Biopsychology

Question 1

The central nervous system

Answer 1

• Consists of the brain + spinal cord
• 2 main functions – the control of behaviour and the regulation of the body’s physiological processes
• The brain has to be able to receive info from sensory receptors and send messages to muscles and glands

Question 2

The brain

Answer 2

• It is responsible for conscious awareness
• It is divided into 2 hemispheres
  The brain is divided into 4 main areas:
• Cerebrum – largest part of the brain. It has 4 lobes and is split into 2 halves (the right and left hemisphere).
• Cerebellum – responsible for motor skills, balance and coordinating the muscles to allow precise movements
• Diencephalon – contains the thalamus (regulates consciousness, sleep and alertness) and the hypothalamus (regulates temp, stress response and hunger and thirst)
• Brain stem – regulates breathing and heart rate

Question 3

the spinal cord

Answer 3

• An extension of the brain
• Its main function is to relay messages between the brain and the rest of the body
• This allows the brain to regulate bodily processes e.g digestion/breathing and coordinate voluntary movement
• It is connected to different parts of the body by pairs of spinal nerves, which connect to specific muscles/glands
• If the spinal cord is damaged, body areas connected to it by nerves below the damage will be cut off and stop functioning

Question 4

The peripheral nervous system:

Answer 4

• Consists of the nervous system throughout the rest of the body
• Transmits messages via neurones to + from the CNS
• Has 2 divisions – the somatic nervous system and the autonomic nervous system

Question 5

the somatic nervous system

Answer 5

• Controls voluntary movements
• Is under conscious control
• It connects the senses with the CNS
• It transmits and receives messages from receptors cells in the sensory organs and then relays these messages to the CNS
• It receives messages from the CNS so that effectors can move and react
• It has sensory pathways and motor pathways
• It controls skeletal muscles
• It is controlled by the motor cortex

Question 6

The autonomic nervous system:

Answer 6

• Helps transmit and receive messages from the internal organs and glands
• It is involuntary (not under conscious control)
• Only has motor pathways
• Controls smooth muscles and internal organs and glands
• It is controlled by the brain stem
• It has 2 divisions – the sympathetic nervous system and the parasympathetic nervous system.

Question 7

Sympathetic nervous system:

Answer 7

• Increases activity
• Is activated when a person is stressed
• Heart rate and breathing increases, digestion stops, salivation reduces, pupils dilate and the flow of blood is diverted from the surface on the skin

Question 8

Parasympathetic nervous system:

Answer 8

• Activates when the body is relaxing and conserving energy
• Heart rate and breathing rate decrease, digestion starts, salivation increases and pupils constrict

Question 9

Neurone definition

Answer 9

specialised nerve cells that move electrical impulses to/from the CNS

Question 10

The structure of a neurone:

Answer 10

• Nucleus – contains the genetic material
• Dendrites – receive an electrical impulses (action potential) from other neurones/sensory receptors. Carry nerve impulses from 1 neurone to the next
• Axon – carried the electrical impulse away from the cell body towards the synapse/axon terminal
• Synapse – the ending of a neurone
• Synaptic knob – the swelling at the end of a neuron – it contains many vesicles that will release neurotransmitters
• Synaptic cleft – small microscopic gaps between 1 neuron and the next
• Myelin Sheath – insulating layer that protects the axon and speeds up the transmission of the electrical impulse
• Schwann cells – make up the myelin sheath
• Nodes of Ranvier – gaps in the myelin sheath – they speed up the electrical impulse along the axon
• Neurotransmitters – chemicals that are released from 1 neuron within the synaptic knob then pass across the synaptic cleft to the next neuron
• Receptor sites – proteins that are on the surface of each cell. They act as receivers to the messages of chemical molecules.
• Cell body – control centre of the neuron

Question 11

Sensory neuron:

Answer 11

• Found in sensory receptors
• Carry impulses from sensory receptors to the CNS via the PNS
• Convert info from sensory receptors into electrical impulses
• When these impulses reach the brain they are converted into sensations e.g heat, pain etc so the body can react appropriately
• Some sensory impulses terminate at the spinal cord allowing reflexes to occur more quickly

Question 12

Motor neuron:

Answer 12

• Located in the CNS but project their axons outside of the CNS
• Send electrical impulses via axons to glands/muscles so they can affect function
• When motor neurons are stimulated, they release neurotransmitters that bind to the receptors on muscles to trigger a response, which leads to movement

Question 13

Relay neuron:

