Urinary system Flashcards
Important functions of the kidney:
- Maintain the _______ consistency of the blood
- ______ many litres of fluid from the blood and return most _______ and ________ to the bloodstream
- Send ______, metabolic _______ and excess ______ out of the body
chemical
filter, water, solutes
toxins, metabolic wastes, excess water
What are the main waste products of the kidneys?
Where do each come from?
Urea - amino acids
uric acid - nucleic acids
creatinine - by-product of creatine phosphate in the muscles
What are the organs, from top to bottom of the urinary system.
Include some blood vessels that supply the kidney (not afferent and efferent/vasa recta).
Adrenal gland, renal artery, renal vein, renal hilum, kidney, ureter, urinary bladder, urethra.
What is the renal hilum?
Similar to the hilum in the lungs, entranceway for blood vessels and the ureter.
What does the ureter do?
Shuttles kidney filtrate to the urinary bladder.
Where are the kidneys located?
retroperitoneally
Lateral to T12-L3 vertebrae
What surrounds the kidney?
What is it made out of?
What is its function?
Renal capsule
Dense irregular CT
Binds to posterior abodminal wall - keeps it affixed and stable
Helps to maintain shape and inhibit the spread of infection
What is a kidney laceration?
Ripped off the posterior abdominal wall.
The kidneys are not even with each other. Why?
The liver pushes the kidney down on the right side.
Internal gross anatomy of the kidney:
- The outer part is called the ______ ______
- interior to this is the _______ _________
- Each part of the above is organized as a ________ __________
- A renal ______ is a chamber through which urine passes
- The _______ ______ surround the apex of the renal pyramids and converge to form ______ ________
renal cortex renal medulla renal pyramid calyx minor calicies major calicies
What is a nephron?
Functional unit of the kidney, makes urine.
Drainage of the kidney occurs through what?
Renal vein
What is the main function of the kidneys?
What is needed to achieve this end?
Filter the blood - need intimate blood supply/contact with blood vessels to achieve this.
Need a dedicated blood supply throughout the nephron
Describe blood flow in a nephron.
In your answer, describe what a glomerulus is and how the kidney is also a portal system.
Blood flows into the glomerulus (a tuft of capillaries) through the afferent arteriole.
Blood leaves the glomerulus through the efferent arteriole.
The efferent arteriole forms the peritubular capillaries which then form the renal vein.
The kidney is a portal system, there are two capillary beds. Instead of having a portal vein, the efferent arteriole is located between the two.
The second capillary bed is the vasa recta or peritubular capillary.
What is a uriniferous tubule?
What is it composed of?
Set of tubules that produce urine.
Nephron - which consists of the renal corpuscle and renal tubules
Collecting duct
The collecting duct is involved in ________ urine.
concentrating
What are the steps in the production of urine?
1 - Glomerular filtration
2 - Tubular resorption (conservation)
3 - Tubular secretion
What is glomerular filtration?
Filtrate of blood leaves the glomerulus and enters the uriniferous (kidney) tubules
What is tubular resoprtion or conservation?
Most nutrients, water, and essential ions are reclaimed from the kidney tubules, back into the blood.
99% of filtrate
What is tubular secretion or elimination?
Active process of removing undesirable molecules from the blood.
1% actually removed
Where is urine produced?
In the nephron
Describe blood flow through a typical nephron starting from the arcuate artery. and ending at the cortical radiate vein.
In your answer provide the processes of urine formation and describe the portal system in the kidneys.
Blood flows from the arcuate artery into the cortical radiate artery (which branches off of it).
Blood then enters the afferent arteriole into the glomerulus, where glomerular filtration occurs, blood is filtered into the kidney tubules.
Next, blood flows to the efferent arteriole.
Essential products are actively resorbed from the kidney tubules into the blood and wastes are secreted into the kidney tubules, to become urine.
Blood flows to the peritubular capillaries and drains into the cortical radiate vein.
The portal system is from one capillary network, the glomeruli, to the secon, the vasa recta. The connecting blood vessel is not a vein but the efferent arteriole.
What is the rate of urinary excretion dependent on?
Rate of glomerular filtration + rate of secretion - rate of resoprtion
What does heparin do?
Blood thinner.
Renal corpuscle.
Two components, these are?
Describe them and describe the specific tissues or blood vessels that are there, along with what cells might be found in some of these layers.
Two components: Glomerulus + Bowman’s capsule
Glomerulus - tuft of capillaries
- capillaries are fenestrated
Bowman’s capsule
- Parietal layer - simple squamous
- Visceral layer (grabs onto glomerulus) - consists of podocytes
What are the three parts of a typical renal tubule?
PCT, LoH, DCT
What is the epithelium of the PCT?
Simple cuboidal
Describe the selectivity of the glomerulus?
Size-selective
Thee components:
- Fenestrations - large enough molecules can get through
- basement membrane - Podocytes/foot processes
This allows only small things like water, electrolytes, amino acids, glucose to go through
Blood cells cannot pass, large or medium sized proteins cannot pass.
Describe the differences in function in the renal tubules.
PCT
- active resoprtion and secretion
LoH
- descending loop: pumps water
- ascending loop: pumps salts (Na+, Cl-)
DCT
- selective resorption and secretion
Describe the histology and cell features in the PCT, LoH, DCT and collecting duct.
PCT
- simple cuboidal
- microvilli - increase surface area for resorption/secretion
- active secretion - need mitochondria
LoH
- Simple squamous for movement of water and ions
Collecting duct
- simple cuboidal/columnar
What is getting transported in the PCT?
