Biology NEURAL TISSUE AND ORGAN SYSTEMS

### KEY TOPICS

star Neural Tissue
star Organ and Organ System
star Morphology and Anatomy

### NEURAL TISSUE

● color{brown}("Neural tissue") exerts the color{violet}("greatest control over the body’s") responsiveness to changing conditions.

● color{violet}("Neurons,") the unit of neural system are color{violet}("excitable cells.")

● The color{brown}("neuroglial cell") which constitute the rest of the color{violet}("neural system") protect and support neurons.

● color{violet}("Neuroglia") make up more than one half the volume of neural tissue in our body.

● When a color{violet}("neuron") is suitably stimulated, an electrical disturbance is generated which swiftly travels along its plasma membrane.

●Arrival of the disturbance at the color{violet}("neuron’s endings,") or output zone, triggers events that may cause stimulation or inhibition of color{violet}("adjacent neurons") and other color{violet}("cells.")

### ORGAN AND ORGAN SYSTEM

● The color{violet}("basic tissues") mentioned above color{violet}("organise") to form color{brown}("organs") which in turn associate to form color{brown}("organ systems") in the color{violet}("multicellular organisms.")

● Such an color{violet}("organisation") is essential for more efficient and better coordinated activities of color{violet}("millions of cells") constituting an color{violet}("organism.")

● Each color{brown}("organ") in our body is made of one or more color{violet}("type of tissues.")

● For color{brown}("example,") our heart consists of all the color{violet}("four types of tissues"), i.e., color{violet}("epithelial, connective, muscular and neural.")

● We also notice, after some careful study that the complexity in color{violet}("organ and organ systems") displays certain discernable trend.

● This discernable trend is called color{brown}("evolutionary trend.")

### MORPHOLOGY AND ANATOMY

● The subjects of study at most basic level include the color{violet}("morphology and anatomy") of three organisms at different color{violet}("evolutionary levels ") to show their color{violet}("organisation") and functioning.

● color{brown}("Morphology") refers to study of form or externally visible features.

● In the case of color{violet}("plants or microbes,") the term color{violet}("morphology") precisely means only this.

● In case of color{violet}("animals") this refers to the external appearance of the color{violet}("organs") or parts of the body.

● The word color{brown}("anatomy") conventionally is used for the study of morphology of internal organs in the animals.