levels of organisation

why do unicellular organisms not need to cells to specialise?

carry out all life functions within a single cell

what are stem cells?

have the potential to become any cell in the body

what is differentiation?

The development of a cell into a specific type. Cells become specialised in structure and in the chemical reactions that they perform

Define tissue and types?

A tissue is a made up of one type of cell, (same structure and function) along with any inter cellular substance, which performs one specific function. Epithelial tissue: cuboidal, ciliated and squamous. Muscle tissue: striated, smooth and cardiac. Connective tissue: collagen

Describe epithelium tissue and it’s function?

Epithelial tissue covers the whole surface of the body. It is made up of cells closely packed and arranged in one or more layers. It is specialised to form the covering or lining of all internal and external body surfaces. The cells sit on a basement membrane, made of collagen and protein. They often have a protective or secretory function

what is Epithelial tissue that occurs on surfaces on the interior of the body called?

endothelium

describe cuboidal epithelium?

Cuboidal epithelium is roughly square or cuboidal in shape. The tissue is just one cell thick. Each cell has a spherical nucleus in the centre

where are cuboidal epithelium cells found?

Found in the ducts of salivary glands and in the lining of the kidney tubules

describe ciliated columnar epithelium?

Elongated cells. Have cilia on their free surfaces. Cilia are capable of rapid, rhythmic, wavelike beatings in a certain direction

where are ciliated columnar epithelium cells found?

found lining tubes in which substances move through - trachea and oviducts

describe squamous epithelium?

Flattened cells on a basement membrane. Fit closely together to provide a smooth, low friction surface. Thinness enables rapid diffusion of gases

where are squamous epithelium cells found?

Form the walls of the alveoli, line the renal (Bowman’s) capsule of the nephron,

state the types of muscle tissue?

skeletal, smooth, cardiac

what percentage of a mammal’s body weight does muscle tissue take up?

40%

what are all muscle tissues made up of and what is their function?

made up of cells or fibres, capable of contraction

what is another name for skeletal tissue?

striped or striated

describe skeletal muscle?

Bands of long cells, or fibres held together by connective tissue. Powerful contractions are possible, but tires easily. Under voluntary control

where are skeletal tissues found?

Attached to bones of the skeleton by tendons, and generates locomotion

describe smooth muscle?

Composed of spindle shaped cells arranged in sheets or bundles (unstriped or unstriated). Contract rhythmically (less powerfully than skeletal) and do not fatigue easily. Involuntary control

where is smooth muscle found?

skin, walls of hollow organs like the digestive and respiratory tracts, walls of blood vessels

describe cardiac muscle?

Cells have stripes but lack long fibres. Contract rhythmically, without any stimulation from nerves or hormones, although these can modify their contraction. cardiac muscle does not tire

where is cardiac muscle found?

the heart

describe connective tissue?

Connective tissue connects, supports or separates tissues and organs. Connective tissue consists of cells separated by extracellular substance. Cells account for only a small fraction of the tissue volume. Contains elastic fibres and collagen fibres in an extracellular fluid or matrix. Between the fibres are fat-storing cells and cells of the immune system

what is the dominant fibre type in most connective tissue?

collagen

what is the primary function of collagen fibres?

to add strength to connective tissue

define organs and give exmaples?

An organ is made up of several tissues in a structural unit, each tissue type works together to perform a specific function; so an organ has many functions. The eye – contains nervous, connective, muscle and epithelial tissues and is the organ of sight. A leaf – contains epidermal, vascular, packing tissue and is specialised for photosynthesis

define an organ system?

a group of organs working together with a particular role

define an organism?

All the systems in the body work together, making an organism, which is a discrete individual