The Human Kidney: Anatomy and Physiology

Summary

In this educational video, Leslie Samuel from Interactive Biology TV delves into the anatomy and physiology of the kidneys, highlighting their crucial role in maintaining homeostasis. The video explains the kidney's structure, including the cortex, medulla, and pelvis, and their functions in blood filtration and urine production. It emphasizes the kidney's remarkable work, filtering 20% of the heart's output and producing about 180 liters of filtrate daily, with only 1 liter excreted as urine due to reabsorption. The concept of the nephron, the kidney's functional unit, is introduced, setting the stage for a deeper exploration of the blood supply in upcoming videos.

Takeaways

• 🧐 The video discusses the anatomy and physiology of the kidney, focusing on its structure and function.
• 🔍 The kidney is composed of the cortex, medulla, and pelvis, each playing a role in blood processing and urine collection.
• 💧 The urinary system's primary functions include cleaning the blood, regulating pH, and maintaining blood pressure to achieve homeostasis.
• 🚰 The kidneys filter and clean blood, removing waste products like ammonia to maintain a balanced internal environment.
• 🩸 A significant amount of blood, about 20% of the cardiac output, is sent to the kidneys for filtration every minute.
• 🔢 The kidneys produce approximately 125 milliliters of filtrate per minute, equating to 180 liters daily.
• 🌊 Despite producing 180 liters of filtrate daily, only about one liter of urine is excreted due to extensive reabsorption.
• 🔬 The nephron, the functional unit of the kidney, is responsible for filtration, reabsorption, secretion, and elimination of waste.
• 📈 The video uses a practical demonstration with water bottles to illustrate the vast amount of blood filtered by the kidneys daily.
• 🔄 The next video will delve into the blood supply of the kidneys, explaining the vessels involved in the filtration process.

Q & A

What are the primary functions of the urinary system as mentioned in the video?

The primary functions of the urinary system are to clean the blood, regulate pH, regulate blood pressure, and maintain homeostasis.

Where does most of the work related to the urinary system take place?

Most of the work related to the urinary system takes place in the kidneys.

What are the three main layers of the kidney as described in the video?

The three main layers of the kidney are the cortex, the medulla, and the pelvis.

What is the role of the cortex in the kidney?

The cortex is the outer layer of the kidney where some of the initial processing of blood occurs.

What is the role of the medulla in the kidney?

The medulla is the middle layer of the kidney where further processing of blood occurs.

How does the pelvis of the kidney contribute to the urinary system?

The pelvis of the kidney is where urine is collected and sent out via the ureters to the bladder.

What percentage of blood from the heart goes to the kidneys every minute?

About 20% of all the blood coming from the heart goes to the kidneys every minute.

How much filtrate is produced by the kidneys every minute, and what does this amount to in a day?

The kidneys produce approximately 125 milliliters of filtrate every minute, which amounts to 180 liters every day.

Why doesn't all the filtrate produced by the kidneys come out as urine?

Not all filtrate comes out as urine because most of it is reabsorbed back into the body, which is essential for maintaining homeostasis.

What is the average amount of urine produced by the kidneys in a day?

On average, the kidneys produce about one liter of urine every day.

What is a nephron and what is its function in the kidney?

A nephron is the functional unit of the kidney where filtration, reabsorption, secretion, and elimination occur. It is where the actual processes of the urinary system take place.

Outlines

00:00

🧐 Introduction to Kidney Structure and Function

This paragraph introduces the topic of the video, which is the anatomy and physiology of the kidney. The speaker, Leslie Samuel from Interactive Biology TV, emphasizes the importance of the kidney in maintaining homeostasis by cleaning the blood, regulating pH, and managing blood pressure. The structure of the kidney is discussed, highlighting the cortex, medulla, and pelvis as key areas where these processes occur. The paragraph also mentions the significant amount of blood that the kidneys filter, with 1.2 liters out of every 5.6 liters of cardiac output being directed to the kidneys for cleaning. The concept of filtrate and urine production is introduced, explaining how the kidneys manage to reabsorb most of the filtrate, resulting in only one liter of urine being produced daily.

05:02

🔬 The Role of Nephrons in Kidney Function

The second paragraph delves into the concept of nephrons, which are the functional units of the kidney where filtration, reabsorption, secretion, and elimination take place. The paragraph describes the process of blood filtration and how the filtrate moves through the nephrons, undergoing reabsorption and secretion before being eliminated as urine. The speaker uses a visual aid to illustrate the vast amount of blood filtered by the kidneys daily, comparing it to the volume of water in multiple five-gallon bottles. The paragraph concludes with a teaser for the next video, which will focus on the blood supply to the kidneys.

