BIOPSYCHOLOGY PART 2

• THE CENTRAL NERVOUS SYSTEM

  What are the 2 main functions of the CNS.

  . The control of behavior

  . Regulation of the body's physiological processes
• What are the functions of the spinal cord?

  . The main function of the spinal cord is to relay information between the brain and the rest o the body.

  . This allows the brain to monitor and regulate bodily processes such as digestion and breathing and to co-ordinate and voluntary movements.

  . The spinal cord is connected to different parts of the parts body by pairs of spinal nerves,which connect with specific muscles and glands.

  . The spinal cord also contains circuits of nerve cells that enable us to perform some simple reflexes without the direct involvement of the brain, e.g. pulling your hand away from something that is hot

  . If the spinal cord is damaged, areas supplied by the spinal cord will be cut from the brain and stop functioning.
• What 4 main areas is the brain divided into?

  . The cerebrum, cerebellum, diencephalon and brain stem
• What is the cerebrum?

  . The cerebrum is the largest part of the brain, and is further divided into 4 different lobes, each of which has a different primary function.

  . Fat Pigs Often Trump.

  . Frontal, Parietal, Occipital, Temporal

  . Frontal lobe-involved in thought and production of speech

  . Occipital lobe-involved in processing of visual imagery

  . Parietal Lobes-involved in sensation and perception and concerned with integrating sensory input, primarily with the visual system

  . Temporal lobe-mainly revolves around hearing and selective listening. It receives sensory information such as sound and speech from the ears
• What is the cerebellum?


  Sits beneath the cerebrum. It is involved in controlling motor skills and balance, coordinating muscles to allow precise movements. Abnormalities in this area can lead to speech and motor problems and epilepsy.
• What is the diencephalon?

  . This lies between the cerebrum and on top of the brain stem.

  . Within this area there are 2 important structures;

  . The Thalamus: acts as a relay station for nerve impulses coming from the senses, routing them to the appropriate part of the brain where they can be processed.

  . The hypothalamus: regulates body temperature, hunger & thirst. It also acts as the link between the endocrine system & the nervous system, controlling the release of hormones from the pituitary gland.
• What is the brain stem?

  . This is responsible for regulating the automatic functions that are essential for life. These include breathing, heartbeat and swallowing.

  . Major and sensory neurons travel through the brain stem, allowing impulses to pass between the brain and spinal cord.
• What is the peripheral nervous system?

  * All the nerves outside the CNS make up the Peripheral Nervous System

  * The function of this part of the nervous system is to relay nerve impulses (messages) from the CNS to the rest of the body and from the body back to the CNS.

  * There are 2 main divisions of the Peripheral Nervous system: The Somatic Nervous System & The Autonomic Nervous System (ANS)
• What is the Somatic nervous system as a division of the Peripheral nervous system?

  -Transmits information from the receptor cells in the sense organs to the CNS. It also receives information from the CNS that directs muscles to act.

  
  

  1. The Somatic nervous system is made up of 12 pairs of Cranial nerves (emerging directly from the underside of the brain) and 31 pairs of spinal nerves (emerging from the spinal cord)

  2. These nerves have both sensory and motor neurons. Sensory neurons relay messages to the CNS and motor neurons relay information from the CNS to other parts of the body.

  3. The somatic nervous system is also involved in reflex actions without the involvement of the CNS, which allows the reflex to occur very quickly.
• What is the Autonomic nervous system as a division of the Peripheral nervous system?


  -Transmits information to and from internal bodily organs. It is 'autonomic' as the system operates involuntarily (it is automatic). It has two main divisions: the sympathetic and parasympathetic nervous systems.

  . The main role of the autonomic nervous system is to govern vital bodily functions within the body such as breathing, heart rate, digestion, sexual arousal and stress response.

  . The ANS has 2 branches to it: The sympathetic branch and the parasympathetic branch.

  . Both of these branches regulate organs but have opposite effects.

  . The sympathetic branch tends to use the neurotransmitter noradrenaline which has stimulating effects.

  . The Parasympathetic branch uses acetylcholine, which has inhibiting effects
• What is the sympathetic branch as a division of the autonomic nervous system?

  . The sympathetic branch is primarily involved in responses that help us deal with emergencies (fight or flight).

  . Neurons from the sympathetic branch travel to virtually every organ/gland within the body, preparing it for rapid action necessary when an individual is under threat.

  . During fight or flight this branch causes physiological changes in the body such as:

  -Dilate pupils

  -Inhibit salivation

  -Relax airways

  -Inhibit activity of stomach

  -Stimulate release of glucose; inhibit gallbladder

  -Inhibit activity of intestines

  -Secrete epinephrine and norepinephrine

  -Relax bladder
• What is the parasympathetic branch as a division of the autonomic nervous system?

  . The parasympathetic branch relaxes a person again after the Sympathetic branch has pushed them into action.

