Transcript p2 - the four main tissues

Unit 5 – Anatomy and physiology for health and social care
Zahira Mahmood
Tissues are a collection of similar cells carrying out a specific functions.
There are four different types of Tissue
• Epithelial Tissues – layers and linings (the lining of the windpipe)
• Connective Tissues – Holds structures together and provide support (cartilage and bone)
• Muscle Tissues – Cells specialised to contract and move parts of the body
• Nervous Tissues – Cells that can convert stimuli to electrical impulses and conduct those impulses
Epithelial tissue covers the whole surface of the body and is specialised to form
the covering or lining of all internal and external body surfaces.
Endothelium is a Epithelial tissue that occurs on surfaces on the interior of the
body.
They are also composed of several layers of cells named compound Epithelia ,
or a single layer named simple Epithelia.
The bottom layer of the cells are attached to the basement membrane for
support. and connection.
There are nerve supplies to Epithelia, however, they are supplied with oxygen
and nutrients from deeper tissues by diffusion.
Diffusion is the passage of molecules from a high concentration to a low
concentration.
Simple Epithelial cells can be squamous, cuboidal, columnar or ciliated.
Squamous Epithelial cells are very flat, with each nucleus forming a lump in the
centre. They fit closely together and they cannot offer much protection and their
function is to allow materials to pass through via diffusion and osmosis. Simple
squamous epithelial is found in the walls of:
- Lung Alveoli
-Blood Capillaries
Cuboidal Epithelial cells are cubed shaped, with spherical nuclei. They often occur
in glandular tissues making secretions. They can be found in:
- Kidney Tubules
-Sweat Ducts
- Glands like the thyroid gland and breast tissue.
Columnar Epithelial Cells are taller with a slightly oval nuclei. They are
occasionally associated with microscopic filaments known as cilia and are then
called Ciliated Epithelia.
Cilia move in wave like motions and are commonly found associated with goblet
cells which hide mucus in the respiratory and alimentary tracts.
The mucus traps unwanted particles such as carbon and the cilia transport dirty
mucus to the exterior.
Columnar cells are found lining the:
- Trachea and bronchi
- Villi in the small intestine
Ciliated columnar epithelium
The main function of the compound epithelia is to protect deeper structures and
multiple layers of cells which obstruct the passage of materials.
The tongue and oesophagus are lined by stratified epithelia consisting of layers of
squamous, cuboidal or columnar cells which eventually become flattened by pressure
from below as they reach the surface.
The skin has an outer layer of Epithelium which is similar in structure to the stratified
epithelium but with extra layer of flattened dead cells on the outside. This is known
as Epidermis.
Stratified
epithelium
Connective tissues lie beneath the Epithelial Tissues, connecting different
parts of the internal structure. They are also widely distributed in the
body.
The cells that lie in the background material are called the Matrix.
The Matrix may be a liquid like in blood, jelly- like areolar tissue, firm as in
cartilage or hard as in the bone.
The Matrix of the tissue is usually obstructed by the connective tissue
cells.
The function of these tissues are to:
-Transport materials
- Give support
- Strengthen and protect
I will explain the connective tissues of:
- Blood
-Cartilage
- Bone
- Areolar tissue
- Adipose tissue
Blood includes straw coloured plasma – The Matrix – in which
various types of blood are carried.
Plasma is mostly water and carries several substances such as
oxygen and carbon dioxide, nutrients such as glucose and amino
acids, salts, enzymes and hormones.
Cartilage is smooth, translucent, firm substance that protects bone ends from friction
during movement, and forms the major part of the nose and the external ear flaps called
Pinnae. It does not contain blood vessels and is nourished by diffusion from underlying
bone.
Bone is much harder substance than cartilage, however, it can be worn away by friction.
Osteocytes – bone cells – are trapped in the hard matrix in concentric rings named
Lamellae.
The bone is created to bear weight and limb bones are hollow, like girders.
The bone is also used to protect weaker tissues such as the Brain, lungs and heart.
Areolar tissue is the most common tissue in the body. It is sticky, white material that binds
muscle groups, blood vessels and nerves together. The matrix is semi-fluid and it contains
collagen fibres and elastic fibres obstructed by cells found in this loose connective tissue.
Areolar tissue offers support to the tissues it surrounds.
This is a technical term for fatty tissue. It is a variation of areolar tissue, in which the
adipose cells have multiplied to obscure other cells and fibres. It is also common for under
the skin and around the organs such as the heart, kidneys and parts of the digestive tract.
Muscle tissue cells specialised to contract and move parts of the body. It is also capable of
responding to stimuli. There are three different types of muscle in the human body:
- Striated
-Non-striated
- Cardiac
Each muscle is created of muscle fibres that are capable of shortening – contracting – and
returning to their original state – relaxation.
Contraction causes movement of the skeleton, soft tissue, blood or specific material, for
example, urine. Muscle has blood and nerve supplies.
Striated muscle known as voluntary, skeletal or striped muscle, is attached to the bones of
the skeleton. Some facial muscles are attached to the skin.
The name ‘ striated’ means striped therefore each individual fibre shows alternate dark
and light banding from muscle protein filaments from which it is made. Some fibres are 30
centimetres long and one hundredth of a millimetre wide.
This type of muscle is also called involuntary, smooth or plain muscle. The muscle fibres are
spindle – or cigar shaped, with single central nuclei, and dovetail with each other. It is found
around hollow internal organs such as the stomach, intestines, iris of the eye and bladder. It
is not attached to bones.
This type of muscle is found only in the four chambers of the heart. Atria and Ventricles . It
can rhythmically contract without receiving any nervous stimuli therefore it differs from
other muscle. Under normal healthy circumstances, cardiac muscle is not allowed to
contract myogenically.
Nervous tissue is only found in the nervous system and consists of the brain, spinal
cord and nerves. It seeks to create consistency, co-ordination, and communication
between different parts of the body whilst receiving stimuli from both external and
internal sources.
The nervous tissue is made of:
Neurons – These are highly specialised nerve cells that transmit nervous impulses.
They are only present in the brain and the spinal cord. They have two special
properties.
1. Propagation of impulses – the ability to conduct impulses
2. Irritability – the ability to respond to a stimulus
Neuroglia – These are connective tissue cells blended with the neurons in the brain
and spinal cord that offer support and protection. The four basic types of
Neuroglia are Ependymal cells, Microglia, Oligodendroglia and Astrocytes.
The heart pumps blood around the body. The muscle tissue around the human
heart, like all tissues in the body relies on blood supply to deliver oxygen and
nutrients. The human heart has a mass between 250 and 350 grams and is about
the size of a fist. It also carries vital materials which help our body function and it
removes wastes such as carbon dioxide.
The brain is a Nervous tissue and it controls and regulates the functions of the body.
Messages are sent to and from the brain. When a message comes into the brain, the
brain tells the body how to react. For instance, if a person touches something hot, the
nerves in their skin will shoot a message of pain to their brain as it monitors and
regulates the body's actions and reactions.