Chapter 3: Biology and Behaviour Flashcards
What does the nervous system consist of?
Central nervous system (CNS)
Peripheral nervous system (PNS)
What does the CNS consist of?
The spinal cord and the brain
What does the PNS consist of?
All the other nerve cells in the rest of the body
What are the 2 nervous systems that the PNS has?
Somatic nervous systems
Autonomic nervous systems
What is the responsibility of the somatic nervous system?
Responsible for voluntary behaviour
What is the responsibility of the autonomic nervous system
Responsible for involuntary behaviour (eg: controlling the heartbeat)
What do neurons do?
Receive, integrate and transport information in the nervous system
What is a neural network?
Neurons communicate selectively with other neurons
This forms a circuit, which is also called a neural network
What happens in the receiving phase?
Neurons receive and absorb chemical signals from other neurons
What happens in the integration phase?
These signals are evaluated
What happens in the transmission phase?
The neurons send out their own chemical signals to there neurons
What do sensory neurons do?
Receive information from the physical world and transit this information to the brain via the spinal cord
What is an example of a sensory neuron?
Somatosensory nerves
What do somatosensory nerves do?
Receive information from the skin and muscles
What do motor neurons do?
Send signals from the brain to the muscles to contract or relax
What are reflexes
Automatic motor responses that occur without thinking
What are the 4 parts of a neuron?
Dendrites
Cell body
Axon
Terminal buds
What is the basic unit of the nervous system?
A neuron
Dendrites
Detect chemical signals form surrounding neurons
They are short and branched
Cell body (soma)
The information form the dendrites is collected and integrated here
Axon
After incoming information is processed, electrical impulses are sent from the cell body to the terminal buds via the axon
Axons are long and thin
Terminal buds
These are branches at the end of the axon
They send chemical signals to the next neuron
What is the synapse?
Where chemical communication between neurons takes place
With what is a neuron covered?
A membrane
What is a membrane?
A fatty protective layer that is insoluble in water
It is also semi permeable
What is an action potential?
The electrical signal that passes along the axon
This causes the terminal buds to release chemicals that transmit signals to other neurons
What is the resting potential?
When the membrane of the neuron is stable, there are more negatively charged ions on the inside of the cell than on the outside
What is the charge at the resting potential?
-70 millivolts (mV)
Inhibitory signals
Hyperpolarise the cell membrane by increasing the negative charge int he cell
This makes it less likely that a neuron will fire
Excitatory signals
Depolarise the cell membrane by reducing the negative charge in the cell
Meks it more likely that a neuron will fire
What happens when the toal input of the neuron exceeds the threshold value (-55 mV)?
An action potential is generated
What are the first 3 steps when a neuron fires?
Sodium channels in the cell membrane open and sodium ions flow into the neuron
Potassium channels in the cell membrane open and potassium ions flow out of the neuron
The neuron is now more positively charged inside than outside
What are the first 3 steps when a neuron fires?
- Sodium channels in the cell membrane open and sodium ions flow into the neuron
- Potassium channels in the cell membrane open and potassium ions flow out of the neuron
- The neuron is now more positively charged inside than outside
What are the 4, 5, 6, 7 steps when a neuron fires?
- The sodium channels close again
- The neuron begins to repolarise
- Potassium channels close
- The neuron eventually regains its original negative resign potential
What is the myelin sheath made of?
Glial cells
What is the myelin sheath?
Accelerates the transmission of electrical signals
Where are Ranvier’s nodes?
The myelin sheath is made up of segments and between these are Ranvier’s nodes
What is the function of Ranvier’s nodes?
It is where the action potential can take place
What is the presynaptic neuron?
The neuron that sends the signal
What is the postsynaptic neuron?
The neuron that receives the signal
What does the terminal button contain?
Neurotransmitters
What doe neurotransmitters do?
Chemicals made in the axon and stored in vesicles
When the action potential has reached the terminal button, the vesicle attaches to the presynaptic membrane and releases neurotransmitters into the synapse
Autoreceptors
Autoreceptors on the presynaptic neuron control the amount of neurotransmitter in the synapse
When there is enough neurotransmitter in the synapse, autoreceptors signal the presynaptic neuron to stop releasing the neurotransmitter
What are agonists?
Substances that enhance the action of the neurotransmitter by, for example, mimicking the neurotransmitters and binding to receptors as if they were the real thing
What are 7 important neurotransmitters for thinking, feeling and behaviour?