  . The parasympathetic branch slows the HR down and reduces blood pressure/reduces pupil size etc

  . The parasympathetic branch is involved with energy conservation and digestion & is known as the 'rest and digest system
• What is the structure and function of neurons?

  * There are 100 billion neurons (nerve cells) in the human nervous system, 80% of these are located in the brain. By transmitting signals electrically and chemically, these neurons provide the nervous system with its primary means of communication.

  * There are 3 types of neuron: sensory neurons, relay neurons and motor neurons

  * Neurons typically consist of a cell body, dendrites and axon

  
  

  -Dendrites at one end of the neuron receive signals from other neurons or from sensory receptors

  -Dendrites are connected to the cell body, the control centre of the neuron which contains a nucleus which contains genetic material of the cell.

  -From the cell body, the impulse is carried along the axon in the form of an electrical signal known as action potential until it terminates at the axon terminal.

  -The axon is covered in a fatty layer of myelin sheath that protects the axon and speeds up electrical transmission of the impulse.

  -Finally at the end of the axon are terminal buttons/axon terminals that communicate with the next neuron in the chain across a gap known as the synapse.
• What is the definition of a neuron?

  The basic building blocks of the nervous system, neurons are nerve cells that process and transmit messages through electrical and chemical signals.
• What are the 3 types of neurons

  1. Sensory Neurons

  These carry messages from the PNS (peripheral nervous system) to the CNS. They have long dendrites and short axons.

  2. Relay Neurons

  These connect the sensory neurons to the motor or other relay neurons. They have short dendrites and short axons.

  3. Motor Neurons

  These connect the CNS to effectors such as muscles and glands. They have short dendrites and long axons.
• What are the 3 types of neurons in more detail

  .Sensory neurons-carry nerve impulses from sensory neurons (receptors for vision/taste/touch) to the spinal cord and brain. They are found in locations such as the eyes/ears/tongue/skin.

  -Convert info from these sensory receptors into neural impulses-when these impulses reach the brain, they are translated into sensations of, for example, visual input, heat, pain etc so that the organism can react appropriately.

  -Some sensory neurons terminate before the brain in the spinal cord-this allows reflexes to occur quickly without the delay of sending impulses to the brain.

  
  

  .Relay neurons-most neurons are neither sensory nor motor, but lie somewhere between the sensory input and the motor output.

  -Relay neurons allow sensory and motor neurons to communicate with each other. These relay neurons lie wholly within the brain and spinal cord.

  
  

  .Motor neurons-located in the CNS and project their axons outside the CNS & directly or indirectly control muscles. Motor neurons from synapses with muscles and control their contractions.

  -When stimulated they release neurotransmitters (chemicals) that bind to receptors on the muscle and trigger a response which leads to muscle movement.
• What is synaptic transmission?

  . Once an action potential has arrived at the terminal button at the end of the axon, it needs to be transferred to another neuron/tissue.

  . To achieve this, it must cross a gap between the presynaptic neuron and the postsynaptic neuron-this gap is called the synapse.

  . Signals between neurons are transmitted chemically across the synapse.

  -When the electrical impulse reaches the end of the neuron (presynaptic terminal) it triggers the release of neurotransmitters (chemicals) from tiny sacs called synaptic vesicles.
• What are neurotransmitters?


  . Neurotransmitters are chemicals that diffuse across the synapse to the next neuron in the chain.

  . Once the neurotransmitter crosses the synapse, it is taken up by the postsynaptic receptor site (the dendrites of the next neuron)

  . Here the chemical message is converted back into an electrical impulse and the process of transmission begins again in this other neuron.

  . Several dozen types of neurotransmitter have been identified in the brain, spinal cord and some glands.

  . Each neurotransmitter has its own specific molecular structure that fits perfectly into a postsynaptic receptor site (like a lock and key)

  . Each neurotransmitter also has its own specific function.
• What is excitation and inhibition?

  -Neurotransmitters have either an excitatory or inhibitory effect on the neuron

  . The neurotransmitter Serotonin causes inhibition in the receiving neuron, resulting in the neuron becoming more negatively charged and less likely to fire.

  . The neurotransmitter/hormone Adrenaline causes excitation in the post-synaptic neuron by increasing its positive charge and making it more likely to fire.
• What is summation?

  . Excitatory and inhibitory influences are summed and must reach a certain threshold in order for the action potential of the postsynaptic neuron to be triggered.

  . If the overall effect of the neurotransmitter is inhibitory then the postsynaptic neuron is less likely to fire. If the overall effect is excitatory it is more likely to fire.
• What is the definition of the endocrine system?


  One of the body's major information systems that instructs glands to release hormones directly into the bloodstream-these are carried towards target organs.
• How do glands work with the endocrine system?

  . The endocrine system works alongside the nervous system to control vital functions in the body.

  . The endocrine system acts much more slowly than the nervous system but has very widespread and powerful effects.

  . The major glands of the endocrine system include the Pituitary gland, Adrenal glands and reproductive organs (ovaries and testes)

  . The pituitary gland, located in the brain is often called the 'master gland' because it controls the release of hormones from all other endocrine glands on the body.
• How are hormones involved in these glands?

