BIOL 318 Exam 4 Questions & Answers 2026 |
Urinary System Functions | Latest Study Guide
BIOL 318 Study Guide Exam 4
URINARY SYSTEM:
Different functions of Urinary system
o Blood filtration: in the glomerulus at the kidney getting passed through
nephrons to get modified and processed to finely tune and refine what we
want to excrete
o Blood volume, pressure, osmolarity changes: depending on proteins
and solute we reabsorb, depends on how much water we absorb and
hormones having to do with blood pressure
o Blood electrolyte balance
o Stimulation of RBC production: erythropoietin
o Help from calcitriol: bone metabolism
o Clear hormones and toxic drugs from blood: kidneys have their own
clearance rate
o Detoxify free radicals: liver and kidney aids in this function
o Produce glucose from amino acids (during extreme starvation):
kidney cells can be converted into this physiological process when we
desperately need glucose
Different types of Nitrogenous Waste
o Ammonia, urea, and uric acid
Name the organs involved in excretions and their excretory products
o Kidneys: once body has extracted what it needs from food and drink, it
sends wastes to the kidneys. The kidneys filter the wastes, including urea,
salt and excess water, which are flushed out of the body as urine.
o Liver: plays a vital role in keeping the body clean. Harmful poisons and
chemical that are either produced in the body or consumed are broken
down and detoxified by the liver. For example, a bi-product of the
metabolic process within the body is ammonia and the liver processes this
into urea, a less harmful substance which continues to be filtered and
excreted by the kidney’s urine.
o Gallbladder: bile, a liquid produced by the liver to break down waste, is
first stored in the gallbladder. When needed, it is discharged into the small
intestine whose role is to break down fats, ethanol and other acidic
wastes.
o Urinary bladder: the waste fluid that is created in the liver and collected in
the kidneys is transferred into the urinary bladder where it is temporarily
stored until the individual urinates. The urinary bladder provides a short-
term solution for storing urine in the body until it is ultimately discharged.
o Ureters: tubes of smooth muscle fiber transfer liquid waste from the
kidneys into the urinary bladder. The urine is moved with peristaltic
movements which force the urine away from the kidneys. The ureters also
have uterovesical valves which ensure the waste fluid does not travel back
into the kidney.
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, o Urethra: runs through penis in males and serves as a carrier of semen as
well as urine for their ultimate discharge out of the body. The urethra tube
is shorter in females and is just above the vaginal opening.
What is the anatomical position of the kidney and the surrounding
structures involved with it?
o Position: anchored against the back of abdominal wall with fibrous
connective tissue. Below diaphragm, adrenal glands on top
o 3 layers of CT surrounding kidneys and adrenal glands
▪ Fibrous capsule: lining surface of kidney and adrenal gland
▪ Perirenal fat capsule: middle layer cushioning kidneys from
trauma
▪ Renal fascia: sheath-like connective tissue, largely very fibrous CT
helping anchor the kidney to the back of the abdominal wall and
keeps things together, like the ureter extending off the kidneys
o Fibrous CT: anchors kidneys to wall to prevent blockages from twisting
Explain arterial blood flow from the aorta to the glomerulus.
1. Aorta
2. Renal artery
3. Segmental arteries
4. Interlobular arteries
5. Arcuate arteries
6. Cortical radiate arteries
7. Afferent arteriole
8. Glomerulus
List and describe different parts of the nephron. What is the function of
each part (general function and specifics)?
o Nephron: smallest functional unit of a kidney, participating in urine
production
o 1.2 million nephrons per kidney
1. Glomerulus: blood enters through afferent arteriole into this capillary
network
▪ Elevated blood pressure, allowing us to filter the blood by allowing
fluid to get pushed out of the blood vessel along with components
due to hydrostatic pressure
▪ Filtrate: what gets filtered out
▪ Changing filtration rate: dilation/constriction of afferent arteriole
2. Bowman’s capsule: collects filtrate from glomerulus and sends it to the
PCT
3. Proximal convoluted tubule (PCT): a lot of reabsorption happening
▪ Simple cuboidal cells having microvilli extending into the
lumen: increase the surface area to allow the cell maximized
efficiency of reabsorption
▪ Function: specific reabsorption of contents we want to keep out of
the urine like water, electrolytes, glucose, etc.
