Guyton and Hall Physiology (Chapter 1 - Homeostasis) *UPDATED 14th edition || Study This!

Summary

This review covers Chapter One of Guyton Hall's 14th Edition medical physiology textbook, focusing on the concept of homeostasis and the human body's internal environment. It discusses the body's composition, the role of cells and organs, and the importance of maintaining a stable extracellular fluid for cellular health. The video explains the difference between intracellular and extracellular fluids, the impact of disrupted homeostasis on health, and the mechanisms by which the body regulates itself, including the nervous and hormonal systems. It also touches on positive and negative feedback loops, and the concept of gain in control systems, providing a foundational understanding of physiological processes.

Takeaways

• 📚 Physiology is the study of mechanisms responsible for life's origin, development, and progression, while pathophysiology deals with disordered body functions.
• 🧠 Cells are the basic building blocks of the body, adapted to perform specific functions, and when grouped together, form organs.
• 🌐 The human body contains more microorganisms than human cells, predominantly in the gastrointestinal tract and on the skin.
• 💧 Approximately 50 to 70 percent of the human body is fluid, with two-thirds inside cells and one-third in the extracellular fluid, also known as the internal environment.
• 🔁 Homeostasis is the maintenance of a stable internal environment, ensuring the extracellular fluid contains the necessary nutrients for cells.
• 🚫 Disease is a state of disrupted homeostasis, where the mechanisms that maintain the internal environment are compromised.
• 🔄 The extracellular fluid can be divided into two types: intravascular (within blood vessels) and interstitial (surrounding cells).
• 🌀 The body's systems work in concert to maintain homeostasis, including the respiratory, gastrointestinal, musculoskeletal, and excretory systems.
• 💉 The nervous and hormonal systems regulate body functions, with the nervous system providing rapid responses and hormones acting through the bloodstream.
• 🛡️ The immune system protects the body against microorganisms, while the integumentary system shields it from the external environment.
• 🔧 Control systems, such as the baroreceptor system for blood pressure, involve sensors, processing units, and effectors to maintain homeostasis through feedback mechanisms.

Q & A

What is the main focus of chapter one in Guyton Hall's medical physiology textbook?

The main focus of chapter one is the internal environment and homeostasis, discussing the mechanisms that maintain a constant internal environment for cells.

What is the difference between physiology and pathophysiology?

Physiology refers to the mechanisms responsible for the origin, development, and progression of life, while pathophysiology is the study of disordered body functions, or issues that arise when these normal mechanisms are disrupted.

What is the composition of the human body in terms of cells and microorganisms?

The human body contains more microorganisms, such as bacteria, than human cells, with these microorganisms mainly residing in the gastrointestinal tract and on the skin.

What percentage of the human body is made up of fluid, and how is it distributed?

Approximately 50 to 70 percent of the human body is fluid, with two-thirds of that fluid being inside the cells and one-third outside the cells in the extracellular fluid.

How does the composition of extracellular fluid differ from intracellular fluid?

Extracellular fluid is primarily composed of salt (sodium chloride), bicarbonate ions, and nutrients, while intracellular fluid contains higher concentrations of potassium, magnesium, and phosphate ions.

What is homeostasis and why is it important for the body?

Homeostasis is the maintenance of a constant internal environment, ensuring that the extracellular fluid has the right constituents for the cells it bathes in. It is crucial for the normal functioning of cells and overall health.

What are the two types of extracellular fluid environments mentioned in the script?

The two types of extracellular fluid environments are the fluid within blood vessels and blood itself, and the interstitial fluid that bathes the cells.

How does the body transport nutrients and oxygen to cells?

The respiratory system picks up oxygen from the environment and transfers it to the blood, while the gastrointestinal tract absorbs nutrients from food, which then enter the bloodstream.

What are the two primary systems that regulate body function according to the script?

The two primary systems that regulate body function are the nervous system, which provides fast and instantaneous responses, and the hormonal system, which uses hormones to send signals through the bloodstream.

What is the purpose of negative feedback in a control system?

Negative feedback in a control system is used to maintain homeostasis by identifying when a signal is abnormal and initiating changes to bring the signal back to a normal or set point.

How does positive feedback differ from negative feedback, and what are some examples?

Positive feedback encourages further change from a set point, leading to greater deviations, unlike negative feedback which aims to restore normalcy. Examples include blood clotting and childbirth.

