Comparative Anatomy (Urinary System)

Summary

This presentation delves into the comparative anatomy of the urinary system, focusing on the kidneys and the renal portal system. It highlights variations in kidney morphology across species, including the absence of a urinary bladder in birds. The renal portal system in birds is discussed, along with the nephron as the kidney's functional unit. The module aims to enable students to differentiate between mammalian and reptilian types of nephrons and understand the unique characteristics of each domestic animal's urinary system.

Takeaways

• 🧬 The urinary system consists of the kidneys, ureters, urinary bladder, and urethra, with variation among species in the kidneys' structure.
• 🐶 In dogs, the kidneys have a smooth surface with a single renal papilla, and the renal pyramids fuse into a renal crest.
• 🐱 Cats have a unique capsular vein in their kidneys, which is not found in other species.
• 🐑 Sheep and goats share similar kidney anatomy with dogs, featuring a renal crest.
• 🐷 Pigs have multilobar kidneys with smooth surfaces and lack a renal crest, featuring minor and major renal calyces instead.
• 🐴 Horses have heart-shaped right kidneys and a distinct internal structure with terminal recesses for urine collection.
• 🕊 Birds have a unique renal portal system in addition to the renal arterial supply and venous return, influencing medication injection sites.
• 🐦 Birds' kidneys are divided into cranial, middle, and caudal lobes, lacking a renal pelvis and calyces, and have both mammalian and reptilian type nephrons.
• 🔍 The renal cortex is the outer layer of the kidney, and the renal medulla is the inner layer, with the renal pelvis collecting urine for the ureters.
• 🌐 The nephron is the functional unit of the kidney, responsible for urine production, with segments including the glomerulus, proximal and distal convoluted tubules, and the collecting duct.
• 🦎 Reptilian type nephrons in birds lack a loop of Henle and are found in the outer zones of the renal lobules, connecting directly to collecting ducts.

Q & A

What are the main components of the urinary system?

The main components of the urinary system are the kidneys, ureters, urinary bladder, and urethra.

How do kidneys vary among different species?

Kidneys can vary among species in terms of their classification as unilobar or multilobar and the presence of a smooth or elevated surface.

Which animal lacks a urinary bladder and how is this reflected in their kidney structure?

Birds lack a urinary bladder, and their kidneys are divided into cranial, middle, and caudal lobes with distinct features compared to mammals.

What is the significance of the renal portal system in birds?

The renal portal system in birds is significant as it provides an additional blood supply to the kidneys, which can affect the excretion rate of medications and the potential for nephrotoxicity.

Why is the caudal body often avoided as an injection site for medications in birds?

The caudal body is avoided as an injection site in birds because the renal portal system can rapidly transport and remove drugs from the kidneys, potentially leading to faster excretion or increased nephrotoxicity.

What are the basic parts of a kidney as described in the script?

The basic parts of a kidney include the renal cortex, renal medulla, renal pelvis, and the renal hilus where important structures like the renal artery, renal vein, and ureter pass through.

What is unique about the renal pelvis in horses?

In horses, the renal pelvis has mucus glands, which give the urine a turbid appearance.

How does the structure of the kidneys in dogs differ from that in cats?

While both dogs and cats have similar kidney structures, cats have a unique feature called the capsular vein.

What is the function of the nephron in the urinary system?

The nephron is the functional unit of the kidney responsible for urine production, with its various segments filtering blood and forming urine that is then conveyed to the renal pelvis.

What are the two types of nephrons found in birds and how do they differ structurally?

Birds have both mammalian and reptilian type nephrons. The reptilian type lacks a segment corresponding to the loop of Henle and is found in the outer zones of the lobules, while the mammalian type includes the loop of Henle and extends into the medullary cones.

How does the presence of a renal crest in some animals affect the urine collection process?

The renal crest, present in animals like dogs and horses, is a fusion of the renal pyramids that projects into the renal pelvis, facilitating the collection of urine from the nephrons.

