Question

(a) All mammals (except a few) have ............ cervical vertebra.

(b) The number of phalanges in each limb of human is ...........

(c) Thin filament of myofibril contains 2 F actins and two other proteins namely .......... and ...........

(d) In a muscle fibre, Ca ++ is stored in .........

(e) ........... and ............. pairs of ribs are called floating ribs.

(f) The human cranium is made up of .......... bones.

Answer 1

All mammals (except a few) have seven cervical vertebrae.

As a rule, all mammals have the same number of vertebrae in their necks regardless of whether they are a giraffe, a mouse, or a human. But, both, sloths and manatees are exceptions to this rule having abnormal numbers of cervical vertebrae.

The number of phalanges in each limb of a human is 14.

Phalanges are better known as your fingers and toes. You have 14 phalange bones in each hand and 14 in each foot, grand total comes up to 56 phalanges.

A thin filament of myofibril contains 2 ‘F’ actins and two other proteins, namely troponin and tropomyosin.

Tropomyosin and troponin are two other proteins found in small quantities in muscle. They help regulate muscle contraction.

Troponin is associated with the thin filaments and can bind to the actin molecules. There is usually one troponin per 6-8 actin molecules.

Tropomyosin is a long thin protein that extends between, and binds to, the troponin molecules.

In a muscle fibre, Ca++ is stored in the sarcoplasmic reticulum.

The sarcoplasmic reticulum is a specialized type of smooth ER that regulates the calcium ion concentration in the cytoplasm of striated muscle cells.

There are 12 pairs of bones found in human rib cage. 11th and 12th pairs of ribs are as called floating ribs.

The human cranium is made up of eight bones.

The entire group of bones that make up the head is called the skull and it too can be divided into two primary groups: the Cranium and the Facial area.

There are eight bones that make up the cranium, and six bones make up the facial area.