A&P II: 26 & 27
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What is the urinary system composed of?
- 2 kidneys
- 2 ureters
- 1 urinary bladder
- 1 urethra
Function(s) of the Urinary System:
- The kidneys regulate blood volume and composition, help regulate blood pressure, sunthesize glucose, relese etythropoietin, participate in vitamin D synthesis, and exrete wastes by forming urine.
- The ureters transport urine from the kidneys to the bladder.
- The urinary bladder stores urine.
- The urethra discharges urine from the body.
Function(s) of the kidneys:
- Regulation of blood ionic composition
- Regulation of blood pH
- Regulation of blood volume
- Regulation of blood pressure
- Maintenance of blood osmolarity
- Production of hormones
- Regulation of blood glucose level
- Excretion of wastes and foreign substances
The kidneys produce 2 hormones:
- Calcitriol (the active form of vitamind D)
- Erythropoietin (stimulates the production of red blood cells)
Kidneys are considered what kind of organs?
Retroperitoneal organs (b/c it is behind the peritoneum of the abdominal cavity)
A typical adult kidney is ____ long, _____ wide, and __ thick. It is about the size of a bar of soap. It had a mass of ___ oz.
- 4-5 in long
- 2-3 in wide
- 1 in thick
- 4.5-5 oz
Near the center of the concave border of the kidney is and indentation called the __________, through which the ureter emerges from the kidney alond with blood vessels, lymphatic vessels, and nerves.
Name the 3 layers that surround each kidney from deep to superficial:
- Renal capsule
- Adipose capsule
- Renal fascia
The deep layer of the kidney. It is a smooth, transparent sheet of dense irregular connective tissue that is cotinuous with the outer coat of the ureter. It serves as a barrier against trauma and helps maitain the shape of the kidney.
The middle layer of the kidney. It is a mass of fatty tissue surrounding the renal capsule. It also protects the kidney from trauma and holds it firmly in place within the abdominal cavity.
The superficial layer of the kidney. A thin layer of dense irregular connective tissue that anchor the kidney to the surrounding structures and to the abdominal wall.
The frontal section through the kidney reveals two distinct regions:
- Renal Cortex (a superficial, light red area)
- Renal Medulla (a deep, darker reddish-brown inner region)
The medulla consist of several cone-shaped _____. The apex of these structures are called _____.
- Renal Pyraminds
- Renal Papilla
The kidney has 2 zones:
- Cortical zone (outer)
- Juxtamedullary zone (inner)
Portions of renal cortex that extend between renal pyramids are called ______.
A ____ consists of a renal pyraminds, its overlying area of renal cortex, and 1/2 of each adjacent renal column.
Together, renal cortex + renal pyramids = ______
Within each kidney, there are 1 million _____. They're considered th functional units of the kidney.
Urine formed by the nephrons drain into large ____, which extend thru the renal papilla.
After papillary ducts, the urine is drained into cuplike structures called ___ & ____ _____. How many of each?
- Minor Calyces (8-18)
- Major Calyces (2-3)
Minor Calyx > Major Calyx > ? > ? > ?
- Renal Pelvis
- Urinary Bladder
Kidneys receive __% of the resting cardiac output via the left and right ____ ____.
The blood flow thru the kidneys is considered, ______. About ___ per minute.
- Renal Blood Flow
Nephrons consist of two parts: (Function?)
- Renal Corpuscle (where blood is filtered)
- Renal Tubule (where filtered fluid passes)
2 components of Renal Corpuscle:
- Glomerular (Bowman's) Capsule
Renal Tubule consists of:
- Proximal Convoluted Tubule
- Loop of Henle (Nephron loop)
- Distal Convoluted Tubule
What part of the nephron lies in the cortex? medulla?
- Cortex: Renal Corpuscle, PCT and DCT
- Medulla: Loop of Henle
The distal convoluted tubules of several nephrons empty into a single ______.
Collecting duct unite and converge into several hundred large ______, wich drain into the _____.
- Papillary Ducts
- Minor Calyx
Kidneys hold 1 million ______ per kidney.
1 million nephrons per kidney.
About 80-85% of nephrons are ____. Their renal copuscle lies in ____, and they have a ____ loop of Henle. They receive their blood supply from peritubular capillaries that arise from ____.
- Cortical Nephrons
- Outer portion of the renal cortex
- Efferent Arterioles
15-20% of nephrons are ___. Their renal corpuscle lies _____ and they have a ___ loop of Henle. They receive blood from the peritubular capilllaries and from _____.
- Juxtamedullary Nephrons
- Deep in cortex, close to medullary
- the Vasa Recta that arise from efferent arterioles
Nephrons with ____loops of Henle enable the kidneys to excrete ___ or ___ ___.
