Levels of organisation

1.2: Cell structure and organisation

What are specialised cells?

Cells that have specific structures and roles

what cells can become any cell type in the body? What is this called?

Stem cells this process is called differentiation

What are tissues?

A group of similar cells working together to perform a function

What are some examples of tissues?

Epithelial Tissue

Muscle tissue

Connective tissue

What is types of epithelial tissue?

Squamous

Cuboidal

Columnar

Ciliated columnar

Glandular

What is the squamous structure and function?

Flattened cells on a basement membrane

The lining tissue covers the surface of organs cavities and tubes

Thin layers of cells for exchange

Where can squamous tissue be found in the body?

Walls of alveoli

Blood vessels

Lining of renal (Bowman’s) capsule of the nephron

What is the cuboidal structure and function?

Cells have cube shape and tissue is one cell thick

It is for secretion and absorption

Where can cuboidal tissue be found in the body?

Kidney tubules (PCT of kidney nephron)

Glandular ducts (eg ducts of salivary glands)

What is columnar structure and function?

Cells are elongated column shaped and some cells have microvilli

Microvilli increase surface area for absorption

Where can columnar tissue be found in the body?

Small intestine

What is ciliated columnar structure and function?

Cells are elongated and column shaped and they have cilia

Cilia waft dust and dirt trapped in mucus out of air passages

Where can ciliated columnar tissue be found in the body?

Trachea

Bronchi

Fallopians tubes (oviducts)

What is glandular structure and function?

Secretory epithelial cells (secrete substances) organise themselves into gland shapes

Secrete enzymes, hormones, saliva, mucus

Where can glandular tissue be found in the body?

Salivary glands

Pancreas

Gastric glands in stomach (mucosa)

What is muscle tissue?

Muscle tissue comes in three main types:

Skeletal

Smooth

Cardiac

What is skeletal muscle structure and function?

It is attached to bones and it has bands of long fibres which can give powerful contraction but the muscle tires easily

They are voluntary muscles

They are called striped / striated muscles (they are striped under a microscope)

Skeletal movement so it moves bones, maintains posture and body position and supports soft tissues

Where can skeletal muscle be found in the body?

Attached to bone by tendons

Generates locomotion in mammals

What is smooth muscle structure and function ?

Has unstriated, individual spindle shaped cells which can shorten in length but contract less powerfully than skeletal muscle

Cells do not have stripes

Rhythmical involuntary contraction but less powerful than skeletal muscle

Where can smooth muscle be found in the body?

Walls of hollow organs

Walls of digestive tract (eg stomach, intestines)

Walls of respiratory tract

Walls of blood vessels

Bladder

Skin

What is the structure and function of cardiac muscle?

Cells have stripes but lack long fibres - the fibres are attached at their ends to adjoining fibres by thick plasma membranes called intercalated discs but they are involuntary muscles.

Rhythmic contractions to pump blood through the heart

Where can cardiac muscle be found in the body?

Heart

What is connective tissue?

It connects supports or separates tissues and organs

What is the structure and function of connective tissue?

Contains cells and elastic and collagen Fibres in an extra cellular fluid (matrix)

Between the fibres are fat storing cells and cells of the immune system

Where can connective tissue be found in the body?

Blood

Lymph

Cartilage

Bone

Ligament

Tendon

Fibrous tissues

What is the structure and function of nervous tissue?

Made of nerve cells (neurons) and glial cells

Generates and transmits electrical impulses, sensory inputs, control muscles and gland, homeostasis