4. Loop of Henle: urine concentration
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, ▪ Descending: downwards flow
▪ Ascending: upwards flow
▪ Function: largely associated with urine concentration as a whole
(descending and ascending) by removing water to help body
conserve it for other cells
5. Distal convoluted tubule (DCT): a lot of secretion and some
reabsorption for urine concentration
▪ Simple cuboidal cells with no microvilli: relatively flat around
lumen
▪ Function: secretion of electrolytes into filtrate of urine being
formed and urine concentration by reabsorbing water
6. Collecting duct: collects contents from DCT to send into the renal
pyramids of the kidney
▪ Function: concentration of urine and water conservation, channels
urine
▪ Many make up the renal pyramids
▪ Multiple nephrons can share the same collecting duct
What are the components of Renal Corpuscle and their function?
o Renal corpuscle: glomerulus + bowman’s capsule
o Function: blood filtration -> collection of filtrates after blood has been
filtered out
o Walls of blood vessel: simple squamous epithelium
Pathway of Urine excretion.
1. Renal pyramids
2. Papilla: point pyramids make, between the pyramid and minor calyx’s of
the kidney
3. Minor calyx’s
4. Major calyx
5. Renal pelvis
6. Ureter: has valves to prevent the backflow of urine, more valves as we
get closer to the bladder
7. Bladder
8. Urethra: where urine exits to the external environment
Juxtaglomerular apparatus
o Juxtaglomerular apparatus: part of DCT and afferent arteriole
o Function: regulate BP and filtration rate
o DCT
▪ Macula densa cells: cuboidal cells detecting the concentration of
sodium in the blood and filtrate
▪ Depending on conditions of sodium flowing through: contract
afferent arteriole through signals sent to the cells, due to water
imbalance and high levels of sodium, which causes the loss of
volume
▪ Can rupture the afferent arteriole if not detected
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, ▪ When BP drops due to a lot of sodium: afferent arteriole
constricts to keep sodium out the glomerulus
o Juxtaglomerular cells: secrete renin when BP drops helping form
angiotensin I -> forms angiotensin II near capillaries of lungs -> stimulates
release of aldosterone from adrenal cortex -> help increase amount of
water reabsorbed at the kidneys -> raise BP
▪ Cells part of the afferent arteriole
What is Glomerular Filtration? What are the structures responsible for
Glomerular Filtration?
o Glomerular filtration rate (GFR): dilation of constriction of the afferent
arteriole
▪ The closer the afferent and efferent arteriole are in diameter, the
more equal the pressure
o At the glomerulus: water and solutes filtered out of the blood
o Fenestrated capillaries
▪ Contain small filtration pores: we expect some solutes and
hormones coming through these pores
▪ Highly permeable: makes filtration easier selecting what can
leave the blood based off of size, typically small to medium
particulates
o Basement membrane: wrapping the outside of the vessel
▪ 2nd filter: filters based on size of molecule; slightly smaller size
things filtered
▪ Negative charges typically repelled within the layer: if the
membrane has a negative charge it is going to repel negative
particulates
• E.g., albumin proteins: slightly negative in terms of
overall charge, don’t expect to see in urine because they
shouldn’t be making it through the membrane
o Small particulates pass through free, mostly positively charged
along with few small negative ions
▪ Major components released and filtered out of capillary:
water, electrolytes, glucose, amino acids, fatty acids, nitrogenous
waste (urea), vitamins
How is GFR regulated?
