Nervous System
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What is the nervous system?
A network of specialised cells that communicate information about an individuals surroundings and itself. It processes this information and causes reactions in other parts of the body.
Why does the nervous system do?
Analyses sensory information from the body and the external environment. It stores some aspects and makes decisions regarding appropriate responses and behaviours
How does the nervous system make motor responses ?
By initiating muscular contractions or glandular secretions
What is the nervous system composed of
Central nervous system Peripheral nervous system
What is the central nervous system composed of ?
Brain and spinal cord
What is the peripheral nervous system composed of?
composed of sensory nerves and motor nerves connecting the CNS to the rest of the body.
What do peripheral nerves contain?
a sensory pathway consisting of sensory nerves and/or a motor pathway consisting of motor nerve cells
What do sensory pathways do?
keep the brain in touch with what is going on in the body’s external and internal environments.
What 2 systems make up the peripheral nervous system?
Somatic nervous system (mostly voluntary) Autonomic nervous system (involuntary)
What is the autonomic nervous system composed of?
sympathetic system parasympathetic system
What do sensory and motor neurons of the somatic nervous system control?
the voluntary movement of skeletal muscles. The somatic nervous system is also responsible for bringing about certain involuntary reflex actions (e.g. limb withdrawal)
What does the autonomic nervous system control?
involuntary responses to stimuli by the body, so there is no conscious control, but under exceptional circumstances some people can suppress certain autonomic responses intentionally.
Name 5 aspects of the body that are regulated by autonomic nerves?
heart blood vessels bronchial tubes alimentary canal sweat glands
How does the ANS try to maintain a stable internal environment ?
by playing the role of HOMEOSTATSIS.
What are the branches of the ANS said to be?
antagonistic and have opposite effects on the SAME organs.
How does the ANS have finely tuned control over effectors?
they are stimulated by both sympathetic and parasympathetic nerves
What does the sympathetic system do?
prepares the body for action (fight or flight) and the expenditure of energy
What does the parasympathetic system do?
calms the body down (rest and digest) and try to conserve energy or resources
What effect does the sympathetic system have on the heart?
Rate and force of contraction of cardiac muscle increases. Result: increased cardiac output of blood.
What effect does the parasympathetic system have on the heart?
Rate and force of contraction of cardiac muscle decreases. Result: decreased cardiac output of blood.
What effect does the sympathetic system have on the bronchioles?
Smooth muscle in wall of bronchiole becomes relaxed. Result: Bore of tube becomes dilated allowing increased volume of air to enter lung.
What effect does the parasympathetic system have on the bronchioles?
Smooth muscle in wall of bronchiole becomes contracted. Result: Bore of tube becomes constricted allowing decreased volume of air to enter lung.
What effect does the sympathetic system have on the digestive tract?
Rate of contraction of smooth muscle in wall of digestive tract decreases. Result: decreased rate of peristalsis
What effect does the parasympathetic system have on the digestive tract?
Rate of contraction of smooth muscle in wall of digestive tract increases. Result: increased rate of peristalsis