Transcript Cells and tissues - Dynamic Learning

Cells and tissues
Published by Hodder Education © 2010 Helen McGuinness
1 Objectives
By the end of this chapter you will be able to recall
and understand the following knowledge:
 the different levels of structural organisation in
the body
 the importance of homeostasis and metabolism
in correct body functioning
 parts of a cell’s structure and their functional
significance
Published by Hodder Education © 2010 Helen McGuinness
2 Objectives
 the structure and function of the main tissue
types in the body
 the interrelationships between the cells and
tissues and other body systems
 common pathologies associated with cells and
tissues.
Published by Hodder Education © 2010 Helen McGuinness
3 Key words
atom
molecule
cell
tissue
organ
system
homeostasis
metabolism
cell
membrane
cytoplasm
nucleus
nucleolus
nuclear
membrane
lysosome
vacuole
ribosome
Golgi body
mitochondria
centrosome
centromere
centrioles
chromatid
diffusion
osmosis
active
transport
filtration
cell
respiration
tissue fluid
meiosis
mitosis
Published by Hodder Education © 2010 Helen McGuinness
4 Structural organisation
of the body
 The human body involves five levels of structural
organisation – atoms and molecules, cells,
tissues, organs and systems.
 Atoms and molecules are the lowest level of
organisational complexity in the body.
 Cells are the smallest units that show
characteristics of life.
Published by Hodder Education © 2010 Helen McGuinness
5 Structural organisation
of the body
 Tissues are a group of similar cells that
perform a certain function.
 Organs are tissues grouped into
structurally and functionally integrated
units.
 Systems are a group of organs that work
together to perform specific functions.
Published by Hodder Education © 2010 Helen McGuinness
6 Structure of a cell
 A cell is the basic, living, structural and functional unit
of the body.
 The principal parts of the cell are the cell membrane
and its organelles which play specific roles in cellular
growth, maintenance, repair and control.
 The cell membrane encloses the cell and protects its
contents. It is semi-permeable and governs the
exchange of nutrients and waste materials.
 The nucleus controls the cell’s activities and contains
the genetic information.
Published by Hodder Education © 2010 Helen McGuinness
7 Structure of a cell
 The cytoplasm is the substance inside the
cell between the plasma membrane and the
nucleus.
 The ribosomes are sites of protein synthesis.
 The endoplasmic reticulum links the cell
membrane with the nuclear membrane and
assists movement of materials out of the cell.
Published by Hodder Education © 2010 Helen McGuinness
8 Structure of a cell
 The Golgi body processes, sorts and delivers
proteins and lipids (fats) to the plasma membrane,
lysosome and secretory vesicles.
 The lysosome is a round sac in the cytoplasm that
contains powerful enzymes to help destroy waste and
worn out cell materials.
 The mitochondria are the ‘powerhouses’ of the cell.
Published by Hodder Education © 2010 Helen McGuinness
9 Structure of a cell
 The centrosome is a dense area of cytoplasm,
containing the centrioles.
 The centrioles are paired small spherical structures
associated with cell division, or mitosis.
 The chromatids are a pair of identical strands that are
joined at the centromere and separate during cell
division.
 The centromere is the portion of a chromosome where
the two chromatids are joined.
Published by Hodder Education © 2010 Helen McGuinness
10 Structure of a cell
Published by Hodder Education © 2010 Helen McGuinness
11 Functions of cells
 Functions of cells include respiration,
growth, excretion, movement, irritability
and reproduction.
Published by Hodder Education © 2010 Helen McGuinness
12 Cellular respiration
 Cells function through the exchange of fluids,
nutrients, chemicals and ions which are carried
out by passive processes such as diffusion,
osmosis and filtration, and active processes
such as active transport.
 Cell respiration is the controlled exchange of
nutrients such as oxygen and glucose and waste
such as carbon dioxide by the cell to activate the
energy needed for the cell to function.
Published by Hodder Education © 2010 Helen McGuinness
13 Cellular respiration
 The fuel required by cells is provided by
glucose from carbohydrate metabolism and
oxygen absorbed from the respiratory system
into the bloodstream.
 Cells are bathed in a fluid known as tissue fluid
or interstitial fluid which allows the interchange
of substances between the cells and the blood,
known as internal respiration.
Published by Hodder Education © 2010 Helen McGuinness
14 The cell’s life cycle
 Cell division is the process by which cells
reproduce themselves.
 Mitosis is cell division that results in an increase
in body cells and involves division of a nucleus.
 Meiosis is reproductive cell division and results
in the fusion of an egg and a sperm into a
zygote.
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15 Introduction to tissues
 A tissue is a group of similar cells that are
specialised for a particular function.
 The tissues of the body are classified into four
main types: epithelial, connective, muscular
and nervous.
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16 Epithelial tissue
 Epithelial tissue provides coverings and linings of
many organs and vessels.
 There are two categories of epithelial tissue: simple
(single layer) and compound (multi-layer).
 There are four different types of simple epithelium:
squamous, cuboidal, columnar and ciliated.
 There are two different types of compound epithelium:
stratified and transitional.