Answer 13

• Found in the CNS
• Connect sensory neurons to motor neurons so they can communicate with each other
• During a reflex arc, the relay neurons are involved in the analysis of the sensation and decide how to respond without waiting for the brain to process the pain

Question 14

Synaptic transmission definition

Answer 14

the process by which nerve impulses are transmitted across the synaptic cleft between 1 neuron and the next. The nerve impulse is carried by neurotransmitters

Question 15

Synaptic transmission

Answer 15

• Within a neuron, messages are transmitted by electrical impulses
• Neurons transmit electrical impulses (action potentials) between the pre-synaptic and post-synaptic neuron
• When the action potential reaches the pre-synaptic terminal, it triggers the release of neurotransmitters from vesicles in the pre synaptic membrane via exocytosis
• The neurotransmitter will diffuse across the synaptic cleft where it binds to the post-synaptic receptor sites
• Synaptic transmission takes a fraction of a second
• The effects of synaptic transmission are terminated by re-uptake – the neurotransmitters are taken back by the vesicles on the pre-synaptic neuron where they are stored for later released.
• The quicker the neurotransmitter is taken back, the shorter the effects
• Neurotransmitters can be excitatory or inhibitory

Question 16

Excitatory neurotransmitters:

Answer 16

• Causes an electrical charge in the membrane of the post-synaptic neuron resulting in an excitatory post-synaptic potential
• The post synaptic neuron is more likely to fire an impulse
• The neuron will aim to activate the neighbouring neuron
• A neurotransmitter is released from the synaptic vesicles into the synaptic cleft and is likely to bind with the post-synaptic receptor and cause a positive electrical charge in the membrane of the post-synaptic neuron
• Example – adrenaline

Question 17

Inhibitory Neurotransmitters:

Answer 17

• Cause an inhibitory post-synaptic potential, making it less likely that the neuron will fire an impulse
• The chemical message will be stopped at the post-synaptic neuron
• A neurotransmitter is released from vesicles in the pre-synaptic neuron into the synaptic cleft. It is less likely to bind with post-synaptic receptor cells and will cause a negative electrical charge in the membrane of the post-synaptic neuron
• Example serotonin

Question 18

Summation:

Answer 18

• The addition of positive and negative post-synaptic potentials
• A nerve cell can receive positive and negative potentials simultaneously
• These potentials are summed and if the net effect of the post-synaptic neuron is inhibitory, the neuron will be less likely to fire and if the net effect is excitatory, the neuron will be more likely to fire
• The likelihood that the neuron will fire an impulse is determined by adding the excitatory and inhibitory synaptic input

Question 19

Direction of synaptic transmission:

Answer 19

• Information can only travel in 1 direction at a synapse
• The vesicles containing neurotransmitters are only present on the pre-synaptic membrane and the receptors for the neurotransmitters are only present on the post-synaptic membrane
• The binding of the neurotransmitter to the receptor enables information to be transmitted to the next neuron
• Diffusion of the neurotransmitters means they can only go from high to low concentration and can only travel from the pre to post synaptic membrane

Question 20

Medication:

Answer 20

• Psychoactive drugs (medication that affects brain function to alter perception/ mood/ behaviour) work by affecting the transmission of neurotransmitters across the synapse
• Some pain medication mimic the effects of inhibitory neurotransmitters – when an inhibitory neurotransmitter binds to the post synaptic receptors, it makes the post-synaptic neuron less likely to fire. Due to summation if inhibitory neurotransmitters are higher than excitatory neurotransmitters, they can inhibit an action potential from occurring – therefore, pain medication would decrease the overall activity, and reducing brain activity may lead to less pain

Question 21

Endocrine system:

Answer 21

• A series of glands which slowly release chemicals to organs in the body
• Provides a chemical system of communication in the body via the bloodstream
• Endocrine gland – produces and secretes hormones into the bloodstream which are required to regulate many bodily functions
• Hormones come into contact with most cells in the body but only affect target cells
• Target cells have the receptors for a specific hormone
• When enough receptor sites are stimulated by a hormone there is a physiological reaction

Question 22

The pituitary gland:

Answer 22

• Located in the brain
• Produces hormones whose primary function is to influence the release of other hormones from other glands in the body
• Controlled by the hypothalamus
• The hypothalamus received info from sources about the basic functions of the body. It sends a signal to the pituitary gland in the form of a releasing hormone. This causes the pituitary gland to release a stimulating hormone into the bloodstream to tell the target gland to release its hormone. As levels of this hormone rise in the bloodstream, the hypothalamus shuts down the production of the releasing hormone and the pituitary gland shuts down the secretion of the stimulating hormone.

