Science Week 3

• The Nervous System controls and coordinates the activities of all your body parts
• Central Nervous System (CNS)


  Receives information from the sense organs, interprets this information, and generates responses. Consists of the brain and the spinal cord.
• Peripheral Nervous System (PNS)


  Connects the Central Nervous System (CNS) to the other parts of the body. Consists of different types of nerves.
• Parts of the PNS

  • Cranial nerves
  • Spinal nerves
• Somatic Nervous System


  Responsible for actions that we can control or actions we are conscious of
• Autonomic Nervous System


  Responsible for the involuntary functions of our body
• Brain


  • Control center of our body
  • Responsible for our learning, thinking, remembering, monitoring our surroundings, interpreting stimulus and responding to it
  • Protected by the skull
  • Composed of 3 main parts: cerebrum, cerebellum and the brain stem
• Cerebrum


  Large upper region of the brain that is divided into 4 lobes and 2 hemispheres
• Cerebellum


  Little brain located beneath the back portion of the cerebrum, responsible for the voluntary movement of the body
• Brain stem


  Also known as the "lower brain", responsible for the involuntary life functions such as heartbeat, breathing and digestion
• Neuron


  Basic functional unit of the nervous system, consists of a cell body and several nerve fibers
• Dendrites


  Nerve fibers that carry impulses towards the cell body
• Axon


  Nerve fibers that carry impulses away from the cell body
• Nerves are classified according to their function
• Types of nerves


  • Autonomic nerves
  • Motor nerves
  • Sensory nerves
• The Endocrine System is composed of many glands that secrete chemical messengers called hormones to the blood vessels to regulate the different activities of the body
• The hypothalamus is a small gland located at the base of the brain that regulates the activities of the body, metabolism and reproduction
• Homeostasis


  The maintenance of internal balance in an organism despite changes in the environment
• Feedback mechanisms help keep factors in our body balanced (homeostasis)
• Negative Feedback


  A control system that reduces or even stops the body from producing change when favorable or stable conditions are met
• Positive Feedback


  A control system that causes the end products of an action to produce more of that action to occur in the feedback loop
• Parts of the Feedback Loop

  • Stimulus
  • Sensor
  • Control Center
  • Effector
  • Response
• Blood Calcium Level Feedback Loop

  1. Rising blood Ca level

  2. Parathyroid Gland

  3. Parathyroid Hormone

  4. Bones

  5. Falling blood Ca level

  6. Thyroid Gland

  7. Calcitonin

  8. Bones

  9. Blood Ca level rising to a set-point
• Blood Glucose Level Feedback Loop


  1. Rising blood glucose level

  2. Pancreas

  3. Insulin

  4. Blood glucose level rises to normal

  5. Declining blood glucose level

  6. Pancreas

  7. Glucagon

  8. Liver

  9. Blood glucose level falls to normal
• Homeostasis is the mechanism used by our body to maintain balance despite of changes
• When our brain detects that there is a high calcium level in our blood


  It signals the parathyroid gland to secrete calcitonin that will help deposit calcium in our bones
• When our brain detects that there is a high glucose or sugar level in our blood


  Insulin is released by our pancreas
• When our body temperature falls below normal

  Our brain signals our skeletal muscles to contract and shiver to generate heat
• Osmoregulation is the ability of our body to maintain temperature