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Unit 3 - Neurobiology and Communication
CfE Higher Human Biology
17. Parts of the Brain
Learning Intentions
I can state the function of the medulla, including breathing, heart rate, arousal and sleep
I can state the function of the cerebellum, including controlling balance, posture and movement
I can describe the role of the limbic system in processing information for memories and influencing
emotional and motivational states
I can state that the cerebral cortex receives sensory information from your surroundings
I can state that the cerebral cortex is the centre for conscious thought
I can state that the cerebral cortex recalls memories and alters behaviour in the light of
experience
I can state that the cerebral cortex co-ordinates voluntary movement
I can describe what is meant by the term localisation of function
I can explain localisation of function in terms of sensory, motor and association areas
I can explain that some association areas deal with thought processes including language,
personality, imagination and intelligence
I can state that information is passed from one side of the brain to the other through a bundle of
nerve fibres called the corpus callosum
I can state that the left cerebral hemisphere deals with information from the right visual field and
controls the right side of the body and vice versa
The Brain
• The brain is an organ composed of three interconnected layers:
• the central core
• the limbic system
• the cerebral cortex (outer layer of cerebrum)
The Central Core
• The central core contains:
• The medulla – which regulates basic life processes such as
breathing, heart rate, sleeping and arousal (being awake and
aware of the environment)
• the cerebellum – which is responsible for controlling balance,
posture and movement
medulla
cerebellum
The Limbic System
• The limbic system is responsible for:
• processing information for long term memories
• regulating emotional states, e.g. fear, aggression and anxiety
• regulating biological motivation, e.g. hunger, thirst and sex drive.
limbic system
The Limbic System
The hypothalamus is part of the limbic system attached to pituitary gland.
This acts as a link between the nervous system and the hormonal (endocrine)
system.
The hypothalamus contains secretory
cells that produce releaser hormones.
These like any other hormone are
transported to the anterior pituitary
gland. These releaser hormones stimulate
the release of pituitary hormones such
as:
• Growth hormone – for growth of the
body and development of long bones
• Thyroid stimulating hormone – needed
to make thyroxin, essential for the
control of metabolism
• Gonadotrophic hormones – first
released during puberty to stimulate
reproductive organs to produce and
release gametes
Role of the Hypothalamus
• Contraction of Smooth Muscle
Some of the axons from the neurons in the hypothalamus extend into the
sympathetic and parasympathetic centres in the brains core. This allows the
hypothalamus to regulate autonomic tasks such as the contraction and
relaxation of smooth (involuntary muscle involved in homeostatic control e.g.
vasoconstriction and contraction.
• Control of Body Temperature
The hypothalamus contains thermoreceptors which are sensitive to
changes in the temperature of blood. The hypothalamus responds
to this information by sending nerve impulse to effectors such as
sweat glands and blood vessels.
Control of Water balance
Osmoreceptors in the hypothalamus are sensitive to changes in the water
concentration of the blood. These changes can trigger production of
antidiuretic hormone (ADH) by the posterior pituitary gland. This hormone
travels to the kidneys where is increases the permeability of the tubules
and collecting ducts to reabsorb water when the concentration of water in
the blood is low.
The Cerebral Cortex
• The cerebral cortex is the outer part of the cerebrum and is the centre of
conscious thought and memories. The cerebrum is split into two halves called
cerebral hemispheres. This is the largest and most complex part of the brain.
• The cerebral cortex has three key functions:
• receives sensory information
• co-ordinates voluntary movement
• making decisions based on experience.
The Cerebral Cortex
• The cerebrum is divided into two halves, the left and right cerebral
hemispheres.
• The left cerebral hemisphere receives information from the right
visual field and controls the right side of the body.
• The right cerebral hemisphere receives information from the left
visual field and controls the left side of the body.
The Corpus Callosum
• The cerebral hemispheres are not entirely separate, they are connected by a
large bundle of nerve fibres known as the corpus callosum.
• The corpus callosum allows the transfer of information between the cerebral
hemispheres and so allows the coordination of brain function, thus enabling the
brain to act as an integrated whole.
The Cerebral Cortex
• The cerebral cortex is highly folded (convoluted) which greatly
increases its surface area, this
• provides greater space for more neurons
• allows for more interconnections between neurons
cerebral cortex
The Cerebral Cortex – Localisation of function
• Within the cerebral cortex, there are three main areas each of which
deals with a particular function.
• the sensory areas – receives information as sensory impulses from
receptors (e.g. sense organs)
• the association areas - analyse and interpret impulses received from
the sensory areas and deals with thought processes, language,
personality, imagination and intelligence.
• the motor areas – act on information from association areas by sending
motor impulses to effectors.
• By this means, coordination of voluntary movement is achieved.
https://www.youtube.com/watch?v=sjbZ9QGyBi8
The Cerebral Cortex
Frontal Lobe
Motor
Area
Temporal Lobe
Medulla Oblongata
Sensory
Area
Sensory
Association
Area
Cerebellum
Spinal cord
All these areas are
duplicated in both
hemispheres with
the exception of the
speech motor area
which is found in the
left hemisphere only
for 90% of the
population.
Interconnections and Communication
The cerebral cortex is the centre of conscious thought. Tiny nerve fibres link
up all the different areas and messages are constantly passing between them
from sensory areas to motor areas via association areas.
This allows the brain to make an integrated response based on all the
collective information. The cerebrum is also able to recoil stored memories and
then alter future decision based on the past experience.
The cerebral cortex is also responsible for:
• Intelligence
• Personality
• Creativity
• Imagination
• conscience
Electroencephalograms – EEG’s
• EEG’s record the electrical activity of the cerebrum.
• EEG’s can indicate different levels of brain activity but are not
precise enough to locate the areas of the brain which are active.
Brain Scans
• Brain scans, such as CAT, MRI or PET scans, provide a more
detailed images of the brain.
• They can detect activity through changes in blood flow or uptake
of glucose and can allow localisation of function to be identified by
showing which areas are most active whilst carrying out a particular
function.
Brain Scans
PET scan of
normal brain
PET scan
Alzheimer’s brain
Split Brain Syndrome
• In rare cases, a person can be born without a corpus callosum or
may have it cut due to serious epilepsy, this results in split brain
syndrome.
• The cerebral hemispheres do not share information and each
processes information separately.
Questions
1.
Describe the functions of the medulla and cerebellum in the central core of the
brain.
2. Describe the functions of the limbic system.
3. Describe the functions of the cerebral cortex.
4. Describe the localisation of functions within the brain
5. Describe where information from one side of the brain is processed.
6. State the function of the corpus callosum
Answers
1. Describe the functions of the medulla and cerebellum in the central core
of the brain.
medulla – regulates breathing, heart rate, sleeping and arousal
cerebellum –responsible for controlling balance, posture and movement
2. Describe the functions of the limbic system.
Processing information for memories,regulating emotional states, e.g. fear,
aggression and anxiety,regulating biological motivation, e.g. hunger,
thirst and sex drive.
Answers (continued)
3. Describe the functions of the cerebral cortex.
Receives sensory information, co-ordinates voluntary movement, making
decisions based on experience
4. Describe the localisation of functions within the brain
• the sensory areas
• the association areas
• the motor areas
Answers (continued)
5. Describe where information from one side of the brain is processed.
In the opposite cerebral hemisphere e.g. Information from the right
side is processed in the left cerebral hemisphere
6. State the function of the corpus callosum
It allows the transfer of information between the cerebral hemispheres