Lessons 01 - 05

Question 1

The Nervous System

Answer 1

A specialised network of cells in the human body and is our PRIMARY INTERNAL COMMUNICATION SYSTEM.
Functions:
- To collect, process and respond to information in the environment
- To coordinate the working of different organs and cells in the body
Divided into the CNS and PNS

Question 2

The Central Nervous System

Answer 2

Made up of the spinal cord and brain
The brain is the CENTRE OF ALL CONSCIOUS AWARENESS. The outer layer, the cerebral cortex, is highly developed in humans and is what distinguishes our higher mental functions from those of animals. Only a few living creatures (jellyfish, sponges, sea squirts) do not have a brain. It is divided into the left hemisphere and the right hemisphere
The spinal cord is an extension of the brain, which is responsible for REFLEX ACTIONS (e.g. pulling your hand away from a fire). It passes messages to and from the brain and connects nerves to the PNS

Question 3

The Peripheral Nervous System

Answer 3

It TRANSMITS MESSAGES via millions of neurons (nerve cells) to and from the CNS. It is divided into the Autonomic Nervous System (ANS) and the Somatic Nervous System (SNS)
ANS: governs VITAL FUNCTIONS in the body such as breathing, heart rate, digestion, sexual arousal and stress responses
SNS: controls MUSCLE MOVEMENT and receives information from sensory receptors

Question 4

The Spinal Cord

Answer 4

The main function is to RELAY INFORMATION between the brain and the rest of the body, allowing the brain to monitor and regulate bodily processes (digestion, breathing) and to coordinate voluntary movements.
The spinal cord is connected to different parts of the body by pairs of spinal NERVES, which connect the specific muscles and glands.
The spinal cord also contains circuits of nerve cells that enable us to perform simple REFLEXES without the direct involvement of the brain (e.g. pulling your hand away from something hot)

Question 5

The Brain

Answer 5

The centre of all conscious awareness
Four main divisions:
- The cerebrum
- The cerebellum
- The diencephalon
- The brain stem

Question 6

The Cerebrum

Answer 6

The largest part of the brain. It is split into four different lobes, each has a different primary function: the frontal lobe, temporal lobe, parietal lobe and occipital lobe. It also split into two halves called cerebral hemispheres. Each hemisphere is specialised for particular behaviours and the two hemispheres communicate via the corpus callosum

Question 7

The Cerebellum

Answer 7

It sits at the back of the cerebrum and is involved in controlling a person’s MOTOR SKILLS AND BALANCE, coordinating the muscles to allow precise movements

Question 8

The Diencephalon

Answer 8

It lies beneath the cerebrum and on top of the brain stem. It contains the thalamus and hypothalamus

Question 9

The Brain Stem

Answer 9

This is responsible for REGULATING AUTOMATIC FUNCTIONS essential for living (breathing, heartbeat and swallowing). Also motor and sensory neurons travel through the brain stem, allowing IMPULSES to pass between the brain and the spinal cord

Question 10

Diagram of the brain

Answer 10

DO I KNOW IT????????

Question 11

The PNS in detail: the Somatic Nervous System

Answer 11

It controls VOLUNTARY MOVEMENT and is under conscious control
Made up of 12 pairs of cranial nerves (nerves that emerge directly from the underside of the brain) and 31 pairs of spinal nerves (nerves from the spinal cord)
The nerves have both sensory and motor neurons.
It is also involved in REFLEX actions without the involvement of the CNS and allows the reflex to occur very quickly
The control centre is in the motor cortex part of the brain
The role is to to CARRY SENSORY INFORMATION from the outside world to the brain and provide MUSCLE RESPONSES via the motor pathway

Question 12

The PNS in detail: the Autonomic Nervous System

Answer 12

It regulates INVOLUNTARY ACTIONS (heart beats, digesting food etc.), so is responsible for regulating automatic internal bodily responses
The control centre is in the brain stem
It plays an important role in HOMEOSTASIS
It consists of only motor pathways
Both the sympathetic and parasympathetic nervous systems regulate the same organs

Question 13

The PNS in detail: the Sympathetic Nervous System (a component of the ANS)

Answer 13

Is involved in responses that help us deal with emergencies (FIGHT/FLIGHT), such as increasing heart rate and blood pressure and dilating blood vessels
Neurons travel to almost every organ and gland within the body, preparing it for RAPID ACTION (e.g. the sympathetic nervous system causes the body to release stored energy, pupils to dilate, hair to stand on end etc.)