Question 23

The pituitary gland has 2 divisions:

Answer 23

1) The anterior pituitary gland
- Releases ACTH which regulates levels of cortisol

2) The posterior pituitary gland
- Releases oxytocin which is crucial for infant/mother bonding

Question 24

Adrenal glands:

Answer 24

• We have 2 adrenal glands situated on top of the kidneys

Adrenal cortex:
- Outer section of the adrenal gland
- Produces cortisol – produced when someone is experiencing chronic stress. Cortisol is also responsible for the cardiovascular system – e.g it increases blood pressure and causes blood vessels to constrict

Adrenal Medulla:
- Inner section of the adrenal gland
- Produces adrenaline – responsible for fight/flight – activated when someone is acutely stressed. Adrenaline increases heart rate, dilates pupils and stops digestion
- Produces noradrenaline – responsible for constricting blood vessels so that blood pressure increases

Question 25

Fight/flight definition

Answer 25

a survival mechanism which enables animals and humans to react quickly to life threatening/stressful situations. Fight – means we deal with the stressor. Flight – means we run away. Both reactions require energy

Question 26

Sympathomedullary pathway:

Answer 26

• The sympathetic nervous is triggered by the hypothalamus. The hypothalamus sends a signal to the adrenal medulla which responds by releasing adrenaline into the bloodstream
• Adrenaline will increase heart rate, constrict blood vessels, increase rate of blood flow, raise blood pressure, divert blood away from the skin/kidneys/digestive syste, increase blood supply to the brain/ skeletal muscles and increase respiration and sweating
• This prepares the body for fight/flight by increasing blood supply and therefore O2 to skeletal muscles for physical action and increasing O2 to the brain for rapid response planning
• The parasympathetic nervous system reduces the stress response when the threat has passed by slowing down heart rate, reduces blood pressure and restarts digestion

Question 27

The hypothalamic pituitary adrenal axis:

Answer 27

• This process describes an ongoing stress
• An event occurs and the hypothalamus registers the event and produces CRF/CRH (corticotrophin releasing factor/hormone)
• CRF/CRH travels to the anterior pituitary gland and releases ACTH
• ACTH travels via the bloodstream to the adrenal glands
• The adrenal cortex is activated and produces cortisol (stress hormone which gives the person a quick burst of energy to deal with stress – in the long term it can cause the immune system to be suppressed) and adrenaline (activates the sympathetic nervous system and causes HR to increase).
• The sympathetic nervous system is activated and fight/flight response begins

Question 28

Fight/flight Evaluation:

Answer 28

Advantages:
1) The fight/flight response makes sense from an evolutionary psychology point of view as it would have helped an individual survive by fighting/fleeing a threat

2) Studies support the claim that adrenaline is essential in preparing the body for stress. People who have malfunctioning adrenal glands don’t have a normal fight/flight response to stress

3) The fight/flight response is adaptive – it allows the person to effectively deal with the stressful situation by either fight or flight. Both of these survival mechanisms are useful and adaptive

Disadvantages:

1) Gray has criticised the fight/flight response. He states that the first reaction to stress is to avoid confrontation and not to fight/flight but to freeze. This involves the person stopping, looking and listening and being hyper-vigilant to danger and alerts in their environment, which could aid how they deal with the stressful situation

2) Taylor criticised the fight/flight response. He has found that females are more likely to ‘tend and befriend’ in times of stress rather than fight/flight. During times of stress females are more likely to protect themselves and their offspring (tend) and form protective alliances with other women (befriend). Women also have the hormone oxytocin which means they are more likely to stay and protect their offspring than run away.

3) Von Dawans has challeneged the idea that males respond to stress by fight/flight. He has found that males also tend and befriend. For example, during the 2001 september 11th terrorist attacks, both males and females showed tend and befriend as they tried to contact loved ones and help one another. Humans are social and tend and befriend helps the species to thrive

4) If the fight/flight response is continually activated, it can cause a rise in blood pressure which can cause damage to the blood vessels. This could lead to heart disease in the long term. The stress hormone cortisol can assist the body to fight viral infections or heal tissue but too much cortisol can be harmful and can suppress the immume system

5) Baxter

Question 29

Localisation of function

Answer 29

• Functions have different locations within the brain
• Research – some functions are more localised than others
• Motor + somatosensory functions are highly localised to parts of the cortex
• Language system uses several areas of the brain – however some components of language may be localised