The Nervous System Control and coordinate the body parts and processes. It receives sensory stimuli from internal and external environments. It responds in a coordinated manner.
Two Division Of The Nervous System The central nervous system (CNS) Made up of the brain and spinal cord. The control center of the body. Receives and transmits messages to all body parts. The peripheral Nervous System Made up of cranial and spinal nerves. Take messages to and from CNS.
Autonomic Nervous System (ANS) regulates the functions of our internal organs such as the heart, stomach and intestines. The ANS is part of the peripheral nervous system. also controls some of the muscles within the body. We are often unaware of the ANS because it functions involuntary and reflexively. For example, we do not notice when blood vessels change size or when our heart beats faster.
Main Parts of The Brain Cerebrum The bulk of the brain Responsible for voluntary actions. Control speech, thinking, emotions and personality. Coordinates messages to and from the brain.
Cerebellum Controls muscular coordination, balance, posture and muscle tone.
Medulla Oblongata Control involuntary activities of internal organs such as heart beat, breathing, peristalsis, temperature regulation.
Hypothalamus Forms the floor and sides of the brain. Control: Blood pressure Heart rate Peristaltic gut movements
Pituitary Glands Water content Body temperature Produce antidiuretic hormone (ADH)
Nerve and Neurone Nerve A bundle of many nerve fibres connecting the central nervous system with parts of the body. Neurone A nerve cell, specialized for the rapid transfer of electrical impulses. It send messages in one detection.
Types of neurones Sensory Neurones Collect information from the body parts and transmit it towards the brain and spinal cord (CNS).
Types of Actions Voluntary Action Actions which are under the person’s control. The person decides to carry out the action.
Involuntary Action An action that is not under the person’s control. It happens automatically, without the person thinking about it. The simplest type of involuntary action is a reflex action. This is an automatic response, over which you have no conscious control.
Spinal Reflex Action This gives us a quick response to stimulus. Impulses pass from sense organ to the spinal cord and straight back to the effectors muscles. This quickly moves the body parts away. This serves to protect the part of the body near the dangerous external stimulus.
When You touches Something Hot When hand touches hot plate temperature and pain receptors in skin are stimulated. Sensory neurons then conduct impulse along the arm, to spinal cord.
The sensory neurons enter the dorsal dorsal root of spinal cord. Impulses passes across spinal cord to relay neurons. After making a quick decision, relay then send impulse to motor neurons.
Motor neurons leave spinal cord at the ventral root. Motor neurons take impulse to the effectors muscle of arm, telling them to contract . Arm is then removed from hot plate.
Knee- Jerk Reflex There is no relay neurone. The stimulus passes directly from sensory to motor neurone. A doctor perform this to check that your nervous system actions are working properly.
Conditioned Reflex Some reactions have to be learned first. After that they can be done without conscious thought. The child learning to walk and riding a bicycle are examples. At first they are voluntary movements. Later they are performed without conscious thought.
They are called condition reflexes because they have to be acquired through learning. Once learned they are controlled by part of the brain which is not concerned with conscious thoughts.
Endocrine System System of coordination and communication in the body. Uses hormones secreted by endocrine glands.
Hormone A chemical substance produced by gland and carried by the blood. This affect one or more body organs.
Types of Glands Endocrine Glands Secrete and release hormones directly into the bloodstream. Example the pituitary gland , secretes ADH into the blood.