Outlines

00:00

🧘 Comparative Anatomy of Kidneys

This module delves into the comparative anatomy of the urinary system, focusing on the kidneys as the central organ. It aims to educate students on the differences in kidney morphology across various domestic animals, the renal portal system in birds, and the distinct types of nephrons found in mammals and reptiles. The urinary system is composed of the kidneys, ureters, urinary bladder, and urethra, with kidneys showing significant variation among species. The kidneys can be classified into unilobar and multilobar types with different surface textures. The module also covers the basic anatomy of the kidney, including the renal cortex, medulla, pelvis, and other structures. The kidneys' position relative to each other and their relationship with the liver in various animals are also discussed.

05:01

🐦 Avian Renal System and Nephron Types

The second paragraph shifts focus to the unique features of the avian renal system, including the absence of a urinary bladder and the presence of a renal portal system. This system receives blood from the caudal body and distributes it through a secondary capillary network, influencing medication injection practices in birds to avoid rapid excretion or potential nephrotoxicity. The nephron, the functional unit of the kidney, is explored in detail, highlighting its role in urine production. The paragraph distinguishes between the mammalian and reptilian types of nephrons, with the latter being unique to birds and lacking a segment corresponding to the loop of Henle. The reptilian type nephrons are situated in the outer zones of the kidney lobules, while the mammalian type nephrons extend into the medullary cones. The summary concludes the comparative anatomy discussion of the urinary system.

Keywords

💡Urinary System

The urinary system is responsible for the production, storage, and elimination of urine in the body. It is a critical system for maintaining the body's fluid balance and removing waste products. In the video, the urinary system is composed of the kidneys, ureters, urinary bladder, and urethra, with variations among species, highlighting the importance of understanding its structure and function across different animals.

💡Kidneys

Kidneys are the primary organs of the urinary system, responsible for filtering blood and producing urine. They are described as varying in morphology among different domestic animals, such as being unilobar or multilobar, with smooth or elevated surfaces. The script discusses the unique characteristics of kidneys in various species, emphasizing their role in the urinary system.

💡Renal Portal System

The renal portal system is a unique blood supply system found in birds, which includes the cranial and caudal renal portal veins. It receives venous blood from the caudal body and distributes it into a second capillary system in the interlobular spaces. The script mentions this system as a reason for avoiding the caudal body for injections in birds, to prevent rapid excretion of medications.

💡Nephron

Nephrons are the functional units of the kidney, responsible for filtering blood and producing urine. The script explains that each nephron is composed of several segments, including the glomerulus, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct. The nephron's structure and function are central to the video's theme of understanding the urinary system.

💡Glomerulus

The glomerulus is a network of capillaries within the nephron where blood filtration occurs to form the glomerular filtrate. It is enclosed by the Bowman's capsule. The script describes the glomerulus as the starting point of urine production, highlighting its importance in the nephron's function.

💡Renal Cortex

The renal cortex is the outer layer of the kidney parenchyma, beneath the renal capsule. It plays a crucial role in the initial filtration of blood in the nephrons. The script mentions the renal cortex in the context of the overall structure of the kidney and its role in the urinary system.

💡Renal Medulla

The renal medulla is the inner layer of the kidney parenchyma, containing the renal pyramids and collecting ducts. It is where the concentrated urine is formed after filtration in the cortex. The script discusses the renal medulla in relation to the formation of urine and its structural differences among species.

💡Renal Papillae

Renal papillae are the projections at the apex of a renal lobule where urine is collected and drips into the renal pelvis. The script describes the presence of single or multiple papillae depending on the kidney's structure, which is an important aspect of urine collection and transport.

💡Renal Pelvis

The renal pelvis is the expanded proximal end of the ureter, which collects urine from the kidneys before it is transported to the urinary bladder. The script explains the renal pelvis's role in urine collection, noting the unique structure in horses with mucus glands.

💡Mammalian Type Nephron

Mammalian type nephrons are characterized by the presence of the loop of Henle, which plays a role in concentrating urine. The script contrasts mammalian type nephrons with reptilian type nephrons, found in birds, to illustrate the differences in urine production and concentration mechanisms across species.

