Sistema Excretor / Renal / Urinário 03 - Histologia P2 (Bexiga, ureteres, uretra e rins)

Summary

In this video, Vinícius Jesus continues the histological study of the renal system, focusing on the urinary pathways and macroscopic aspects. The video explores the structure and function of collecting tubules, discussing their role in modifying the glomerular filtrate and transporting it through various regions of the kidney. The discussion also covers the histology of the renal pelvis, ureters, bladder, and urethra, detailing their layers, functions, and the role of different epithelial cells. The video concludes with an overview of the male and female urethras and the processes involved in urination and storage.

Takeaways

• 😀 The script is focused on histology and macroscopic aspects of the renal system, including a detailed study of urinary pathways.
• 😀 The first video covered nephron anatomy, while this video continues the discussion by focusing on urinary pathways.
• 😀 Collecting ducts, which do not form part of the nephron, are made of simple cuboidal epithelium and modify filtrate from the nephron.
• 😀 The collecting ducts have three recognizable regions: cortical, medullary, and papillary.
• 😀 Intercalated cells in the collecting ducts actively transport hydrogen ions (H+) and play a crucial role in maintaining acid-base balance.
• 😀 In the presence of antidiuretic hormone (ADH), collecting ducts become permeable to water, leading to more concentrated urine.
• 😀 The renal pelvis is the starting point of the urinary pathways and connects with the ureters, which transport urine to the bladder.
• 😀 The structure of the ureters includes a mucosa, fibroelastic connective tissue, and muscular layers that push urine into the bladder.
• 😀 The bladder stores urine and its mucosa stretches as it fills, flattening the transitional epithelium.
• 😀 The male and female urethras differ in length, with the male urethra serving both urinary and reproductive functions.
• 😀 The male urethra has three parts: prostatic, membranous, and spongy (penile), and it is lined with various types of epithelium including stratified squamous and columnar.

Q & A

What are the main components of the renal system discussed in this video?

The video discusses the renal system's histology, focusing on the renal tubules, collecting ducts, and urinary pathways, including the macroscopic aspects of the renal system.

What are the collecting ducts, and how do they differ from nephrons?

The collecting ducts are structures formed by a different embryological origin than nephrons. They are lined by simple cuboidal epithelium and are responsible for transporting and modifying the ultrafiltrate of the nephron towards the minor calyces of the kidney.

What are the two types of cells found in cortical collecting ducts?

The two types of cells found in the cortical collecting ducts are the principal cells and the intercalated cells. The principal cells have oval central nuclei and microvilli, while the intercalated cells have numerous apical vesicles and a rounded central nucleus.

What is the role of intercalated cells in the collecting ducts?

Intercalated cells are responsible for actively transporting and secreting hydrogen ions (H+) against a concentration gradient, thereby helping to regulate the body's acid-base balance.

How do collecting ducts change in response to antidiuretic hormone (ADH)?

In the presence of ADH, the collecting ducts become permeable to water, allowing for water reabsorption. In the absence of ADH, the ducts are impermeable to water, resulting in the excretion of hypotonic urine.

What is the function of the renal papilla and how is it involved in urine formation?

The renal papilla is where the collecting ducts converge, leading the modified ultrafiltrate towards the minor calyces. It plays a crucial role in directing urine from the kidneys to the rest of the urinary tract.

What are the main characteristics of the ureters?

The ureters are hollow tubes about 25-30 cm in length that transport urine from the kidneys to the bladder. They have a mucosa lined with transitional epithelium and a fibroelastic lamina propria, and are surrounded by muscular layers that propel urine.

What is the anatomical feature called the 'trigone' in the bladder?

The trigone is a triangular area in the bladder formed by the openings of the two ureters and the urethra. The mucosa of the trigone remains smooth and does not form folds.

How does the epithelium of the bladder change as it fills with urine?

As the bladder fills with urine, the transitional epithelium becomes flattened due to the distension of the bladder, even though the type of epithelium does not change.

How does the urethra differ between males and females?

The female urethra is shorter and lined with transitional epithelium near the bladder and stratified squamous epithelium along its length. The male urethra is longer, with three parts: the prostatic, membranous, and spongy (penile) urethra, and it is responsible for both urinary and reproductive functions.