Which statement best describes the central nervous system? a) it senses stimuli and carries out a reaction. b) it secretes hormones. c) it is made up of all nerve cells. d)it is made up of the brain and the spinal cord.

The correct answer is -

D) It is made up of the brain and the spinal cord.

Central nervous system (CNS) is a part of the nervous that is primarily composed of two sub parts, which are brain and spinal cord.

Spinal cord lies inferior to the brain and it links majority of the PNS (peripheral nervous system) to the brain. It also transmits sensory information from various parts of body to the brain.

On the other hand, brain intergrates the sensory information (received from various body parts that possess sensory receptors) , processes it, and produces appropriate response, which is carried by motor neurons to the respective parts.

Thus, option D) is the right answer.

question#1

ans:

cell is the basic unit of organization of all living things. cells are often called the building block of life and it is the smallest unit of life. the study of cell is called cell biology. cell consists of cytoplasm enclosed within membrane, which contain bio-molecules such as proteins and nucleic acid.

two third of cell is water, which means that two-third of your whole body is water. the rest is the mixture of molecules, mainly proteins, lipids and carbohydrates.

question#2

ans:

organ:

an organ is a group of tissues specialized to form a functional unit. an example is the heart in animals.

organ system:

an organ system is a group of several organs whose functions are synchronized to release an effective action in a living organism. an example is digestive system.

question#3

different systems perform different function at tissue level. for example, the respiratory system facilitates breathing. in the alveoli tissue of the lungs, the exchange of oxygen and carbon dioxide molecules between the air and the bloodstream occurs by passive transport, so that oxygen is taken in and carbon dioxide and water are removed. different systems of the body carry out different functions. for example, your digestive system is responsible for taking in and processing food, while your respiratory system working with your circulatory system is responsible for taking up oxygen and getting rid of carbon dioxide.

question#4

different systems perform different function at tissue level. for example, the respiratory system facilitates breathing. in the alveoli tissue of the lungs, the exchange of oxygen and carbon dioxide molecules between the air and the bloodstream occurs by passive transport, so that oxygen is taken in and carbon dioxide and water are removed. different systems of the body carry out different functions. for example, your digestive system is responsible for taking in and processing food, while your respiratory system—working with your circulatory system is responsible for taking up oxygen and getting rid of carbon dioxide.

question#5

our body works because of the interactions that happen between organs and organ systems.  

for example:  

the heart to regulate blood flow throughout the body. the blood carries oxygen and nutrients to the cells and carries carbon dioxide and waste away from the cells. body systems work together in maintaining a constant internal environment. when this balance is disrupted, the body systems may not function properly, and human health can suffer.   you start to feel bad.

true. until louis pasteur developed the rabies vaccine, “vaccines” had referred only to the cowpox inoculation for smallpox. hope this : )