The ner vous system has t wo main Human nervous system
functions:
Key terms:
• To collect, process and responds
• Nervous system: Consists of the central
to information in the Peripheral central
nervous system and the peripheral
nervous system. Communicates using
environment nervous system /PNs) nervous system ((NG)
• To co-ordinate the working of
electrical signals. ANS
different organs and cells in the - -Autonomic SomaH(
Spinal
• Central nervous system (CNS): Consists nervous nervous Brain
body system system Lord
of the brain and the spinal cord and is
↓
the origin of all complex commands and ↓
LINS
The ner vous system is divided into SympalhOHs Parasympathetic
decisions
-
nervous nervous
t wo subsystems:
• Peripheral nervous system (PNS): Sends system system
• Central ner vous system (CNS)
information to the CNS from the
• Peripheral ner vous system (PNS)
outside world, and transmits messages
from the CNS to muscles and glands in
the body.
• Somatic nervous system (SNS):
The central ner vous system (CNS) - what its made up of
Transmits information from receptor
The central ner vous system is made up of the brain and spinal cord:
cells in the sense organs to the CNS. It
• The brain is the central of all conscious awareness. The brains outer layer, the cerebral
also receives information from the CNS
cortex, is only 3mm thick and covers the brain like an orange peel covered an orange. It is
that directs muscles to act
only found in mammals
• Autonomic nervous system (ANS):
• The brain is highly developed in humans and is what distinguishes our higher mental
Transmits information to and from
functions from those of other animal. Only a few living creatures - sponges, sea squirts
internal bodily organs. It is 'autonomic'
and jellyfish do not have a brain.
as the system operates involuntarily
• The spinal cord is an extension of the brain. It passes messages to and from the brain and
(i.e. automatic). It has t wo main
connects ner ves to the PNS. It is also responsible for reflex actions such ad pulling you
divisions: the sympathetic and
hand away from a hot plate.
parasympathetic nervous systems
The peripheral ner vous system (PNS) - what its made up of
The role of the nervous system:
The peripheral ner vous system transmits messages, via millions of neurons (ner ve cells), to
The nervous system is a specialised
and from the central ner vous system, the peripheral ner vous system is further subdivided
net work of cells in the human body and is
into the:
our primary internal communication
• Automatic ner vous system (ANS): governs vital functions in the body such as breathing,
system. It is based on electrical and
heart rate, digestion, sexual arousal and stress system
chemical signals whereas the endocrine
• Somatic ner vous system (SNS): governs muscle movement and relieves information from
system is based on hormones.
sensory receptors
, Biopsychology: The Endocrine system
Key terms: The Endocrine system: Glands and Hormones
• Endocrine system: One of the body's major The endocrine system works alongside the nervous system to control vital
information systems that instructs glands to functions in the body. The endocrine system acts more slowly than the ner vous
release hormones directly into the system but has very widespread and powerful effects. Various glands in the
bloodstream. These hormones are carried body, such as the thyroid gland, produce hormones. Hormones are secreted into
towards target organs in the body. the bloodstream and affect any cell in the body that has a receptor for that
Communicates via chemicals. particular hormone.
• Gland: An organ in the body that synthesises
substances such as hormones Most hormones affect cells in more than one body organ, leading to many
• Hormones: Chemical substances that circulate diverse and powerful responses. For example, the thyroid gland produces the
in the bloodstream and only affect target hormone thyroxine. This hormone affects cells in the heart (increases heart
organs. They are produced in large quantities rate. It also affects cells throughout the body increasing metabolic rates (the
but disappear quickly. Their effects are very chemical processes taking place in the cells). This in turn affects growth rates.
powerful
• Fight or Flight response: The way an animal The key endocrine gland is the pituitary gland, located in the brain. It is often
responds when stressed. The body becomes called the 'master gland' because it controls the release of hormones from all
physiologically aroused in readiness to fight an the other endocrine glands in the body.
aggressor or, in some cases flee.
• Adrenaline: A hormone produced by the The Endocrine system: Endocrine and ANS working together (fight or flight)
adrenal glands which is part of human body's Often the endocrine system and the autonomic nervous system (ANS) work in
immediate stress response system. Adrenaline parallel with one another, for instance during a stressful event. When a
has a strong eflect on the cells of the stressor is perceived (your friend jumps out to frighten you or you think about
cardiovascular system - stimulating heart your upcoming exams) the first thing that happens is a part of the brain called
rate, contracting blood vessels and dilating air the hypothalamus activates the pituitary gland and this triggers activity in
passages. the sympathetic branch of the autonomic ner vous system. The ANS changes
from its normal resting state (the parasympathetic state) to the
physiologically aroused sympathetic state.