Chapter 26 Flashcards
(119 cards)
1
Q
Urinary system
A
Consists of two kidneys, two ureters, one urinary bladder, and one urethra.
2
Q
What is the order of urine flowing through the urinary system?
A
Kidneys (filter blood of wastes and excrete them into urine) -> ureters -> urinary bladder -> urethra
3
Q
What are the eight functions of the kidneys?
A
- Excretion of wastes.
- Regulation of blood ionic composition.
- Regulation of blood pH.
- Regulation of blood volume.
- Regulation of blood pressure.
- Maintenance of blood osmolarity.
- Production of hormones.
- Regulation of blood glucose level.
4
Q
Nitrogenous wastes
A
What urea, ammonia, creatinine, uric acid, and urobilin are collectively known as. All contain nitrogen, hence the name nitrogenous wastes.
5
Q
Describe the location, description, and function of the kidneys
A
6
Q
True or false: the kidneys are said to be retroperitoneal.
A
True
7
Q
Renal hilum
A
Indentation through which the ureter emerges from the kidneys, along with blood vessels, lymphatic vessels, and nerves.
8
Q
What are the three layers that surround each kidney? Describe them:
A
- Renal capsule: deep layer; is a smooth, transparent sheet of dense irregular connective tissue that is continuous with the outer coat of the ureter. Serves as a barrier against trauma and helps maintain the shape of the kidneys.
- Adipose capsule: middle layer; is a mass of fatty tissue surrounding the renal capsule. Protects the kidneys from trauma and holds it firmly in place within the abdominal cavity.
- Renal fascia: superficial layer; is a thin layer of dense irregular connective tissue that anchors the kidney to the surrounding structures and to the abdominal wall.
9
Q
What are the two distinct regions of the kidneys? Describe them:
A
- Renal cortex: superficial, light red region of the kidneys.
- Renal medulla: deep, darker reddish-brown inner region of the kidneys.
10
Q
Renal pyramids
A
Found within the renal medulla.
11
Q
Renal papilla
A
Narrower end of renal pyramids. Point towards the renal hilum.
12
Q
What two zones can the renal cortex be divided into?
A
- Cortical zone (outer)
- Juxtamedullary zone (inner)
13
Q
Renal columns
A
What the cortical zone and juxtamedullary zone are collectively referred to as.
14
Q
Parenchyma
A
What the renal cortex and renal pyramids of the renal medulla are collectively referred to as.
15
Q
Nephrons
A
Functional units of the kidneys. Found in the parenchyma.
16
Q
What is the path of urine drainage?
A
Collecting duct -> papillary duct -> minor calyx -> major calyx -> renal pelvis -> ureter -> urinary bladder
17
Q
Renal sinus
A
Cavity within the kidney that contains part of the renal pelvis, the calyces, and branches of the renal blood vessels and nerves. Adipose tissue helps stabilize the position of these structures in the renal sinus.
18
Q
What is the path of blood in the kidneys?
A
Renal artery -> segmental arteries -> interlobar arteries -> arcuate arteries -> cortical radiate arteries -> afferent arterioles -> glomerular capillaries -> efferent arterioles -> peritubular venules -> cortical radiate veins -> arcuate veins -> interlobar veins -> renal vein
19
Q
Vasa recta
A
Long, loop-shaped capillaries that extend from some efferent arterioles. Supply tubular portions of the nephron in the renal medulla.
20
Q
Renal nerves
A
Many of them originate in the renal ganglion and pass through the renal plexus into the kidneys along with the renal arteries. Renal nerves are part of the sympathetic division of the
autonomic nervous system. Most are vasomotor nerves that regulate the flow of blood through the kidney by causing vasodilation or vasoconstriction of renal arterioles.
21
Q
Renal corpuscle
A
Part of a nephron where blood plasma is filtered.
22
Q
What are the two components of a renal corpuscle? Describe them:
A
- Glomerulus: capillary network
- Glomerular capsule (Bowman’s capsule): a double-walled epithelial cup that surrounds the glomerular capillaries. Filters blood plasma before passing into the renal tubule.
23
Q
What are the three components of the renal tubule?