💡Reptilian Type Nephron

Reptilian type nephrons, found in birds, lack a segment corresponding to the loop of Henle and are contained in the outer zones of the lobules. The script explains that these nephrons are connected to the collecting ducts and are similar to those found in reptiles, indicating an evolutionary adaptation in the urinary system of birds.

Highlights

The presentation compares the urinary system's kidneys across different domestic animals.

A brief discussion on the renal portal system in birds is included.

The nephron, as the functional unit of the kidney, is identified and compared between mammals and reptiles.

The urinary system is composed of kidneys, ureters, the urinary bladder, and the urethra, with variations among species.

Birds lack a urinary bladder, unlike mammals.

Kidneys can be classified as unilobar or multilobar with variations in surface texture.

Dogs, cats, goats, sheep, and horses have unilobar kidneys with a single renal papilla.

Pigs have multilobar kidneys with a smooth surface and multiple papillae.

Large ruminants have multilobar kidneys with a lobated surface and multiple papillae.

Birds' kidneys are divided into cranial, middle, and caudal lobes.

The right kidney is generally higher than the left in domestic mammals except in pigs.

The basic parts of the kidney include the renal cortex, medulla, pelvis, and helus.

Dogs have renal pyramids fused into a renal crest.

Cats have a unique capsular vein in their kidney anatomy.

Sheep and goats share similar kidney anatomy with dogs.

Pigs' kidneys have minor and major calluses but lack a renal crest.

Horses have a heart-shaped right kidney and a unique terminal recess structure.

Birds possess a renal portal system with unique blood supply and return mechanisms.

The renal portal system in birds may affect medication injection sites and drug excretion rates.

The nephron structure includes the glomerulus, convoluted tubules, loop of Henle, and collecting duct.

Birds' kidneys contain both mammalian and reptilian type nephrons with distinct structures.

Reptilian type nephrons in birds lack a segment corresponding to the loop of Henle.

