Unit 3 – Anatomy and Physiology in health and
social care - 2021
How cells work
Every individual is composed of billions of microscopic units called cells.
Cells carry out vast numbers of chemical reactions and processes that make up the
essence of life itself. After looking at the structure and functioning of cells you will
discover how cells work together, managing the energy you use.
Cells rarely exist in isolation.
They are usually grouped together with other similar cells,
which carry out particular tasks.
Groups of cells are known as tissues. Different types of tissues are commonly grouped
together to form an organ, which carries out a particular function.
Groups of organs responsible for major tasks or functions in the body are called organ
systems, or body systems.
The largest cell in the human body is the female ovum, which can just be seen with
the naked eye.
Most cells are much smaller than this and microscopes are needed to view them.
Ordinary light microscopes, such as those found in school or college laboratories, are
quite good for viewing tissues and organs but not very useful for looking inside
individual human cells.
Electron microscopes are necessary to see the detail of cell contents.
These are highly expensive instruments requiring trained operators to prepare and
interpret the specimens. It is possible to take photographs of objects magnified using
a microscope (photomicrographs) so that other people can use them, and also
diagrams made from them, instead.
Function and structure of cells – 1st on the scale ( CELLS – tissues
– organs – organ system)
Details of the interior of a cell are often referred to as the ultrastructure of the cell
(‘ultra’ means ‘beyond what is considered normal’).
This is because they can only be seen with immense magnification.
Before the electron microscope was developed, the inside of a cell was considered to
be a granular sort of ‘soup’, but it is now known that the ultrastructure is highly
organised and composed of many different bodies that carry out their own functions.
The very tiny bodies inside a cell are known as organelles because they have
different physical (and chemical) compositions and carry out their own functions.
Although you will learn about a typical human cell, there are actually lots of different
types of cells each with their own characteristics.
The ‘typical cell’ exists only for study purposes and has no specialisation.
When studying actual cells in the body, you must adapt your knowledge to the
specific type of cell being considered.
For example, a mature red blood cell does not have a nucleus, so any description of
the ultrastructure of a red blood cell would not include the nucleus.
The living material that makes up whole cells is called protoplasm and is subdivided
into the cytoplasm and the nucleus.
Under a light microscope cytoplasm appears granular with no distinct features.
The cytoplasm is the site where most complex chemical reactions occur, mainly
directed by the nucleus.
The nucleus, which is also responsible for inherited characteristics can be seen as a
dark body, usually centrally placed.
,Both the whole cell and the nucleus are surrounded by a membrane, which appears as
a single line.
Cell ultrastructure is so complex and highly organised that it has its own branch of
science – cytology, the study of cells.
In this unit you will learn about the structure and functions of the cell membrane, the
KEY TERMS
organelles in the cytoplasm and the nucleus.
Cell – the basic unit of living material.
Tissues – groups of cells joined together to carry out a particular task.
Organ – a collection of tissues joined together to carry out a specific function.
Electron microscope – a very powerful type of microscope, needed to see inside
cells.
Photomicrograph – a photograph taken of an object magnified using a microscope.
Organelle – a tiny body inside a cell, which carries out its own functions.
Protoplasm – means ‘first material’, refers to anything inside the cell boundary.
Cytoplasm – ‘cell material’, refers to anything inside the cell boundary and outside
the nucleus.
Nucleus – the central part of the cell, which is enclosed in a membrane and is
Cell membrane - controls the passage of substance into and out of the cell.
The electron microscope shows the cell membrane to be a phospho-lipid-protein
bilayer.
The lipids are small, fatty molecules in two layers (bilayer), with larger protein
molecules inserted at intervals partly or
completely through the bilayer.
The lipid molecules are phospholipids.
The phosphate head is water soluble and the
two lipid chains are insoluble in water.
This is why the two layers align themselves,
with the lipid chains facing one another.
The fluid surrounding cells (called tissue
fluid) and the cytoplasm are both watery
environments next to the phosphate heads.
Protein molecules often form channels through the membrane for substances to pass
to and from the cell. The protein molecules also act as identity markers or reception
sites for other molecules such as hormones, which are important to those cells.
This structure is often termed the ‘fluid mosaic model’ of the cell membrane.
