Structural Organisation in Animals 3 Flashcards
describe the structure of muscle tissue
Each muscle is made of many long, cylindrical fibres
arranged in parallel arrays. These fibres are composed of
numerous fine fibrils, called myofibrils. Muscle fibres
contract (shorten) in response to stimulation, then relax
(lengthen) and return to their uncontracted state in a
coordinated fashion
what is the function of muscle tissue
Their action moves the body to adjust
to the changes in the environment and to maintain the
positions of the various parts of the body. In general,
muscles play an active role in all the movements of the body.
describe skeletal muscles
Skeletal muscle tissue is closely attached to skeletal
bones. In a typical muscle such as the biceps, striated
(striped) skeletal muscle fibres are bundled together in a
parallel fashion (Figure 7.7a). A sheath of tough connective
tissue encloses several bundles of muscle fibres
describe the smooth muscles
The smooth muscle fibres taper at both ends (fusiform) and do not
show striations (Figure 7.7b). Cell junctions hold them together and they
are bundled together in a connective tissue sheath. The wall of internal
organs such as the blood vessels, stomach and intestine contains this type
of muscle tissue. Smooth muscles are ‘involuntary’ as their functioning
cannot be directly controlled. We usually are not able to make it contract
merely by thinking about it as we can do with skeletal muscles.
describe cardiac muscle
Cardiac muscle tissue is a contractile tissue present only in the heart.
Cell junctions fuse the plasma membranes of cardiac muscle cells and
make them stick together (Figure 7.7c). Communication junctions
(intercalated discs) at some fusion points allow the cells to contract as a
unit, i.e., when one cell receives a signal to contract, its neighbours are
also stimulated to contract.
describe neural tissue what is it basic unit
Neural tissue exerts the greatest control over
the body’s responsiveness to changing
conditions. Neurons, the unit of neural
system are excitable cells
what are neuroglial cells
The
neuroglial cell which constitute the rest of
the neural system protect and support
neurons. Neuroglia make up more than onehalf the volume of neural tissue in our body.
what happens when a nueron is stimulated
When a neuron is suitably stimulated,
an electrical disturbance is generated
which swiftly travels along its plasma membrane. Arrival of the disturbance at the neuron’s endings, or output
zone, triggers events that may cause stimulation or inhibition of adjacent
neurons and other cells
why do tissues organise to form organs
The basic tissues mentioned above organise to form organs which in turn
associate to form organ systems in the multicellular organisms. Such an
organisation is essential for more efficient and better coordinated activities
of millions of cells constituting an organism. Each organ in our body is
made of one or more type of tissues. For example, our heart consists of all
the four types of tissues, i.e., epithelial, connective, muscular and neural.
what is the trend shown in the structue, function of organisation of tissue
the complexity in organ and
organ systems displays certain discernable trend. This discernable trend
is called evolutionary trend
define:
i) morphology
ii)anatomy
i) Morphology refers to study of form or externally visible features. In the
case of plants or microbes, the term morphology precisely means only
this. In case of animals this refers to the external appearance of the organs
or parts of the body.
ii)The word anatomy conventionally is used for the
study of morphology of internal organs in the animals.
how do muscle cells differ from cardiac muscle
cardiac muscle has centrally located nucleus
it is involuntary
