Biopsychology: Divisions of the nervous system Flashcards
What are the 2 main functions of the brain?
1- To collect, process and respond to information in the environment;
2- To coordinate and direct the working of different organs and cells within the body.
Draw the divisions of the nervous system
The Nervous System
Peripheral NS
Central NS
Somatic NS
Brain
Spinal Cord
Autonomic NS
Sympathetic Branch
(switch on)
Parasympathetic Branch
(switch off)
Describe the brain in terms of the central nervous system
- Involved in all psychological processes;
- Main job is to ensure life is maintained;
- Primitive parts of the brain - responsible for vital functions such as breathing and our heartbeat (i.e., the brain stem);
- Other areas of the brain - responsible for higher order thinking such as planning and problem solving (i.e., prefrontal cortex)
Describe the spinal cord in terms of its role in the CNS
- Carries messages (using neurons) to and from the brain to the peripheral nervous system (PNS);
- I.e., it relays information to and from the brain and the rest of the body;
- Allows the brain to monitor bodily processes like breathing and digestion;
- Also allows the brain to coordinate all bodily movements;
- The spinal cord can also coordinate bodily movements when reflexing.
Describe a reflex arc
A reflex arc is an automatic (involuntary) and rapid response to a stimulus, which minimises any damage to the body from potentially harmful conditions, such as touching something hot. Reflex actions are therefore essential to the survival of many organisms. A reflex arc follows this general sequence and does not involve the conscious part of the brain. This is why the response is so fast.
1- Receptor in the skin detects a stimulus (the change in temperature).
2- Sensory neuron sends electrical impulses to a relay neuron, which is located in the spinal cord of the CNS. Relay neurons connect sensory neurons to motor neurons.
3- Motor neuron sends electrical impulses to an effector.
4- Effector produces a response (muscle contracts to move hand away).
Describe the peripheral nervous system
- All the nerves outside the CNS;
- Relay nerve impulses from the CNS to the rest of the body and from the body back to the CNS;
- Initially, from 12 pairs of cranial nerves (under brain) and 31 pairs of spinal nerves (connecting to the spinal cord) lots of sensory and motor pathways allow the CNS to connect to the outside world.
Describe the somatic NS
- CONTROL CENTRE = motor and somatosensory cortex;
- Made up of 12 pairs of cranial nerves and 31 pairs of spinal nerves;
- Connects the CNS to our senses;
- Contains both sensory and motor neurons;
- Two main components:
- Sensory (afferent) pathways - transmit and receive information from the senses such as visual information from the eyes and auditory information from the ears to brain (sensory neurons);
- Motor (efferent) pathways - direct voluntary movement of skeletal muscles and orchestrate all of our movements from brain (motor neurons).
Describe the autonomic NS
- CONTROL CENTRE = top of brain stem (hypothalamus and pituitary gland);
- Responsible for functions that keep the body in a stable state (homeostasis), E.g. controls heart rate, perspiration, eye sensitivity, digestion etc.;
- Many of its functions are ‘automatic’ – require little/no conscious thought;
- The ANS is comprised of two branches that work on the same organs yet have opposite effects:
- Sympathetic branch: switch on
- Parasympathetic branch: switch off
Describe the role of the sympathetic branch
Sympathetic branch: switch on
When exposed to threats it activates and prepares the body for rapid action.
It carries out certain biological changes which prepare the body for activity.
E.g., it increases heart rate and blood pressure but slows down other non essential processes that consume energy e.g., digestion.
Describe the role of the parasympathetic branch
Parasympathetic branch: switch off
Tries to store and conserve resources once emergency has passed.
It returns the body to a normal, balanced state.
E.g., it slows down heart rate and blood pressure and increases digestion again.
Hence, the opposite action to the sympathetic branch.
What are 4 key differences between the SNS and the ANS?
1- The autonomic nervous system unconscious / involuntary, whereas the somatic nervous system is under conscious control;
2- The SNS has both sensory and motor neurons, whereas the ANS uses only motor neurons;
3- The ANS controls internal organs / glands of the body, while the SNS controls skeletal muscle / movement;
4- The control centre for the SNS is located in the motor and somatosensory cortex, whereas the control centre for the ANS is located in the brain stem (pituitary gland / hypothalamus).
5 steps in order of an arc reflex
-stimulus
- sensory neuron
- control centre (spinal cord/relay neurone)
- motor neuron
- effector (muscle)