What is the role of a cell membrane?
A cell membrane, or a plasma membrane role in the cell is to control the passage of
the substance into and out of the cell through a semi-permeable membrane using the
state of diffusion.
Cytoplasm – site of all chemical reaction.
Cytoplasm is a semi-fluid material, likened to a gel, capable of flowing slowly.
Many chemical reactions are carried out here.
The collective term for these reactions is metabolism and you will find that this term is
frequently used in physiological and biological texts.
Complex storage sugars, such as glycogen and melanin (the dark pigment responsible
for skin and hair colour), are found in cytoplasm.
Cytoplasm provides an environment in which other organelles can operate in.
Within the cytoplasm, materials moved by diffusion, which can only work for short
distances.
What is the role of the cytoplasm in the cell?
,The cytoplasm is where all chemical reactions can be found. It is a semi fluid material
like gel that provides an environment for other organelles to operate in. These
materials move by diffusion and produce chemical reactions called metabolism.
Nucleus – controls what happens in the cell.
This is usually the largest structure inside the cell and, when viewed under a
microscope, it stands out as a dark shape as it takes up dyes or stains very easily.
Most cells have a single, central, spherical nucleus but there are many variations.
Some muscle cells have many nuclei and are, therefore, called ‘multinucleate’.
Red blood cells and platelets do not have a nucleus and are said to be ‘anucleate’.
Some white blood cells have distinct, lobed nuclei.
Apart from red blood cells and platelets (which cannot reproduce and have a limited
lifespan), most cells separated from their nuclei will die.
The nuclear membrane has a structure similar to that of the cell membrane, but with
gaps or pores, through which proteins and nucleic acids pass.
The cell is said to go through cycles of division (mitosis), replication (synthesis) and
resting (interphase). When a cell is not dividing it is said to be ‘resting’ or interphase
and the nuclear material appears like a thick, tangled mass and is called the
chromatin network.
A smaller, darker sphere is often visible, the nucleolus.
This is a source of ribonucleic acid (RNA), one of the nucleic acids.
There may be more than one nucleolus present in some cells.
When a cell is in the process of dividing (mitosis), the chromatin network separates
into distinct black threads known as chromosomes.
There are 23 pairs of chromosomes in a human cell, containing specific sequences of
deoxyribonucleic acid (DNA), another nucleic acid.
DNA is responsible for all our inherited characteristics, such as hair and eye colour.
The sequences of DNA are our genes.
The nucleus controls nearly all the activities of the cell and has been likened to the
architectural drawing or blueprint from which the cell operates.
What is the role of the Nucleus in the cell?
The Nucleus controls what happens inside the cell. It is made up of DNA with 23 pairs
of chromosomes presented in humans and specific patterns of DNA control
characteristics e.g., hair colour and eye colour.
KEY TERMS
Metabolism – the sum of all the chemical reactions occurring in human
physiology that involves using or releasing energy from chemical substances.
Chromatin network – the dark tangled mass seen in the nucleus of a resting cell.
Ribonucleic acid (RNA) – nucleic acid found in both the cell and the nucleus,
responsible for the manufacture of cell proteins such as pigments, enzymes and
hormones.
Chromosomes – long threads of DNA and protein seen in a dividing cell, which
contain the genetic material, or genes, responsible for transmitting inherited
characteristics.
Deoxyribonucleic acid (DNA) – nucleic acid found only in the chromatin network
Cell organelles – Found inside cells
and are like mini organs for the cell.
Organelles are various components of a cell with a
distinct structure and their own functions and can
be likened to miniature organs (hence the term
‘organelles’).
, Organelles include:
Centrioles Ribosomes
Mitochondria Golgi
Endoplasmic reticulum apparatus
Centrioles – used for cell division
Lysosomes.
and sharing DNA.
Every cell in the body has two small organelles called centrioles.
Centrioles play a part in cell division and are usually found near the cell nucleus lying
at right angles to each other.
However, they cannot be seen unless the cell is dividing when they may be seen
through the microscope as one or two black dots.
They are made of protein strands called microtubules, which move to opposite ends of
the cell at the start of cell division, where they make even more microtubules, which
are known as the mitotic spindle.
