Overview, Structure and Function of the Kidney Flashcards
What is the key to maintaining homeostatsis?
the kidney, it regulates or balances intake with excretion and excretes metabolic wastes and drugs
T/F. Renal function is dynamic or constantly changing.
True.
What are the functions of the kidney?
- elimination of metabolic waste (urea)
- regulation of water (via osmosis) and salts
- removal of foreign chemicals (drugs)
- gluconeogenesis
- production of hormones
What hormones are produced by the kidney?
- erythropoietin - acts in the bone marrow to stimulate syntesis of new erythrocytes
- renin - part of the renin-angiotensin-aldosterone cascade to regulate blood pressure
- 1,25-dihydroxyvitamin D - regulate calcium absorption
T/F. Of the 28 liters of total body water, the kidneys look at the 15 liters that is in the plasma.
False, Of the 28 liters of total body water, the kidneys look at the 3 liters that is in the plasma.
End stage renal disease (ESRD) can be acute or chronic. Which requires hemodialysis?
chronic ESRD
ESRD patients have a reduced ability to eliminate nitrogenous wastes and excess ___ is converted to ___. How does this excess product effect the patient’s health.
nitrogen; ammonium
the blood is alkalized which leads to an increased pH in the oral cavity
What are some manifestations of renal disease on oral health?
ammonia breath
gingival enlargement
xerostomia
tooth problems (premature loss, narrowing pulp chambers, necrosis beneath fillings or crowns)
What are contraindications for ESRD patients?
- nephrotoxic drugs such as tetracycline, acyclovir, aspirin, and NSAIDs
- increased susceptibility to bleeding due to destruction of platelets
The kidney is a ___ organ in the abdominal cavity with an outer ___ and inner ___.
retroperitoneal; cortex; medulla
What are the functional units of the kidney?
nephrons
In the renal ___, blood is filtered in the ___ and filtrate passes through tubule of nephron.
cortex; glomerulus
In the renal ___ there are portions of nephron tubule involved with concentration and collection of ___.
medulla; urine
Tubules empty into the renal ___ and then into ___, which drain into the urinary bladder and the bladder is drained by the ___.
pelvis; ureter; urethra
T/F. Each kidney contains ~1.2 x 10^6 nephrons.
True.
T/F. A nephron includes a cluster of capillaries and a long, hollow tube with a wall that is several cell layers thick.
False, A nephron includes a cluster of capillaries and a long, hollow tube with a wall that is ONE cell layer thick.
What does the renal corpuscle include? What structures follow it?
glomerulus and capsule
proximal (convoluted) tubule, loop of Henle, distal (convoluted) tubule, collecting duct (shared by several nephrons)
Describe the superficial or cortical nephrons.
- the glomerulus is at the top of the cortex and the loop of Henle doesn’t go deep into the medulla
- its filtrate is not as concentrated
- it is the majority of nephrons in humans
Describe the juxtamedullary nephron.
- it sits close to the cortex/medualla junction with its loop of Henle deep in the medulla
- concentrates the filtrate to a greater degree
During ___, the solutes (and the water they are dissolved in) pass from the blood into the tubular fluid in the renal ___.
filtration; capsule
Where does filtration occur? How much plasma is filtered?
glomerular capillaries
15-20%
Where does blood leaving the glomerular capillaries flow?
via efferent arterioles into the peritubular capillaries (vasa recta) to the vein
What process occurs when substances are transported from the blood in the peritubular capillaries that are surrounding the convoluted tubules into the tubular fluid?
secretion
What process occurs when substances are transported from the tubular fluid into the blood into the peritubular capillaries?
reabsorption
T/F. Secretion and absorption occur throughout the length of the tubules.
True.
What happens in each scenario:
- X is filtered and secreted, but not reabsorbed
- Y is filtered and some of it is reabsorbed
- Z is filtered and completely reabsorbed
- all is excreted into the urine
- small bit is excreted
- none is excreted
The ___ is a dense capillary bed where filtration occurs surrounded by ___ ___ (or Bowman’s capsule), which collects the filtrate from the blood entering via the ___ arterioles.
glomerulus; renal capsule; afferent
T/F. Blood flow through the glomerulus is regulated by smooth muscle contraction in afferent AND efferent arterioles.
