Explanation

Flat bones are found in areas like the skull and ribs.

They providing protection and surface for muscle attachment.

They are thin and flattened compared to other bone types.

Explanation

Hydrochloric acid (HCl) is secreted by the stomach lining.

It activates pepsinogen into pepsin, an enzyme that digests proteins.

HCl also kills harmful bacteria in food and creates an acidic environment.

Proper protein digestion is essential for amino acid absorption in the small intestine.

Explanation

• The average adult has a blood volume of about 5 liters, though this can range from 4.5 to 5.5 liters
• Male: About 5.5 liters.
• Female: About 4.5 liters.
• Proportion: Blood makes up roughly 7% of a person's total body weight. 

Explanation

The medulla oblongata is located in the brainstem.

It regulates involuntary functions such as heartbeat, breathing, and blood pressure.

The cardiac center within the medulla controls heart rate and force of contraction.

It receives signals from the autonomic nervous system (sympathetic and parasympathetic).

Explanation

Blood circulation rate in human arteries varies, fastest in the aorta (around 30-40 cm/s) 

In capillaries, the speed drops significantly to allow nutrient and gas exchange.

Blood velocity is highest in arteries, moderate in veins, and slowest in capillaries.

Proper circulation speed ensures efficient delivery of oxygen and nutrients throughout the body.