A
- Proximal convoluted tubule (PCT)
- Nephron loop (loop of Henle)
- Distal convoluted tubule (DCT)
24
Q
Collecting duct (CD)
A
What distal convoluted tubules (DCT) empty into. Collecting ducts then unite and converge into several hundred large papillary ducts, which drain into the minor calyces.
25
What is the difference between the descending limb of the nephron loop and the ascending limb of the nephron loop?
Descending limb of the nephron loop: the first part of the nephron loop that begins at the point where the proximal convoluted tubule takes its final turn downward. It begins in the renal cortex and extends downward into the renal medulla.
Ascending limb of the nephron loop: the second part of the nephron loop when it makes the hairpin turn and returns to the renal cortex where it terminates at the distal convoluted tubule.
26
What is the difference between cortical nephrons and juxtamedullary nephrons? (Image of both on pg. 928-929)
Cortical nephrons: 80-85% of nephrons; their renal corpuscles lie in the outer portion of the renal cortex, and they have short nephron loops that lie mainly in the cortex and penetrate only into the outer region of the renal medulla. The short nephron loops receive their blood supply from peritubular capillaries that arise from efferent arterioles.
Juxtamedullary nephrons:15-20% of nephrons; their renal corpuscles lie deep in the cortex, close to the medulla, and they have a long nephron loop that extends into the deepest region of the medulla. Long nephron loops receive their blood supply from peritubular capillaries and from the vasa recta that arise from efferent arterioles.
27
What two portions does the ascending limb of the nephron loop of juxtamedullary nephrons consist of?
1. Thin ascending limb
2. Thick ascending limb
28
Glomerular capsule (Bowman's capsule)
Consists of visceral and parietal layers.
29
Podocytes
Modified simple squamous epithelial cells found in the visceral layer of the glomerular capsule. Form the inner wall of the capsule.
30
Capsular space
The space between the two layers of the glomerular capsule, which is continuous with the lumen of the renal tubule.
31
What type of cell(s) make up the proximal convoluted tubule (PCT)?
Simple cuboidal epithelial cells with prominent brush borders of microvilli.
32
What type of cell(s) make up the nephron loop: descending limb and thin ascending limb?
Simple squamous epithelial cells.
33
What type of cell(s) make up the nephron loop: thick ascending limb?
Simple cuboidal to low columnar epithelial cells.
34
What type of cell(s) make up most of the distal convoluted tubule (DCT)?
Simple cuboidal epithelial cells.
35
What type of cell(s) make up the last part of the distal convoluted tubule (DCT) and all of the collecting duct (CD)?
Simple cuboidal epithelium consisting of principal cells and intercalated cells.
36
Macula densa
What columnar tubule cells in the final part of the ascending limb of the nephron loop are known as. They make contact with the afferent arteriole serving the renal corpuscle.
37
Juxtaglomerular (JG) cells
Modified smooth muscle fibers found in the walls of afferent (and sometimes efferent) arterioles.
38
Juxtaglomerular apparatus (JGA)
What the juxtaglomerular (JG) cells and the macula densa are collectively referred to as. The JGA helps regulate blood pressure within the kidneys.
39
Principal cells
Found in the last part of the distal convoluted tubule (DCT) and in the collecting duct (CD). Large amount of them. Have receptors for antidiuretic hormone (ADH) and aldosterone.
40
Intercalated cells
Found in the last part of the distal convoluted tubule (DCT) and in the collecting duct (CD). Small amount of them. Play a role in the homeostasis of blood pH.
41
What three basic processes do nephrons and collecting ducts perform to produce urine?
1. Glomerular filtration
2. Tubular reabsorption
3. Tubular secretion (removes a substance from the blood)
42
Glomerular filtrate
The fluid that enters the capsular space.
43
Filtration fraction
The fraction of blood plasma in the afferent arterioles of the kidneys that becomes glomerular filtrate.
44
Filtration (endothelial–capsular) membrane
Leaky barrier formed by glomerular capillaries and podocytes. Permits filtration of water and small solutes but prevents filtration of most plasma proteins and blood cells.
45
What are the three filtration barriers of the filtration (endothelial–capsular) membrane? Describe them:
1. A glomerular endothelial cell: contain fenestrations (pores) and mesangial cells (contractile cells that help regular glomerular filtration)
2. Basement membrane
3. Filtration slit formed by a podocyte: contain pedicels (footlike processes extending from podocytes that wrap around glomerular capillaries), filtration slits (spaces between pedicels), and slit membranes (thin membranes that extends across each filtration slit)
46
What are the three reasons that the volume of fluid filtered by the renal corpuscle is much larger than in other blood capillaries?
