introduction to physiology: cell and general physiology Flashcards
What is the most abundant cell in the human body?
Although the red cells
are the most abundant of any single type of cell in the body,
there are about 75 trillion additional cells of other types
that perform functions different from those of the red cell.
How many cells does the human body has?
The entire body, then, contains about 100 trillion cells
Our body is made up of 60 % what?
About 60 percent of the adult human body is fluid, mainly
a water solution of ions and other substances.
What is intracellular fluid?
Although
most of this fluid is inside the cells and is called intracellular
fluid, about one third is in the spaces outside the cells
and is called extracellular fluid.
What is the extracellular fluid?
This extracellular fluid is
in constant motion throughout the body.
It is transported
rapidly in the circulating blood and then mixed between
the blood and the tissue fluids by diffusion through the
capillary walls
about one third is in the spaces outside the cells
and is called extracellular fluid
Why is the extracellular fluid called the internal environment?
In the extracellular fluid are the ions and nutrients
needed by the cells to maintain cell life. Thus, all cells live
in essentially the same environment—the extracellular
fluid.
For this reason, the extracellular fluid is also called
the internal environment of the body, or the milieu intérieur,
a term introduced more than 100 years ago by the
great 19th-century French physiologist Claude Bernard.
Differences Between Extracellular and Intracellular
Fluids
The extracellular fluid contains large
amounts of sodium, chloride, and bicarbonate ions plus
nutrients for the cells, such as oxygen, glucose, fatty acids, and amino acids.
It also contains carbon dioxide that is being transported from the cells to the lungs to be excreted,
plus other cellular waste products that are being transported
to the kidneys for excretion.
The intracellular fluid differs significantly from the
extracellular fluid; for example, it contains large amounts
of potassium, magnesium, and phosphate ions instead of
the sodium and chloride ions found in the extracellular
fluid. Special mechanisms for transporting ions through
the cell membranes maintain the ion concentration differences
between the extracellular and intracellular fluids.
These transport processes are discussed in Chapter 4.
What are the contents of extracellular fluid?
The extracellular fluid contains large
amounts of sodium, chloride, and bicarbonate ions plus
nutrients for the cells, such as oxygen, glucose, fatty acids,
and amino acids.
It also contains carbon dioxide that is being transported from the cells to the lungs to be excreted,
plus other cellular waste products that are being transported
to the kidneys for excretion.
NCB
What are the contents of intracellular fluid?
The intracellular fluid differs significantly from the
extracellular fluid; for example, it contains large amounts
of potassium, magnesium, and phosphate ions instead of
the sodium and chloride ions found in the extracellular
fluid. Special mechanisms for transporting ions through
the cell membranes maintain the ion concentration differences
between the extracellular and intracellular fluids.
These transport processes are discussed in Chapter 4.
KMP- kiss my pussy :inside
What is homeostasis?
The term homeostasis is used by physiologists to mean
maintenance of nearly constant conditions in the internal
environment.
Essentially all organs and tissues of the body
perform functions that help maintain these relatively constant
conditions.
For instance, the lungs provide oxygen
to the extracellular fluid to replenish the oxygen used by
the cells, the kidneys maintain constant ion concentrations,
and the gastrointestinal system provides nutrients.
A large segment of this text is concerned with the manner
in which each organ or tissue contributes to homeostasis.
To begin this discussion, the different functional
systems of the body and their contributions to homeostasis
are outlined in this chapter; then we briefly outline the
basic theory of the body’s control systems that allow the
functional systems to operate in support of one another.
Extracellular fluid is transported through all parts of the
body in two stages.
- The first stage is movement of blood through the body in the blood vessels,
- and the second is movement of fluid between the blood capillaries and the intercellular spaces between the tissue cells.
As blood passes through the blood capillaries, continual
exchange of extracellular fluid also occurs between
the plasma portion of the blood and the interstitial fluid
that fills the intercellular spaces. This process is shown
in Figure 1-2.
The walls of the capillaries are permeable
to most molecules in the plasma of the blood, with the
exception of _________, which are too
large to readily pass through the capillaries.
plasma protein molecules
Therefore,
large amounts of fluid and its dissolved constituents
diffuse back and forth between the blood and the tissue
spaces, as shown by the arrows. This process of diffusion
is caused by__________ of the molecules in both the plasma and the interstitial fluid. That is, the fluid and
dissolved molecules are continually moving and bouncing
in all directions within the plasma and the fluid in the
intercellular spaces, as well as through the capillary pores.
kinetic motion
Few cells are located more than 50 micrometers from a
capillary, which ensures diffusion of almost any substance
from the capillary to the cell within a few seconds.
Thus,
the extracellular fluid everywhere in the body—both that
of the plasma and that of the interstitial fluid—iscontinually
being mixed, thereby maintaining homogeneity of the
extracellular fluid throughout the body.
T or F
true
Origin of Nutrients in the Extracellular Fluid
- Respiratory System
- Gastrointestinal Tract
- Liver and Other Organs That Perform Primarily
Metabolic Functions - Musculoskeletal System.
How does the respiratory system provide nutrients ?
The blood picks up oxygen in the alveoli, thus
acquiring the oxygen needed by the cells. The membrane
between the alveoli and the lumen of the pulmonary
capillaries, the alveolar membrane, is only 0.4 to 2.0
micrometers thick, and oxygen rapidly diffuses by molecular
motion through this membrane into the blood.
Musculoskeletal System.
How does the musculoskeletal
system contribute to homeostasis?
The answer is
obvious and simple:
Were it not for the muscles, the body
could not move to the appropriate place at the appropriate
time to obtain the foods required for nutrition.
The musculoskeletal system also provides motility for protection
against adverse surroundings, without which
the entire body, along with its homeostatic mechanisms,
could be destroyed instantaneously.
Removal of Metabolic End Products
- Removal of Carbon Dioxide by the Lungs.
- Kidneys
- Gastrointestinal Tract.
- Liver.
Regulation of Body Functions
- Nervous System
- Hormone Systems.
Protection of the Body
- Immune System.
- Integumentary System
Positive Feedback Can Sometimes Be Useful.
- clotting
- child birth: uterine contractions
- generation of nerve signals
What is feed-forward control?
some movements of the body occur so
rapidly that there is not enough time for nerve signals to
travel from the peripheral parts of the body all the way
to the brain and then back to the periphery again to control
the movement. Therefore, the brain uses a principle
called feed-forward control to cause required muscle contractions.
That is, sensory nerve signals from the moving
parts apprise the brain whether the movement is performed
correctly. If not, the brain corrects the feed-forward
signals that it sends to the muscles the next time the
movement is required.
What is adaptive control?
This is called adaptive control. Adaptive control,
in a sense, is delayed negative feedback.