What is adaptive control and how does it relate to homeostasis?

Adaptive control is a mechanism where the body makes an immediate correction to a signal without waiting for processing, which may result in overshooting or undershooting the set point. It's part of the body's attempt to maintain homeostasis.

Outlines

00:00

📚 Introduction to Medical Physiology

This paragraph introduces the 14th edition of 'Guyton Hall's Medical Physiology' textbook, emphasizing that it serves as an update to the 13th edition. The narrator encourages viewers to follow along with their textbooks while the video focuses on the main points of each chapter to facilitate understanding of key concepts within the comprehensive textbook. The chapter begins with a definition of physiology as the study of mechanisms behind life's origin, development, and progression, contrasting it with pathophysiology, which deals with disordered body functions. It discusses the basic building blocks of the body, cells, and how they form organs. The human body's composition is highlighted, noting that 50 to 70 percent of it is fluid, with two-thirds inside cells and one-third in the extracellular fluid, also known as the internal environment. The differences between extracellular and intracellular fluids are outlined, focusing on the composition of salts, nutrients, and ions. The concept of homeostasis is introduced as the maintenance of a stable internal environment, which is crucial for cell health, and disease is presented as a disruption of this homeostasis. The paragraph concludes by explaining how various body systems contribute to maintaining homeostasis and the role of compensatory mechanisms in disease.

05:01

🔬 Homeostasis and Body Systems

The second paragraph delves into the specifics of how the body maintains homeostasis, focusing on the extracellular fluid's role in providing nutrients to cells. It explains the distinction between the internal environment within blood vessels and the interstitial fluid that bathes cells. The paragraph discusses how the respiratory system, gastrointestinal tract, liver, and musculoskeletal system work together to supply oxygen, nutrients, and remove waste products. The importance of the nervous and hormonal systems in rapid and widespread signaling is highlighted, as well as the immune and integumentary systems' roles in protection. The concept of control systems is introduced with blood pressure regulation as an example, explaining the baroreceptor system's function in negative feedback loops. The paragraph also touches on positive feedback mechanisms, such as blood clotting and childbirth, and contrasts them with negative feedback. It concludes with a discussion of adaptive control, which involves immediate responses that may overshoot or undershoot the set point, and how the brain adjusts these responses over time.

10:03

🧠 Control Systems and Physiological Variability

The final paragraph continues the discussion on control systems, focusing on adaptive control and feed-forward mechanisms. It uses the example of catching a ball to illustrate how the brain learns to adjust responses to achieve a set point. The paragraph emphasizes that while homeostatic mechanisms strive to maintain set points, individual variability due to factors like weight, height, diet, age, sex, environment, and genetics means that these set points can differ. It concludes by summarizing the chapter's content and hints at the next chapter's focus on cell functions. The narrator also directs viewers to resources for studying the entire textbook, including the 13th edition and the website www.studyabis.info.

Keywords

💡Physiology

Physiology is the scientific study of the functions and mechanisms which work in living organisms to sustain life. In the context of the video, physiology is discussed as the set of mechanisms that allow for the origin, development, and progression of life. It is contrasted with pathophysiology, which is the study of disordered body functions. The script uses physiology to introduce the concept of homeostasis and how disruptions in these normal mechanisms can lead to disease.

💡Homeostasis

Homeostasis refers to the maintenance of a stable internal environment within an organism by a network of interconnected feedback mechanisms. The video script explains that homeostasis is crucial for the proper functioning of cells, which are bathed in extracellular fluid. It is the process by which the body keeps variables like temperature, pH, and salt concentration relatively constant despite changes in the external environment. Disease occurs when homeostasis is disrupted.

💡Extracellular Fluid

Extracellular fluid is the liquid found outside of cells, also known as the internal environment. The video describes how two-thirds of the body's fluid is within cells and one-third is extracellular. Extracellular fluid contains nutrients needed for cells and is primarily composed of sodium chloride, bicarbonate ions, and other necessary nutrients. It is the environment in which cells exist and function.

💡Intracellular Fluid

Intracellular fluid is the liquid found inside cells. The script contrasts this with extracellular fluid, highlighting that intracellular fluid contains higher concentrations of potassium, magnesium, and phosphate ions. These ions are essential for various cellular functions, distinguishing the internal environment of the cell from that of the extracellular space.

