Biological Approach Flashcards
What are the two control systems in humans?
Nervous system, endocrine system.
What are the two divisions of the human nervous system? What do they consist of/do?
The central nervous system (CNS) which consists of the brain and spinal chord. The peripheral nervous system (PNS) which consists of millions of neurons that carry messages to and from the CNS.
What are the 3 neurons in the PNS called?
Motor, sensory, and interconnecting (or relay) neurons.
What are the two divisions of the PNS?
Autonomic nervous system and the somatic nervous system.
What are the two divisions of the autonomic nervous system?
Sympathetic nervous system and the parasympathetic nervous system.
What do motor neurons do?
Carry messages away from the CNS to the organs and muscles.
What is the structure of a motor neuron?
It has a cell body with many dendrites branching off it. The dendrites have a large surface area. An axon branches off from the cell body, covered in a myelin sheath. Synaptic terminals come from the end of the axon.
How do motor neurons work?
The dendrites connect with other neurons and carry nerve impulses towards the cell body. The axon carries the nerve impulses away from the cell body.
What are the cells surrounding the axon?
Schwann cells wrap around to form an insulation layer called the myelin sheath which is white fat.
What is the gap between neurons called?
A synapse.
What do sensory neurons do?
Carry messages from the receptors in the body (PSN to the CNS.
What are some examples of receptors?
Sense organs, muscles, skin and joints.
What do receptors do?
They detect physical and chemical changes in the body and relay these messages to other interconnecting neurons or motor neurons.
What is the reflex arc?
A stimulus, such as a hammer hitting a knee, is detected by receptor cells in the PNS which then conveys a message along a sensory neuron. The messages reaches the CNS where it connects with an neuron. This then transfers the messages to a motor neuron, which carries the message to an effector (e.g. muscle) which causes the muscle to contract.
What are the lengths of the fibres in the three types of neuron?
Motor - short dendrites, long axons.
Interconnecting - short dendrites, short/long axons.
Sensory - long dendrites, short axons.
What do synapses do? What is that known as?</p>
Allow electrical messages from one neuron to transfer to an adjacent neuron. It is known as a synaptic transmission
Explain synaptic transmission.</p>
The nerve impulse arrives at a pre-synaptic terminal. This triggers the release of neurotransmitters which must be taken up immediately by the post-synaptic neuron or it will be reabsorbed by the synaptic terminal or be broken down by enzymes. If transmitted, the impulse is carried along the post-synaptic neuron until it reaches the next synaptic terminal.
What is a neurotransmitter?</p>
A chemical substance released from a synaptic vesicle that affects the transfer of an impulse to another nerve of muscle.
What are some examples of neurotransmitters? How can they influence the post-synaptic neuron?
Dopamine, acetylcholine, serotonin. They can act in an inhibitory way (decrease the firing of a cell) or an excitatory way (increase the firing of a cell).
What is thought to be the cause of schizophrenia in terms of neurotransmitters?
Thought to be the result of excessive activity of the neurotransmitter dopamine. Neurons are too excitatory, and transfer too many messages throughout the brain as a result. When this happens, symptoms of schizophrenia appear.
How can the symptoms of schizophrenia be controlled?
With anti-psychotic drugs such as chlorpromazine. They block the receptor sites for dopamine.
Explain the study of Phineas Gage.
Whilst working on a railroad, he was preparing to black a section of rock using explosives to create a new railway line. Gage dropped his tamping iron onto the rock, causing the explosive to ignite. The explosion hurled the metre-length iron pole through Gage’s left cheek, passed behind his left eye and exited his skull and brain form the top of his head. The pole was found metres away covered in bits of Gage’s brain.
What was the aftermath of Phineas Gage’s accident?
He survived, and after months of rest and recovery looked to get his job back. However no one would employ him due to his personality change from kind and reserved to boisterous, rude and grossly blasphemous.
What is localisation?
Specific areas of the cerebral cortex are associated with particular physical and psychological functions.
What is lateralisation?
The dominance of one hemisphere of the brain for particular physical and psychological functions.
What is a hemisphere?
Hemisphere means ‘half’; the brain has a left and right hemisphere.
What are two scientists that were involved in the research of localisation of cortical function?
Paul Broca and Karl Wernicke.
What can hemisphere’s control?
Speech and language.
What are the three concentric layers of the brain and what do they do?
Central core - regulates out most primitive and involuntary behaviour.
Limbic system - controls our emotions.
Cerebrum - regulates higher intellectual processes.
What is the central core also known as?
The brain stem.
What does the hypothalamus do and where is it?
It is located in the midbrain in the central core and regulates out eating, drinking and sexual behaviour and regulates the endocrine system to maintain homeostasis.
What is homeostasis?
The process by which the body maintains a constant psychological state.
What structure is contained in the limbic system?
The hippocampus.
What does the hippocampus do? How was this conclusion drawn?
It is thought to play a key role in memory. Patients would have their hippocampus removed to treat severe forms of epilepsy, and upon recovery suffered from anterograde amnesia.
What is anterograde amnesia?
Unable to form new memories.
Why does the cerebral cortex appear grey, and what is it?
It is the outermost layer of the cerebrum. It appears grey because of the location of the cell bodies and is thus known as grey matter.
What lies underneath the cerebral cortex?
Myelinated axons which appear white - so is known as white matter.
How are the right and left hemispheres of the cerebrum connected?
By bundles of fibres called the corpus callosum.
What does the corpus callosum do?
It enables messages that enter the right hemisphere to be conveyed to the left hemisphere and vice versa.
What are the four lobes of the cerebrum and what do they do?
Frontal lobe - awareness of what we are doing (consciousness).
Parietal lobe - sensory and motor movements.
Temporal lobe - auditory ability and memory acquisition.
Occipital lobe - vision.
Where is the motor area located and what does it do?
In the parietal lobe. It is responsible for controlling voluntary movement. Movements on the right side of the body are controlled by the left hemisphere and vice versa.
Where is the somatosensory area located and what does it do?
In the parietal love, separated from the motor area by the central sulcus. It responds to heat, cold, touch, pain and our sense of body movement.
What is the amount of somatosensory area associated with a particular part of the body related to?
Its use and sensitivity - e.g. rats whiskers have a separate cortical area. Human hands and face talk up more than half.
How do the eyes connect to the occipital lobe? Therefore, what does damage of one hemisphere result in?
Nerve fibres from the inner half of the retina cross at the optic chiasm and travel to opposite sides of the brain. Damage to the left hemisphere can result in a loss of vision in the right eye.
What is the optic chiasm?
The point at which the nerve fibres from both eyes converge.
Where is the auditory area located? What is it responsible for?
In the temporal lobe. It analyses speech-based information.
What is the Wernicke’s area and where is it?
Found in the left temporal lobe, it is responsible for comprehension of speech. Damage causes Wernicke’s aphasia - speech is rapid and disorganised (no grammatical sense).
What is a split-brain patient? What were they being treated for?
They have undergone a corpus callosotomy where a large part of the corpus callosum is lesioned (cut). This was a treatment for severe forms of epilepsy.
What is the result of split-brain surgery?
The two hemispheres of the brain cannot communicate as effectively.
What research was done on split-brain patients?
Roget Sperry and Michael Gazzaniga tested various cognitive and perceptual processes. They administered tasks known to be associated with each hemisphere of the brain to the patients. They discovered that the two halves of the brain were able to function independently.