- Very dilute or very concentrated urine
The glomerular (Bowman's) capsule consists of visceral and parietal layers. The visceral layer consists of ____. The parietal layer consists of ____.
- Podocytes - modified simple squamos epithelium
- Simple squamos epithelium
Name th 2 different types of cells present in the distal convoluted tubule (DCT) and collecting ducts:
- Principal Cells
- Intercalated Cells
To produce urine, nephrons and collecting ducts perform three basic processes:
- Glomerular Filtration
- Tubular Reabsorption
- Tubular Secretion
On average, the daily volume of glomerular filtrate in adults is ____ liters in females and ____ liters in males.
- 150 liters of filtrate/day (females)
- 180 liters of filtrate/day (male)
More than 99% of glomerular filtrate returns to bloodstream via tubular reabsorption, so only ____ liters are excreted as urine.
What are the 3 barriers thru which filtration occurs in the glomerulus?
- Glomerular endothelial cells
- Basal Lamina
- a filtration slit formed by a Podocyte
As a barrier, ____ are quite leaky because they have large _____ (pores) that measure 0.07-0.1um in diameter. This size pemits ____ in blood plasma to exit capillaries but prevents filtration of ___ and ____.
- Glomerular endothlial cells
- All solutes
- Blood cells & Blood platelets
These contractile cells help regulate glomerular filtration:
Mesangial cells (contract > GFR decreases)
This layer in the glomerulus prevents filtration of larger plasma proteins. It consists of minute collagen fibers & proteoglycans in a glycoprotein matrix.
Extending from each podocyte are thousands of foot-like processes called _____. It forms ____.
Pedicels allow the passage of molecules having a diameter smaller than 0.006-0.007um, including water, glucose, vitamins, ____, very small ___, ammonia, urea and ____.
- Amino Acids
- Plasma Protein
Glomerular filtration depends on 3 main pressures.
1 ____ filtration & 2 ____ filtration. (List them)
- 1 Promotes: Glomerular Blood Hydrostatic Pressure (GBHP)
- 2 Opposes: Capsular Hydrostatic Pressure (CHP) & Blood Colloid Osmotic Pressure (BCOP)
List the pressures in the Bowman's capsule:
- GBHP (55mmHg) OUT
- CHP (15mmHg) IN
- BCOP (30mmHg) IN
The total pressure that promotes filtration. What is the average? What is the formula?
- Net Filtration Pressure (NFP) 10mmHg.
- NFP (10) = GBHP (55) - CHP (15) - BCOP (30)
How many gallons of filtrate is made per day?
- 40 gallons of filtrate per day (females)
- 50 gallons of filtrate per day (males)
The amount of filtrate formed in all the renal corpuscles of oth kidneys each minute is ____. It averages ___ gal/day.
- Glomerular Filtration Rate (GFR)
- 40-50 gal/day
The mechanisms that regulate glomerular filtration rate in two main ways:
- By adjusting blood flow into and out of the glomerulus
- By altering the glomerular capillary surface area available for filtration
3 mechanisms control GFR:
- Renal Autoregulation
- Neural Regulation
- Hormonal Regulation
This capability helps the kidney maintain a constant renal blood flow and GFR despite normal, everyday changes n blood pressure.
Renal autoregulation consists of two mechanisms:
- Myogenic Mechanism
- Tubuloglomeular Feedback
Occurs when stretching triggers contraction of smooth muscle cells in the walls of afferent arterioles.
Normalizes renal blood flow and GFR within seconds
The 2nd contributor to renal autoregulation, ______, is named so because part of the renal tubules (macula densa) provides feedback to the glomerulus.
Like most blood vessels of the body, those of the kidneys are supplied by _____ ANS fibers that release ______.
Norepinephrine causes ______.
What are the two consequences of lowering renal blood flow?
- Reduces urine output, which help conserve blood volume
- Permits greater blood flow to other body tissue
2 hormones contribute to regulation of GFR. How?
- Angiotensin II: reduces GFR
- Atrial Natriuretic Peptide (ANP): increases GFR
This hormone is a very potent vasoconstrictor that narrows both afferent and efferent arterioles and reduces renal blood flow, thereby decreasing GFR.
Stretching of the atria, as occurs when blood volume increases, stimulates secretion of ___. By causing relaxation of the glomerular mesangial cells, ___ increases the capillary surface area available for filtration. (GFR ^, surface area ^)
ANP (Atrial Natriuretic Peptide)
Normally, about __% of filtered water is reabsorbed
Reabsorption that occurs between cells?
Reabsorption that occurs through cells?