These threads connect to chromosomes to give the new cells formed the correct
amount of DNA.
What is the role of the centrioles in the cell?
Centrioles are used for cell division under typically found near the nucleus lying
perpendicular to each other. they are made of protein strand's that move to the
opposite ends of the cell once cell division starts, please threads connect to the
chromosomes to give the cells formed the correct amount of DNA.
Mitochondria – provides energy for the cell.
Every cell in the body has at least 1000 rod-shaped or spherical bodies, known as
mitochondria, which are concerned with energy release.
Very energy-active cells (like muscle and liver cells) will have many more.
The remembering bound organelles having a double membrane the outer membrane
is smooth and the inner is highly convoluted Forming folds called cristae.
Each mitochondrion (singular) has a double-layered membrane, like the cell
membrane but the inner layer is folded at intervals, producing a series of ‘shelves’ or
ridges known as cristae.
The enzymes responsible for the end stages of glucose oxidation (cell respiration) are
located on the cristae.
The energy released from glucose is trapped and stored until required by a ‘chemical
battery’ called.
adenosine triphosphate (ATP).
Glucose combined with oxygen produces ATP.
When energy is required for building complex molecules, or for doing work such as
contracting muscles, the ATP breaks down to adenosine diphosphate (ADP), releasing
energy.
The ADP is then recycled, to be built up once more into ATP, using the energy
released from glucose.
What is the role of mitochondria in the cell?
Mitochondria provides energy for the cell, so it is able to move to avoid contract and
to provide secretory substances. it is commonly called the power path of the cell. they
have two membranes the outer one is smooth and the inner one is highly convoluted
forming folds called cristate. In the Cristate, there are enzymes present that are
responsible for end stage glucose oxidisation (cell respiration) which is glucose and
oxygen reacting together to form ATP, Adenosine triphosphate, The energy source for
the cell. if the cell needs to build complex molecules or contract muscles, the ATP
breaks down to ADP, adenosine diphosphate, releasing more energy. the ADP is
recycled back into ATP using the energy released from glucose. mitochondria are
usually Oval and found in large numbers inside a very active cell that needs energy.
social care - 2021
How cells work
Every individual is composed of billions of microscopic units called cells.
Cells carry out vast numbers of chemical reactions and processes that make up the
essence of life itself. After looking at the structure and functioning of cells you will
discover how cells work together, managing the energy you use.
Cells rarely exist in isolation.
They are usually grouped together with other similar cells,
which carry out particular tasks.
Groups of cells are known as tissues. Different types of tissues are commonly grouped
together to form an organ, which carries out a particular function.
Groups of organs responsible for major tasks or functions in the body are called organ
systems, or body systems.
The largest cell in the human body is the female ovum, which can just be seen with
the naked eye.
Most cells are much smaller than this and microscopes are needed to view them.
Ordinary light microscopes, such as those found in school or college laboratories, are
quite good for viewing tissues and organs but not very useful for looking inside
individual human cells.
Electron microscopes are necessary to see the detail of cell contents.
These are highly expensive instruments requiring trained operators to prepare and
interpret the specimens. It is possible to take photographs of objects magnified using
a microscope (photomicrographs) so that other people can use them, and also
diagrams made from them, instead.
Function and structure of cells – 1st on the scale ( CELLS – tissues
– organs – organ system)
Details of the interior of a cell are often referred to as the ultrastructure of the cell
(‘ultra’ means ‘beyond what is considered normal’).
This is because they can only be seen with immense magnification.
Before the electron microscope was developed, the inside of a cell was considered to
be a granular sort of ‘soup’, but it is now known that the ultrastructure is highly
organised and composed of many different bodies that carry out their own functions.
The very tiny bodies inside a cell are known as organelles because they have
different physical (and chemical) compositions and carry out their own functions.
Although you will learn about a typical human cell, there are actually lots of different
types of cells each with their own characteristics.
The ‘typical cell’ exists only for study purposes and has no specialisation.
When studying actual cells in the body, you must adapt your knowledge to the
specific type of cell being considered.
For example, a mature red blood cell does not have a nucleus, so any description of
the ultrastructure of a red blood cell would not include the nucleus.