1. Glomerular capillaries present a large surface area for filtration because they are long and extensive. Mesangial cells regulate how much surface area is available. When mesangial cells are relaxed, surface area is maximal, and glomerular filtration is very high. Contraction of mesangial cells reduces the available surface area, and
glomerular filtration decreases.
2. The filtration membrane is thin and porous. Despite having several layers, the thickness of the filtration membrane is only 0.1 mm. Glomerular capillaries also are about 50 times leakier than blood capillaries in most other tissues, mainly because of their large fenestrations.
3. Glomerular capillary blood pressure is high. Because the efferent arteriole is smaller in diameter than the afferent arteriole, resistance to the outflow of blood from the glomerulus is high. As a result, blood pressure in glomerular capillaries is considerably higher than in blood capillaries elsewhere in the body.
47
Glomerular filtration depends on three main pressures. One pressure promotes filtration and two pressures oppose filtration. What are these three main pressures? Describe them:
1. Glomerullar blood hydrostatic pressure (GBHP): the blood pressure in glomerular capillaries. Generally, GBHP is about 55 mmHg. Promotes filtration by forcing water and solutes in blood plasma through the filtration membrane.
2. Capsular hydrostatic pressure (CHP): the hydrostatic pressure exerted against the filtration membrane by fluid already in the capsular space and renal tubule. CHP opposes filtration and represents a “back pressure” of about 15 mmHg.
3. Blood colloid osmotic pressure (BCOP): is due to the presence of proteins such as albumin, globulins, and fibrinogen in blood plasma, also opposes filtration. Average BCOP in glomerular capillaries is 30 mmHg.
48
Glomerular filtration rate (GFR)
The amount of filtrate formed in all renal corpuscles of both kidneys each minute.
49
What three mechanisms control glomerular filtration rate (GFR)?
1. Renal autoregulation
2. Neural regulation
3. Hormonal regulation
50
What two mechanisms are involved in renal autoregulation?
1. Myogenic mechanims
2. Tubuloglomerular feedback
51
What is the major stimulus, mechanism and site of action, and effect on glomerular filtration rate (GFR) of myogenic mechanisms?
52
What is the major stimulus, mechanism and site of action, and effect on glomerular filtration rate (GFR) of tubuloglomerular feedback?
52
What is the major stimulus, mechanism and site of action, and effect on glomerular filtration rate (GFR) of neural regulation?
53
What is the major stimulus, mechanism and site of action, and effect on glomerular filtration rate (GFR) of angiotensin II?
54
What is the major stimulus, mechanism and site of action, and effect on glomerular filtration rate (GFR) of atrial natriuretic peptide (ANP)?
55
A substance being reabsorbed from the fluid in the tubule lumen can take one of two routes before entering a peritubular capillary. What are they?
1. It can move between adjacent tubule cells.
2. It can move through an individual tubule cell.
56
What is the difference between the apical membrane and the basolateral membrane?
Apical membrane: contacts the tubular fluid. Do not have sodium-potassium pumps (Na+–K+ ATPases).
Basolateral membrane: contacts interstitial fluid at the base and sides of the tubule cell. Have sodium-potassium pumps (Na+–K+ ATPases).
57
What is the difference between paracellular reabsorption and transcellular reabsorption?
Paracellular reabsorption: water and solutes in tubular fluid return to the bloodstream by moving between tubule cells.
Transcellular reabsorption: solutes and water in tubular fluid return to the bloodstream by passing through a tubule cell.
58
What is the difference between primary active transport and secondary active transport?
Primary active transport: energy derived from hydrolysis of ATP is used to “pump” a substance across a membrane (Eg. Sodium–potassium pump).
Secondary active transport: energy stored in an ion’s electrochemical gradient, rather than hydrolysis of ATP, drives another substance across a membrane.
59
Transport maximum (TM)
The maximum amount of a substance that can be reabsorbed per unit time.
60
What is the difference between obligatory water reabsorption and facultative water reabsorption?