Question 14

The PNS in detail: the Parasympathetic Nervous System (a component of the ANS)

Answer 14

This RELAXES a person AFTER the emergency has passed and returns us to our ‘normal’ resting state (e.g. it slows the heartbeat down and reduces blood pressure. It also starts digestion again)

Question 15

Sensory neurons

Answer 15

These CARRY messages from the PNS to the CNS. They have LONG dendrites and SHORT axons
They are found in RECEPTORS (e.g. eyes, ears, tongue, skin) and carry nerve impulses to the spinal cord and brain. When the impulses reach the brain, they are translated into ‘sensations’ (e.g. vision, hearing, taste and touch). Not all sensory neurons reach the brain, as some stop at the spinal cord allowing for quick reflex actions

Question 16

Relay neurons

Answer 16

These CONNECT the sensory neurons to the motor or other relay neurons. They have SHORT dendrites and SHORT axons
They are found in the brain and spinal cord and allow sensory and motor neurons to communicate

Question 17

Motor neurons

Answer 17

These CONNECT the CNS to effectors such as muscles and glands. They have SHORT dendrites and LONG axons
They control MUSCLE MOVEMENTS. When motor neurons are stimulated, they release neurotransmitters that bind to the receptors or muscles to trigger a response, which leads to movement

Question 18

Structure of a neuron

Answer 18

[image in booklet]
Neurons vary in size from less than a millimetre to over a metre
The cell body (or soma) include NUCLEUS, which contains the genetic material of the cell. Dendrites (branch-like structures) stick out of the cell body and carry nerve impulses from neighbouring neurons TOWARDS the cell body
The axon carries the impulses AWAY from the cell body down the length of the neuron. The axon is covered in a fatty layer of myelin sheath (relay neurons do not have a myelin sheath), that PROTECTS the axon and speeds up electrical transmission of the impulse
The myelin sheath is segmented by gaps called nodes of Ranvier. These SPEED UP the transmission of the impulse by forcing it to ‘jump’ across the gaps along the axon.
At the end of the axon are terminal buttons (axon terminals) that COMMUNICATE with the next neuron in the chain across the synapse, ready for synaptic transmission

Question 19

Synaptic Transmission

Answer 19

Refers to the process by which a nerve impulse passes across the synaptic cleft from one neuron (the presynaptic neuron) to another (the postsynaptic neuron)
When in resting state, the inside of the cell is negatively charged. When activated by a stimulus, the inside of the cell becomes positively charged for a split second, causing an ACTION POTENTIAL to occur. This creates an electrical IMPULSE that travels down the axon towards the end of the neuron (this process is electric transmission).
Once an action potential has arrived at the axon terminal, it needs to cross the synaptic cleft (the physical gap between the neurons). On the axon terminal, there are synaptic VESICLES (sacs) that contain neurotransmitters that help in the transfer of the action potential.
EXOCYTOSIS happens
The released neurotransmitter DIFFUSES across the synaptic gap where it binds to specialised receptors, which are activated.
RE-UPTAKE happens

Question 20

Synapse

Answer 20

It includes the end of the pre-synaptic neuron, the membrane of the post-synaptic neuron and the gap in between (the synaptic cleft)

Question 21

Exocytosis

Answer 21

When the action potential reaches the vesicles, it causes them to RELEASE their contents (neurotransmitters)

Question 22

Re-uptake

Answer 22

This terminates the effects of synaptic transmission
The neurotransmitter is TAKEN UP again by the pre-synaptic neuron where it is stored for later release. The QUICKER the neurotransmitter is taken back, the SHORTER the effects

Question 23

Neurotransmitters

Answer 23

CHEMICAL MESSENGERS that carry signals from the pre-synaptic neuron across the synaptic gap to the receptor site on the post-synaptic neuron.
They can be classed as either excitatory or inhibitory in their action
A nerve cell can receive both EPSPs and IPSPs at the same time. The likelihood of the cell firing is determined by adding up the excitatory and inhibitory synaptic input. The net result (summation) determines whether the cell fires or not.

Question 24

Inhibitory neurotransmitters

Answer 24

They are generally responsible for CALMING the mind and body, including sleep and filtering out unnecessary excitatory signals
An inhibitory neurotransmitter binding to a post-synaptic receptor results in an inhibitory post-synaptic potential (IPSP), making it LESS LIKELY that the neuron will fire
Examples: serotonin

Question 25

Excitatory neurotransmitters

Answer 25

These tend to ACTIVATE your behaviour (makes something happen)
Examples: adrenaline, dopamine
An excitatory neurotransmitter binding to a post-synaptic receptor causes an electrical charge in the membrane of the post-synaptic neuron, resulting in an excitatory post-synaptic potential (EPSP) which means that the post-synaptic cell is MORE LIKELY to fire