o Myogenic
▪ Stretch mechanism
▪ Arterial pressure increases -> stretches muscle around
afferent arteriole
▪ Effect: smooth muscle constricts limiting the amount of blood
going into the glomerulus
▪ Function: prevents blood flow from changing too dramatically
▪ Largely prevalent during a dramatic increase in blood
pressure
o Sympathetic control
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Urinary System Functions | Latest Study Guide
BIOL 318 Study Guide Exam 4
URINARY SYSTEM:
Different functions of Urinary system
o Blood filtration: in the glomerulus at the kidney getting passed through
nephrons to get modified and processed to finely tune and refine what we
want to excrete
o Blood volume, pressure, osmolarity changes: depending on proteins
and solute we reabsorb, depends on how much water we absorb and
hormones having to do with blood pressure
o Blood electrolyte balance
o Stimulation of RBC production: erythropoietin
o Help from calcitriol: bone metabolism
o Clear hormones and toxic drugs from blood: kidneys have their own
clearance rate
o Detoxify free radicals: liver and kidney aids in this function
o Produce glucose from amino acids (during extreme starvation):
kidney cells can be converted into this physiological process when we
desperately need glucose
Different types of Nitrogenous Waste
o Ammonia, urea, and uric acid
Name the organs involved in excretions and their excretory products
o Kidneys: once body has extracted what it needs from food and drink, it
sends wastes to the kidneys. The kidneys filter the wastes, including urea,
salt and excess water, which are flushed out of the body as urine.
o Liver: plays a vital role in keeping the body clean. Harmful poisons and
chemical that are either produced in the body or consumed are broken
down and detoxified by the liver. For example, a bi-product of the
metabolic process within the body is ammonia and the liver processes this
into urea, a less harmful substance which continues to be filtered and
excreted by the kidney’s urine.
o Gallbladder: bile, a liquid produced by the liver to break down waste, is
first stored in the gallbladder. When needed, it is discharged into the small
intestine whose role is to break down fats, ethanol and other acidic
wastes.
o Urinary bladder: the waste fluid that is created in the liver and collected in
the kidneys is transferred into the urinary bladder where it is temporarily
stored until the individual urinates. The urinary bladder provides a short-
term solution for storing urine in the body until it is ultimately discharged.
o Ureters: tubes of smooth muscle fiber transfer liquid waste from the
kidneys into the urinary bladder. The urine is moved with peristaltic
movements which force the urine away from the kidneys. The ureters also
have uterovesical valves which ensure the waste fluid does not travel back
into the kidney.
messages.downloaded_by
, o Urethra: runs through penis in males and serves as a carrier of semen as
well as urine for their ultimate discharge out of the body. The urethra tube
is shorter in females and is just above the vaginal opening.
What is the anatomical position of the kidney and the surrounding
structures involved with it?
o Position: anchored against the back of abdominal wall with fibrous
connective tissue. Below diaphragm, adrenal glands on top
o 3 layers of CT surrounding kidneys and adrenal glands
▪ Fibrous capsule: lining surface of kidney and adrenal gland
▪ Perirenal fat capsule: middle layer cushioning kidneys from
trauma
▪ Renal fascia: sheath-like connective tissue, largely very fibrous CT
helping anchor the kidney to the back of the abdominal wall and
keeps things together, like the ureter extending off the kidneys
o Fibrous CT: anchors kidneys to wall to prevent blockages from twisting
Explain arterial blood flow from the aorta to the glomerulus.
1. Aorta
2. Renal artery
3. Segmental arteries
4. Interlobular arteries
5. Arcuate arteries
6. Cortical radiate arteries
7. Afferent arteriole
8. Glomerulus
List and describe different parts of the nephron. What is the function of
each part (general function and specifics)?
o Nephron: smallest functional unit of a kidney, participating in urine
production
o 1.2 million nephrons per kidney
1. Glomerulus: blood enters through afferent arteriole into this capillary
network
▪ Elevated blood pressure, allowing us to filter the blood by allowing
fluid to get pushed out of the blood vessel along with components
due to hydrostatic pressure
▪ Filtrate: what gets filtered out
▪ Changing filtration rate: dilation/constriction of afferent arteriole
2. Bowman’s capsule: collects filtrate from glomerulus and sends it to the
PCT
3. Proximal convoluted tubule (PCT): a lot of reabsorption happening
▪ Simple cuboidal cells having microvilli extending into the
lumen: increase the surface area to allow the cell maximized
efficiency of reabsorption
▪ Function: specific reabsorption of contents we want to keep out of
the urine like water, electrolytes, glucose, etc.
