The Nervous System and Unconscious & Conscious Responses Flashcards
KKDP 1
Human Nervous System:
Highly complex, organised network of specialised cells enabling the brain to receive information from inside and outside the body, process this information for meaningful interpretation and respond appropriately
● Neurons are the building blocks of the nervous system
main functions of the NS
- Receive information a sensory receptors located throughout the body)
- Process information (at the brain; combines new info with that already stored in the brain)
- Coordinate a response to information (a movement, for example)
Revi ew of the Neuron:
A neuron is a nerve cell that receives and transmits neural information. The nervous system is composed of billions of neurons arranged in neural pathways along which neural messages are transmitted. In this way, the neuron is the basic structural and functional unit of the nervous system.
Disions of the Nervous System
Central Nervous System:
● Brain
● Spinal Cord
Peripheral Nervous System:
● Somatic Nervous System
● Autonomic Nervous System
○ Sympathetic Nervous System
○ Parasympathetic Nervous System
The Central Nervous System:
The central nervous system comprises the brain and its extension, the spinal cord.
the brain
The brain is an intricate network of cells that plays a tal role in processing information received through neural pathways from the body and in directing actions within the body.
● Responsible for rtually everything we feel, think and do.
● Master organ
the spinal cord
The spinal cord is the long, thin bundle of nerve fibres that extends from the base of the brain to the lower back.
Two major functions of the spinal cord are to:
● Receive sensory information from the body ( a the peripheral nervous system) and send these messages to the brain for processing
● Receive motor information from the brain and send it to relevant parts of the body ( a the peripheral nervous system) to control muscles, glands and internal organs so that appropriate actions can be taken.
The Peripheral Nervous System
The peripheral nervous system (PNS) is the entire network of nerves located outside the CNS.
Its primary, overarching role is to carry information to and from the CNS.
● Carries information to the CNS from the body’s muscles, organs and glands (about the internal en ronment) and from the sensory organs (about the external en ronment)
● Carries information from the CNS to the body’s muscles, organs and glands. The peripheral nervous system does this through its two di sions: the somatic nervous system and the autonomic nervous system.
Divisions of the PNS - Somatic Nervous System
The Somatic Nervous System (SNS): a network of nerves that carry sensory info (afferent information) to the central nervous system and motor information (efferent information) from the central nervous system.
Functions of the Somatic Nervous System:
● Allows an indi dual to receive information from their external en ronment
● Enables voluntary movement
Divisions of the PNS - Autonomic Nervous System
The Autonomic Nervous System (ANS): a subdi sion of the PNS that connects the CNS to the body’s internal organs and glands, pro ding feedback to the brain about their acti ties.
● The ANS is autonomous: unconsciously controlling and regulating internal functions to maintain sur val.
● This is achieved by regulating (involuntary) sceral muscles, organs and glands
For Example: heart rate, breathing rate, digestion, salivating, and perspiration
Di sions of the Autonomic Nervous System
The autonomic nervous system consists of three subdivisions that complement and counterbalance each other’s activity:
1. The Sympathetic Nervous System is the division of the ANS that increases the activity of most visceral muscles, organs and glands
2. The Parasympathetic Nervous System is the division of the ANS responsible for decreasing the activity of most visceral muscles, organs and glands
3. The Enteric nervous system, which is dedicated to the gastrointestinal tract and therefore helps regulate digestion
IMPORTANT NOTE:
Both the sympathetic nervous system and parasympathetic nervous system are always active; one is just usually dominant.
NOTE:
● The sympathetic nervous system is activated in stressful situations that would evoke sympathy from other people.
● The parasympathetic nervous system can be compared to a parachute, returning the body to optimal and balanced functioning a er it has been energised.
Sympathetic Nervous System:
The Sympathetic Nervous System: activates internal muscles, organs and glands to prepare the body for vigorous acti vity or to deal with a stressful or threatening situation.
● It’s purpose is predominantly sur vival
● Stressor detected leads to immediate response For example it’s responsible for:
● Heart rate and respiration increase
● Sugar and fats are released to pro de energy to muscles
● Pupils dilate to allow more light into the eye to improve sion
● Increased sweating to cool the body
● Digestion slows and bladder control is reduced
How does this Happen?
- Excitatory neurotransmitters (dopamine) trigger the fight-flight response
- This activates the adrenal glands (above kidneys)
- They release stress hormones (EG: adrenaline) into the bloodstream
- These stress hormones activate muscles, organs and other glands
Parasympathetic Nervous System:
The Parasympathetic Nervous System: helps to maintain the internal body envi ronment in a steady, balanced state of normal functioning.
● Is the more o en the dominant system
● Rest and digest system (control of digestion occurs alongside the enteric NS)
● Counterbalances the effects of the sympathetic NS
● Sympathetic NS activation is almost immediate, however, Parasympathetic
NS restoration can take time due to the lingering presence of stress hormones in our system