Question 26

The Endocrine System

Answer 26

Works ALONGSIDE the nervous system to control vital functions in the body
Acts much more SLOWLY than the nervous system but has WIDESPREAD and powerful effects
Glands produce HORMONES, which are secreted into the bloodstream and affect any cell in the body that has a receptor for that particular hormone
Most hormones affect cells in several organs or throughout the body, leading to many diverse and powerful responses

Question 27

Gland | Hormone | Effect

Answer 27

[image in booklet]

Question 28

Some hormones to remember

Answer 28

Thyroxine, found in thyroid, regulates body’s metabolic rate and protein synthesis
Adrenaline, found in adrenal medulla, fight or flight repsonse
Oestrogen, ovaries, regulation of female reproducive system

Question 29

Pituitary Gland

Answer 29

The MAJOR endocrine gland, located in the brain
Controls the RELEASE OF HORMONES from all the other endocrine glands in the body
The hypothalamus controls the release of hormones from the pituitary gland
Divided into an anterior and posterior portion or lobe

Question 30

Anterior pituitary
Posterior pituitary

Answer 30

[image in booklet]

Question 31

The fight or flight response to stress

Answer 31

When a person is in a threatening or stressful situation, their heart beats faster, breathing is quicker and muscles tense.
This response evolved as a SURVIVAL mechanism, allowing humans and animals to act quickly in threatening situations

Question 32

Fight or flight (the amygdala and hypothalamus)

Answer 32

When faced with a threat, the amygdala is activated. It associates SENSORY signals (senses: see, hear, smell, feel) with EMOTIONS associated with fight or flight (fear, anger).
The amygdala then sends a DISTRESS SIGNAL to the hypothalamus, which functions like the command centre in the brain. It communicates with the rest of the body through the sympathetic nervous system.
The body’s response to stressors involved acute (sudden) stressors and chronic (ongoing) stressors

Question 33

Fight or flight: Response to acute (sudden) stressors

The Sympathetic Nervous System (SNS)

Answer 33

When triggered, it prepares the body for rapid action, sending a signal through the adrenal medulla, which releases adrenaline
ADRENALINE:
- Heart beats faster, pushing blood to muscles and vital organs, increasing blood pressure
- Breathing becomes faster so you can take in as much oxygen as possible
- Blood sugar and fats are released, supplying energy

Question 34

Fight or flight: Response to acute (sudden) stressors

The Parasympathetic Nervous System

Answer 34

When the threat has passes, the parasympathetic branch of the ANS DAMPENS the stress response.
It SLOWS the heartbeat down and reduces blood pressure. Also, digestion begins again

Question 35

Fight or flight: Response to chronic (ongoing) stressors

Answer 35

The second system, which kicks in if the brain continues to perceive something as threatening
The hypothalamus activates the HPA axis:
H - the Hypothalamus
The HPA axis relies on a series of hormonal signals to keep the sympathetic nervous system working. The hypothalamus releases corticotrophin-releasing hormone (CRH) into the bloodstream in response to the stressor
P - the Pituitary gland
CRH causes the pituitary to produce and release adrenocorticotrophic hormone (ACTH), which is transported in the bloodstream to its target site on the adrenal glands
A - the Adrenal gland
ACTH stimulates the adrenal cortex to release various stress-related hormones, including cortisol, which is responsible for many of the fight or flight effects (some are positive - a quick burst of energy - and some are negative - impaired cognitive performance)

The HPA axis is very efficient at regulating itself. Both the hypothalamus and pituitary gland have special receptors that initiate a reduction in CRH and ACTH levels if there is a high level of cortisol

Question 36

Evaluation of fight or flight

Answer 36

+ Makes sense from an evolutionary psychology perspective, because it would have helped an individual to survive, by either fighting or fleeing from a threat
+ Studies support the idea of adrenaline being essential for preparing the body for stress. People who have malfunctioning adrenal glands do not have a normal fight or flight response
- It does not take into account other responses. Gray (1988) suggests that the first response is to avoid confrontation altogether - to ‘freeze’. During the freeze response, animals and humans are super-vigilant, while they judge the situation to decide the best course of action.
- The fight or flight response is typically a male response. Females adopt a ‘tend and befriend’ response. According to Taylor et al. (2000), women are more likely to protect their offspring (tend) and form alliances with other women (befriend) than fight or flee. Fleeing may be seen a sign of weakness. However, Von Dawans (2012) found that males also tend and befriend, for example, during the September 11th 2001 attacks, both males and females showed tend and befriend as they tried to contact loved ones and helped others. This suggests that tend and befriend is relative to both males and females.
- Modern day life does not require such an intense biological response. It was useful for our ancestors. Another point is that fight or flight can have a negative effect on our health. Humans who face a lot of stress continually increase their blood pressure, which can cause damage to their blood vessels and cause heart disease. This suggests the fight or flight response is maladaptive in modern day life