💡Pathophysiology

Pathophysiology is the study of the functional changes resulting from disease. The video script uses this term to describe what happens when there is an issue with normal physiological mechanisms, leading to disordered body function. It is the process of understanding how diseases disrupt homeostasis and the body's attempts to compensate for these disruptions.

💡Microorganisms

Microorganisms are tiny organisms that are invisible to the naked eye, such as bacteria and fungi. The video script points out that there are more microorganisms living in and on the human body than human cells. These microorganisms, particularly those in the gastrointestinal tract, play a role in human health and disease.

💡Nutrients

Nutrients are substances that an organism needs for growth, health, and the maintenance of life. The video script mentions nutrients in the context of what the extracellular fluid contains to support cell function. Nutrients are taken in by the body through the gastrointestinal tract, processed by the liver, and used by cells for energy and growth.

💡Waste Products

Waste products are substances that are left over after the body has used what it needs from the food and oxygen it takes in. The script discusses how the body produces waste products such as carbon dioxide, which is excreted by the lungs, and other metabolic waste products that are excreted by the kidneys. Waste management is a critical aspect of maintaining homeostasis.

💡Nervous System

The nervous system is a part of the body that coordinates its functions by transmitting signals between different parts. The video script explains that the nervous system allows for fast and instantaneous changes in the body. It is involved in the rapid response to stimuli and is part of the body's control systems that help maintain homeostasis.

💡Hormonal System

The hormonal system, also known as the endocrine system, uses hormones to send signals through the bloodstream to affect organs in other areas of the body. The video script contrasts this system with the nervous system, indicating that hormonal signals can take longer to act but are also crucial for maintaining homeostasis over longer periods and in response to various physiological needs.

💡Immune System

The immune system is a complex network of cells, tissues, and organs that work together to defend the body against harmful microorganisms and foreign substances. The video script mentions the immune system as a protective mechanism of the body against infections and diseases caused by these microorganisms.

💡Gain

In the context of control systems, gain is a measure of how effectively a system can bring an abnormal change back to normal or to the set point. The video script uses the example of baroreceptors to explain how gain can be calculated by dividing the amount of correction by the amount of abnormality left. A higher gain indicates a more effective control system.

Highlights

Introduction to the 14th Edition of Guyton Hall's Medical Physiology textbook.

Definition of physiology and its role in the origin, development, and progression of life.

Explanation of pathophysiology as the study of disordered body function.

The basic building blocks of the body are cells, each adapted to perform specific functions.

Surprising fact: There are more microorganisms in and around the human body than human cells.

The human body is composed of 50 to 70 percent fluid, with two-thirds inside cells and one-third in the extracellular fluid.

The extracellular fluid, also known as the internal environment, is crucial for cell nutrition.

Differences between extracellular and intracellular fluids, particularly in salt and nutrient content.

Homeostasis defined as the maintenance of a constant internal environment for cell health.

Disease as a state of disrupted homeostasis and the body's compensatory mechanisms.

Extracellular fluid is divided into blood and interstitial fluid, with different roles in the body.

The body's systems responsible for nutrient intake, waste removal, and protection.

The nervous and hormonal systems as mechanisms for rapid and widespread signaling in the body.

Control systems in the body, including negative feedback loops for maintaining homeostasis.

The concept of gain as a measure of a control system's effectiveness in restoring homeostasis.

Positive feedback mechanisms and their role in processes like blood clotting and childbirth.

Adaptive control as a rapid response mechanism that may overshoot or undershoot the set point.

Physiological variability and how individual differences affect homeostatic mechanisms.

