discharge or urine
203
Voiding
Peeing
204
Steps of Micturition (3)
1. Stretch receptors in the wall of the urinary bladder are stimulated
2. Neuron signals are sent through pelvic nerves into spinal cord
3. Urination involves conscious relaxation of external urethral sphincter, allowing relaxation of internal urethral sphincter
205
How are the stretch receptors in the bladder stimulated?
Nerve endings pick up stretch/tension and signal the brain
206
What happens in the spinal cord when the neuron signals reach them?
Motor neurons controlling the detrusor muscle are stimulated which leads to the detrusor muscle contracting
207
What part of the brain gets stimulated with signals to make you aware that you have to pee?
Cerebrum
208
Incontinence
Inability to control urination
209
Damage to what leads to incontinence? (3)
Urethral sphincters
Pelvic nerves
Central nervous system
210
UTI
Urinary Tract Infection
211
Urinary Tract Infection
Bacterial infection
212
Lower UTI
Bacterial infection of the urinary bladder
213
Upper UTI
Bacterial infection of bladder and ureters and renal pelvis
214
How do you prevent a UTI?
Keeping proper hydration and hygiene
215
What are symptoms of a urinary tract infection?
Frequent urination
Pain with urination
Flank pain
Fever
216
What are kidney stones?
Mineral deposits that form in urine in the kidneys
217
Where are kidney stones painful?
As they pass through the ureters
218
What kind of mineral are kidney stones usually?
80% of the time, calcium oxalate
219
How do you prevent kidney stones?
Staying hydrated
220
Where do kidney stones form?
Very concentrated urine
221
What is a KUB?
An x-ray that looks at the kidneys, ureters, and bladder