The living material that makes up whole cells is called protoplasm and is subdivided
into the cytoplasm and the nucleus.
Under a light microscope cytoplasm appears granular with no distinct features.
The cytoplasm is the site where most complex chemical reactions occur, mainly
directed by the nucleus.
The nucleus, which is also responsible for inherited characteristics can be seen as a
dark body, usually centrally placed.
,Both the whole cell and the nucleus are surrounded by a membrane, which appears as
a single line.
Cell ultrastructure is so complex and highly organised that it has its own branch of
science – cytology, the study of cells.
In this unit you will learn about the structure and functions of the cell membrane, the
KEY TERMS
organelles in the cytoplasm and the nucleus.
Cell – the basic unit of living material.
Tissues – groups of cells joined together to carry out a particular task.
Organ – a collection of tissues joined together to carry out a specific function.
Electron microscope – a very powerful type of microscope, needed to see inside
cells.
Photomicrograph – a photograph taken of an object magnified using a microscope.
Organelle – a tiny body inside a cell, which carries out its own functions.
Protoplasm – means ‘first material’, refers to anything inside the cell boundary.
Cytoplasm – ‘cell material’, refers to anything inside the cell boundary and outside
the nucleus.
Nucleus – the central part of the cell, which is enclosed in a membrane and is
Cell membrane - controls the passage of substance into and out of the cell.
The electron microscope shows the cell membrane to be a phospho-lipid-protein
bilayer.
The lipids are small, fatty molecules in two layers (bilayer), with larger protein
molecules inserted at intervals partly or
completely through the bilayer.
The lipid molecules are phospholipids.
The phosphate head is water soluble and the
two lipid chains are insoluble in water.
This is why the two layers align themselves,
with the lipid chains facing one another.
The fluid surrounding cells (called tissue
fluid) and the cytoplasm are both watery
environments next to the phosphate heads.
Protein molecules often form channels through the membrane for substances to pass
to and from the cell. The protein molecules also act as identity markers or reception
sites for other molecules such as hormones, which are important to those cells.
This structure is often termed the ‘fluid mosaic model’ of the cell membrane.
What is the role of a cell membrane?
A cell membrane, or a plasma membrane role in the cell is to control the passage of
the substance into and out of the cell through a semi-permeable membrane using the
state of diffusion.
Cytoplasm – site of all chemical reaction.
Cytoplasm is a semi-fluid material, likened to a gel, capable of flowing slowly.
Many chemical reactions are carried out here.
The collective term for these reactions is metabolism and you will find that this term is
frequently used in physiological and biological texts.
Complex storage sugars, such as glycogen and melanin (the dark pigment responsible
for skin and hair colour), are found in cytoplasm.
Cytoplasm provides an environment in which other organelles can operate in.
Within the cytoplasm, materials moved by diffusion, which can only work for short
distances.
What is the role of the cytoplasm in the cell?
,The cytoplasm is where all chemical reactions can be found. It is a semi fluid material
like gel that provides an environment for other organelles to operate in. These
materials move by diffusion and produce chemical reactions called metabolism.
Nucleus – controls what happens in the cell.
This is usually the largest structure inside the cell and, when viewed under a
microscope, it stands out as a dark shape as it takes up dyes or stains very easily.
Most cells have a single, central, spherical nucleus but there are many variations.
Some muscle cells have many nuclei and are, therefore, called ‘multinucleate’.
Red blood cells and platelets do not have a nucleus and are said to be ‘anucleate’.
Some white blood cells have distinct, lobed nuclei.
Apart from red blood cells and platelets (which cannot reproduce and have a limited
lifespan), most cells separated from their nuclei will die.
The nuclear membrane has a structure similar to that of the cell membrane, but with
gaps or pores, through which proteins and nucleic acids pass.
The cell is said to go through cycles of division (mitosis), replication (synthesis) and
resting (interphase). When a cell is not dividing it is said to be ‘resting’ or interphase
and the nuclear material appears like a thick, tangled mass and is called the
chromatin network.
A smaller, darker sphere is often visible, the nucleolus.
This is a source of ribonucleic acid (RNA), one of the nucleic acids.
There may be more than one nucleolus present in some cells.
