A2 The Human Brain Flashcards
How is the brain formed?
During embryonic development, the anterior part of the neural tube will expand to form the brain during cephalisation.
What is the function of the brain?
The brain functions as an integration and coordination system for the control of body systems. It processes sensory information received from the body and relays motor responses to effector organs.
Describe the external structures of the brain.
- The cerebral cortex (cerebrum).
This is an outer layer of tissue organised into two cerebral hemispheres (left and right) and composed of four distinct lobes (frontal, parietal, occipital and temporal). - The cerebellum.
This is a separate structure at the base of the brain. It is responsible for coordinating unconscious motor functions such as balance and movement. - The brainstem.
This is the posterior part of the brain that connects to the spinal cord. It includes the pons, the medulla and the midbrain and controls automatic and involuntary activities (breathing, swallowing, heart rate).
Describe the internal structures of the brain: hypothalamus, pituitary gland and corpus callosum.
- Hypothalamus
This functions to maintain homeostasis via the coordination of the nervous and endocrine systems. - Pituitary gland
This produces hormones that regulate other glands and target organs. It is composed of the anterior and posterior lobes. - Corpus callosum
This is a bundle of nerve fibres which connects the two cerebral hemispheres in the cerebral cortex ensuring that both sides of the brain can communicate and send signals to each other.
Explain the functions of the lobes/cortexes in the brain.
For My Sister Please Offer Tea.
- Frontal lobe (cerebrum)
Planning, organising and emotions. Includes Brocas Area which controls the production of speech. - Motor cortex
Movement. - Sensory lobe
Sensations. - Parietal lobe (cerebrum)
Perception. - Occipital lobe (cerebrum)
Vision - Temporal lobe (cerebrum)
Memory and auditory processing. Includes the Wernickes area which controls understanding of written and spoken language.
Describe the function of the left and right hemispheres in the brain.
The left hemisphere is responsible for speech, language logic and computations. It coordinates the right side of the brain.
The right hemisphere is responsible for spatial abilities, creativity, facial recognition and processing music. It coordinates the left side of the brain.
*Because of cross over wiring damage to one side of the brain affects the opposite side of the body.
What is the role of the nucleus accumbens?
This is involved in the pleasure reward pathway and is found within each cerebral hemisphere. It secretes neurotransmitters responsible for feelings of pleasure.
What is the result of the large size of the cerebral cortex in the brain?
The disproportional enlargement of the cerebral cortex in humans is responsible for our capacity for cognitive thought.
What is the correlation between body size and brain size?
There is a positive correlation between body size and brain size however there is not a correlation between brain size and intelligence.
Define encephalization.
The amount of brain mass relative to an animal’s body mass.
What are methods used to identify brain functions?
- Animal experiments
- Brain damage (lesions)
- FMRI (functional magnetic resonance imaging)
Describe how animal experiments can be used to study the brain.
Animal experimentation can be used to identify function of parts of the brain by stimulating regions with electrodes or removing via lobotomy. Such methods are highly invasive and potentially damaging so animal models are used rather than humans. Animal studies are limited by the differences between animal and human brains, making valid comparisons difficult.
Example: Mice and rats have been used to develop drug treatments for diseases such as MS.
Describe how brain damage can be used to study the brain.
Lesions are abnormal areas of brain tissue which can indicate the effect of the loss of a brain area. Autopsies after death or scans of the brain can be used to identify lesions. However, the effects of lesions can be difficult to identify, as many functions may involve multiple brain areas and the brain has the capacity to re-learn certain skills (neuroplasticity).
Example: Split brain patients have been used to identify specific roles of the left and right cerebral hemisphere.
Describe how FMRI can be used to study the brain.
FMRI records changes in blood flow within the brain to identify activated areas. It is non-invasive as a harmless dye is injected to make the blood flow visible. It can be used to identify multiple brain regions involved in complex, integrated brain activities as the brain activity can be observed in real time.
Example: FMRI studies have been used to diagnose ADHD and dyslexia, as well as monitor recovery from strokes.
What is an autopsy and how is it used to study the brain?
An autopsy is a post-mortem examination of a corpse via dissection in order to evaluate causes of death. Comparisons can be made between the brains of healthy and diseased corpses to identify affected brain areas.
