Skeletal System

Question 1

Major types skeletons found in the animal kingdom

Answer 1

Hydrostatic - fluid filled body cavity which is enclosed by the body wall. e.g: gastrovascular cavity of cnidarians, psedocoelom in nematodes and coelom in annelids.
Exoskeleton - rigid outer covering of the body.
Endoskeleton - hard skeleton which is buried in soft tissues of the animal.

Question 2

Common functions of the skeletal system

Answer 2

Support
Protection
Movement

Question 3

2 main parts of the human skeleton and its constituents

Answer 3

Axial skeleton - skull, vertebral column, sternum and ribs
Appendicular skeleton - girdles (pectoral and pelvic) and limb bones

Question 4

Human skull consists of how many bones

Answer 4

21

Question 5

Sutures

Answer 5

Immovable / ossified joints

Question 6

Bones in the cranium

Answer 6

Frontal bone
2 parietal bones
Occipital bone
2 temporal bones
Ethmoid bone
Sphenoid bone

Question 7

Thirteen other bones forming the skeleton of the face.

Answer 7

two zygomatic bones (cheek), the maxilla (upper jaw bone), two nasal bones, two lacrimal bones, the vomer, two palatine bones, two inferior conchae and the mandible (lower jaw bone).

Question 8

Human cranial capacity

Answer 8

nearly 1.5 L

Question 9

Which structures permits nodding movements

Answer 9

On the inferior surface of the cranium there is foramen magnum to provide passage to spinal cord. Two smooth rounded knobs (Occipital condyles) on either side of the foramen magnum articulates with the first vertebrae (atlas vertebrae) which permits nodding movements.

Question 10

fontanelles

Answer 10

In the cranium, soft membranous regions called fontanelles are present which allow slight compressions at birth facilitating parturition. Fontanelles become replaced by bones within 1-2 years of life.

Question 11

sinuses

Answer 11

Several air filled cavities lined by ciliated mucous membrane are present in the skull (in the sphenoid, ethmoid, maxillary and frontal bones). Sinuses provide resonance to voice and reduce the weight of the skull.

Question 12

2 processes of lower jaw

Answer 12

Condyloid process which articulates with the temporal bone to form the temporal-mandibular joint; Coronoid process which gives attachment to muscles and the ligaments

Question 13

Temporal bone contains three processes

Answer 13

zygomatic process (which forms part of the zygomatic arch), mastoid process and styloid process. They provide surfaces for muscle attachments.

Question 14

Vertebral column

Answer 14

Vertebral column is a strong flexible rod consisting of 26 linearly arranged bones. It consists of 24 separate vertebrae extending downwards from the occipital bone of the skull, the sacrum (formed from 5 fused vertebrae) and coccyx (formed from 4 small fused vertebrae).

Question 15

No.of cervical, thoracic and lumbar vertebrae

Answer 15

7 cervical
12 thoracic
5 lumbar

Question 16

Main function of the curvatures of spinal cord

Answer 16

Maintaining erect posture

Provides protection to the spinal cord

Question 17

Which type of vertebrae is known as the typical vertebrae

Answer 17

Lumbar vertebrae

Question 18

Special features of cervical vertebrae

Answer 18

transverse processes of a cervical vertebra have a foramen on each side to provide passage for the vertebral artery. The spinous process of these vertebrae is bifid.

Question 19

Special features of axis vertebrae

Answer 19

It has a small body with a superior projections called odontoid process which articulates with the atlas vertebra above. The head pivots (turns on side to side) on this joint

Question 20

Thoracic cage consists of

Answer 20

thoracic cage (which is made up of sternum, ribs and thoracic vertebrae)

Question 21

How many pairs of ribs are found in the thoracic cage

Answer 21

12

Question 22

Contribution of human axial skeleton to maintain upright posture

Answer 22

Presence of 2 primary curvatures and 2 secondary curvatures
Size of vertebrae becomes larger towards the end of the vertebral column
Sacral vertebrae are fused to form a large triangular shaped sacrum to support the weight

Question 23

Upper limb consists of

Answer 23

Humerus, radius, ulna, 8 carpel bones, 5 metacarpal bones and 14 phalanges

Question 24

Lower limb consist of

Answer 24

Femur, tibia, fibula, patella, 7 tarsal bones, 5 metatarsal bones and 14 phalanges

Question 25

What is the heaviest, strongest and the longest bone in the body

Answer 25

Femur

Question 26

Osteoporosis

Answer 26

Osteoporosis is a condition associated with the reduction of bone density due to the exceedance of the bone reabsorption rate over the deposition rate. Factors causing osteoporosis include hormonal imbalances (especially at menopause), calcium deficiency and environmental factors.

Question 27

Osteoarthritis

Answer 27

Osteoarthritis is a degenerative non-inflammatory disease that causes pain and restricted movements in the affected joints. risk factors include excessive use of affected joints, female gender, increasing age, heredity and obesity.

Question 28

Slipped disc

Answer 28

An injury or weakness can cause the inner portion of the intervertebral disc to protrude through the outer ring. This condition is called ‘slipped disc’.

Question 29

Main types of joints and their locations

Answer 29

Ball and socket - Shoulder joint (incomplete), Hip joint (complete)
Hinge joint - Elbow joint, knee joint, ankle joint, joints between phalanges
Pivot joint - Odontoid process of the axis with atlas

Question 30

Lateral and medial

Answer 30

A lateral orientation is a position away from the midline of the body. For instance, the arms are lateral to the chest, and the ears are lateral to the head. A medial orientation is a position toward the midline of the body. An example of medial orientation is the eyes, which are medial to the ears on the head.O

Question 31

What is the currently accepted model of striated muscle contraction

Answer 31

Sliding filament theory

Question 32

Muscle contraction

Answer 32

Skeletal muscle contain myofibrils. Striated muscle cells contain repeating units known as sarcomeres. Within these contractile units thick filaments (myosin) and thin filaments (actin) are present.

Currently accepted model of skeletal muscle contraction is the sliding filament theory. According to this theory sarcomeres are found within Z lines to which actin filaments bind while myosin filaments are bound to the M line which is present at the middle of the sarcomere. Myosin filaments contain myosin heads which has binding sites on the actin filament. When an ATP molecule bound to the myosin head at the resting stage is hydrolysed, it causes the myosin head move into a higher energy state which causes the myosin heads to bind to actin filaments forming a cross bridge. Only due to the action of Ca2+ ions binding sites of actin filaments becomes functional. As a result the actin filaments are pulled over the myosin filaments resulting the muscle to contract.