The kidney is referred to as an excretory organ because it excretes nitrogenous wastes.
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It is also a major homeostatic organ because it maintains the electrolyte, fluid and acid-base balance of the blood.
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Urine is continuously formed by the kidneys and is routed down the ureters by the mechanism of peristalsis to a storage organ called the bladder
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Eventually, the urine is conducted to the body exterior by the urethra.
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In the male, the urethra is 20 centimeters long and transports both urine and sperm
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The female urethra is 4 centimeters long and transports only urine.
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Voiding or emptying the bladder is
called micturation
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Voiding has both voluntary and involuntary components.
The voluntary sphincter is the external sphincter.
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An inability to control this sphincter is referred to as incontinence
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Hypertonic
the concentration of solutes is greater outside the cell than inside it
** high solute
Hypotonic
the concentration of solutes is greater inside the cell than outside of it
** low solute
Isotonic
the concentration of solutes is the same both inside and outside of the cell
Osmoregulation
The process of regulating water potential in order to keep fluid and electrolyte balance within a cell or organism relative to the surrounding
Osmolarity
The osmotic concentration of a solution expressed as osmoles of solute per liter of solution.
*** affected by solute
More solute more osmotic pressure
Less solute less osmotic pressure
Excess potassium ion is eliminated from the body by?
Tubular secretion
In the presence of ADH (anti diuretic hormone) one would produce concentrated or diluted urine?
more concentrated
Bowman's capsule and the glomerulus make up the?
renal corpuscle
Why is incontinence a normal phenomenon in the child under 11⁄2 to 2 years old?
Because they have not yet gained muscle control over their external spincter
What events may lead to its occurrence in the adult?
-Spinal cord injury
-emotional problems
-bladder irritability
-or some other pathology of the urinary tract
smooth membrane, tightly adherent to the kidney surface on
fibrous capsule
portion of the kidney containing mostly collecting ducts
medulla
portion of the kidney containing the bulk of the nephron structures
cortex
superficial region of kidney tissue
cortex
basinlike area of the kidney, continuous with the ureter
renal pelvis
a cup-shaped extension of the pelvis that encircles the apex of a pyramid
minor calyx
area of cortical tissue running between the medullary pyramids
renal column
site of filtrate formation
glomerulus
primary site of tubular reabsorption
proximal convoluted tubule
secondarily important site of tubular reabsorption
distal convoluted tubule
structure that conveys the processed filtrate (urine) to the renal pelvis
distal convoluted tubule
blood supply that directly receives substances from the tubular cells
peritubular capillaries
its inner (visceral) membrane forms part of the filtration membrane
glomerular capsule
In vertebrates (humans) where is urea produced?
-liver from NH3 and CO2
Urea is produced when ammonia (NH 3 ) is combined with……?
CO2
How does its high-pressure condition in the glomerulus aid its function of filtrate formation?
The higher the capillary pressure, the more filtrate will be formed.
The basic functional unit of the kidney is the?
nephron
Compare and contrast the composition of blood plasma and glomerular filtrate?
-B lood plasma → contains red and white blood cells, blood proteins, glucose, water, nitrogenous waste and salts.
-Glomerular filtrate → contains everything blood plasma does without most of the blood proteins
Explain the mechanism of tubular secretion, and explain its importance in the urine formation process?
- Tubular secretion is the reverse process of tubular reabsorption. Substances such as hydrogen and potassium ions and creatinine move either from the blood of the peritubular capillaries through the tubular cells or from the tubular cells into the filtrate to be disposed of in the urine. This process is important for the disposal of substances not ready in the filtrate and as a device for controlling blood pH
Compare and contrast the composition of blood plasma and glomerular filtrate?
B lood plasma → contains red and white blood cells, blood proteins, glucose, water, nitrogenous waste and salts.
-Glomerular filtrate → contains everything blood plasma does without most of the blood proteins
The outermost layer of kidney tissue is the?
-Renal cortex
List components of urine from a healthy person?
-Healthy urine consists of water, ammonia, potassium, hydrogen, little sodium, little creatine, little uric acid and urea and little bilirubin, if any of these substance is present in too much (or to little) quanity then it becomes unhealthy. Substances not normally in urine-glucose, protein, RBC, WBC and hemoglobin.
Trace a drop of blood from the time it enters the kidney via the renal artery until it leaves the kidney through the renal vein.
Renal Artery to segmental artery lobar artery interlobar artery arcuate artery interlobular artery afferent arteriole glomerulus efferent arteriole peritubular capillary bed interlobular vein arcuate vein interlobar vein
In response to a drop in overall blood pressure, ___ stimulates constriction of the glomerular inlet and even greater constriction of the outlet?
angiotensin II
The process of urine formation involves…?
