Book Questions Ch. 25 & 26 Flashcards
The lowest concentration of nitrogenous waste occurs in the
renal vein
The glomerular capillaries differ from other capillary networks in the body because they
are derived from and drain into arterioles
Damage to the renal medulla would interfere first with the functioning of the
collecting ducts
Which is reabsorbed by the proximal convoluted tubule cells?
Na+, K+, and amino acids
Glucose is not normally found in the urine because
glucose is reabsorbed by the tubule cells
Filtration at the glomerulus is inversely related to
capsular hydrostatic pressure
Tubular reabsorption
of glucose and many other substances is a Tm-limited active transport process
If freshly voided urine sample contains excessive amounts of urochrome, it has
a dark yellow color
Conditions such as diabetes mellitus and starvation are closely linked to
ketonuria
Which of the following is/are true about ADH?
it is secreted in response to an increase in extracellular fluid osmolality
Body water content is greatest in
infants
Potassium, magnesium, and phosphate ion are the predominant electrolytes in
intracellular fluid
Sodium balance is regulated primarily by control of amount(s)
excreted in urine
Water balance is regulated by control of amount(s)
ingested and excreted in the urine
Two main substances regulated by the influence of aldosterone on the kidney tubules
potassium and sodium
Two substances regulated by the parathyroid hormone
calcium and phosphate
Two substances secreted into the proximal convoluted tubules in exchange for sodium ions
ammonium ions and hydrogen ions
Part of an important chemical buffer system in plasma
bicarbonate
Two ions produced during catabolism of glutamine
ammonium ions and bicarbonate
Substance regulated by ADH’s effect on renal tubules
water
Which of the following factors will enhance ADH release?
decrease in ECF volume and increase in ECF osmolality
The pH of blood varies directly with
HCO-3
In an individual with metabolic acidosis, a clue that the respiratory system is compensating is provided by
rapid, deep breathing
What is the importance of perineal fat capsule that surrounds the kidney?
it cushions the kidney against blows and helps the kidney hold it in place
Trace the pathway a creatinine molecule takes from a glomerulus to the urethra. Name every microscopic or gross structure it passes through on its journey
A creatine molecule travels the following route from a glomerulus to the urethra. It first passes through the glomerular filtration membrane, which is a porous membrane made up of a fenestrated capillary endothelium, a thin basement membrane, and the visceral membrane of the glomerular capsule formed by the podocytes. The creatine molecule then passes through the proximal convoluted tubule, the loop of Henle, and the distal convoluted tubule, and into the collecting duct in which it travels into the medulla through the renal pyramids. From the medulla the molecule enters the renal pelvis, and leaves the kidney via the ureter. Then it travels to the urinary bladder and then to the urethra.
Explain the important differences between blood plasma and glomerular filtrate, and relate the differences to the structure of the filtration membrane
Renal filtrate is a solute-rich fluid without blood cells or plasma proteins because the filtration membrane is permeable to water and all solutes smaller than plasma proteins. The capillary endothelium restricts passage of formed elements, whereas the anion-rich basement membrane holds back most protein and some smaller anionic molecules.
Describe the mechanisms that contribute to renal autoregulation
The mechanisms that contribute to renal autoregulation are the myogenic mechanism and the tubuloglomerular feedback mechanism. The myogenic mechanism reflects the tendency of vascular smooth muscle to contract when it is stretched. An increase in systemic blood pressure causes afferent arterioles to constrict, which impedes blood flow into the glomerulus and prevents glomerular blood pressure from rising to damaging levels. Conversely, a decline in systemic blood pressure causes dilation of afferent arterioles and an increase in glomerular hydrostatic pressure. Both responses help maintain a normal GFR.
The tubuloglomerular mechanism reflects the activity of the macula densa cells in response to a slow filtration rate or low filtrate osmolarity. When so activated they release chemicals that cause vasodilation in the afferent arterioles.
