ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell
Terminology
Histology – The microscopic study of the structure of tissues and cells.
A Cell – The smallest unit of matter that can live independently and
reproduce itself. Constantly moving and changing.
A group of cells form tissue.
A group of tissues form an organ.
Function of cells – to carry out chemical activities needed to sustain life.
Function of tissues – to provide for a division of labour among body cells.
Structure & Function of a general cell
A general cell is encased in a cell membrane and made up of protoplasm
(colourless, jelly-like material), salts, carbohydrates, lipids and amino
acids. Its general function is to provide growth, repair and reproduction.
The protoplasm is in two distinct parts – cytoplasm and nucleus.
Vacuoles
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Debbie Kemp
ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell
Cytoplasm
This forms the outer part of the cell and is encased in a cell or plasma
membrane. In the cytoplasm are:

Mitochondria – these contain enzymes that release energy to
convert ADP to ATP (refer to the muscular system)

Centrosome – this is the dense part of the cytoplasm closest to
the centre (nucleus). It contains centrioles (in pairs) and each of
these is made up of 9 bundles of microtubules, which are involved
in cell division (mitosis)

Ribosomes – these contain RNA (ribonucleic acid) and are bound
to protein in strands. They are involved in growth and cell repair.

Golgi Apparatus – these contain proteins/enzymes, lipids and
collagen that combine to secrete polysaccharides (carbohydrates)
that are transported to other parts of the cell for use as energy.

Lysosomes – these contain powerful enzymes, which break down
any bacteria or dead cell parts.

Vacuoles – empty spaces in the cytoplasm used to store waste for
future breakdown into energy.

Endoplasmic Reticulum – a membrane network that facilitates the
transportation of different substances through the cytoplasm
(message system).

Centromere – where the chromosomes join.

Chromatids – two strands of chromosomes held together by a
centromere.
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Debbie Kemp
ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell
Nucleus
This forms the inner part of the cell and is encased in a double nuclear
membrane. The outer membrane is linked with the endoplasmic reticulum
so RNA can pass from the nucleus to the cytoplasm.
The nucleus controls all the structure (organelle) in the cytoplasm. The
cytoplasm inside the nucleus is called neuroplasm and contains DNA
(deoxyribonucleic acid), which carries our genetic code and chromatin,
which forms strands of chromosomes (genes). When two strands of
chromatids join they form a chromasome and the point at which they
join is called the centromere. It is via the centromere that genetic
information is exchanges between two ‘parent cells’. Cell division
(mitosis) then occurs and the new ‘daughter cells’ are then identical.
DNA has been replicated. The nucleus also contains nucleolus that
programmes how the ribosomes in the cytoplasm are formed (for which
purpose).
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Debbie Kemp
ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell
How substances enter & leave the cell
The cell membrane is made of protein threads and lipids. These keep the
contents of the cell together, but also let in and out other substances,
like a filter. Some substances can cross into the cell, some are blocked.
Substances go into and out of a cell in different ways:

Diffusion – the membrane is porous, and small molecules, like
oxygen and carbon dioxide, can pass through.

Osmosis – when the concentration is greater in one side of the
membrane, water passes through to that side until the
concentration is equal on both sides. When the pressure is the
same in both sides it is called isotonic pressure.

Dissolution – large fatty substances that will not diffuse dissolve
into the fatty or lipid part of the membrane.

Active transport – when substances are too large to pass through
and won’t dissolve, a carrier substance in the cell membrane takes
them from the outside to the inside, like glucose and amino acids.

Filtration – The force of fluid’s weight pushes against the porous
surface, and fluid is moved through the membrane.
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Debbie Kemp
ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell
Cell Division
New cells evolve from old cells = mitosis = our bodies grow and repair.
Meiosis = sex cell (gamates) reproduction (eggs and sperm).
Mitosis
Cellular reproduction from a single cell to two daughter cells. The
constant division of cells to continue life.
Extremely rapid from conception to birth, rapid in childhood, slightly
slower following puberty, gradually slowing through the remainder of life.
For growth (as in child to adult), repair of damage (as in wounds) and
replacement of old cells (as they are recycled).
Phases of division (IPMAT):
North Pole
N
Centrosome
c
Equator
South Pole
Chromosomes
c
Centrosome
S

Interphase – Resting (living and processing). Genetic material
(DNA) is reproduced and cell increases in size. The new cell
carrying the same information as the old one.