- filtration of the plasma, reabsorption from the filtrate, and the secretion into the filtrate
What is important functionally about the specialized epithelium (transitional epithelium) in the bladder?
- The cells can slide past one another giving the tissue the ability to stretch and recoil as the bladder fills and empties
Atrial natriuretic peptide reduces blood volume and pressure by?
- Increasing glomerular filtration rate
-Inhibiting rennin and aldosterone secretion
-Inhibiting the action of ADH on the kidney
-Inhibiting NaCl reabsorption by the collecting duct
An interplay between calcium reserves in the bone, the rate of absorption, and the rate of excretion reflects calcium homeostasis. Explain this?
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Calcium reabsorption by the kidneys is promoted by the hormone?
parathyroid hormone
Trace the anatomical pathway of a molecule of creatinine (metabolic waste) from the glomerular capsule to the urethra. Note each microscopic and/or gross structure it passes through in its travels. Name the subdivisions of the renal tubule.
Glomerular Capsule → Proximal Convulated Tubule → Loop of Henle → Distal Convulated Tubule → Collecting Tubule → Papillary Duct → Minor Calyx → Renal Pelvis → Ureter → Bladder → Urethra
Explain why urinalysis is a routine part of any good physical examination?
Finding "abnormal" constituents in the urine may indicate pathology
Presence of glucose in the urine is indication of…?
- Glycosuria
- causes could be excess carbohydrate intake of diabetes mellitus
Substances larger than ________ are normally not allowed to pass through the filtration membrane?
albumin
In the presence of ADH (anti diuretic hormone)urine production increases or decreases?
*** decreases
Which has a greater specific gravity: 1 ml of urine or 1 ml of distilled water?
Explain your answer why?
- URINE; BECAUSE IT CONTAINS DISSOLVED SOLUTES, WHICH ARE NOT FOUND IN DISTILLED WATER AND ADD TO THE DENSITY OF THE SAMPLE
How does a urinary tract infection influence urine pH?
alkaline
Urine is carried to the urinary bladder by?
the ureters
Name the primary nitrogenous waste product in humans?
Urea
Glucose and albumin are both normally absent in the urine, but the reason for their exclusion differs.
Explain the reason for the absence of glucose?
Explain the reason for the absence of albumin?
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Name the three major nitrogenous wastes found in the urine?
Uric acid
-Urea
-creatine
List functions of the kidneys?
-They filter blood plasma
-They regulate blood volume and pressure by eliminating or conserving water
-They regulate the osmolarity of the body fluids by controlling the relative amounts of water and solutes
-They secrete rennin
-They secrete erythropoietin
-They collaborate with the lungs to regulate the concentration of CO2 and the acid–base balance
-They carry out the final step in synthesizing calcitriol and thereby contribute to calcium homeostasis
The blood-filtering structure of the kidney is called the?
Glomerulus
The primary function of the proximal convoluted tubule is?
-absorption of ions
-organic molecules
-Vitamins
-water
Why is glucose in the urine an indicator of diabetes mellitus?
-when blood glucose is very high, the filtered glucose occupies all the transport carriers and it is no longer reabsorbed
Nitrogenous waste product is a by product of….?
Protein metabolism
The expanded end of the ureter forms the?
-renal pelvis
The innermost layer of kidney tissue is the?
-renal medulla
Tubular reabsorption involves what kind of transportation?
- active transport
-facilitated diffusion
-cotransport
-countertransport
What type of response by the afferent arterioles would you expect if blood pressure increased?
The afferent arterioles would constrict
A glomerulus is?
-the network of capillaries found inside the corpuscle
The urine-forming units of the kidney are the?
- nephrons
What is Gout?
a common type of arthritis
What leads to Gout i.e. what is the cause of Gout?
-Gout is caused by a build-up of uric acid in the body. Uric acid is a waste product that is produced during the process of metabolism (when the body breaks down food to use as energy).
Byproduct of protein catabolism that constitutes approximately one-half of all nitrogenous waste is…..?
-urea
The function of calcitonin is to?
Decreases Blood Calcium by causing Ca to move from blood into bone
What would be the effect on urine output if sodium channels in the tubule cells were inhibited?
The volume would increase
All urine specimens become alkaline and cloudy on standing at room temperature. Explain why?
-This is a result of bacterial metabolism of urinary components
Explain the mechanism of tubular secretion, and explain its importance in the urine formation process?
