bio

• SENSORY AND MOTOR MECHANISM
• Plant response to light

  1. In the plant stem, positive phototropism - stem grows towards the light

  2. In the plant root, negative phototropism - root grows away from the light
• Auxin


  Plant hormones that regulate various growth and developmental processes in plants
• Plant response to gravity

  1. Roots grow down (positive gravitropism)

  2. Stems and leaves grow up (negative gravitropism)
• Plant response to wind and touch

  1. Closing up or curling around what they touch (thigmotropism)

  2. Opening and closing leaves, petals, or other parts (thigmonastic responses)

  3. Modifying physical structure to withstand environmental stress (thigmomorphogenesis)
• Sensory processing involves all central actions of information processing which connect the initial stages of sensory reception with the development of subjective sensory perception
• Animals typically respond only to stimuli that they choose. They filter out those stimuli that surrounds them and react to those that they choose to embrace
• The brain's processing of sensory input and motor output is cyclical rather than linear
• Motor Mechanism


  Any activity that results from stimulation of the muscles, including glandular activity as well as reflexes and voluntary and involuntary muscle contractions
• Sensory Mechanism


  The physiological process by which organisms detect, process, and respond to stimuli from their environment, typically involving sensory organs
• Sensory Receptors allow for Sensory Perception in Animals
• The sensory system detects signals from the outside environment and communicates it to the body via the nervous system. The sensory system relies on specialized sensory receptor cells that transduce external stimuli into changes in membrane potentials
• Neuron


  The fundamental units of the brain and nervous system, responsible for receiving sensory input from the external world, for sending motor commands to our muscles, and for transforming and relaying the electrical signals
• Basic Neuron Types


  • Motor neurons
  • Sensory neurons
  • Interneurons or associative neurons
• Motor neurons

  Regulates muscle contraction that allows for both voluntary and involuntary movements of the muscles
• Sensory neurons


  Sensory nerves transport sensory information such as touch, vision, taste, and smell
• Interneurons or associative neurons


  Holds information between the motor and sensory neurons
• Interneurons connect separate neurons within the brain and spinal chords
• Sensory Nerves bear impulses from the outer part of the body(periphery) to the central nervous system
• Motor Nerves carry impulses from the central nervous system to the outer parts of the body(muscles, skin, glands, etc.)
• Monosynaptic (single-connection) reflex pathway


  The simplest form of neural pathways, like the knee-jerk reflex
• Stimuli


  Changes in the environment that prompt a response or reaction in an organism. They can be physical, chemical, or biological factors that trigger sensory receptors, leading to a response by the nervous system
• Types of Stimuli


  • Auditory
  • Visual
  • Tactile
  • Chemical
• Sensory Receptor Cells


  Specialized neurons or specialized sensory cells which synapse with a neuron
• Different Sensory Receptor Cells

  • Mechanoreceptors
  • Chemoreceptors
  • Photoreceptors
  • Nociceptors
  • Thermoreceptors
• Mechanoreceptors


  Respond to physical deformation of the cell membrane from mechanical energy or pressure, including touch, stretch, motion, and sound
• Chemoreceptors


  Respond to specific molecules, often dissolved in a specific medium (saliva or mucus), or airborne molecules
• Photoreceptors


  Respond to radiant energy (visible light in most vertebrates, visible as well as UV lights in most insects)
• Nociceptors


  Respond to "noxious" stimuli, or essentially anything that causes tissue damage
• Thermoreceptors


  Respond to heat and cold
• Human and many other vertebrates have at least five special senses: olfactory (smell), gustation (taste), equilibrium (balance and body position), Optical (vision) and Auditory (hearing). Additionally, we humans possess general senses, also called as somatosensation, which respond to stimuli such as temperature, pain, pressure, and vibrations
• The nervous system must receive information about the world in order to respond, interact and keep the body stable and safe
• Specialized cells and tissues inside these organs receive raw inputs and convert them into signals that the nervous system can use
• Sclera


  The portion of the skin that preserves internal structures and surrounds a circular portal shaped of the by cornea, iris and pupil
• Cornea


  Transluscent enough that the light can reach the eye, and curved so that it can be focused into the pupil behind it
• Pupil


  A hole in the color disc of the iris, maintaining optimal vision by regulating the amount of light that enters the eye under various lighting conditions
• Iris


  Dilates or constricts, changing how much light travels through the pupil and the lens
• Retina


  Delicate membrane of nervous tissue that involves photoreceptor cells
• Photoreceptor


  Specialized neurons that detect light and when they hyperpolarize, they send visual impulses in the form of electrical signals to the brain
• Lens


  Acts as a dynamic optical element that adjusts its curvature to focus light onto the retina