Science

• Structure of the nervous system

  • Central nervous system (brain and spinal cord)
  • Peripheral nervous system (nerves that connect the central nervous system to the rest of the body)
• Cells make up a tissue, tissues make up an organ, and organs make up a system
• Cells make up a tissue, then tissues make up an organ, and organs make up a system
• The nervous system connects all your body parts and transmits signals from one part to another
• Nervous system


  A system of cells, tissues, and organs that regulates the body's responses to internal and external stimuli
• Major divisions of the nervous system

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
• Central Nervous System (CNS)


  • Serves as the main processing center for the entire nervous system
  • Consists of the brain and spinal cord
• Brain


  • Organ located within the skull that functions as organizer and distributor of information for the body
  • Has three main parts: Cerebrum, Cerebellum, Brain Stem
• Spinal Cord


  • Serves as a channel for signals between the brain and the rest of the body, and controls simple musculoskeletal reflexes without input from the brain
• Peripheral Nervous System (PNS)


  • Connects the central nervous system to the organs and limbs
  • Has two main divisions: Somatic Nervous System, Autonomic Nervous System
• Somatic Nervous System


  • Associated with the voluntary control of body movements
  • Has two main parts: Spinal Nerves, Cranial Nerves
• Autonomic Nervous System


  • Associated with the involuntary control of body movements
  • Has two subdivisions: Sympathetic, Parasympathetic
• Neuron


  The basic unit of the nervous system, also called nerve cell
• There are billions of neurons in the body, some exist alone while others are joined together to form organs like the brain and spinal cord
• Parts of a neuron

  • Cell body containing the nucleus
  • Dendrites that carry impulses towards the cell body
  • Axons that carry impulses away from the cell body
• Nerve impulse


  A combination of an electrical charge and a chemical reaction that travels along a neuron
• Nerve impulses cannot jump from one neuron to another, they are transmitted through the release of a chemical called neurotransmitter across the synapse
• Stimulus


  Any factor in the environment that may trigger a nerve impulse
• Response

  A reaction to a stimulus
• Messages do not travel in both directions along the same neuron, only the axon releases neurotransmitters
• Reaction time


  The length of time between application of a stimulus and detection of a response
• How the nervous system controls body processes

  1. Stimulus detected by sensory neurons

  2. Message transmitted to brain

  3. Brain processes information and sends response

  4. Response transmitted through motor neurons

  5. Organ responds to stimulus
• Damage to the nervous system can cause paralysis of the body
• At the time of trip will win the game
• Sensory Neurons


  Transmit information from receptors to the brain
• Motor Neurons


  Transmit information from the brain to effectors
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• When a receptor such as an organ perceives a stimulus, the impulse is sent to the brain by the sensory neurons, which then transmit information from one nerve cell to another. As the message reaches the brain, it processes the information and commands an effector such as a muscle or an organ to respond. The message coming from the brain is sent through the motor neurons.
• Similar to the nervous system, the endocrine system controls and regulates body processes. Generally, the endocrine system is in control of the mechanisms in the body that slowly take place, such as cell growth. Rapid processes, such as body movement and breathing, are controlled by the nervous system. Although these two systems are different, they work together in a coordinate manner to enable the body to function properly.
• Endocrine System


  Composed of glands that secrete different types of hormones that affect almost every cell, organ, and function of our body
• Endocrine glands secrete chemicals known as hormones into the bloodstream, which carries them throughout the body. When a hormone in the blood reaches the target organ, it produces a notable effect.
• Major endocrine glands

  • Pituitary
  • Thyroid
  • Parathyroid
  • Thymus
  • Adrenal
  • Pancreas
  • Reproductive (Testes and Ovaries)
• The endocrine system consists of glands that secrete chemicals called hormones to control various body processes. This control system usually brings about slow changes in the body because chemical messengers move more slowly than nerve impulses.
• Hormones affect various processes in the body as they regulate and balance the functioning of organs, tissues, and cells. Hormones have great impact on your growth, appearance, emotions, and reproductive functions.
• Hormones act in very small amounts. If the organ and hormones do not produce the regulated amount of chemicals to your body, it may result in an abnormality of your body. This condition is called hormonal imbalance. An increase or decrease in its amount may have a significant effect in the human body.
• For most living creatures, reproduction is basically a normal process controlled by hormones. Even though human reproduction is also controlled by hormones, the process is rather more complicated.
• Parts of the Male Reproductive System

  • Testis
  • Scrotum
  • Penis
  • Vas deferens (tube)
  • Urethra
  • Seminal vesicle
  • Prostate gland
  • Bulbourethral gland
• Parts of the Female Reproductive System

  • Ovary
  • Oviduct
  • Uterus
  • Vagina
• When a female reaches puberty, egg cells start to develop in her ovaries that produce the sex cells. It is also the time when the body develops the capacity to conceive.