- Tubular secretion is the reverse process of tubular reabsorption. Substances such as hydrogen and potassium ions and creatinine move either from the blood of the peritubular capillaries through the tubular cells or from the tubular cells into the filtrate to be disposed of in the urine. This process is important for the disposal of substances not ready in the filtrate and as a device for controlling blood pH
A renal pyramid voids urine into?
the minor calyx
The process of filtration occurs at?
corpuscle of nephron
Which of the following processes in urine formation is important for regulating blood pH: Filtration; Secretion; reabsorption? Why?
-Secretion
The functional unit of kidney is called what?
-nephron
What is the advantage of excreting nitrogenous wastes as urea rather than as ammonia?
-urea is less toxic than ammonia
List factors that contribute(s) to the higher filtration rate in the glomerular capillaries compared with other capillary beds?
- glomerular capillaries are fenestrated
- the diameter of the efferent arteriole is smaller than the diameter of the afferent arteriole
- the visceral layer of the glomerular capsule is very porous
How would eating a high-protein diet affect filtration?
Due to higher colloid osmotic pressure in the glomerular blood, the net filtration pressure would be lower and less filtrate would form
Blood plasma is filtered in which portion of the nephron?
- renal corpuscle
How urinary system does regulate body pH?
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List substances that are found in plasma but would not be found in normal filtrate?
proteins
The portion of the nephron closest to the renal corpuscle is the?
-proximal convoluted tubule
Drinking too much alcohol results in a headache the next day. Why does this happen?
-Alcohol inhibits ADH secretion
Conical-shaped structures that are located in the renal medulla are called?
-pyramids
What is the function of reabsorption?
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Materials are returned to the blood from the filtrate by…… process?
-selective reabsorption
Substances and molecules move out of capillaries into the corpuscle space due to….?
-pressure differences
The transfer of fluid from the glomerulus to Bowman's capsule (corpuscle space) is mainly due high pressure in the……?
glomerulus capillaries
Why is the osmolarity of medullary fluid in the kidney almost four times higher than the osmolarity of plasma?
- loop of Henle acts as a countercurrent multiplier and contributes solutes to the interstitial fluid & urea is recycled from the collecting duct and is transported to the interstitial fluid
** anatomical structure of loop of Henle
- Glucose and amino acids are reabsorbed from the glomerular filtrate by the….convoluted tubule?
the proximal convoluted tubule
How does ADH contribute to the formation of concentrated urine?
-ADH increases the permeability of the collecting duct to water by stimulating the insertion of aquaporins into the luminal membrane
When stimulated by aldosterone, the reabsorption of Na+ is increased along which tubule of nephron?
-the distal tubule
Increased ADH secretion is most likely when…….?
-sweating-induced dehydration increases plasma osmolarity
Why human urine more acidic is i.e. what makes it acidic?
Presence of hydrogen ions
What is the advantage of urine being acidic?
To act as a nonspecific defense
Why the kidneys have one of the highest metabolic rates of all body organs?
-it operates an extensive set of active-transport ion pumps
Alcoholic beverages, increased urine excretion because….?
-inhibited secretion of antidiuretic hormone (ADH)
What role do the vasa recta play in urine formation?
-it removes solutes and water
-balances solute reabsorption and osmosis in the medulla
The portion of the nephron that attaches to the collecting duct is the?
-distal convoluted tubule
When considering drug administration, why is it important to know the renal clearance rate of the drug?
-It dictates the dosage and frequency of administration of drugs
Suppose 3 friends decide to an experiment on themselves. One person drinks 1 liter water, a second person drinks 1 liter of beer, and a third drinks 1 liter of concentrated salt solution. They monitor their urine production for several hours. Explain who will you expect to have the greatest and who will you expect to have the least amounts of urine, respectively? Explain why?
beer- most urine
salt - less urine
The process of voiding the bladder is called?
micturition
Antidiuretic hormone (ADH) functions at the cellular level by causing an increase in the number of…..?
- aquaporin molecules of collecting duct cells
The largest solute component of urine…….?
-Urea
Urine is produced by which organ of urinary system?
kidneys
A patient feels radiating pain from the side of her body to the anterior abdominal wall. An MRI shows a bulging renal pelvis. Which is the most likely cause?
-A kidney stone lodged in the ureter
What features of the bladder predispose it to being able to stretch and relax repeatedly?
- the walls are highly folded into rugae and the epithelium is transitional
What is the functional difference between a male urethra and a female urethra?
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The “U” shape structure of the nephron tubules is called?
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Micturition is another term for?
the elimination of urine
Aldosterone promotes ……..retention in the kidneys?
sodium retention
Explain why the glomerulus is such a high-pressure capillary bed?
-Both fed and drained by arterioles; the afferent arterioles has a larger diameter than the efferent
How does its high-pressure condition aid its function of filtrate formation?
-the higher the capillary pressure, the more filtrate will be formed