Structural Organisation in Animals 2

Question 1

what are connective tissue

Answer 1

Connective tissues are most abundant and widely distributed in the body
of complex animals. They are named connective tissues because of their
special function of linking and supporting other tissues/organs of the
body. They range from soft connective tissues to specialised types, which include cartilage, bone, adipose, and blood.

Question 2

what are fibres secreted by the cell? what is matrix

Answer 2

In all
connective tissues except blood, the cells secrete fibres of
structural proteins called collagen or elastin. The fibres
provide strength, elasticity and flexibility to the tissue.
These cells also secrete modified polysaccharides, which
accumulate between cells and fibres and act as
matrix (ground substance).

Question 3

what are types of connective tissue

Answer 3

Connective tissues are
classified into three types: (i) Loose connective tissue,
(ii) Dense connective tissue and (iii) Specialised
connective tissue.

Question 4

what is loose connetive tissue

Answer 4

Loose connective tissue has cells and fibres loosely
arranged in a semi-fluid ground substance

Question 5

areolar tissue

Answer 5

areolar tissue present beneath the skin (Figure 7.4). Often
it serves as a support framework for epithelium. It
contains fibroblasts (cells that produce and secrete fibres),
macrophages and mast cells.

Question 6

adipose tissue

Answer 6

Adipose tissue is another
type of loose connective tissue located mainly beneath the
skin. The cells of this tissue are specialised to store fats.
The excess of nutrients which are not used immediately
are converted into fats and are stored in this tissue.

Question 7

what are the 2 types of dense tissue

Answer 7

Fibres and fibroblasts are compactly packed in the
dense connective tissues. Orientation of fibres show a
regular or irregular pattern and are called dense regular
and dense irregular tissues. In the dense regular
connective tissues, the collagen fibres are present in rows
between many parallel bundles of fibres. Tendons, which
attach skeletal muscles to bones and ligaments which
attach one bone to another are examples of this tissue.
Dense irregular connective tissue has fibroblasts and
many fibres (mostly collagen) that are oriented differently
(Figure 7.5). This tissue is present in the skin.

Question 8

what is cartilage

Answer 8

The intercellular material of cartilage is solid and pliable
and resists compression. Cells of this tissue (chondrocytes)
are enclosed in small cavities within the matrix secreted by
them (Figure 7.6a). Most of the cartilages in vertebrate
embryos are replaced by bones in adults. Cartilage is
present in the tip of nose, outer ear joints, between adjacent
bones of the vertebral column, limbs and hands in adults.

Question 9

what is bone

Answer 9

Bones have a hard and non-pliable ground substance
rich in calcium salts and collagen fibres which give bone
its strength (Figure 7.6b). The bone cells (osteocytes) are
present in the spaces called lacunae

Question 10

function of bone tissue

Answer 10

It is the main tissue that provides
structural frame to the body. Bones support and protect
softer tissues and organs.

Limb bones, such as
the long bones of the legs, serve weight-bearing functions.
They also interact with skeletal muscles attached to them
to bring about movements. The bone marrow in some bones
is the site of production of blood cells.