When a cell is in the process of dividing (mitosis), the chromatin network separates
into distinct black threads known as chromosomes.
There are 23 pairs of chromosomes in a human cell, containing specific sequences of
deoxyribonucleic acid (DNA), another nucleic acid.
DNA is responsible for all our inherited characteristics, such as hair and eye colour.
The sequences of DNA are our genes.
The nucleus controls nearly all the activities of the cell and has been likened to the
architectural drawing or blueprint from which the cell operates.
What is the role of the Nucleus in the cell?
The Nucleus controls what happens inside the cell. It is made up of DNA with 23 pairs
of chromosomes presented in humans and specific patterns of DNA control
characteristics e.g., hair colour and eye colour.
KEY TERMS
Metabolism – the sum of all the chemical reactions occurring in human
physiology that involves using or releasing energy from chemical substances.
Chromatin network – the dark tangled mass seen in the nucleus of a resting cell.
Ribonucleic acid (RNA) – nucleic acid found in both the cell and the nucleus,
responsible for the manufacture of cell proteins such as pigments, enzymes and
hormones.
Chromosomes – long threads of DNA and protein seen in a dividing cell, which
contain the genetic material, or genes, responsible for transmitting inherited
characteristics.
Deoxyribonucleic acid (DNA) – nucleic acid found only in the chromatin network
Cell organelles – Found inside cells
and are like mini organs for the cell.
Organelles are various components of a cell with a
distinct structure and their own functions and can
be likened to miniature organs (hence the term
‘organelles’).
, Organelles include:
Centrioles Ribosomes
Mitochondria Golgi
Endoplasmic reticulum apparatus
Centrioles – used for cell division
Lysosomes.
and sharing DNA.
Every cell in the body has two small organelles called centrioles.
Centrioles play a part in cell division and are usually found near the cell nucleus lying
at right angles to each other.
However, they cannot be seen unless the cell is dividing when they may be seen
through the microscope as one or two black dots.
They are made of protein strands called microtubules, which move to opposite ends of
the cell at the start of cell division, where they make even more microtubules, which
are known as the mitotic spindle.
These threads connect to chromosomes to give the new cells formed the correct
amount of DNA.
What is the role of the centrioles in the cell?
Centrioles are used for cell division under typically found near the nucleus lying
perpendicular to each other. they are made of protein strand's that move to the
opposite ends of the cell once cell division starts, please threads connect to the
chromosomes to give the cells formed the correct amount of DNA.
Mitochondria – provides energy for the cell.
Every cell in the body has at least 1000 rod-shaped or spherical bodies, known as
mitochondria, which are concerned with energy release.
Very energy-active cells (like muscle and liver cells) will have many more.
The remembering bound organelles having a double membrane the outer membrane
is smooth and the inner is highly convoluted Forming folds called cristae.
Each mitochondrion (singular) has a double-layered membrane, like the cell
membrane but the inner layer is folded at intervals, producing a series of ‘shelves’ or
ridges known as cristae.
The enzymes responsible for the end stages of glucose oxidation (cell respiration) are
located on the cristae.
The energy released from glucose is trapped and stored until required by a ‘chemical
battery’ called.
adenosine triphosphate (ATP).
Glucose combined with oxygen produces ATP.
When energy is required for building complex molecules, or for doing work such as
contracting muscles, the ATP breaks down to adenosine diphosphate (ADP), releasing
energy.
The ADP is then recycled, to be built up once more into ATP, using the energy
released from glucose.
What is the role of mitochondria in the cell?
Mitochondria provides energy for the cell, so it is able to move to avoid contract and
to provide secretory substances. it is commonly called the power path of the cell. they
have two membranes the outer one is smooth and the inner one is highly convoluted
forming folds called cristate. In the Cristate, there are enzymes present that are
responsible for end stage glucose oxidisation (cell respiration) which is glucose and
oxygen reacting together to form ATP, Adenosine triphosphate, The energy source for
the cell. if the cell needs to build complex molecules or contract muscles, the ATP
breaks down to ADP, adenosine diphosphate, releasing more energy. the ADP is
recycled back into ATP using the energy released from glucose. mitochondria are
usually Oval and found in large numbers inside a very active cell that needs energy.