True.
The ___ ___ is located at the intersection of the ___ ___ of the distal tubule with afferent and efferent arterioles.
juxtaglomerular apparatus; macula densa
The JGA secretes the hormone ___. What is its function?
renin - regulates systemic blood pressure, and therefore, glomerular blood flow
Blood flow through the glomerulus is regulated by the ___ nervous system associated with ___ neurons. It constricts the arteriolar smooth muscles to ___ blood flow through the glomerulus.
sympathetic; afferent; decrease
The proximal convoluted tubule drains the renal capsule. what is reabsorbed?
- 2/3 of the filtered salt and water is returned to blood and peritubular capillaries
- reabsorbs all filtered glucose and amino acids and returns them to blood and peritubular capillaries
What are the three limbs of the loop of Henle?
- thin descending limb
- thin ascending limb
- thick ascending limb
These differences depend on the nature of epithelial cells (size, shape, and function)
T/F. The loop of Henle is the site of countercurrent multiplication needed to produce concentrated urine, but the loop itself produces a dilute filtrate. Very powerful diuretics work in the loop.
True, it creates an osmotic gradient which can be used to concentrate urine (it doesn’t concentrate urine itself)
The ___ tubule drains the loop of Henle and continues ___ of solutes and regulation of ___.
distal; reabsorption; calcium
The ___ ___ collects fluid from multiple nephrons and extends from the ___ through the ___. It regulates ___, ___, and water.
collecting duct; cortex; medulla; sodium; potassium
What is the rate of excretion of a solute through the kidney, expressed as amount per unit time or amount per volume of blood?
renal clearance
Renal clearance can be used to measure ___ ___ ___ based on what three criteria?
glomerular filtration rate
- the substance must be freely filtered in the glomerulus
- the substance is not secreted
- the substance is not reabsorped
What is the GFR in a normal kidney?
125ml/min or 180L/day
125ml/min (females) and 90-140 ml/min (male)
What substances are used to measure GFR?
inulin and creatinine
___ is a small polysaccharide that is freely filtered and not secreted or absorbed.
Inulin
___ is a product of muscle metabolism that is freely filtered, not reabsorbed with almost no secretion. What are its normal levels?
Creatinine
less than 1+/-0.5mg/dl
if greater than 10 then patient requires dialysis
Glomerular capillaries are ___ with ___ (cells) around the capillaries forming ___ slits.
fenestated; podocytes; filtration
What is acellular and essentially protein-free?
filtrate
What is freely filtered? What is this dependent upon?
glucose, salts, and amino acids
size is a factor: 42 A not filtered
charge is a factor
The ___ ___ (basement membrane) is ___ charged so filtration of moderately sized, negatively-charged solutes is limited.
basal lamina; negatively
___ occurs due to pressure differences between the blood in the ___ and the fluid in the ___. Pressure comes from what two sources?
Filtration; capillaries; capsule
hydrostatic pressure (pressure due to fluid) P in capillaries is > P in capsule fluid
oncotic pressure (pressure due to solutes in fluid (including those not dissolved)) π in capillaries > π in capsule fluid
What does net filtration pressure favor? What is affected by blood flow into and out of the glomerulus? What is critical to maintain filtration?
filtration from the blood into the capsule fluid
GFR
P gradient
T/F. Despite changes in systemic blood pressure, renal blood flow (RBF) remains fairly constant (as does GFR).
True.
How is autoregulation achieved?
- myogenic interactions
2. tubuloglomerular feedback
Explain the myogenic mechanism.
vascular smooth muscle tends to contract when it is stretched and constricted or dilation of smooth muscle in afferent or efferent arterioles has contrasting effects on RBF
Explain the tubuloglomerular feedback.
feedback from the JGA adjusts afferent arteriole diameter and, thus, GFR
↑ systemic BP → ↑ GFR → ↑ ___ in tubular fluid → ↑ ___ at macula densa → ↑ resistance in ___ arterioles → ↓ GFR
NaCl; NaCl
afferent
What extrinsic factors regulate RBF and GFR?
- diet
- dehydration or hemorrhaage
- sympathetic nervous system
- angiotensin II, aldosterone, and natriuretic peptide
