Structural Organisation in Animals Test - 7

The haemoglobin content per 100 ml of blood of a normal healthy human adult is in the range of 12-16 g. Haemoglobin acts as respiratory carrier. It is responsible for picking up oxygen from lungs and transporting it to all parts of body through blood. Maintaining a healthy level of haemoglobin in blood is essential for sufficient supply of oxygen to cells or tissues. Level of haemoglobin less than 12g/100ml leads to anaemia and weakness.

The muscle present in our thigh is striated and voluntary muscles. They are attached with bone for movement and works according to our will.

Epithelium tissues contain keratin, muscles fibres contain actin and areolar connective tissue contain collagen but melanin is absent in neuron.

The close connection between an axon and dendrite of next neuron is called synapse. Nerve impulses passes through it in the form of neurotransmitter due to presence of synaptic fluid present in it.

The muscles which is immune to fatigue are cardiac muscles present exclusively in heart. They works form birth till death without getting fatigue.

Apocrine glands is kind of exocrine gland found in the skin, breast, eyelids and ears. Mammary glands are present in breast that release milk in mammals.

There are two pairs of testes present in the 10th and 11th segments.Their vasa deferentia run up to the 18 th segment
where they join the prostatic duct

The excretory organs occur as segmentally arranged coiled tubules called nephridia. They are of three types: (i) septal nephridia (ii) integumentary nephridia and (iii) pharyngeal nephridia.

The excretory system of earthworm contains a pair of nephridia in every segment, except for the first three and the last ones. Three types of nephridia are found in earthworm: integumentary, septal, and pharyngeal. The pharyngeal nephridia are present as three paired tufts in the 4th, 5th and 6th segments.

Earthworms are known as ‘friends of farmers’ because they make burrows in the soil and make it porous which helps in respiration and penetration of the developing plant roots.