  . Each gland in the endocrine system produces different hormones (chemical messengers), which regulate the activity of organs and tissues in the body.

  . Hormones 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 entire body leading to many diverse and powerful responses. For example the thyroid gland produces the hormone thyroxin. This affects the cells in the heart (increases heart rate). It also affects cells throughout the body increasing metabolism and this in turn affects growth rates.
• What are the 2 parts of the pituitary gland?

  The anterior (front) pituitary

  The posterior (back) pituitary
• What are examples of the hormones the pituitary gland releases?

  . Anterior releases ACTH-stimulates the adrenal gland to produce cortisol. Also produces hormones in control of reproductive functioning (luteinising hormone and follicle stimulating hormone)

  . Posterior releases oxytocin-stimulates contractions of the uterus during childbirth and is important in mother-infant bonding.
• What are the 2 parts of the adrenal glands?

  . Adrenal cortex (outer part of the adrenal gland)

  . Adrenal medulla (inner part 'middle' of the adrenal gland)
• What are examples of the hormones the adrenal gland releases?

  . Adrenal cortex releases cortisol-supports cardiovascular functions etc. produced during stress. Low levels=low blood pressure and poor immune functioning. Also produces aldosterone which maintains blood volume and pressure.

  . Adrenal medulla releases adrenaline & noradrenaline for flight or fight. Adrenaline increases the heart rate and blood flow and noradrenaline constricts blood vessels.
• How is the amygdala and hypothalamus involved in the fight or flight response?


  . When you are faced with a threat, an area of the brain called the amygdala is activated. This associates sensory signals (what we see, hear, smell) with emotions associated with fight or flight, such as fear or anger.

  . The amygdala then activates the hypothalamus which functions like a command centre in the brain communicating with the rest of the body through the sympathetic branch of the nervous system.

  . The body's response to stress involves 2 major systems-1 for acute/sudden stressor such as personal attack, and a 2nd for chronic/on-going stressors such as a stressful job.
• What is the fight or flight response?

  . A sequence of activity within the body that is triggered when the body prepares itself for defending by attacking (fight) or running to safety (flight). Involves changes in the nervous system and secretion of hormones.

  . For shorter term stress (30 secs)
• What is the HPA response?


  . Describes the sequence of bodily activity in response to stress that involves the hypothalamus, pituitary gland and adrenal cortex.

  . Active during longer term stress.
• How is the fight or fight response part of the autonomic nervous system?

  . This is part of the Autonomic Nervous system response

  . Remember this has 2 branches:

  . The sympathetic branch-arouses the body ready for fight or flight.

  . The Parasympathetic branch-restores the body to a state of relaxation.

  . The 'fight or flight' response is used when we need an immediate response to a stressor.
• What is the process of the fight or flight response?

  The Hypothalamus-->Activates--->The ANS (sympathetic branch)--->Causes--->The Adrenal Medulla--->To release--->Adrenaline and Nor-Adrenaline--->Gets body ready for fight or flight--->Physiological reactions (pupils dilate, digestion stops, blood diverted)

  . Once the threat has passed the parasympathetic branch dampens down the stress response and returns the body back to normal.
• What is the process of the HPA response?

  The Hypothalamus-->Activates-->Pituitary Gland-->Causes the release of--->ACTH--->Which acts on--->Adrenal cortex--->To release---->Cortisol and Glucose--->Liver releases energy, the immune system is suppressed.

  . Cortisol gives you a quick burst of energy along with the glucose.
• What is the evaluation of the fight or flight response?

  - The 'tend and befriend response'

  . Taylor (2000) suggests that for females, behavioural responses to stress are more characterised by a pattern of tend and befriend than fight or flight.

  . This involves protecting themselves and their young through nurturing behaviours (tending) and forming protective alliances with other women (befriending)

  . Women may have a completely different system for coping with stress because their responses evolved in the context of being a primary caregiver of their children. Fleeing too readily at any sign of danger would put a female's offspring at risk.

  
  

  -Negative consequences of the fight or flight response

  . The problem for modern humans is when the stress response is repeatedly activated.

  . Although cortisol can give a burst of energy, too much cortisol suppresses the immune response, shutting down the very process that fights infection.

  . This means the stress response can actually harm the body.

  
  

  -Fight or flight does not tell the whole story

  . Gray (1988) argues that the first phase of reaction to a threat is not fight or flight but to avoid confrontation.

  . Prior to responding with attacking or running away animals display a 'freeze response'. This is a response where the animal is hyper-vigilant.

  . The advantages for humans is it makes them look for new information to make the best response for the threat.

  
  

  -Von Dawans et al (2012) challenged the view that men use fight or flight and women respond with tend and befriend. They found that acute stress can actually lead to greater cooperative and friendly behaviour, even in men. This could explain the human connection that happens during times of crises such as 9/11 terrorist attacks in New York.