Transcripts

hi welcome to our fifth module

in this presentation we will compare one

of the most important parts of the

urinary system

the kidneys we will also have a short

discussion on the renal portal system

and the nephron being the functional

unit of the kidney

at the end of this presentation each

student should be able to compare the

morphology of the kidneys of the

different domestic animals

discuss the renal portal system of birds

and identify and compare the mammalian

and reptilian type of nephrons

the urinary system is composed of the

kidneys the ureters

the urinary bladder and the urethra

among the organs

the kidneys show variation among species

it is also good to point that birds lack

the urinary bladder

compared to mammals with a very distinct

urinary bladder

kidneys can be classified as unilobar

or multilobar with either smooth or

elevated surface

unilobar kidneys are described to have a

smooth surface

and a single renal papilla as found in

dogs

cats small ruminants like goats and

sheep

and horse multilobar kidneys with smooth

surface and multiple papillae is present

in pigs

while multilobar kidneys with a lubated

surface

and multiple papillae is present in

large ruminants

birds on the other hand have kidneys

divided into cranial

middle and codal lobes as variation is

present only in the kidneys

this module will focus only on the gross

comparative notes of the kidneys

the renal portal system and comparison

of mammalian and reptilian type of

nephron

in general the right kidney is always

higher than the left in all domestic

mammals

except in pigs because of this if you

recall the anatomy of the liver

a renal impression is present on the

caudate process and the right hepatic

lobe of those animals

before we compare the kidneys of each

animal let us first review the basic

parts of the organ

shown here is a gross and a section

kidney of a dog

the renal cortex is the outer layer of

the kidney parenchyma beneath the

capsule

while the renal medulla is the inner

layer of the parentima

here is the renal helus where various

important structures like renal artery

renal vein and the ureter is passing

through

the renal pelvis is the expanded

proximal end of the urethra

this is the one collecting the formed

urine from the kidneys to the ureter

here is a schematic illustration of the

kidney to show the other distinct parts

the kidneys are basically lobulated

meaning they are composed of

lobules each renal lobule

has a renal papilla

this is the apex of a renal lobule that

drips urine into the proximal end of the

ureter

the renal calluses are cup-shaped

structures receiving urine from the

renal papillae

the kidneys of dogs are being shaped as

shown here

the renal pyramids fused into renal

crest and

projects into a distinct renal pelvis

in cats it is smaller than in dogs

however

the distinguishing characteristic of

their kidneys is the presence of

capsular vein

this is unique in cats

in sheep and goats the anatomy of the

kidney is the same as in dogs

they also have the renal crest instead

of the individual renal papillae

however this is in contrast with the

large ruminants

their kidneys are lobated and locks the

renal pelvis

they have minor calluses embracing the

renal papillae that lead into the major

calluses

and into the urethra please note that

each lobe has its own cortex and medulla

in pigs the kidneys are also being

shaped

externally the kidneys are the same with

others with smooth kidney

due to the fused cortex as shown here

however

the medulla is infused it has minor

and major calluses thus it lacks the

renal crest

present in dog

the right kidney of a horse is heart

shape while the left kidney is being

shaped

internally it has a structure called

terminal recess

which are long tube like extensions that

collect

and carry urine from the kidney pose to

the small renal pelvis

same with the dog it has a renal crest

instead of the renal papillae

interestingly the wall of the renal

pelvis has mucus glands

which give the horse urine a turbid

appearance

in birds the kidneys lie on the ventral

surface of the sin sacrum

it is divided into cranial middle and

caudal lobes

both renal pelvis and renal calluses are

missing

uniquely birds possess a renal portal

system

in addition to the expected renal

arterial blood supply

and the renal venus return the system is

consists of the cranial

renal portal vein and the caudal renal

portal vein

the system receives venous blood from

the caudal body and distributes it

into a second capillary system in the

interlobular spaces

the renal portal system has been used as

a justification

for avoiding the caudal body as a site

for injection of medications in birds

one reason for this avoidance is that

the drugs may be more rapidly excreted

when injected here than is desirable due

to their being immediately transported

to

and removed by the kidney another

concern is that drugs that are

potentially nephrotoxic

or those that are damaging to the

kidneys may be more so when they

are first distributed and diluted to the

kidneys

via the portal system

now we proceed to the nephron the

nephron is the functional unit of the

kidney

here is a schematic illustration of the

mammalian nephron

the nephrons are responsible for urine

production while the subsequent

collecting tubules convey the urine to

the renal pelvis

each nephron is composed of several

segments

this can be more appreciated in

histology and physiology classes

but let us take a quick view of its

parts

the glomerulus is a tuft of capillaries

where the blood is filtered to form the

glomerular filtrate

this is enclosed by the glomerular

capsule or the bowman's capsule

the next segment is the proximal

convoluted tubule

then the loop of henle which is composed

of a descending

and the ascending limb then it will

become the distal convoluted tubule

and finally to the collecting dock where

the formed urine will be released via

the individual renal papillae

or renal crest the renal pelvis or renal

calluses depending on the species

bird's kidney contain two different

types of nephron

and one type is markedly different in

structure compared to the nephrons of

mammalian kidneys

this unique type of nephron is termed a

reptilian type nephron and is similar to

those found in the kidneys of reptiles

here is the reptilian type nephron the

glomerulus of the reptilian type

nephrons are found in the lobules of

bird kidneys and a renal tubule connects

each glomerulus to a collecting duck

also found in the same lobule however

the tubules of the reptilian type

nephrons do not

include a segment that corresponds to

the loop of henle

and the tubules of the reptilian type

nephrons are contained in the outer

zones of the lobules

where they are connected to the

collecting ducts

in contrast the mammalian type nephrons

have the loop of henle

as shown here and extend downward into

the medullary cones that support the

lobules

again birds have both mammalian and

reptilian type of nephrons

and that ends our discussion on the

comparative anatomy of the urinary

system