Obligatory water reabsorption: 90% of absorption; water reabsorbed with solutes in tubular fluid. Occurs in the proximal convoluted tubule (PCT) and the descending limb of the nephron loop.
Facultative water reabsorption: 10% of absorption; regulated by antidiuretic hormone (ADH) and occurs mainly in the collecting ducts.
61
Na+ symporters
Located in the apical membrane. There are many types of Na+ symporters.
62
Na+–glucose symporters
Located in the apical membrane. A type of Na+ symporter. Two Na+ and a molecule of glucose attach to the symporter protein, which carries them from the tubular fluid into the tubule cell. The glucose molecules then exit the basolateral membrane via facilitated diffusion and they diffuse into peritubular capillaries.
63
Na+–H+ antiporters
Promote transcellular reabsorption of Na+ and secretion of H+.
64
Aquaporin-1
Integral protein in the plasma membrane that is a water channel that greatly increases the rate of water movement across the apical and basolateral membranes. Found in cells lining the proximal convoluted tubule and the descending limb of the nephron loop.
65
What does the nephron loop do with regards to reabsorption?
The nephron loop sets the stage for independent regulation of both the volume and osmolarity of body fluids.
66
Na+–K+–2Cl− symporters
Cells in the thick ascending limb have symporters that simultaneously reabsorb one Na+, one K+, and two Cl−.
67
Na+–Cl− symporters
Located in apical membrane. Promotes reabsorption of Na+ and Cl−.
68
What five hormones regulate tubular reabsorption and secreation?
1. Angiotensin II
2. Aldosterone
3. Antidiuretic hormone
4. Atrial natriuretic peptide
5. Parathyroid hormone
69
What is the major stimuli that trigger release, mechanism and site of action, and effects of angiotension II?
70
Renin
Enzyme secreted by the juxtaglomerular cells when blood volume and pressure decrease, and the walls of the afferent arterioles are stretched less. Sympathetic stimulation can also stimulate juxtaglomerular cells to secrete it. Renin clips off a 10–amino acid peptide called angiotensin I from angiotensinogen.
71
Angiotensinconverting enzyme (ACE)
Converts angiotensin I to angiotensin II.
72
What three main ways does angiotensin II affect renal physiology?
1. It decreases the glomerular filtration rate by causing vasoconstriction of the afferent arterioles.
2. It enhances reabsorption of Na+ and water in the proximal convoluted tubule by stimulating the activity of Na+–H+ antiporters.
3. It stimulates the adrenal cortex to release aldosterone, a hormone that in turn stimulates the principal cells in the
collecting ducts to reabsorb more Na+ and secrete more K+. The osmotic consequence of reabsorbing more Na+ is that more water is reabsorbed, which causes an increase in blood volume and blood pressure.
73
What is the major stimuli that trigger release, mechanism and site of action, and effects of aldosterone?
74
What is the major stimuli that trigger release, mechanism and site of action, and effects of antidiuretic hormone (ADH)?
75
Aquaporin-2
Water channel proteins found in tiny vesicles within principal cells. ADH stimulates insertion of the aquaporin-2–containing vesicles into the apical membranes via exocytosis. As a result, the water permeability of the principal cell’s apical membrane increases, and water molecules move more rapidly from the tubular fluid into the cells.
76
What three factors does the degree of facultative water reabsorption caused by ADH in the late distal tubule and collecting duct depend on?
1. Normal hydration
2. Dehydration
3. Overhydrated
77
What is the major stimuli that trigger release, mechanism and site of action, and effects of atrial natriuretic peptide (ANP)?
78
What is the major stimuli that trigger release, mechanism and site of action, and effects of parathyroid hormone (PTH)?
79
What are the five conditions along the path of tubular fluid?
1. Because the osmolarity of the interstitial fluid of the renal medulla becomes progressively greater, more and more water is reabsorbed by osmosis as tubular fluid flows along the descending limb toward the tip of the nephron loop. As a result, the fluid remaining in the lumen becomes progressively more concentrated.
2. Cells lining the thick ascending limb of the loop have symporters that actively reabsorb Na+, K+, and Cl− from the tubular fluid. The ions pass from the tubular fluid into thick ascending limb cells, then into interstitial fluid, and finally some diffuse into the blood inside the vasa recta.