- Paracellular Reabsorption: between cells
- Transcellular Reabsorption: through cells
Water reabsorbed with solutes in tubular fluid is termed ____, bcause water is "obliged" to follow the solutes.
Obligatory water reabsorption
Where does obligatory water reabsorption occur? How much water is reabsorbed?
- PCT & descending loop of Henle
Reabsorption of the final 10% of water is termed ______. Where does it occur?
- Facultative water reabsorption
- Occurs mainly in the collecting ducts
The largest amount of solute and water reabsorption from filtered flud occurs in the:
PCT (proximal convoluted tubule)
Reabsorbed in the PCT:
65% of ____, ____, and ____.
__% of other "stuff".
- Water, sodium, and potassium
Although 15% of water is reabsorbed in ___ limb (loop of Henle), no water is reabsorbed in the ___ limb.
By the time fluid reaches the end of the DCT, __%of filtered substances and water have returned to the blood.
There are 2 different types of cells present at the late or terminal part of the DCT. (Function?)
- Principal Cells: reabsorb sodium and potassium
- Intercalated Cells: reabsorb potassium and hydrochloric acid. Secrete hydrogen.
When blood volume and blood pressure decreases, the walls of the afferent arterioles are stretched less and the JGA cells secrete the enzyme ___ into the blood. Why?
Renin: clips off a 10-amino-acid peptide called Angiotensin I from Angiotensinogen.
(2) Angiotensin I + ___ = Angiotensin II
ACE (Angiotensin Converting Enzyme)
A hormone that stimulates the principal cells in collecting ducts to reabsorb more sodium and chloride and secrete more potassium.
Released by the posterior pituitary. This hormone regulates facultative water reabsorption by increasing the water permeability of principal calls in the last part of DCT and collecting ducts.
ADH (antidiuretic hormone)
This hormone increases the excretion of sodium in urine (natriuresis) and increases urine output (diuresis),which decreases blood volume and blood pressure. Relaxes mesangial cells.
ANP (Atrial natriuretic peptide)
This hormone increases rebsoprtion of calcium. (Released by the parathyroid gland)
PTH (Parathyroid Hormone)
The ureters are __in long and are thick-walled, narrow tubes that vary in diameter but usually __in
- 10-12in long
- 0.5 in diameter
3 layers of tissue form the walls of the ureters: (deep to superficial)
Urinary bladder capacity averages __. It is smaller in females because the uterus occupies the space just superior to the urinary bladder.
1 quart (700-800mL)
The female urethra is _in in length and __in in length for males.
The male urethra is divided ino 3 regions:
- Prostatic urethra
- Membranous urethra
- Spongy urethra (longest portion)
About 2/3 of body fluidis is ___ or ____. The other 1/3 is _____.
- Intracellular fluid (ICF) or cytosol
- Extracellular fluid (ECF)
About 80% of the ECF is ____, and 20% is ____. (Function?)
- Interstitial fluid (ISF): fluid between cells
- Plasma: liquid portion of blood
Lymph fluid, cerebrospinal fluid, synovial fluid, aqueous humor and vitreous body, endolymph and perilymph are under which category of fluid?
Interstitial fluid (ISF)
Two general barriers seperate intracellular fluid, interstitial fluid, and blood plasma:
- Plasma membrane
- Blood vessel walls
Only in ___, are the walls thin enough to permit the exchange of waters and solutes between blood and interstitial fluid.
Lymph vessels return __ liters of fluid per day
What 4 processes allow continual exchange of water and solutes among body fluid compartments?
What is the prmary means of water movement?
What two ways are used by the body to gain water?
- Metabolic synthesis
Daily water gain from these 2 processes is about __ mL. How?
- Ingestion (main source): ingested liq (1600mL) + moist foods (700mL) = 2300mL/day
- Metabolic synthesis: metabolic water produced when electrons accepted by oxygen.
On average, daily water loss is approximately ____.
An area in the hypothalamus, known as the ______, urges us to drink.
When body mass decreases by __% due to fluid loss, mild dehydration exists.
The major hormone that regulates water loss is ______.
ADH (antidiuretic hormone)
In the first step of urine production, water and most solutes in blood plasma move across the wall of glomerular capllaries into the glomerular capsule and then into the renal tubule.
As filtered fluid flows along the renal tubule and thru the collecting duct, tubule cells rabsorb about 99% of the filtered water and many useful solutes. The water and solute return to the blood as it flows thru the peritubular capillaries and vasa recta.
As fluid flows along the renal tubule and thru the collecting duct, the tubule and duct cells secrete other materials, such as wastes, drugs, and excess ions, into the fluid.
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