Keywords

💡Kidney

The kidney is an organ that plays a crucial role in filtering waste products from the blood, regulating blood volume and blood pressure, and maintaining electrolyte balance. In the video, the kidney is central to the discussion of the urinary system's functions, particularly in cleaning the blood and maintaining homeostasis. The script describes the kidney's structure, including the cortex, medulla, and pelvis, and how they contribute to the kidney's overall function.

💡Homeostasis

Homeostasis refers to the body's ability to maintain a stable internal environment despite changes in external conditions. It is essential for the proper functioning of cells and the overall health of an organism. In the video, homeostasis is mentioned as a key reason why the kidney's functions are vital, as they help to maintain balance in the body by filtering out waste and regulating pH levels.

💡Cortex

The cortex is the outer layer of the kidney, where initial blood filtration occurs. It is the starting point for the kidney's process of cleaning the blood. In the script, the cortex is described as part of the kidney's layered structure, highlighting its role in the initial stages of filtration.

💡Medulla

The medulla is the middle layer of the kidney, where further processing of the filtrate takes place. It is involved in the concentration of urine and plays a role in the reabsorption of water and electrolytes. The video script mentions the medulla as a part of the kidney's structure where additional processing occurs after the initial filtration in the cortex.

💡Pelvis

The pelvis in the context of the kidney is the central, funnel-shaped area where urine collects before being transported to the bladder via the ureters. The script describes the pelvis as the region where urine is collected and sent out of the kidney, emphasizing its role in the final stages of urine formation.

💡Blood Supply

The blood supply to the kidney is critical for its function, as it delivers blood that needs to be filtered. The video script mentions that a significant amount of blood from the heart goes to the kidneys, highlighting the importance of the blood supply for the kidney's ability to clean the blood and maintain homeostasis.

💡Filtrate

Filtrate is the fluid that is produced when blood is filtered through the kidney's glomeruli. It contains water, electrolytes, glucose, and waste products. The script explains that approximately 125 milliliters of filtrate are produced every minute, contributing to the total of 180 liters per day, most of which is reabsorbed back into the body.

💡Reabsorption

Reabsorption is the process by which the kidney reclaims useful substances from the filtrate back into the bloodstream. This process is essential for conserving water, glucose, and essential electrolytes. The video script emphasizes reabsorption as a key mechanism that accounts for the difference between the large volume of filtrate produced and the smaller volume of urine excreted.

💡Ureters

Ureters are the tubes that transport urine from the kidneys to the bladder. They play a critical role in the urinary system by ensuring that urine flows in one direction, preventing backflow. The script mentions the ureters as the pathway through which urine is sent from the kidney's pelvis to the bladder.

💡Nephron

A nephron is the functional unit of the kidney, consisting of a glomerulus and a tubular system. It is responsible for the filtration, reabsorption, secretion, and elimination of waste products. The video script describes nephrons as the structures within the kidney's medulla where the actual processes of blood filtration and urine formation occur.

💡Cardiac Output

Cardiac output refers to the volume of blood pumped by the heart per minute. It is a measure of the heart's efficiency in circulating blood throughout the body. The script provides the figure of 5.6 liters per minute as the cardiac output, with 1.2 liters of this amount going to the kidneys, illustrating the significant proportion of blood that is filtered by the kidneys.

Highlights

Introduction to the kidney's anatomy and physiology.

The urinary system's basic functions: cleaning the blood, regulating pH, and blood pressure.

Importance of homeostasis for maintaining a balanced internal environment.

The kidney's role in the urinary system for filtering and cleaning the blood.

Kidney structure explained: cortex, medulla, and pelvis.

Blood supply to the kidneys and its significance for kidney function.

Cardiac output and the percentage of blood that goes to the kidneys.

Filtrate production and the process of reabsorption in the kidneys.

Daily urine production and the role of reabsorption in the urinary system.

Practical demonstration of blood filtration using a five-gallon water bottle analogy.

Introduction to the nephron as the functional unit of the kidney.

Process of filtration, reabsorption, secretion, and elimination within the nephron.

The kidney's function in eliminating waste and maintaining essential substances in the body.

Upcoming video content预告: diving deeper into the blood supply of the kidneys.

Interactive Biology TV's mission to make biology fun and engaging.

The significance of the 20% of cardiac output dedicated to the kidneys for filtering.

The conversion of 180 liters of filtrate to approximately one liter of urine daily.

Transcripts

- In this video, we're gonna be looking at the kidney

it's anatomy and physiology, structure and function.

Let's do this.

