Psychology- (Biopsychology)

• The nervous system is divided into two parts;

  The Central Nervous System (CNS)

  The Peripheral Nervous System (PNS)

  These systems are clearly connected and work together so the whole system functions effectively.
• The CNS is made up of the brain and the spinal cord.
• The brain is central to maintaining life and has many functions including:

  Basic functions such as regulating body temperature, heart rate and breathing

  Language (production and understanding)

  Co-ordinating movement

  Coding sensory data from the sensory organs

  Problem-solving and planning
• The Spinal Cord ensures that signals from the brain are transmitted to the rest of the body via the PNS.
• The PNS transmits messages throughout the whole body from the brain and also relays messages back to the brain
• The PNS is divided into two sections:

  The Somatic Nervous System

  The Autonomic Nervous System
• The Somatic Nervous System transmits and receives messages from the senses:

  An example of this would be visual information from the eyes or touch information from the skin

  It then directs the muscles to move appropriately

  For example: If your eyes are registering that there is a car coming toward you, the Somatic System would be telling your muscles to move and to get you out of the way.
• The Autonomic Nervous System transmits and receives information from the organs
• The ANS is divided into two further sections:

  The Sympathetic Nervous System

  The Parasympathetic Nervous System
• The Sympathetic System is associated with the 'fight or flight' response:

  • It prepares the body for physical activity e.g. running away or fighting.
  • It is utilised when the body is in an 'alert' state e.g. when crossing the road.
  • It can accelerate heart rate, widen bronchial passages for increased breathing capacity (needed when running), decrease activity of the large intestine (no time for the toilet when you're in danger!), constrict blood vessels, cause pupil dilation, activate goose bumps, start sweating and raise blood pressure.
• The Parasympathetic System is popularly known as the 'rest and digest' system:

  • It helps to conserve the body's activity levels and energy by decreasing activity to be used later
  • It regulates bodily functions like digestion and urination
  • It slows heart and breathing rates, lowers blood pressure as the body enters a state of relaxation
  • Relaxation enables the body to go into 'standby' (recovery mode): the more time spent in a PNS state, the healthier a person will be
• Think about the sympathetic and parasympathetic systems as being like the accelerator and brake in a car (SNS = accelerator; PNS = brake).
• Ross is cooking himself a meal and he is about to touch a really hot plate as he is serving up

  Using the peripheral nervous system, outline how Ross is likely to respond to avoid burning himself

  (4 marks)

  • Ross receives a signal from the skin in his hand that he can sense heat (the skin is the sense organ)
  • This signal is sent from the senses via the PNS and then to the CNS
  • The PNS sends a signal to the muscles in his hand i.e. 'Remove your hand from this plate now!'
  • The muscles in his hand go into action and Ross takes his hand off the hot plate.
• • Neurons are cells within the nervous system
• Neurons send messages around the body to our sense organs, glands and organs and then relay information back from these to the central nervous system
• There are three main types of neuron, each with its own distinct function:

  Sensory

  Motor

  Relay
• All 3 types of neuron have dendrites, cell bodies and an axon
• Sensory Neurons:

  • These are cells that send information to the brain regarding the senses; these are also known as afferent neurons as they carry information from the Peripheral Nervous System (PNS) towards the Central Nervous System (CNS)
  • They keep the brain informed about the external and internal environment via processing information coming from the eyes, ears, nose, skin and tongue
  • They can only transmit messages i.e. like a one-way street
  • They have long dendrites and, relatively, short axons
  • The cell body is usually to the side of the cell
• Motor Neurons:

  These carry signals from the Central Nervous System (CNS) toward the organs, muscles and glands in the body

  In this respect, they are efferent neurons as they carry information away from the CNS toward the PNS

  As they can both transmit and receive messages i.e. like a two-way street

  They have short dendrites and, relatively long axons

  If it is connected to muscle, then it is known as a motor end plate
• Relay Neurons:

  These are also known as Interneurons as they can take on the role of sensory and motor neurons in the nervous system

  They connect the sensory neurons to the motor neurons

  They are based in the CNS and carry signals/messages across this part of the nervous system

  As they can both transmit and receive messages i.e. like a two-way street

  Characteristically, they have short axons and short dendrites
• A nerve is a bundle of neurons
• Neurone

  
• Match the type of neuron to the statement below:

  a)Motor Neuron

  b) Sensory neuron

  c) Relay Neuron

  1)Sends messages to the brain regarding information coming from the eyes and ears

  2) Can communicate with other types of neurons

  3) Has the longest dendrites

  4) Can connect to a muscles or gland

  5) Is only found in the Central Nervous System

  1) b

  2) c

  3) b

  4) a

  5) c
• The junction where two neurons meet is known as a synapse
• A synapse consists of a presynaptic knob, synaptic cleft and postsynaptic membrane
• Synapses that use acetylcholine (ACh) as a neurotransmitter are described as cholinergic synapses
• A neurotransmitter is a chemical which is secreted by a neuron within the nervous system to stimulate a target cell.
• Transmission at a synapse

  1. Electrical impulse arrives at presynaptic neuron

  2. Neurotransmitters released from vesicles

  3. Neurotransmitters diffuse across synaptic cleft

  4. Neurotransmitters bind with receptor molecules

  5. Postsynaptic neuron generates electrical impulse

  6. Impulse travels down axon of postsynaptic neuron

  7. Neurotransmitters destroyed or recycled
• When an electrical impulse arrives at the end of the axon on the presynaptic neuron, chemical messengers called neurotransmitters are released from vesicles at the presynaptic membrane
• The neurotransmitters diffuse across the synaptic cleft and temporarily bind with receptor molecules on the postsynaptic membrane
• This stimulates the postsynaptic neuron to generate an electrical impulse that then travels down the axon of the postsynaptic neuron
• The neurotransmitters are then destroyed or recycled to prevent continued stimulation of the second neuron, which could cause repeated impulses to be sent
• The human endocrine system is composed of glands that secrete chemicals called hormones directly into the bloodstream.
• The blood carries the hormone around the body, and when it reaches a target cell/organ it produces an effect.
• Compared to the nervous system the effects of hormones are slower but they act for longer.
• Important structures in the endocrine system are:

  Pituitary gland: the ‘master gland’ making hormones e.g. Follicle Stimulating Hormone

  The pancreas: produces insulin which regulates the blood glucose level

  The thyroid: produces thyroxine which controls the metabolic rate and affects growth

  Adrenal glands: produces adrenaline

  Ovaries (females): produce estrogen

  Testes (males): produce testosterone
• The pituitary gland in the brain is a ‘master gland’ which secretes several hormones into the blood in response to body conditions.

  These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects.
• Endocrine glands synthesise substances such as hormones and release them into the bloodstream.
• Hormones are chemical substances that circulate in the bloodstream and only affect target organs.

  They are produced in large quantities and can be very powerful

  They control ongoing internal functions and enable our bodies to react according to changes in the environment.
• • The pituitary gland is often referred to as the ‘master gland’ because it controls the production and release of other hormones from other glands in the endocrine system.
  • It is controlled by the hypothalamus.
  • The anterior lobe releases an adrenocortical trophic hormone (ACTH), which stimulates the adrenal cortex and the release of cortisol
  • The posterior lobe released oxytocin, which is responsible for uterus contractions during childbirth.
  • Oxytocin helps regulate our emotional responses and pro-social behaviours, including trust, empathy, and the processing of bonding cues.