Acetylecholine (ACh)
Noradrenaline
Serotonin
Dopamine
Gamma aminobutyric acid (GABA)
Glutamate
Endorphins
Acetylcholine (ACh)
Responsible for motor control between nerves and muscles
Botox suppresses ACh release, paralysing the muscles and reducing wrinkles
ACh antagonists cause temporary memory loss
Noradrenaline
Involved in excitement, attention and alertness
Serotonin
Involved in various psychological activities, mainly in emotional states, impulse control and dreams
Low levels of serotonin cause sad and anxious moods, hunger and aggressive behaviour
Drugs that block the reuptake of serotonin cause more serotonin to remain in the synapses
Dopamine
Helps direct behaviour towards rewards
Low levels of dopamine cause problems with movement (eg: Parkinson’s disease)
Gamma aminobutyric acid (GABA)
The primary inhibitory neurotransmitter
Low levels of GABA can cause synaptic excitation to go out of control and lead to epileptic seizures
Glutamate
The primary excitatory neurotransmitter
Glutamate is important for learning and memory by strengthening synaptic connections
High levels of glutamate can lead to overmstiumuation of the brain resulting in epileptic seizures an brain damage
What is the phrenological system?
The function that is most often used would result in an enlarged brain in a certain location related to that functions
It is therefore possible to feel from the outside what kind of personality someone had
What is psychophysiological assessment?
The study of bodily response to certain tasks or events
What is the issue with
What is the device used for electrophysiology?
Electroencephalogram (EEG)
What is the issue with electroencephalogram (EEG)?
There is often a lot of noise with the data
How do you avoid the issues with the electroencephalogram (EEG)?
Use repeated measurements are often made with one person
Filters the noise
This is called event related potential (ERP)
What do brain imaging techniques measure?
Changes in the amount and rate of blood flow
What are 4 types of brain imaging techniques?
Positron emission tomography (PET)
Magnetic resonance imaging (MRI)
Functional magnetic resonance imaging (fMRI)
Transcranial magnetic stimulation (TMS)
Positron emission tomography (PET)
A radioactive substance is injected into the blood
The scan can ‘read’ the radiation from the substance
This makes it possible to see where the most radioactive material is
Magnetic resonance imaging (fMRI)
Uses the blood flow in the brain to map the working brain
Whereas a PET scan measures blood flow directly, fMRI does so indirectly by measuring differences in oxygen levels
When patients perform tests during the scan, it becomes possible to understand which brain area is important for a particular task
Transcranial magnetic stimulation (TMS)
A powerful magnetic field interferes with brain activity in a specific brain region
This makes it possible to measure whether certain regions are essential for specific psychological functions
From where to where is the spinal column?
Runs from the vertebrae to the base of the skull
What is the function of the spinal column?
To coordinate reflexes, transport sensory information to the brain, and transport motor signals from the brain to other parts of the body
What does the spinal column consist of?
Grey matter and white matter
What is grey matter?
The cell bodies of the neuron
What is white matter?
Axons and fatty myelin sheaths
What does grey matter consist of?
Mainly of neuron bodies that do not have myelinated axons and only communicate with nearby neruons
What does white matter consist of?
Mainly of myelinated axons that travel through brain regions
What parts does the brainstem consist of?
The medulla
The pons
The midbrain
What do the nerves in the brainstem control?
The basic functions of survival, such as heartbeat and breathing
What does damage to the brainstem lead to?
Usually death
What network does the brainstem contain?
A network of neruons called the reticula formation
What does the reticular formation do?
Relays information to the cerebral cortex and influences general alertness and sleep stages
To what is the cerebellum connected to?
To the back of the brainstem
For what is the cerebellum important for?
Important for motor learning and motor memory
Where is the forebrain?
It is above the cerebellum and brainstem
What does the forebrain consist of?
Left and right hemisphere
What are the 5 subcortical areas?
Thalamus
Hypothalamus
Hippocampus
Amygdala
Basal ganglia
Thalamus
Almost all sensory information (except smell) goes to the thalamus before being sent to the relevant regions fo the cerebral cortex
Hypothalamus
Necessary for survival as it is responsible for basic needs such as eating, drinking and mating
Hippocampus
Important for forming new memories
There is also evidence that the hippocampus is important for navigating the environment
Amygdala
Involved in learning biologically relevant stimuli that are important for survival
The amygdala plays a role in responding to stimuli that evoke fear
It is also involved in evaluating facial expressions, especially fearful facial expressions
In addition, the amygdala is involved in enhancing memory when emotions are strong
Basal ganglia
Responsible for planning and executing movement
The basal ganglia receive information from the whole cerebral cortex and send it back to the motor planning area of the brain
What happens when the basal ganglia is damaged?
Tremors
Learning of moment and habits
What is also part of the basal ganglia?
The nucleus accumbens
What is the nucleus accumbens responsible for?
Responsible for experiencing rewarding and motivating behaviour
It is where dopamine is released
What is the outermost layer of the forebrain?
The cerebral cortex (cortex)
What are slits?
Some folds or wrinkles in the cortex are deep grooves that divide the brain into sections
Each hemisphere in the brain has what?
4 lobes
What are the 4 lobes?
