Week 3 - The Urinary System Flashcards
(74 cards)
1
Q
define elimination
A
- the excretion of waste products primarily through the urinary system (in the urine) and the GI system (bile & feces)
2
Q
list the 5 major roles of the kidneys
A
- filter and excrete water soluble metabolic wastes
- regulate blood vol & bp
- production of erythropoietin
- regulation of electrolytes
- regulate pH
3
Q
where are metabolic wastes filtered from? how are they excreted?
A
- filtered from the blood into filtrate
- excreted in the urine
4
Q
list 3 metabolic wastes the kidneys filter & excrete
A
- urea
- uric acid
- creatinine
5
Q
how are metabolic wastes produced?
A
- waste products are generated during metabolism in cells
6
Q
what is urea
A
- waste product produced when we metabolize amino acids/the detoxification of ammonium
7
Q
describe how the metabolism of amino acids forms urea; include whether or not ammonium is toxic to the body
A
- each amino acid contains an amino head & acid tail
- the amino head contains nitrogen
- when we break down proteins into amino acids & then break down the amino acids for fuel, the nitrogen in the amino head becomes ammonium
- ammonium is very toxic to the body & we do not want it to accumulate
- to avoid this accumulation, we deliver aa to the liver which removes the ammonium and creates urea thru the urea cycle
- urea is then put back into the blood & removed thru the kidneys
8
Q
is urea toxic or non-toxic to the body
A
- no but its elevations are
9
Q
what is uric acid
A
- waste product produced due to DNA and RNA catabolism
10
Q
what 2 things does accumulation of uric acid cause?
A
- kidney stones
2. gout
11
Q
what is creatine
A
- by-product produced from muscle tissue
- specifically it is a breakdown product of creatine phosphate
12
Q
describe how creatine is formed from the breakdown of creatine phosphat
A
- creatine phosphate is what the muscle tissue uses to regenerate ATP when we use our muscles vigorously
- creatine phosphate donates a phosphate to ADP to create ATP
- and then we are left with creatinine
13
Q
is creatine toxic to the body?
A
- it is not toxic itself, but it’s elevation is
14
Q
how do the kidneys regulate blood volume & pressure? (3)
A
- alter the amt of urine produced
- release the enzyme renin into the blood
- antidiuretic hormone released from the pituitary gland acts on the kidneys
15
Q
when is renin released? what is the function of renin?
A
- renin is released when blood volume &bp is low
- it then acts on angiotensignogen to convert it to angiotensin 1
16
Q
describe the RAAS system
A
- renin is released when bp low
- turns angiotensinogen into angiotensin 1
- ACE turns angiotensin 1 into angiotensin 2
- angiotesin 2 causes vasoconstricition & aldo secretion
17
Q
what is the function of aldo
A
- tells the kidneys to keep Na and water & get rid of K+
18
Q
what is the function of ADH
A
- tells the kidneys to keep water
19
Q
what triggers the kidneys to produce erythropoietin
A
- produces it in response to low blood O2 levels
20
Q
what does erythropoietin do>
A
- stimulaed erythrocyte production in the bone marrow
21
Q
list 5 main electrolytes the kidneys regulate
A
- Na
- K
- Ca
- Cl
- Phosphate
22
Q
list 3 ways the kidneys regulate electrolytes
A
- alteration of the urine conc
- alteration of urine composition
- activation of vit D
23
Q
describe why the kidneys need to activate vit D? what does this activation cause?
A
- when we absorb vit D into our skin via the sun it is inactive
- the kidneys then activate the vit D
- activation of vit D promotes Ca++ absorption in the small intestine
24
Q
what other hormone promotes Ca++ absorption
A
- parathyroid hormone
25
how do the kidneys regulate the body's pH
- control the amount of H+ secreted
- & the amount of HCO3- reabsorbed from the filrate
note: for every molecule of H+ secreted, one HCO3- is reabsorbed
26
where are the kidneys located? what are they partially protected by>
- located posterior to the peritoneum in the retroperitoneal area
- partially protected by the lower ribs
27
where do the kidneys receive blood from? where do these come from?
- the renal arteries
| - these branch directly from the aorta
28
how do the kidneys return their cleansed blood to the heart?
- thru the renal veins into the inferior vena cava
29
describe the movement of urine (4 steps)
1. it is produced in the kidneys
2. travels down the ureters
3. moves into the urinary bladder for storage
4. then leaves the body thru the urthera using contraction of the bladder
30
each kidney is covered by ____ and _____
- a fibrous capsule
| - layer of adipose tissue
31
where are pain receptors located in the urinary system? what does this mean
- none in the kidney
= pain only present when there is impingement on the renal capsule (fibrous capsule) or in the ureter (because these 2 have pain receptors)
- no pain if shrunken, pain if swollen
32
where does blood go once it enters the kidney?
- it is transported by smaller arteries to the outer portion of the kidney = the cortex
33
where is the majority of blood in the kidney filtered?
- in the cortex
34
what is the innner portion of the kidney called
- the medulla
35
what is the function of the medulla (2)
- alters the composition of the filtrate (thru reabsorption)
| - creates urine
36
which area of the kidney is highly suscpetible to ischemic damage? why?