4. Loop of Henle: urine concentration
messages.downloaded_by
, ▪ Descending: downwards flow
▪ Ascending: upwards flow
▪ Function: largely associated with urine concentration as a whole
(descending and ascending) by removing water to help body
conserve it for other cells
5. Distal convoluted tubule (DCT): a lot of secretion and some
reabsorption for urine concentration
▪ Simple cuboidal cells with no microvilli: relatively flat around
lumen
▪ Function: secretion of electrolytes into filtrate of urine being
formed and urine concentration by reabsorbing water
6. Collecting duct: collects contents from DCT to send into the renal
pyramids of the kidney
▪ Function: concentration of urine and water conservation, channels
urine
▪ Many make up the renal pyramids
▪ Multiple nephrons can share the same collecting duct
What are the components of Renal Corpuscle and their function?
o Renal corpuscle: glomerulus + bowman’s capsule
o Function: blood filtration -> collection of filtrates after blood has been
filtered out
o Walls of blood vessel: simple squamous epithelium
Pathway of Urine excretion.
1. Renal pyramids
2. Papilla: point pyramids make, between the pyramid and minor calyx’s of
the kidney
3. Minor calyx’s
4. Major calyx
5. Renal pelvis
6. Ureter: has valves to prevent the backflow of urine, more valves as we
get closer to the bladder
7. Bladder
8. Urethra: where urine exits to the external environment
Juxtaglomerular apparatus
o Juxtaglomerular apparatus: part of DCT and afferent arteriole
o Function: regulate BP and filtration rate
o DCT
▪ Macula densa cells: cuboidal cells detecting the concentration of
sodium in the blood and filtrate
▪ Depending on conditions of sodium flowing through: contract
afferent arteriole through signals sent to the cells, due to water
imbalance and high levels of sodium, which causes the loss of
volume
▪ Can rupture the afferent arteriole if not detected
messages.downloaded_by
, ▪ When BP drops due to a lot of sodium: afferent arteriole
constricts to keep sodium out the glomerulus
o Juxtaglomerular cells: secrete renin when BP drops helping form
angiotensin I -> forms angiotensin II near capillaries of lungs -> stimulates
release of aldosterone from adrenal cortex -> help increase amount of
water reabsorbed at the kidneys -> raise BP
▪ Cells part of the afferent arteriole
What is Glomerular Filtration? What are the structures responsible for
Glomerular Filtration?
o Glomerular filtration rate (GFR): dilation of constriction of the afferent
arteriole
▪ The closer the afferent and efferent arteriole are in diameter, the
more equal the pressure
o At the glomerulus: water and solutes filtered out of the blood
o Fenestrated capillaries
▪ Contain small filtration pores: we expect some solutes and
hormones coming through these pores
▪ Highly permeable: makes filtration easier selecting what can
leave the blood based off of size, typically small to medium
particulates
o Basement membrane: wrapping the outside of the vessel
▪ 2nd filter: filters based on size of molecule; slightly smaller size
things filtered
▪ Negative charges typically repelled within the layer: if the
membrane has a negative charge it is going to repel negative
particulates
• E.g., albumin proteins: slightly negative in terms of
overall charge, don’t expect to see in urine because they
shouldn’t be making it through the membrane
o Small particulates pass through free, mostly positively charged
along with few small negative ions
▪ Major components released and filtered out of capillary:
water, electrolytes, glucose, amino acids, fatty acids, nitrogenous
waste (urea), vitamins
How is GFR regulated?
o Myogenic
▪ Stretch mechanism
▪ Arterial pressure increases -> stretches muscle around
afferent arteriole
▪ Effect: smooth muscle constricts limiting the amount of blood
going into the glomerulus
▪ Function: prevents blood flow from changing too dramatically
▪ Largely prevalent during a dramatic increase in blood
pressure
o Sympathetic control
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