The LoH?
The DCT?
PCT
- water, Na+, Cl-, glucose, amino acids
LoH
- Na+, Cl-, water
DCT
- K+, H+, drugs, toxins, NH2
Collecting tubules/ducts
- Receives urine from ______ and rains into the _______ _____
- Plays an important role in conserving ______ _______; pumps _____
DCT
papillary duct
bodily fluids
water
When you wake up, your urine is usually darker. Why?
dehydrated state, conserve more water, so more concentrated and thus darker urine.
What are the two different nephron types?
Cortical nephrons
Juxtamedullary nephrons.
Cortical nephrons:
- __% of neprhons
- almost entirely within the renal _______
- efferent arteriole supplies ________ _______
85
cortex
peritubular capillaries
Juxtamedullary nephrons:
- ___ of nephrons
- Loop of Henle extends deep into the _______
- Efferent arterioles supply both the ________ _______ and ________ ________
15
medulla
peritubular capillaries
vasa recta
The loop of Henle is responsible for concentrating the ______.
urine
The neprhons are associated with two types of capillary beds - i.e. a _______ system.
What are they?
Portal system
Glomerulus
Peritubular capillaries and vasa recta
Glomerulus:
- Produces ______ that moves through the rest of the ________ tubule
- Fed and drained by arterioles (________ and ________)
Peritubular capillaries:
- Arise from _________ arterioles
- Absorb _______ and _______ from cells after _________
Vasa recta:
- Part of the __________ nephrons
- Part of the kidney’s _______-concentrating mechanism
filtrate
uriniferous
afferent and efferent
efferent
water, solutes, resorption
juxtamedullary
urine
Nephrons are drained by what?
Cortical radiate vein
Ureters:
- Carry _____ from the kidneys to the ______ ______
- – this is accomplished by _______ and _______ contractions
- ______ entry into the bladder prevents _______ of urine
Urine urinary bladder gravity peristaltic oblique backflow
Histology of ureter
- Mucosa –> ?
- Muscularis –>?
- Not a serous membrane but….
Mucosa:
- transitional epithelium underlain with lamina propria
Muscularis mucosa
- two layers of smooth muscle:
- inner longitudinal layer
- outer circular layer
Not a serous membrane but adventitia (behind peritoneum) - affixes it to other organs
Describe the transitional epithelium of the ureter.
Located in the mucosa.
When relaxed, more cuboidal and columnar, when stretched, the apical cells become more cuboidal
What is the difference in the muscularis layers of the digestive system and urinary system?
Similar layers (except when the stomach is considered) but different order.
Urinary bladder: - \_\_\_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_\_ sac - Stores and expels \_\_\_\_\_ -- full bladder is \_\_\_\_\_\_\_ in shape and expands into the \_\_\_\_\_\_\_\_\_ cavity -- an empty bladder lies entirely within the \_\_\_\_\_\_\_ Prostate gland (\_\_\_\_\_) [who has them] - lies directly \_\_\_\_\_\_\_ to the bladder - surround the \_\_\_\_\_\_\_
Collapsible muscular sac urine spherical, abdominal pelvis males inferior urethra
The ______ comes out of the bladder.
An enlarged ________ leads to difficulty in urinating.
Why do women get UTI’s more often?
urethra
prostate
Anus is closer to urethra, urethra is smaller.
Histology of the urinary bladder:
- Mucosa - what type of epithelium, underlain with what?
- Muscularis layer
- -specific muscle here
- last layer, not a serous layer
Mucosa
- transitional epithelium
- lamina propria
Muscular layer
- detrusor muscle
- -3 layers of smooth muscle which act to squeeze urine from the bladder during urination
- Adventitia
Urethra:
- Thin-walled tube which drains _____ from the ______ to the ______ of the body
Epithelium of urethra:
- _________ (can be more than one word) epithelium at the _______ end (near the bladder)
- ________ and ________ _________ (mid _______ in males)
- ________ _______ epithelium at the ______ end (near the urethra opening)
urine, bladder, outside
transitional - proximal, near bladder
Pseudostratified columnar and stratified - mid urethra in males
Stratified squamous - distal end, near urethal opening
Describe the internal urethral sphincter.
- Involuntary smooth muscle
- thickening of the detrusor muscle
Describe the external urethral sphincter.
Voluntary skeletal muscle which inhibits urination
- relaxes when one urinates
What is toilet training?
Gaining voluntary control of the external sphincter.
What can happen to older people and women after having children regarding micturition.
Lose ability to keep contractive state, get leaking out - internal urethral sphincter
What is a similarity between the stomach and urinary bladder?
In what direction does the ureter enter the bladder?
Which sphincter is voluntary, which is involuntary?
Which sphincter comes first?
Both have ruggae to allow expansion.
The ureter comes in obliquely or on a diagonal.
Voluntary - external
Involuntary - internal
Internal closer to bladder, external closer to urethral opening
Describe, very generally, the steps of micturition.
1 - Stretch receptors in bladder signal to the spinal cord and pons
2 - impulses sent to micturition center in sacral spinal cord triggering reflex
3 - Parasympathetic fibres cause detrusor muscle to contract and open the internal urethral sphincter
4 - Sympathetic fibres are inhibited
5 - Somatic motor neurons to external urethral sphincter are inhibited, causing the muscle to relax
The _______ ______ can initiate micturition or delay its occurrence for a limited period of time.
cerebral cortex