- the medulla
| - it is very metabolically active but has low O2 tension because blood goes to the cortex first
37
describe the shape of the medulla; what are these called
- arranged in triangular shaped structures = medullary pyramids
38
where does the urine go after the medulla alters the composition & forms urine?
- drains into collecting ducts in the medulla
- then goes through the renal calcyes which combine to form one big funnel called the renal pevlis
- the urine goes from the renal pelvis into the ureters for transport to the urinary bladder
39
why is blood pressure to the kidneys importanT
- important to maintain filtration
| - NOT to satisfy the metabolic needs of the tissue
40
at rest, the kidneys receive ___% of the cardiac output
25%
41
list 2 things that cause less cardiac output to go to the kidneys
- exercise
| - exertion
42
what is the average blood pressure in the glomerular capillaries
- ~55 mmHg
43
what 2 things maintain glomerular blood pressure? what is the formula
- flow through the afferent arteriole (BFG)
- high resistance to flow in the efferent arteriole (RG)
BPg = BFg x Rg
44
the glomerular blood pressure is the driving force for what?
- to create filtration
45
describe the relation between BFg and BPg; what would cause BPg to increase? decrease?
- if BFg increases with afferent arteriole dilation = increased BPG
- if BFG decreases with afferent aertiorole constiction = decreased BPG
46
describe the relation between RG and BPG; what would cause BPG to increase? decrease?
- RG is increased with efferent constriction = increased BPG
| - RG is decreased with efferent dilation = decreased BPG
47
what effect does increased BPG have on filtration? decreased?
- increased BPG = increased filtration
| - decreased BPG = decreased filtration
48
the glomerular capillaries are formed from...?
- the afferent arteriole
49
what are glomerular capillaries composed of? (3)
- fenestrations
- basement membrane in between
- podocytes
50
what is the glomerulus?
- a tuft of capillaries surrounded by bowman's capsule
51
what are fenestrations
- endothelial cells with holes in them
52
what are podocytes
- epithelial cells with foot-like structures & slits
53
does fluid first go thru the fenestrations or podocytes
- fenestrations --> basement membrane --> podocytes
54
what is Bowman's capsule continuous with?
- the renal tubule
55
what is the juxtaglomerular apparatus? what is it made of?
- regulatory unit composed of:
1. afferent arteriole
2. efferent arteriole
3. juxtaglomerular cells
4. macula densa
56
what is the function of the juxtaglomerular cells
- secrete renin in response to low BP or SNS stimulation
57
what is the function of the macula densa (3)
- part of the distal tubule
- senses changes in the conc of the filtrate
- can dilate or constrict the arterioles appropriately
58
what is the function of the fenestrations in the glomerular capillaries
- only allow particles less than 8 nm to pass
59
what is a con to the size limit of the fenestrations? how do we overcome this?
- proteins like albumin are smaller than 8 nm
- the capillary basement membrane contains negatively charged proteoglycan which repels other anions (negatively charged molecules) like albumin
60
describe the role/relation between inflammation & the immune system to the glomerulus
- the glomerulus is commonly injured by immune complexes
- this complexes get caught in the fenestrations or slits
- this produces an inflammatory response in an attempt to destroy the immune complex thru phagocytosis
61
what is nephritic syndrome
- occurs if the immune complexes are within the endothelial layer (on the fenestration side of the basement membrane) & accessible to phagocytes
62
what is nephrotic syndrome
- occurs if the immune complexes lie within the epithelial cells (podocytes) and are not accessible to phagocytes
63
what does inflammation of the glomerulus cause
- allows protein to inter the filtrate & urine
64
describe the urine in nephritic vs nephrotic syndrome
- nephritic = there are blood cells in the urine = hematuria
| - nephrotic = there are not
65
what 3 forces regulate filtration thru the glomeruluar capillaries
1. glomerular (blood) hydrostatic P
2. blood colloid osmotic P
3. capsular hydrostatic P
66
what does the glomerular blood hydrostatic P cause? what is the pressure exerted?
- pushes fluid out of the glomerulus
| = 55 mmHg
67
what does the blood colloid osmotic P cause? what is the amt of pressure exerted?
- pushed water back into the glomerular capillary because there are more proteins in the blood
= 30 mmHg
68
what does the capsular hydrostatic pressure cause? what is the amt of pressure exerted?
- pushes a small amount of fluid back into the capillary
| = 15 mmHg
69
what helps increase the permeability of the glomerular capillaries? (2)
- fenestrations
| - higher bp compared to other capillaries
70
what is the glomerular filtration rate
- the amount of blood plasma filtered thru the capillaries in 1 min
71
what is the typical glomerular filtration rate?
125 mL/min
72
how is GFR primarily regulated
- by altering the BPg (and therefore altering BFg and Rg)
73
what 2 things cause an increase in GFR
- afferent dilation = increased flow thru the capillaries
| - efferent constriction = increased resistance to flow
74
what 2 things cause a decrease in GFR
- afferent constriction = decreased flow thru the capillaries
- efferent dilation = decreased resistance