Occipital
Parietal
Temporal
Frontal
What does the corpus callusum do?
Connects the hemispheres and allows information to flow between them
Occipital lobe
Located at the back of the head and is important for processing visual information
The primary visual cortex organises visual information
The secondary visual cortex processes attributes of the visual image such as colours, shapes and movements
Parietal lobe
Contains the nerves that receive information form the skin
The left temporal lobe receives sensory information from the right half of the body and the right temporal lobe receives sensory information from the left half of the body
The primary somatosensory cortex is a strip at the front of the lobe that runs from top to bottom in both hemispheres
This is where the sensation of body parts is registered, with more sensitive body parts occupying a larger area fo the brain
What can parietal damage cause and what is it?
Haemineglections
Patients do not register anything on the left side, even though their eyes are otherwise well intact
Temporal lobe
Contains the brain areas responsible for hearing
The fusiform face area (FFA) is located where the temporal and occipital lobes meet
This area is active when looking at faces
Damage to this area can lead to limitations in recognising people, but not in recognising objects
Frontal lobe
Responsible for planning and moving
The neurons in the primary motor cortex project directly on the spinal cord to move the body’s muscles
The rest of the frontal lobe consists of the prefrontal cortex
The prefrontal cortex is reasonable for directing and painting attention, planning, understanding other people and behaving according to cultural norms
Who was Phineas Gage?
Was an American railway worker who had an accident at work in 1848 while constructing a railway, curing severe damage to his prefrontal cortex
What happened to Phineas Gage after the accident?
Gage’s personality had changed in a remarkable way
He exhibited inappropriate and antisocial behaviour, where previously he had been a responsible, calm and socially adapted person
What does Phineas Gage show?
That specific parts of the brain play a role in specific psychological processes
Why do we have a split brain?
In the past, the corpus callous was split to prevent epileptic seizures.
What is the left hemisphere dominant in?
Language, because of Broca’s area
What happens when a split brain patient sees two images flashing simultaneously on a screen? One in the right and one in the left visual field?
The patient only reports the image that was shown on the right
This is because the left hemisphere only sees the image on the right and can therefore only talk about this image
The person is unable to talk about what the right hemisphere saw in the left field of vision, because this hemisphere cannot produce language
What does the somatic nervous system do?
Transmits sensory signals to the CNS via the nerves
Skin, muscles and joints send signals to the spinal cord and brain
The brain an spinal cord send signals to the muscles, joints and skin
What does the autonomic nervous system do?
Is responsible for controlling the body’s internal environment by stimulating the glands and maintaining the internal organs
Glands and internal organs send signals to the spinal cord and brain
The brain and spinal cord send signals to the glands and internal organs
What are the 2 systems that the autonomic nervous system is divided into?
The sympathetic and parasympathetic nervous systems
How is the sympathy part activated?
When one is active, for example by increasing the heart rate
When is the parasympathetic part activated?
It is activated when resting
What does the endocrine system influence?
Influences thoughts, behaviour and actions
What is the difference between the endocrine system and the nervous system?
The way ti communicates and its speed
How does the nervous system communicate?
It is fast
Uses electrochemical signals
How does the endocrine system communicate?
Slower and uses hormones
What are hormones?
Are chemical substances released into the bloodstream by the endocrine glands
What are examples of endocrine glands?
Pancreas
Thyroid
Testes
Ovaries
How are the endocrine glands controlled?
Controlled by the hypothalamus via signals to the pituitary gland
When does the hypothalamus secrete the releasing factor?
Neural activation causes the hypothalamus to secrete a particular releasing factor, causing the pituitary gland to release a hormone specific to that factor
The hormone then travels through the bloodstream to endocrine sites throughout the body
What do pituitary glands control?
Important processes such as development, fertility and breastfeeding
What are chromosomes?
Structures made of DNA (deoxyribonucleic acid)
What are segments of the DNA strands called?
Genes
How many chromosomes does a human cell usually have?
23 pairs of chromosomes in each cell
What does each gene contain?
Specific instruction for the formation fo a certain polypeptide and one or more of these polypeptides together from of protein
What are proteins?
The substances that form the structure of cells and control their activities
What is the effect of the environment on proteins?
Influences which proteins are produced and when
What happens with a dominant gene?
It is always expressed if ti is present
What happens with a recessive gene?
Only expressed if it is combined with a similar gene from the other parent
What is the genotype?
The genetic make up of an organisms and does not change
What is the phenotype?
Contains all the observable physical characteristics
What is polygenic?
The characteristic is determined by several genes in interaction with the environment
How many combinations of the 23 chromosomes are possible?
8 million
How are monozygotic twins (identical twins) made?
Result of a zygote splitting into two
How are dizygotic twins made?
Occur when two sparely fertilised eggs develop simultaneously
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