Transcripts

welcome to the review of chapter one of

Guyton Hall's medical physiology

textbook this is the 14th Edition we've

already covered the entire 13th edition

and this is just an update to the

textbook feel free to grab your textbook

and follow along with this video but

we're just going to cover the main

points of each chapter so then it helps

you to focus on the key Concepts moving

through this pretty large textbook so

starting with chapter one which is the

internal environment effectively going

over homeostasis so starting off with a

bit of a definition physiology is the

mechanisms that are responsible for the

origin development and progression of

life when we have an issue with our

physiology we end up with

pathophysiology which is the study of

the disordered body function so

effectively when we get an issue to

these normal mechanisms that allow the

progression of Life the basic building

blocks of our body are cells cells are

specifically adapted to perform one

under a few functions and when you group

a bunch of cells together you end up

with an organ it might be a surprise to

some that we actually have more

microorganisms which are unrelated to

human cells so little bacteria Etc which

mainly live in our gastrointestinal

tract but also on our skin there's

actually more microorganisms in our and

around our body than our own cells

talking about the human body about 50 to

70 percent of the entire human body is

actually fluid even though we seem like

solid structures we're actually mainly

made out of fluid two-thirds of that

fluid is within our cells one-third is

outside the cells in the extracellular

fluid which is also termed the internal

environment because that is the fluid

that oil cells are bathed in so that

internal environment contains all the

nutrients for those cells that it's

bathing in the main differences between

our extracellular so outside the cell

and they'll intracellular or inside the

cell fluids is that the extracellular

fluid is mainly made out of salt or

contains a lot of salt sodium chloride

but then also bicarbonate ions plus all

the nutrients needed for the cells

whereas within the cell itself we have a

lot of potassium magnesium and phosphate

ions so that actually brings us to what

homeostasis is because homeostasis is

the maintenance of a constant internal

environment so that extracellular fluid

making sure it has all the right

constituents for the cells which it's

bathing in disease on the other hand is

a state of disrupted homeostasis so that

maintenance of our nearly constant

internal environment of whichever

particular organ or area of the body is

now disrupted so homeostasis is no

longer at play there are mechanisms that

get set in to try to maintain normal

function so then let's say your kidneys

get disease there is going to to be a

little compensatory mechanism so then we

are still able to provide some functions

of the kidneys keep us going in the

short term but in the long term that's

when we actually run into a lot of

issues and that's what pathophysiology

really is is trying to explain these

physiological processes that are altered

within disease and injury we can then

break out extracellular fluid into

really two types of environments we've

got the blood vessels and the blood

within it that's transporting that

portion of our extracellular fluid

around the body so from one organ all

the way to another organ at a different

part of the body for instance and then

we then have the extracellular fluid

that's between the cells which is

bathing the cells so fast transport from

around the body and then it then

diffuses across into the extracellular

fluid that's surrounding the cells

called the interstitial fluid just about

all the molecules Within in the blood

can diffuse out of the blood vessels

except for your plasma proteins so

whether all these nutrients come from

that end up in our extracellular fluid

that surrounding the cells or within the

interstitial fluid our Respiratory

System picks up all the oxygen from the

environment and then dumps it into the

blood to be centered around the body our

gastrointestinal tract picks up all the

nutrients so everything we eat gets

dissolved down and then those nutrients

enters the bloodstream and then our

liver actually collects all that

nutrients all that raw ingredients from

our gut processes it and then turns it

into a form that our body can then use

our musculoskeletal system our bones and

our muscles Etc that provides motility

for us to go and seek food consume the

nutrients and effectively get away from

predators Etc once we have used all of

our metabolic products so we've used the

oxygen we have used the nutrients we

then produce waste products so carbon

dioxide for instance which gets excreted

by the lungs so the blood will take that

carbon dioxide from the tissues to the

lungs for it to get excreted our kidneys

get rid of excesses of ions and water

and other metabolic waste products like

urine creatinine our gastrointestinal

tract will obviously get rid of any

undigested material that doesn't get

absorbed and then our liver detoxifies

and removes harmful chemicals that we

absorb throughout that we have these two

systems that regulate our body function

so our nervous system which is a very

fast and instantaneous change you're

able to send signals very fast through

our nervous system but then we also have

hormone systems which use hormones which

are little signals that go through our

bloodstream to affect organs in other

areas so we can send signals either

through our nervous system or through

our hormonal system our body then needs

to be protected so our immune system

which protects us against those

microorganisms and then our skin or

antigumentary system which protects us

against the outside environment we then

also need to be able to not only consume

nutrients convert them into usable forms

so then we can get around we then need

to replicate and produce more offspring

and that's where reproduction comes in

so that allows us to create more beings

and continue with this life so getting

into more of the nitty-gritty about

Control Systems we have several examples

that are given the blood pressures may

be the easiest one to understand where

