Textbook Solutions: Human Body - Class 5 PDF Download

Exercises

1.
Ans:

2.
Ans: a. (2) bones - Bones act as a storage site for minerals like calcium and phosphorus, which are essential for various bodily functions.
b. (2) cranium - The cranium, also known as the skull, is a bony structure that encases and safeguards the brain.
c. (1) wrist - Gliding joints, which allow bones to slide over one another, are present in the wrist.
d. (2) Involuntary - Involuntary muscles, such as those in the heart, lungs, and digestive system, operate continuously without conscious control.
e. (2) cerebellum - The cerebellum is responsible for coordinating muscle movements and maintaining balance.
f. (3) spinal cord - The spinal cord plays a crucial role in reflex actions, which are rapid, automatic responses to stimuli.

3. 
Ans: a. 206
b. bone marrow
c.  skeletal
d. Clear, bright, sparkling
e. cotton buds

4. 
Ans: a. False - Hinge joints, like those in the elbow and knee, permit movement in only one direction, similar to a door hinge.
b. True - The muscular system comprises muscles, which contract to produce movement, and tendons, which connect muscles to bones.
c. False - The cerebrum is the largest part of the brain.
d. True - The spinal cord runs through a protective channel formed by the vertebrae of the vertebral column, also known as the backbone.
e. False - Sensory nerves convey messages from the sense organs to the brain, while motor nerves transmit signals from the brain to muscles, prompting action.

5.
Ans: a. The skeletal system provides:

• Shape and support to the body, giving us our structure and allowing us to stand upright.
• Protection for delicate internal organs such as the brain (protected by the cranium) and the heart and lungs (protected by the ribcage).
• A site for red blood cell production in the bone marrow.
• Storage for minerals like calcium and phosphorus.
• The framework for movement, allowing for a wide range of motion when muscles attached to the bones contract.

b. The vertebral column, or backbone, is composed of 33 bones called vertebrae. These vertebrae are ring-shaped and stacked one upon another.

• The design of the vertebral column provides flexibility, allowing us to bend forward, backward, and sideways.
• The spinal cord, a crucial part of the nervous system, passes through a channel within the vertebral column.
• The lowest four vertebrae are fused together to form the coccyx, and the five above that form the sacrum.

c. The last two pairs of ribs are called "floating ribs" because they are not attached to the sternum (breastbone) in the front.
d. 

• The cranium, commonly known as the skull, is made up of eight bones tightly joined together.
• Its primary function is to protect the brain, the control centre of the body.

e. The cerebrum is the largest part of the brain and contains millions of neurons (nerve cells).
It is responsible for higher-level thinking functions, including:

• Thinking
• Speaking
• Learning
• Remembering

f. Here are three ways to care for your eyes:

• Ensure adequate lighting when reading: Reading in dim light can strain the eyes.
• Avoid holding books too close to your eyes: Maintaining a comfortable distance helps prevent eye strain.
• Limit screen time: Prolonged exposure to television and other screens can be detrimental to eye health.

Think and Answer HOTS

Ans: a. The bowler used a ball-and-socket joint to bowl over-arm. Ball-and-socket joints allow for a wide range of motion, including rotation, which is necessary for a bowler's arm movement. The shoulder joint, a ball-and-socket joint, allows the arm to swing in a circular motion for the over-arm delivery.
b. Sneezing involves involuntary muscles. A sneeze is a reflex action, meaning it's an automatic response that we don't consciously control. Involuntary muscles, such as those in the diaphragm and chest, contract forcefully to expel air from the lungs during a sneeze.
c. Sensory nerves helped the brain recognise the spiciness of the food. Sensory nerves are responsible for transmitting signals from the sense organs (in this case, taste buds on the tongue) to the brain. When you eat spicy food, the taste buds detect the chemical compounds that create the sensation of spiciness and send this information to the brain via sensory nerves.
d. Trying to grab a falling bottle is a reflex action. It's an automatic, rapid response to a stimulus (the bottle slipping) that occurs without conscious thought. The spinal cord plays a primary role in coordinating this quick movement, allowing you to react instinctively to prevent the bottle from breaking.

Distinguish Between the Following

Ans: a.
b.