(upbeat music)

What's up bio nerds Leslie Samuel here

from Interactive Biology TV where we're making biology fun

and we're gonna layer deeper.

In the last video we spoke about,

I gave an introduction to the urinary system,

and we said that the urinary system

had some basic functions.

Number one, cleaning the blood.

Number two, regulate pH,

then regulate blood pressure and some other functions.

Now these are very important functions

if you wanna maintain homeostasis,

you want there to be balanced in your internal environment.

Balance is very important.

Now we're gonna take it deeper by looking

at the place where most of this stuff is happening

and that's in your kidneys.

First I wanna talk about the structure of the kidney.

As you can see here, we have different layers in the kidney.

The outermost layer is what we see here as the cortex.

That is the outer layer.

All right, that little part of there,

that is the cortex.

And that's where some of the processing happens.

Next, we have the medulla

and that's more kind of like the middle layer

and that's where some more processing happens.

And then we have the pelvis,

that region right there is where you're basically collecting

the urine and sending it out via the ureters.

You could see there's a ureter right here.

That is where the pee is gonna go down to the bladder.

Now the kidney is gonna be very much involved

in filtering and cleaning the blood.

You have a lot of blood.

That's going to the kidney

and here you can see some of the blood supply,

in the next video we're gonna dive deeper

in the blood supply and look at which vessels are coming to

and which vessels are going away from the kidney.

This is gonna be very important for you to understand

the function of the kidneys.

But for right now, what I want you to understand

is that blood is coming obviously from the heart

and it's getting to your kidneys and it's being cleaned

because we gotta have some clean blood.

We gotta have homeostasis,

we gotta get the bad stuff out.

We gotta get rid of the ammonia

and all of that stuff, regulate the pH.

You get the point.

Now I want you to get a good idea of how much work

the kidney is actually doing.

When the heart is working, hopefully your heart is working.

If you're watching this video,

fortunately, your heart is working.

It is pumping blood throughout the body

and the cardiac output

the amount of blood that's leaving the heart

at any given time is about 5.6 liters every single minute,

5.6 liters.

Now of that, about 1.2 liters,

goes to the kidneys every minute.

That's like 20% of all the blood that's coming

from the heart is going to the kidneys and it's filtered

and going through the processes that we are talking about

in the urinary system.

So we're filtering about 20%

of that blood at any given time.

Of that when we filter the blood,

we produce approximately 125 milliliters

of filtrate every single minute.

Now, I don't know if that sounds like a lot to you

but what that ends up being is 180 liters every single day.

Now, can you imagine if all of that had to come out as pee,

fortunately, that doesn't happen.

In fact, we produce about one liter

of urine every single day.

Now some of y'all produce way more urine that that.

So if we're making 180 liters of filtrate every day

but only producing one liter per day of urine,

all of the rest has to be reabsorbed into the body.

Reabsorption is what accounts for the difference.

Now I wanna make this practical for you.

Right here I have a five gallon bottle of water.

Now I have 10 gallons,

10 gallon, this 10 gallon.

it's not full of water but you get the point,

actually, hold on.

Wait, 15 gallons of water.

Okay, this demonstration isn't gonna work.

Okay, imagine I have 10 of those,

10 of those five gallon bottles of water.

And that is approximately how much blood your kidneys

are filtering every single day.

This is one liter.

This is one of those pancake things.

You fill it with the butter and then you could squeeze.

And then it pours the pancake.

It doesn't matter.

But this is how much I need to get from that.

The difference between this and those 10 bottles

is how much reabsorption has to happen in the body.

As you can see, it's a lot of filtering

and a lot of reabsorption.

If you think that's a whole lot,

go ahead and hit subscribe

and tap that bell notification icon to be notified whenever

I create more awesome content.

And maybe somehow that's gonna make

the process happen better.

I don't know.

Anyhow, we have one more important concept to cover.

And that is the concept of the nephron.

Because as you look into the medulla,

if you take a very powerful microscope

what you're gonna see is that

we have a bunch of these little structures

and these structures are called nephrons.

And these are actually the functional units of the kidney.

This is where the filtration, the reabsorption,

the secretion, and the elimination

is actually happening.

Right up here in this region

we're gonna start with some filtration happening.

And as the filtrate moves through these tubes

you're gonna get some reabsorption.

You're gonna get some secretion.

And then you're gonna get via this last tube over a here

the elimination as it collects then into the ureters.

And then it goes down to the bladder stores up there

until that blessed time where you go

and you relieve yourself

and you do the process of elimination.

So the kidney has these amazing functions that helps us

to get rid of the bad stuff, hold onto the good stuff.

It filters the blood and the blood supply

is what we're gonna talk about in the next video.