3. Although solutes are being reabsorbed in the thick ascending limb, the water permeability of this portion of the nephron is always quite low, so water cannot follow by osmosis. As solutes - but not water molecules - are leaving the tubular fluid, its osmolarity drops to about 150 mOsm/liter. The fluid entering the distal convoluted tubule is thus more dilute than plasma.
4. While the fluid continues flowing along the distal convoluted tubule, additional solutes but only a few water molecules are reabsorbed. The early distal convoluted tubule cells are not very permeable to water and are not regulated by ADH.
5. Finally, the principal cells of the late distal convoluted tubules and collecting ducts are impermeable to water when the ADH level is very low. Thus, tubular fluid becomes progressively more dilute as it flows onward. By the time the tubular fluid drains into the renal pelvis, its concentration can be as low as 65–70 mOsm/liter. This is four times more dilute than blood plasma or glomerular filtrate.
80
Osmotic gradient
The countercurrent multiplier establishes an osmotic gradient in the interstitial fluid of the renal medulla that enables production of concentrated urine when ADH is present.
81
What two types of countercurrent mechanisms exist in the kidneys? Describe them:
1. Countercurrent multiplication: the process by which a progressively increasing osmotic gradient is formed in the interstitial fluid of the renal medulla as a result of countercurrent flow.
2. Countercurrent exchange: the process by which solutes and water are passively exchanged between the blood of the vasa recta and interstitial fluid of the renal medulla as a result of countercurrent flow.
82
Countercurrent multiplier
What the long nephron loop is said to function as, since it establishes the osmotic gradient in the renal medulla.
83
What are the four steps involved in the production of concentrated urine by the kidneys?
1. Symporters in thick ascending limb cells of the nephron loop cause a buildup of Na+ and Cl− in the renal medulla.
2. Countercurrent flow through the descending and ascending limbs of the nephron loop establishes an osmotic gradient in the renal medulla.
3. Cells in the collecting ducts reabsorb more water and urea.
4. Urea recycling causes a buildup of urea in the renal medulla.
84
Countercurrent exchanger
What the vasa recta is said to function as, since countercurrent flow between the descending and ascending limbs of the vasa recta allows for exchange of solutes and water between the blood and interstitial fluid of the renal medulla. Maintains the osmotic gradient in the renal medulla.
85
Urinalysis
An analysis of the volume and physical, chemical, and microscopic properties of urine.
86
Water accounts for about __% of the total volume of urine.
95
87
What is the volume of normal urine?
One to two liters in 24 hours; varies
considerably.
88
What is the color of normal urine?
Yellow or amber; varies with urine concentration and diet. Color due to urochrome (pigment produced from breakdown of bile) and urobilin (from breakdown of hemoglobin). Concentrated urine is darker in color. Color affected by diet (reddish from beets), medications, and certain diseases. Kidney stones may produce blood in urine.
89
What is the turbidity of normal urine?
Transparent when freshly voided; becomes turbid (cloudy) on standing.
90
What is the odor of normal urine?
Mildly aromatic; becomes ammonia-like on standing. Some people inherit ability to form methylmercaptan from digested asparagus, which gives characteristic odor. Urine of diabetics has fruity odor due to presence of ketone bodies.
91
What is the pH of normal urine?
Ranges between 4.6 and 8.0; average 6.0; varies considerably with diet. High-protein diets increase acidity; vegetarian diets increase alkalinity.
92
What is the specific gravity (density) of normal urine?
Specific gravity (density) is ratio of weight of volume of substance to weight of equal volume of distilled water. In urine, 1.001–1.035. The higher the concentration of solutes, the higher the specific gravity.
93
What two blood scanning tests can provide information about kidney function?
1. Blood urea nitrogen (BUN) test: measures the blood nitrogen that is part of the urea resulting from catabolism and deamination of amino acids.
2. Measurement of plasma creatinine: results from catabolism of creatine phosphate in skeletal muscle.
94
Renal plasma clearance
The volume of blood that is “cleaned” or cleared of a substance per unit of time. The clearance of a solute depends on the three basic processes of a nephron: glomerular filtration, tubular reabsorption, and tubular secretion.
95
Inulin
A plant polysaccharide. The clearance of inulin is used to measure glomerular filtration rate (GFR).
