6th monthly test

• Homeostasis - is the state of stability inside an organism's body.
• Nervous system - is the organ system which performs many functions in the body, mostly for control and regulation.
• Brain - is the main organ in the nervous system which receives impulses from the body, processes data, initiates appropriate responses to stimuli, and regulated and maintain homeostasis in the body.
• Nervous system consist of the brain, the spinal cord, and the neurons.
• Spinal cord - is a cylindrical bundle of nerve of fibers that extends the medulla and vertebral column.
• Reflex - is an automatic response to a stimuli that does not need thought or thinking.
• the fear of the truck hitting you is what we call a stimulus.
• HOMEOSTASIS COMPONENTS

  1. CHANGE

  2. RECEPTOR

  3.CONTROL CENTER

  4. EFFECTOR
• Sympathetic mechanism - works when a person is in a though situation.
• Parasympathetic mechanism - kicks in and stimulates the opposite reaction to restore the body into its normal state.
• Change - is anything that requires a cell to react.
• Receptor - when a change occurs, the receptor detects it and alerts to proper control center to counteract it inn order to return the cell and the overall system into a balanced state.
• Control center - is the one which receives impulses from the receptors and sends commands to the effector to counteract the change in the environment.
• Effector - acts on the impulses from its control center that will counteract the changes and return the internal and extends cell environment to a balanced state.
• Neuron or the nerve cell - is a major component of the brain and the spinal cord of the central the nervous system.
• Sensory or afferent neurons - receives stimuli from the outside environment and sends them to the brain.
• Interneuron - which is found in the brain and the spinal cord, relays impulses from afferent to efferent neurons.
• Motor or efferent neuron - transmits impulses from the brain or the spinal cord to the muscles or glands in the body.
• 2 DIVISIONS OF NERVOUS SYSTEM

  1. CENTRAL NERVOUS SYSTEM
  2. PERIPHERAL NERVOUS SYSTEM
• the neuron is composed of the cell body or the soma that contains the nucleus of the cell.
• Inside the cell bod are granular structures called nissl bodies.
• The axon in the neuron is surrounded by an insulating layer called as the myelin sheath that is made up of Schwann cells.
• There are periodic gaps in the myelinated axons called the nodes of Ranvier.
• These gaps allow the impulses to jump in the myelinated axon. This process called saltatory conduction.
• The axon is a long projection from the cell body which carries the impulses in the nerves to the knob-like swellings at the end of the axon that release neurotransmitters called axon terminals.
• When the axon terminals release neurotransmitters to the synapse they will be received by the fibers that project in the adjacent neuron called dendrites.
• In order for a message to be transferred, the message should jump into the space in between neurons called as synapse.
• And instead of electricity, the neurons transport message from one neuron to another with the use of certain chemical called neurotransmitters.
• The neurotransmitters are transported and released in the synapse with the use of synaptic vesicles that are seen from the axon terminal and it is received by the receptors of the dendrites in the next neuron.
• The central nervous system is made up of the brain and the spinal cord.
• The brain is the central processing unit of the nervous system. It is made up of approximately 100 billion neurons that do not have the capacity to regenerate when they are destroyed.
• The hindbrain is the rear lower part of the brain, comprising the cerebellum, pons, and medulla oblongata.
• The medulla oblongata is the continuation of the spinal cord within the skull and contains control centers for the heart and lungs.
• The pons connects the upper and lower parts of the brain. It is responsible for controlling breathing and sleep cycles.
• the cerebellum, which is about the size of a plum and is found at the back of the brain. It is the most neuron-densed region of the brain. The cerebellum controls the body's posture and the coordination of voluntary movement.
• The midbrain is the smallest region in the human brain. This region plays an important role in reward-based learning and it relays the sensory input from the body to the forebrain.
• The last of the three regions of the brain is the forebrain. It contains the cerebrum, thalamus and hypothalamus.
• The function of the thalamus is to sort and send most of the sensory signals to and from the proper regions of the cerebral cortex.
• The hypothalamus is the control center of the homeostasis of the internal environment. It receives signals of the state of the body and regulates body temperature, thirst, and appetite.
• The reticulated activating system is a set of connected nuclei in the brain that is responsible for regulating the information that comes to the brain from the sense organs.