Published by Hodder Education © 2010 Helen McGuinness
17 Epithelial tissue
Type
Simple
squamous
Structure
Location
Function
A single layer of flat,
scale-like cells with a
central nucleus
The cells fit closely
together, rather like a
pavement, producing a
very smooth surface
Lines the alveoli of
the lungs
Simple
cuboidal
Single layer of cube-like
cells
Ovaries, kidney
tubules, thyroid
gland, pancreas
and salivary glands
Secretion and
absorption
Simple
columnar
Single layer of tall,
cylindrical column cells
with nucleus situated
towards base of cell
Lines the small and
large intestine,
stomach and gall
bladder
Secretion and
absorption
Lines blood and
lymphatic vessels
and the heart
Allows for
exchange of
nutrients, wastes
and gases
Published by Hodder Education © 2010 Helen McGuinness
18 Epithelial tissue
Type
Simple ciliated
(columnar)
Structure
A form of columnar
epithelium
Single layer of
rectangular cells that
contain hair-like
projections (cilia) from
its surface
Location
Function
Lines the upper part
of respiratory system
Also lines the uterine
tubes
The beating of the
cilia carries
unwanted particles
along with mucus
out of the system
Helps propel the
ova towards the
uterus
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19 Connective tissue
 Connective tissue is the most abundant type
of body tissue. It connects tissues and organs
to give protection and support.
 Connective tissue consists of the following
different types: areolar, adipose, white
fibrous, yellow elastic, lymphoid, blood,
bone and cartilage.
Published by Hodder Education © 2010 Helen McGuinness
20 Connective tissue
Type
Structure
Location
Function
Areolar
Most widely distributed
type of connective tissue
in body
A loose, soft and pliable
tissue containing collagen,
elastin and reticular fibres
Under the skin, between
muscles, supporting blood
vessels and nerves and in
the alimentary canal
Provides strength,
elasticity, connects
and supports
organs
Adipose
A type of areolar tissue
containing fat cells
(adipocytes)
Surrounds organs such as
kidneys and heart
Under the skin
(subcutaneous layer)
between bundles of
muscle fibres, in yellow
bone marrow of long
bones and as a padding
around joints
Provides
insulation, support
and protection
Emergency energy
reserve
Published by Hodder Education © 2010 Helen McGuinness
21 Connective tissue
Type
Structure
Location
Function
White
fibrous
Strong, connecting tissue
made up of mainly closely
packed bundles of white,
collagenous fibres, with very
little matrix
Contains cells called
fibrocytes between bundles
Forms tendons which
attach muscle to bone,
ligaments which tie bones
together and as an outer
protective covering for
some organs such as the
kidney and bladder
Provides strong
attachment between
different structures
Yellow
elastic
Consists of branching yellow
elastic fibres with fibrocytes in
the spaces between the fibres
Arteries, trachea, bronchi
and lungs
To allow stretching of
various organs, followed
by a return to original
shape and size
Lymphoid
Semi-solid matrix with fine
branching fibres
Specialised cells called
lymphocytes
In the lymph nodes, spleen,
tonsils, adenoids, walls of
the large intestine and
glands in small intestine
Forms part of the
lymphatic system whose
function is to protect the
body from infection
Published by Hodder Education © 2010 Helen McGuinness
22 Connective tissue
Type
Structure
Location
Function
Blood
Also known as liquid
connective tissue, contains
the blood cells erythrocytes,
leucocytes and thrombocytes
which float within fluid called
plasma
Contained within blood
vessels
Helps maintain
homeostasis of the
body by transporting
substances throughout
the body, by resisting
infection and
maintaining heat
Bone
Hardest and most solid of all
connective tissues
Tough, dense compact bones
and slightly less dense
cancellous bone
Bones
Protects and supports
other organs and soft
tissues
Cartilage
Much firmer tissue than other
connective tissues; matrix is
quite solid
See next slide on types
of cartilage
See next slide on types
of cartilage
Published by Hodder Education © 2010 Helen McGuinness
23 Cartilage
Type
Description
Location
Function
Hyaline
cartilage
Most abundant cartilage
found in the body
Smooth, bluish-white, glossy
tissue
Contains numerous cells
called chondrocytes from
which cartilage is produced
Found on the surfaces of the
parts of bones which form
joints
Forms costal cartilage which
attach ribs to sternum
Forms part of the larynx,
trachea and bronchi
Provides a hardwearing low friction
surface within joints
Provides flexibility in
the nose and
trachea
White fibrous
cartilage
Tough but slightly flexible
Composed of bundles of
collagenous white fibres in a
solid matrix with cells
scattered among them
As pads between the
vertebrae called the
intervertebral discs and in the
symphysis pubis which joins
pubis bones together
Support and to join
together or fuse
certain bones
Yellow elastic
fibrocartilage
Yellow elastic fibres running
through solid matrix, between
which chondrocytes are
situated
Forming the pinna (lobe of
the ear) and forming the
epiglottis
Provides support
and maintains shape
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24 Membrane
Type
Description
Location
Function
Mucous
membrane
Lines body cavities and outer
layer of organs
Lines respiratory, digestive,
urinary and reproductive tracts
Lines openings to external
environment and secretes
viscous slippery fluid (mucus)
that coats and protects
underlying cells
Serous
membrane
Lines body cavities not open to
external environment and covers
many organs
Two layers: parietal which lines
the wall of body cavities and
visceral which provides external
covering to organs in body
cavities
Pericardium of the heart
Pleural membranes in the lungs
Peritoneum lining the abdominal
organs
Lines body cavities not open to
external environment and
secretes a thin, watery
(serous) fluid that lubricates
organs to reduce friction as
they rub against one another
and against wall of cavities
Synovial
membrane
Lines joint cavities of freely
movable joints
Lines spaces around certain joint
cavities (shoulder, hip and knee)
Secretes synovial fluid that
provides nutrition and
lubrication to joints so they
move without undue friction
Published by Hodder Education © 2010 Helen McGuinness