Renal autoregulation maintains a relatively constant kidney perfusion over an arterial pressure range from about 80 to 180 mm Hg, preventing large changes in water and solute excretion.
Describe the mechanism of extrinsic regulation of GFR, and their physiological role
Sympathetic nervous system controls protect the body during extreme stress by redirecting blood to more vital organs. Strong sympathetic stimulation causes release of norepinephrine to alpha-adrenergic receptors, causing strong vasoconstriction of kidney arterioles. This results in a drop in glomerular filtration, and indirectly stimulates another extrinsic mechanism, the renin-angiotensin mechanism. The renin-angiotensin mechanism involves the release of renin from the granular juxtaglomerular cells, which enzymatically converts the plasma globulin angiotensinogen to angiotensin I. Angiotensin I is further converted to angiotensin II by angiotensin converting enzyme (ACE) produced by capillary endothelium. Angiotensin II causes vasoconstriction of systemic arterioles, increased sodium reabsorption by promoting the release of aldosterone, decreases peritubular hydrostatic pressure, which encourages increased fluid and solute reabsorption, and acts on the glomerular mesangial cells, causing a decrease in glomerular filtration rate. In addition, angiotensin II results in stimulation of the hypothalamus, which activates the thirst mechanism and promotes the release of antidiuretic hormone, which causes increased water reabsorption in the distal nephron. Other factors that may trigger the renin-angiotensin mechanism are a drop in mean systemic blood pressure below 80 mm Hg, and activated macula densa cells responding to low plasma sodium.
Describe what is involved in active and passive tubular reabsorption
Active tubular reabsorption requires ATP
Passive tubular encompasses diffusion, facilitated diffusion, and osmosis
Explain how the peritubular capillaries are adapted for receiving reabsorbed substances
Peritubular capillaries are low pressure, porous capillaries that readily absorb solutes and water from the tubule cells as these substances are reclaimed from the filtrate.
Explain the purpose of tubular secretion
The purpose of tubular secretion is to eliminate drugs, certain wastes, and excess ions and in maintaining acid-base balance of the blood.
How does aldosterone modify the chemical composition of urine
Aldosterone targets the principal cells of the collecting ducts and cells of the distal portion of the DCT.
As a result, little or no Na+ leaves the body in urine.
Explain why the filtrate become hypotonic (lower osmotic pressure) as it flows through the ascending limb of the nephron loop.
As it flows through the ascending limb of the loop
of Henle, the filtrate becomes hypotonic because it is impermeable to water, and because sodium and chloride are being actively pumped into the interstitial fluid, thereby decreasing solute concentration in the tubule. The interstitial fluid at the tip of the loop of Henle and the deep portions of the medulla are hypertonic because:
(1) the loop of Henle serves as a countercurrent multiplier to establish the osmotic gradient, a process that works due to the characteristics of tubule permeability to water in different areas of the tubule and ion transport to the interstitial areas
(2) the vasa recta acts as a countercurrent exchanger to maintain the osmotic gradient by serving as a passive exchange mechanism that removes water from the medullary areas but leaves salts behind. The filtrate at the tip of the loop of Henle is hypertonic due to the passive diffusion of water from the descending limb to the interstitial areas.
How does the urinary bladder anatomy supports its storage function?
When empty, the bladder collapses into its basic pyramidal shape & its wall are thick and thrown into folds(rugae).
As urine accumulates, the bladder expands, becomes pear shaped, and rises superiorly in the abdominal cavity.
The muscular wall stretches and thins, the rugae disappear.
These changes allow the bladder to store more urine w/o a significant rise in internal pressure.
Define micturition and describe the micturition reflex
Micturition (a.k.a urination) is emptying of the bladder.
Micturition reflex is stretching of the bladder wall.
Describe the changes that occur in kidney and bladder anatomy and physiology in old age.
Three sets of kidneys develop from intermediate mesoderm.
With age, nephrons are lost, the filtration rate decreases, and tubule cells become less efficient at concentrating urine.
Bladder capacity and tone decrease with age
