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.