Biology- Notes
11/10/22
3 TYPES OF EPITHELIAL TISSUE:
A tissue is a group of cells that are specialised to work together to carry out a particular
function. A tissue can contain more than 1 cell type:
● Connective, e.g cartilage, bone and blood
● Epithelial(they line the outer surfaces of organs & make up blood vessels)
● Muscle
● nervous
Epithelial Tissue
These tissues are found lining organs and surfaces in animals.
They can be divided into 3 different types:
● Squamous epithelial
● Columnar epithelial
● Endothelium
1. Squamous Epithelial tissue
Simple squamous epithelial tissue is a lining tissue and is one cell thick.
It's made from flattened specialised squamous cells. These cells form a thin,smooth, flat
layer. Which makes them ideal when rapid diffusion is needed.
They line various structures, for example, the Alveoli in the lungs; they provide a short
diffusion pathway for a fast diffusion of O2 into the blood and CO2 into the lungs.
2. Columnar epithelial tissue
This is made up from column-shaped cells.
Sometimes the cells are ciliated ( with hair-like structures on surface)
Ciliated epithelium lines the trachea in the respiratory system to protect the lungs from
infection. This is done by sweeping pathogens away from the lungs.
Sometimes goblet cells can be present. They are also column shaped and are present in the
respiratory tract. They secrete mucus to help trap unwanted particles present in the air we
breathe. Protects our lungs bc it stops bacteria reaching the alveoli.
, 3. Endothelial Tissue
Consists of a layer of flattened cells that are 1 layer thick. They provide a short diffusion
pathway for movement of substances such as;
● Products of digestion into blood capillaries
● Blood plasma and tissue fluid in/out of blood capillaries.
They’re very similar to squamous epithelial cells, the main difference is where they’re
located in the body.
They cover the inner surface of structures such as the blood vessels. These cells cover the
entire Circulatory system, they interface between the vessel wall+blood.
—-------------------------------------------------------------------------------------------------------
If the inner lining of arteries is damaged, WBC will repair the damage, which encourages
the growth of smooth muscle and the breakdown of fatty substances such as cholesterol
under the endothelium lining in the arteries.
This process of deposition is called Atherosclerosis. These deposits, called Atheromas,
may build up enough to break through the inner endothelial lining of the artery.
—-------------------------------------------------------------------------------------------------------
MUSCLE TISSUE
The 3 types;
● Cardiac muscle cell
● Skeletal muscle cell
● smooth muscle cell
Skeletal muscle
The main features:
1. Fibres: striated, tubular, and multi nucleated
2. Voluntary muscle
3. Usually attached to the skeleton.
● Long cylindrical, and striated.
● Multinucleated because they’re formed from the fusion of embryonic myoblasts.
Each nucleus regulates the metabolic requirements of the sarcoplasm(cytoplasm)
around it.
11/10/22
3 TYPES OF EPITHELIAL TISSUE:
A tissue is a group of cells that are specialised to work together to carry out a particular
function. A tissue can contain more than 1 cell type:
● Connective, e.g cartilage, bone and blood
● Epithelial(they line the outer surfaces of organs & make up blood vessels)
● Muscle
● nervous
Epithelial Tissue
These tissues are found lining organs and surfaces in animals.
They can be divided into 3 different types:
● Squamous epithelial
● Columnar epithelial
● Endothelium
1. Squamous Epithelial tissue
Simple squamous epithelial tissue is a lining tissue and is one cell thick.
It's made from flattened specialised squamous cells. These cells form a thin,smooth, flat
layer. Which makes them ideal when rapid diffusion is needed.
They line various structures, for example, the Alveoli in the lungs; they provide a short
diffusion pathway for a fast diffusion of O2 into the blood and CO2 into the lungs.
2. Columnar epithelial tissue
This is made up from column-shaped cells.
Sometimes the cells are ciliated ( with hair-like structures on surface)
Ciliated epithelium lines the trachea in the respiratory system to protect the lungs from
infection. This is done by sweeping pathogens away from the lungs.
Sometimes goblet cells can be present. They are also column shaped and are present in the
respiratory tract. They secrete mucus to help trap unwanted particles present in the air we
breathe. Protects our lungs bc it stops bacteria reaching the alveoli.
, 3. Endothelial Tissue
Consists of a layer of flattened cells that are 1 layer thick. They provide a short diffusion
pathway for movement of substances such as;
● Products of digestion into blood capillaries
● Blood plasma and tissue fluid in/out of blood capillaries.
They’re very similar to squamous epithelial cells, the main difference is where they’re
located in the body.
They cover the inner surface of structures such as the blood vessels. These cells cover the
entire Circulatory system, they interface between the vessel wall+blood.
—-------------------------------------------------------------------------------------------------------
If the inner lining of arteries is damaged, WBC will repair the damage, which encourages
the growth of smooth muscle and the breakdown of fatty substances such as cholesterol
under the endothelium lining in the arteries.
This process of deposition is called Atherosclerosis. These deposits, called Atheromas,
may build up enough to break through the inner endothelial lining of the artery.
—-------------------------------------------------------------------------------------------------------
MUSCLE TISSUE
The 3 types;
● Cardiac muscle cell
● Skeletal muscle cell
● smooth muscle cell
Skeletal muscle
The main features:
1. Fibres: striated, tubular, and multi nucleated
2. Voluntary muscle
3. Usually attached to the skeleton.
● Long cylindrical, and striated.
● Multinucleated because they’re formed from the fusion of embryonic myoblasts.
Each nucleus regulates the metabolic requirements of the sarcoplasm(cytoplasm)
around it.
