Lesson 1 The Nervous System Flashcards
The Central Nervous System (CNS)
The Central Nervous System (CNS) consists of the brain and spinal cord. It has two main functions, the control of behaviour and the regulation of the body’s physiological processes. In order to do this the brain must be able to receive information from the sensory receptors (eyes, ears, skin etc.) and be able to send messages to the muscles and glands of the body in response
What is the CNS made up of
The brain and the spinal cord
The brain
The brain is divided into four main areas:
A) Cerebrum – This is the largest part of the brain. It has four lobes, and is spilt down the middle into two halves, called the right and left hemisphere.
B) Cerebellum - Responsible for motor skills, balance and coordinating the muscles to allow precise movements.
C) Diencephalon - Contains the thalamus (regulates consciousness, sleep and alertness) and the hypothalamus (regulates body temperature, stress response and hunger and thirst).
D) Brain stem - Regulates breathing and heart rate.
The spinal cord
The main function of the spinal cord is to relay information between the brain and the rest of the body. This allows the brain to monitor and regulate bodily processes, such as digestion and breathing, and co-ordinate voluntary movement. The spinal cord is connected to different parts of the body by pairs of spinal nerves, which connect to specific muscles and glands. If the spinal cord is damaged, body areas connected to it by nerves below the damage will be cut off and stop functioning.
What is the nervous system split into
CNS and PNS
The Peripheral Nervous System
The Peripheral Nervous System (PNS) consists of the nervous system throughout the rest of the body (e.g. not the brain or spinal cord). The PNS transmits messages via neurons (nerve cells) to and from the CNS. The PNS has 2 divisions: The somatic nervous system and the autonomic nervous system.
What is the PNS split into
The somatic nervous system and Autonomic Nervous system
The Somatic Nervous System
The somatic nervous system controls voluntary movements and is under conscious control. It connects the senses with the CNS and has sensory pathways AND motor pathways. It controls skeletal muscles. The somatic nervous system is controlled by the motor cortex.
The Autonomic Nervous System
The Autonomic Nervous System (ANS) is involuntary (i.e. not under conscious control). It ONLY has motor pathways and it controls smooth muscles and the internal organs and glands of the body. The ANS is controlled by the brain stem.
What is the Autonomic Nervous System split into
Sympathetic Nervous System and Parasympathetic Nervous System
Sympathetic Nervous System
This is activated when a person is stressed. Heart rate and breathing increase, digestion stops, salivation reduces, pupils dilate, and the flow of blood is diverted from the surface on the skin (fight or flight response).
Parasympathetic Nervous System
This is activated when the body is relaxing and so conserving energy. Heart rate and breathing reduce, digestion starts, salivation increases, and pupils constrict.
