Special senses-smell receptor, pathway taste- taste buds, pathway and special senses-vision - structure of eye ball, retina image forming mechanism, colour vision and colour blindness?

Special senses - Smell receptor:
The sense of smell is mediated by specialized cells called olfactory receptor neurons (ORNs) located in the olfactory epithelium, which is found in the upper part of the nasal cavity. These ORNs have specialized receptors on their cilia that can detect different odor molecules. When an odor molecule binds to a specific receptor, it triggers a signal that is transmitted to the olfactory bulb in the brain through the olfactory nerve. From there, the information is processed and interpreted, allowing us to perceive different smells.

Pathway - Taste buds:
Taste buds are specialized sensory organs located on the tongue and other parts of the oral cavity. They contain taste receptor cells that can detect different taste qualities, including sweet, sour, salty, bitter, and umami. When we eat or drink something, molecules from the food or drink interact with the taste receptors on the taste buds. This triggers a signal that is transmitted to the brain through the facial, glossopharyngeal, and vagus nerves. The brain then processes this information, allowing us to perceive different tastes.

Special senses - Vision - Structure of the eyeball:
The eyeball is a complex structure that plays a crucial role in vision. It consists of several components, including the cornea, iris, lens, retina, and optic nerve. The cornea is the transparent outermost layer that helps focus incoming light onto the retina. The iris is the colored part of the eye that controls the amount of light entering the eye through the pupil. The lens is a flexible structure that further focuses the light onto the retina. The retina is the innermost layer of the eye that contains specialized cells called photoreceptors, which detect light and convert it into electrical signals. The optic nerve carries these signals from the retina to the brain for processing.

Retina image forming mechanism:
The retina contains two types of photoreceptor cells: rods and cones. Rods are responsible for vision in low light conditions and do not perceive color, while cones are responsible for color vision and work best in bright light. When light enters the eye and reaches the retina, it is absorbed by the photoreceptor cells. This triggers a chemical reaction that generates electrical signals. These signals are then transmitted to other retinal cells, such as bipolar cells and ganglion cells, which process and transmit the information to the brain through the optic nerve. The brain then interprets these signals as visual images.

Color vision and color blindness:
Color vision is made possible by the presence of three types of cones in the retina, each sensitive to different wavelengths of light corresponding to red, green, and blue. These cones work together to allow us to perceive a wide range of colors. However, some individuals have a condition called color blindness, where one or more types of cones are defective or absent. This results in an inability to distinguish certain colors or perceive them differently. The most common form of color blindness is red-green color blindness, where individuals have difficulty differentiating between red and green hues.