we have a sensor which is Target having

a particular signal so this example is

the Baro receptor system which is only

sensing our blood pressure

this sensor or receptor is going to

identify when that signal is abnormal so

for example when our blood pressure

increases our baroreceptors are going to

identify that then tell our brain or

Vaso motor centers effectively the

processing unit that processing unit

will then send out another signal to our

effectors to try to reduce that high

blood pressure and in this example it's

our sympathetic nervous system these are

all new Concepts for you obviously being

chapter one but effectively we've got a

sensor identifies a certain signal when

that signal is abnormal it goes to the

processing unit which then sends out a

signal to affect change that changes

hopefully going to bring that signal

back to normal to whatever the reference

set point is which is our example of a

negative feedback so negative feedback

is effectively saying that we have a set

point as soon as we have a change

outside of that set point there is all

these changes that occur to bring it

back to normal game is an objective

measure of how well that control system

is able to bring that signal back to

normal so for instance if we have a set

point we then have a change that brings

our signal out or our control system out

of whack if we actually have signals

that can recover some of that loss but

not quite go back to normal we can then

figure out our gain by dividing the

correction where we came from divided by

the gain of how much of an abnormality

is left so if you can imagine if you

have a larger correction that means you

have greater gain and a better control

system the example here that they give

you is our baroreceptors and if you give

it a lot of fluid into your circulatory

system so if you just pump a lot of

fluid into your circulatory system your

blood pressure is going to go up now if

you have a baroreceptor control system

that's working that's going to help

bring your blood pressure down but

that's not going to perfectly bring it

down to normal how much it brings it

down divided by how much is left is

going to be your gain if you have

extremely high gain that means you are

able to bring your blood pressure pretty

close to your set point there's

different physiological control

mechanisms that require higher gain for

instance your temperature system needs

to have a very very good gain so as soon

as you have a slight change in your

temperature it's brought back to almost

your set point so gain is an objective

measure of how well a certain control

system can bring an abnormal change to

your homeostasis back to normal positive

feedback is the opposite of negative

feedback where you get a signal change

that then encourages even more change so

you get a change out side of normal a

signal then says hey let's let's just

keep doing that and then you keep

getting a greater change away from your

previous set point

pretty uncommon so there are some

examples of this so blood clotting for

instance where you suddenly have a cut

and then your blood clotting system gets

activated that signal occurs but you

actually want blood clotting to continue

because clearly you've got an injury to

tissues so then it keeps going

childbirth is another example where once

labor has started you want it to

continue and then nerves signals too

once a nerve signal starts to get

propagated you want it to continue the

important thing about these positive

feedback systems is that they're a part

of a larger negative feedback control so

blood clotting will continue to a point

and then there's a larger system that's

actually going to control it bring it

back to normal once the bleeding has

been stopped and controlled so positive

feedback has its place but it's usually

a part of a larger negative feedback the

last little control system that we're

going to talk about here is adaptive

control and this is where there's not

enough time for you to go through that

processing unit and bring that change

back to normal so the signal occurs and

you need to correct the signal instantly

that means that you might overshoot it

or not quite reach the set point which

means that there's this feed forward

control is what they call it so

effectively the signal comes in then

instantly it's brought back to a certain

point that's feed forward control your

brain will then analyze what was done

and then say hey we actually didn't

quite reach the set point next time we

see that signal we're going to go a

little bit further or the other examples

of it overshoots so we get a change and

then that feed forward brings it

straight away but over the set point

your brain is going to say no next time

we need to not be as aggressive an

example there can be something as simple

as you know catching a ball initially

when you go to catch a ball that's

coming at you quite quickly you might

quickly put your hands in a certain

region at first when you're a child

trying to learn how to catch a ball

you're going to be missing and your

brain's going to be saying when you've

got an object coming towards you at a

certain degree you need to go into this

certain region and eventually you get to

a point where your feet forward control

is pretty good where you can actually

instantly grab that object flying

through the air now all that being said

we do have physiological variability so

we have these homeostatic mechanisms to

bring things back to certain set points

but everyone's slightly different based

on your weight height diet age sex

environment genetics Etc so we do talk

about these mechanisms generally as

these are the mechanisms set for

correcting a certain abnormality but

just remember everyone has a slightly

different set point and Effectiveness

for controlling our homeostasis that is

effectively the end of chapter one next

we'll be talking about the cell and its

functions if you are looking for the

entire chapters we have done the entire

13th edition already which is still good

enough to study from you can find that

on our study this home page for YouTube

but then also on our website at

www.studyabis.info otherwise I hope this

was helpful and we'll see in the next

chapter