Prophase – centrosome divides into 2 centriola which move away
from each other (N & S poles), yet are still joined in the middle.
Chromatin in nucleus shortens/thickens to form two
chromosomes. The nucleoli disappear.

Metaphase – nuclear membrane disappears. Chromosomes move to
centre of cell (across the equator), still attached to the
centrosome threads and are clearly visible.

Anaphase – centromere stretches and centrioles move further
apart. Pairs of chromosomes divide and the identical halves move
to each end of the cell. Spindle threads of centrosome form new
centrosomes for each new daughter cell.

Telophase – new nuclear membranes appear around each pair of
chromosomes = new nucleus. Two chromatids prevent further
DNA replication (the bit that goes wrong in cancer). Spindle
fibres of centrosome disintegrate. Cell membrane continues to
form two new daughter cells.
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Debbie Kemp
ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell
Meiosis
Reproduction of sex cells (gamates), which have a half package of
chromosomes (23).
When male sex cell (sperm) joins with the female sex cell (ovum), each
carrying 23 chromosomes, the new cell (zygote), now containing the full
46 chromosomes, can grow into a new human being.
From this point onwards the zygote reproduces itself via mitosis.
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Debbie Kemp
ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell
Types of tissues
As cells endlessly divide, they become specialised for different
functions and same function cells then group together to form same
type tissues.
There are 4 main tissue types:
1. Epithelium (covering)
2. Connective (supporting)
3. Muscle (movement)
4. Nervous (control)
Most organs contain several tissue types:
1. Epithelial tissue – the lining covering and glandular body tissues.

Its function is to protect, absorb, filter and secrete (porous).

The cells are closely packed and lie on a basement membrane
that connects them to structures below.

There are two types of epithelial tissue:
o Simple – single layer of identical cells.
There are four types of simple epithelial tissue:
1. Squamous (pavement) – single layer of flattened cells
forming smooth membrane. E.g. heart, blood and
lymph vessels, alveoli of lungs
2. Cuboidal – cube shaped layer. E.g. kidneys and some
glands.
3. Columnar – rectangular layer which secretes mucus.
Alimentary tract (digestion).
4. Ciliated – columnar cells with cilia (fine hairs). E.g.
respiratory passage and uterine tubes.
o Compound – several thicker layers of various shaped
cells. Top layers brow up from below. Main function is to
protect structures below. There are two types of
stratified epithelial tissue:
1. Stratified squamous – columnar at bottom layers and
flattened as they grow to the surface. May be either
non-keratinised (which are wet so that wear and tear
is minimised, e.g. lining of mouth, pharynx, etc), or
keratinised (which are dry, e.g. skin, hair, nails. The
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Debbie Kemp
ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell
protein keratin is present to form a tough
waterproof layer).
2. Transitional – layers of pear shaped cells found in
lining of bladder. Allows for stretching as bladder
fills.
2. Connective tissue – The cells forming this tissue are more widely
separated from each other and inter-cellular substance is
present. Major functions: binding and support, protection,
transport and insulation. This tissue type is found in all organs as
it supports the specialised tissue.
The different cells involved in all types of connective tissue are:

Fibroblasts – large flat cells with irregular processes which
produce collagen and elastic fibres and a matrix of cellular
material. Fibroblasts are particularly active in tissue repair
(cuts), etc.

Macrophanges – irregular shaped cells with granules in the
cytoplasm. Their purpose is to defend the tissues from
bacteria.

Plasma cells – secrete specific antibodies into the blood.

Mast cells – produce heparin, serotonin and histamine when
there is damage to tissue.

Fat cells – found in adipose tissue.
Types of connective tissue

Areolar – loose connective tissue found in almost every part of
the body and gives elasticity and strength. Semi-permeable.
Contains fibroblasts and mast cells.