96
Para-aminohippuric acid (PAH)
An organic ion. The clearance of PAH is used to measure renal plasma flow.
97
Renal plasma flow
The amount of plasma that passes
through the kidneys in one minute.
98
Describe the location, description, and function of the ureters
99
What are the three layers of tissues that form the walls of the ureters? Describe them:
1. Mucosa: deepest layer; a mucous membrane with transitional epithelium and an underlying lamina propria of areolar connective tissue with considerable collagen, elastic fibers, and lymphatic tissue.
2. Muscularis: intermediate layer; composed of inner longitudinal and outer circular layers of smooth muscle fibers.
3. Adventitia: superficial layer; composed of areolar connective tissue containing blood vessels, lymphatic vessels, and nerves that serve the muscularis and mucosa.
100
Describe the location, description, and function of the urinary bladder
101
Trigone
A small triangular area in the floor of the urinary bladder.
102
Internal urethral orifice
The opening into the urethra.
103
What are the three layers of tissues that form the walls of the ureters? Describe them:
1. Mucosa: deepest layer; a mucous membrane with transitional epithelium and an underlying lamina propria.
2. Muscularis (detrusor muscle): intermediate layer; composed of three layers of smooth muscle fibers: the inner longitudinal, middle circular, and outer longitudinal layers.
3. Adventitia: superficial layer; composed of areolar connective tissue that is continuous with that of the ureters.
104
Internal urethral sphincter
Involuntarily controls opening and closing of urethra.
105
External urethral sphincter
In deep muscles of perineum; voluntarily controls opening and closing of urethra.
106
Serosa
A layer of visceral peritoneum over the superior surface of the urinary bladder.
107
Micturition
Discharge of urine from the urinary bladder. Also known as urination or voiding.
108
Micturition center
Triggered by stretch receptors in the wall of the urinary bladder. Found in sacral cord segments S2 and S3 and stimulates the micturition reflex.
109
Micturition reflex
Discharges urine from the urinary bladder via parasympathetic impulses that cause contraction of the detrusor muscle and relaxation of the internal urethral sphincter muscle and via inhibition of impulses in somatic motor neurons to the external urethral sphincter.
110
Describe the location, description, and function of the urethra
111
What are the two layers of tissues that form the walls of the male urethra? Describe them:
1. Mucosa: deepest layer.
2. Muscularis: superficial layer.
112
What three regions can the male urethra be subdivided into? Describe them:
1. Prostatic urethra: passes through the prostate.
2. Intermediate (membranous) urethra: passes through the deep muscles of the perineum; the shortest portion.
3. Spongy urethra: passes through the penis; the longest portion.
113
What two reproductive structures does the prostatic urethra contain?
1. Ducts that transport secretions from the prostate.
2. The seminal vesicles and ductus (vas) deferens, which deliver sperm into the urethra and provide secretions that both neutralize the acidity of the female reproductive tract and contribute to sperm motility and viability.
114
Bulbourethral glands (Cowper’s glands)
Empty into the spongy urethra. They deliver an alkaline substance prior to ejaculation that neutralizes the acidity of the urethra. The glands also secrete mucus, which lubricates the end of the penis during sexual arousal.
115
Urethral glands (Littré glands)
Discharge mucus during sexual arousal
and ejaculation.
116
External urethral orifice
The opening of the urethra to the exterior. Is located between the clitoris and the vaginal opening.
117
What are the two layers of tissues that form the walls of the female urethra? Describe them:
1. Mucosa: deepest layer; a mucous membrane composed of epithelium and lamina propria (areolar connective tissue with elastic fibers and a plexus of veins). Near the urinary bladder, the mucosa contains transitional epithelium that is continuous with that of the urinary bladder; near the external urethral orifice, the epithelium is nonkeratinized stratified squamous epithelium. Between these areas, the mucosa contains stratified columnar or pseudostratified columnar epithelium.
2. Muscularis: superficial layer; consists of circularly arranged smooth muscle fibers and is continuous with that of the urinary bladder.
118
What are the six waste management systems we have in the body besides the urinary system?
1. Body buffers
2. Blood
3. Liver
4. Lungs
5. Sweat (sudoriferous) glands
6. Gastrointestinal tract
