Nervous system 3rd quarter Science

• Feedback mechanism is a process where the output of a system is returned to the system as input, affecting the system's subsequent output
• The two types of feedback mechanisms are positive feedback and negative feedback
• An example of a feedback mechanism in our body is the regulation of body temperature. When the body temperature rises, sweat glands are stimulated to produce sweat, which cools the body down
• Neuron is the basic functional unit of structure and function of the nervous system
• Types of Neurons:

  • Sensory Neuron: Receives initial stimuli from the sense organs where most receptors are located
  • Interneuron: Reads impulses received from sensory neurons, determines the response to be generated, and passes the impulse to motor neurons
  • Motor Neuron: Transmits impulses from the brain and spinal cord to effector cells, which may be muscles, organs, or glands
• Functions of the Nervous System:

  1. Sensation:

  • Involves receiving information about the environment, either external or internal stimuli
  • Example: Stimulus - Mosquito on your skin; receptors pick up the stimulus, triggering a nerve impulse in the sensory neuron

  2. Integration:

  • Stimuli received by sensory structures are communicated to the nervous system for processing
  • The nerve impulse travels to interneurons in the CNS, where stimuli are compared or integrated with memories of previous stimuli

  3. Response:

  • The nervous system produces a response in effector organs (muscles or glands) due to sensory stimuli
  • Example: Stimulus - Mosquito on your skin; nerve impulse travels to motor neurons that send impulses to the muscles, resulting in killing the mosquito
• Nervous System - It is the control system of the body
• Nervous System - It enables the body to gather information from the outside environment and respond quickly
• Central Nervous System (CNS) - is the command center for the entire body; it processes information and sends instructions to other parts of the body.
• Cerebrum - makes up 85% of the human brain. It is divided into 4 lobes: parietal, Temporal, occipital, and frontal lobes.
• Cerebellum - is the second largest part of the brain and is located behind the Brain stem.
• Brain stem - connects the spinal cord to the rest of the brain.
• Peripheral Nervous System (PNS) - is the link between the central nervous system (brain and spinal cord) to the rest of the body. It is made up of a network of bundled ropelike structures called nerves, which extend or branch out from the central nervous system to the different organs of the body. The PNS gathers and delivers information to and from the central nervous system
• Autonomic Nervous System - regulates activities that are not under conscious control. It means, this PNS is responsible for our involuntary movements.These happen automatically, without thinking about them. Some of the examples are breathing, salivating, contraction of the heart muscle and intestines.
• Sympathetic Division - dominates in times of physical and emotional stress or whenever the body requires some action. It controls the “fight-or-flight” response during a stressful situation like the nervousness we experience when speaking before an audience or taking a quiz
• Parasympathetic Division - is most active under normal conditions; it keeps the body functioning even when the person is not active.
• Somatic Nervous System - is the part of the peripheral nervous system that stimulates skeletal muscles under our conscious control. It regulates voluntary activities such as muscular movement.
• Movement Control - The somatic nervous system plays a vital role in initiating and controlling the movements of your body. This system is responsible for nearly all voluntary muscle movements
• Sensory Input - The somatic system is also responsible for processing sensory information that arrives via external stimuli. It processes the senses of hearing, smell, taste, and touch
• Feedback Mechanism:

  • A process through which the level of one substance influences the level of another substance
  • Can be positive or negative feedback
• Positive Feedback:

  • Rising levels of hormones feedback to increase hormone production, intensifying the response
• Negative Feedback:

  • Rising levels of hormones feedback to decrease the production of the hormones, reducing the effect of a stimulus
• Negative feedback affects the production and release of hormones in the menstrual cycle

  • High levels of one hormone may inhibit the production of another hormone
  • Negative feedback mechanism in the menstrual cycle keeps hormone levels relatively stable
• Feedback Mechanisms in Menstrual Cycle:

  1. Follicle Stimulating Hormone (FSH) stimulates the ovaries to release estrogen. High levels of estrogen prevent the further production of FSH.

  2. Estrogen stimulates the release of luteinizing hormone (LH) from the pituitary gland, which controls the production of progesterone. High levels of progesterone inhibit the further release of LH