Phys 1 Flashcards
(57 cards)
1
Q
how many nephrons in a kidney?
A
1 million
2
Q
What are the 4 main functions of the nephron (aka blood processing unit)
A
- filtration
- reabsorption
- secretion
- excretion
3
Q
functions of the kidney (there are a ton)
A
- filter plasma and produce urine
- excrete metabolic waste products
- reabsorb glucose and amino acids from filtrate
- regulate Ca and phosphate uptake
- regulate water homeostasis
- regulate extracellular vol. –> BP
- regulate electrolytes
- acid base homeostasis
- gluconeogenesis
- endocrine function
4
Q
what are the endocrine components of the kidney? (4)
A
- kinins
- 1, 25-dihydroxycholecalciferol
- EPO
- renin
5
Q
What 2 diseases cause the largest prevalence of kidney dysfunction?
A
- DM
2. HTN
6
Q
What type of endothelium is found within the glomerulus?
A
fenestrated
7
Q
characteristics of the afferent arteriole that feeds the glomerulus
A
- high resistance vessel
- high pressure
- larger diameter than efferent
8
Q
what is the general function of the afferent arteriole?
A
to force fluid and solutes from the circulation to the glomerulus to form filtrate
9
Q
mesangial cells
- where
- function
A
- between capillaries
- contractile cells that regulate the filtration rate and restrict large particles
10
Q
What is the glomerular capsule aka bowman’s capsule?
A
- a blind sac of the nephron
- surrounds the glomerulus
- receives filtrate
11
Q
podocytes
A
- cells that surround the capillaries
- they have foot like extensions that function as pores for another layer of filtration
12
Q
PCT cell type
A
cuboidal
13
Q
characteristics of the PCT
A
- high in mitochondria (think active transport occurring here)
- dense w/ microvilli
14
Q
what mainly occurs at the PCT?
A
-active reabsorption of water and solutes (glc) from the filtrate
15
Q
descending limb of the LoH
A
- thin
- squamous epithelium
- permeable to water
16
Q
ascending lib of the LoH
A
- thick
- cuboidal epithelium
- solute secretion (i.e Na)
17
Q
What are the 2 types of nephrons?
A
- cortical nephrons
2. jextamedullary nephrons
18
Q
cortical nephrons
A
- make up 85% of nephrons
- short loops
19
Q
juxtamedullary nephrons
A
- 15% (even though this is what we talk about the most)
- long loops
- have vasa recta
20
Q
characteristics of the DCT
A
- cuboidal cells
- lack microvilli (b/c not as much reabsorption occurring)
- empty to collecting duct
21
Q
peritubular capillaries arise from what?
A
the efferent arteriole
22
Q
function and characteristics of the peritubular capillaries
A
- surround the renal tubule
- low pressure and porous
- readily absorb water and solutes
- return fluid to the renal vein
23
Q
2 renal capillary beds
-function
A
- glomerulus
- produces filtrate - peritubular capillaries
- reabsorbs most of the filtrate
24
Q
What is the point of contact between the DCT and the afferent arteriole?
A
juxtaglomerular apparatus
25
what are the 2 cell populations that make up the juxtaglomerular apparatus?
- juxtaglomerular cells
| - macula densa
26
the juxtaglomerular apparatus functions to regulate what?
- blood volume
- BP
- GFR
27
juxtaglomerular cells (aka granular cells)
- where
- function
- in the afferent artery wall
| - enlarged smooth muscle cells that function to produce and store renin in granules
28
juxtaglomerular cells sense what?
low BP
29
what juxtaglomerular cells release renin in response to low BP, what is the effect?
- vasconstriction (systemic)
| - increases blood vol. which therefore increases BP
30
where is the macula densa located?
in the distal tubule
31
the macula densa is sensitive to what?
NaCl concentration in the late ascending limb
32
What is the outcome when the macula densa senses a decrease in NaCl concentration?
- vasodilation of afferent arteriole: this increases GFR
| - increase in renin release: increases blood vol. and pressure
33
what coalesce to form the collecting ducts?
DCTs
34
The epithelium of the collecting ducts consist of what 2 cell types?
1. principal cells (P cells)
| 2. intercalated cells (I cells)
35
principal cells of the collecting ducts function
- Na reabsorption
| - H2O reabsorption in response to vasopressin
36
intercalated cells of the collecting ducts function
- acid secretion
| - HCO3 transport
37
which cells have more microvilli and mitochondria, P or I?
I cells
38
vasopressin effect at the collecting duct
it opens pores creating an aquaporin to allow for a lot of water absorption
39
renal medullary interstitial cells (RMIC)
- where
- cell type
- in kidney interstitial tissue
| - specialized fibroblast like cells
40
RMICs produce what (2)
1. COX-2
- PG
- PGI2
2. Prostaglandin synthase (PGES)
- PGE2
41
what effect does the COX2 produced by the RIMCs have?
vasodilation and anti-coagulation
42
what effect does the PGES produced by the RIMCs have?
vasodilation
43
how much blood to the kidneys receive at rest?
- 1.2-1.3 L/min
- just under 25% of the CO
- under close systemic and intrinsic control
44
pressure throughout the system
- systemic
- glomerular
- peritubular
- renal vein
- mean systemic arterial pressure: 100 mm Hg
- glomerular capillary P: 45 mm Hg
- peritubular capillaries: 8 mm Hg
- renal vein P: 4 mm Hg
45
comparing glomerular capillary pressure to systemic arterial pressure
glomerular P is about 40% of the systemic arterial pressure
46
innervation of the kidney
SNS via the thoracic and lumbar sympathetic trunk
47
innervation of the adrenal glands
thoracic sympathetic trunk
48
What is the effect of the SNS on renal circulation in times of stress?
- stimulation of adrenal medulla --> release of NE
- beta 1 adrenergic receptors:
* juxtaglomerular cells release renin
* renal tubular cells reabsorb water and Na
- alpha-1 receptors:
* vasocontrict the arterioles
49
what mechanism is responsible for autoregulation of renal blood flow?
- myogenic mechanism
| - vascular smooth muscle tends to contract when stretched
50
how does the myogenic autoregulation mechanism work?
when BP increases, the afferent arteriole constricts to reduce the glomerular pressure
51
what makes up the tubuloglomerular feedback mechanism?
the macula densa cells of the JGA of the DCT
52
what does the tubuloglomerular feedback mechanism respond to?
- increased osmolality and flow
- this causes vasocontriction
- therefore slowing GFR and increasing processing time
(and vice versa)
53
EPO
- what
- prodcued by
- in response to
- protein hormone
- produced mainly by kidney interstiital cells (but also liver)
- in response to hypoxia
54
function of EPO
- circulates in response to hypoxia
- binds receptors on proeyrthroblasts in BM
- increases the production and maturation of RBCs
55
calcitriol
- aka
- what
- produced by
- aka 1,25 dihydroxyvitamin D3
- active form of vit. D
- produced by the kidney
56
calcitriol is produced in response to what?
PTH (increase in blood Ca)
57
what is the action of calcitriol?
- kidneys
- GI
- bone marrow
- kidneys: increase tubular reabsorption of Ca
- GI: increase absorption of Ca
- bone: release Ca from bone