Adipose – fat cells containing large globules of fat. Two types:
White – 20-25% of body weight and is found supporting
kidneys, eyes, between muscle fibres and under skin
(insulation).
Brown – scapula, nape of neck and walls of large blood vessels
of trunk. Involved in maintaining body temperature as it is
more richly supplied with blood.

White Fibrous – made up mainly of collagen fibres found in
ligaments, outer protective covering of kidneys, lymph nodes
and brain & muscle sheaths (fascia).
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Debbie Kemp
ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell

Yellow elastic – made up of mainly elastic fibres secreted by
fibroblasts. Found in organs where alteration of shape is
needed, e.g. walls of blood vessels.

Blood – fluid connective tissue containing 45% cells suspended
in 55% plasma.

Lymphoid – Lymphocyte cells are found in the blood, lymph
nodes, spleen, small and large intestine and protect against
bacterial infection.

Cartilage – firmer tissue. Cells are called chondrocytes. Three
types: hyaline, white fibrocartilage and yellow elastic
fibrocartilage. Hyaline is found on articular surfaces of joints.
White fibrocartilage (white) is found between vertebral
discs, knee, hip and shoulder joints and in ligaments. Yellow
elastic fibrocartilage (yellow) is found in the epiglottis, ear
lobe, as it is extremely pliable.

Bone – these cells (osteocytes) are surrounded by collagen
fibres, strengthened by calcium and phosphate, thus giving
strength and rigidity. Bone has a great capacity for growth in
the first 20 years of life.
Two types of bone:
1. Compact – solid and dense.
2. Cancelious (spongy) – fine, honeycomb appearance.
Function = protection.
3. Muscle tissue – Three types of muscle tissue:

Striated (skeletal) – These cells are cylindrical and up to 35cm
long (a fibre). They have several nuclei just under the cell
membrane (sarcolemma). The cells or fibres lie parallel to each
other, giving a striped appearance. Sarcoplasm, the cytoplasm
of muscle fibres, contains
o Bundles of myofibrids – contractile proteins actin and
myosin
o Many mitochondria (ATP production)
o Glycogen, a carbohydrate for energy use
o Myoblobin, an oxygen binding protein that stores oxygen
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Debbie Kemp
ITEC Anatomy, Physiology & Holistic Massage Course
Histology – The Cell

Non-striated (smooth) – These cells are spindle shaped with
only one nucleus and no distinct sarcolemma, but rather a fine
membrane surrounding each fibre. Bundles of fibres form
sheets of muscle and are found in the walls of involuntary
muscles, e.g. respiratory tract.

Cardiac – Each cell has a nucleus with branches, which gives
this muscle the appearance of a sheet of muscle and not
individual fibres. The connecting branches allow heart
contractions to flow from cell to cell so that each does not
have to be stimulated separately.
4. Nervous tissue – 2 types:

Neurones - excitable cells which initiate, receive, conduct and
transmit information.

Non-excitable cells – which support the neurones
5. Membranes
Body membranes are thin sheets of tissue that cover the body,
line body cavities, and cover organs within the cavities in hollow
organs.
Mucous Membranes are epithelial membranes that consist of
epithelial tissue that is attached to an underlying loose
connective tissue. These membranes, sometimes called mucosae,
line the body cavities that open to the outside. The entire
digestive tract is lined with mucous membranes. Other examples
include the respiratory, excretory, and reproductive tracts.
Serous Membranes line body cavities that do not open directly to
the outside, and they cover the organs located in those cavities.
Serous membranes are covered by a thin layer of serous fluid
that is secreted by the epithelium. Serous fluid lubricates the
membrane and reduces friction and abrasion when organs in the
thoracic or abdominopelvic cavity move against each other or the
cavity wall. Serous membranes have special names given according
to their location. For example, the serous membrane that lines
the thoracic cavity and covers the lungs is called pleura.
Synovial membranes are delicate, thin inner layers that
constitute part of the articular capsule of a synovial joint.
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Debbie Kemp