Biopsychology

• Peripheral Nervous System (PNS)


  • Transmits messages throughout the body from the brain and relays messages back to the brain
  • Divided into the Somatic System and the Autonomic System
• The sympathetic and parasympathetic systems are important when studying hormones, the endocrine system, and stress
• Sympathetic System

  Increases activity
• Central Nervous System (CNS)


  • Made up of the brain and the spinal cord
  • Functions include language, coordinating movement, coding sensory data, problem-solving, planning, and regulating body functions
• Autonomic System


  • Transmits and receives information from the organs
  • Divided into the Sympathetic System and the Parasympathetic System
• The sympathetic and parasympathetic systems can be compared to the accelerator or brake in a car
• Parasympathetic System


  Helps to conserve the body's activity levels and energy by decreasing or maintaining activity
• The nervous system is divided into two parts: The Central Nervous System (CNS) and The Peripheral Nervous System (PNS)
• Somatic System


  • Transmits and receives messages from the senses, directs muscles to move appropriately
• Worked example

  Ross receives a signal from the skin in his hand that he can sense he is about to touch a really hot plate, he is likely to respond to avoid burning himself
• Neurons are cells within the nervous system
• Neurons are essential for everyday survival as they send messages around the body to sense organs, glands, and organs, and relay information back to the central nervous system
• Sensory neurons

  • Send information to the brain regarding the senses, also known as afferent neurons as they carry information from the Peripheral Nervous System (PNS) towards the Central Nervous System (CNS), keep the brain informed about the external and internal environment via processing information coming from the eyes, ears, nose, skin, and tongue, can only transmit messages, have long dendrites and relatively short axons, and the cell body is usually to the side of the cell
• Relay neurons


  • Also known as Interneurons as they can take on the role of sensory and motor neurons in the nervous system, connect the sensory neurons to the motor neurons, based in the CNS and carry signals/messages across this part of the nervous system, can both transmit and receive messages, have short axons and short dendrites
• Ross is about to touch a really hot plate

  Using the peripheral nervous system, Ross is likely to respond to avoid burning himself by receiving a signal from the skin in his hand that senses heat, sending this signal via the PNS to the CNS, and then the PNS sending a signal to the muscles in his hand to move away quickly, resulting in the muscles withdrawing from the plate
• It is believed that there are about as many neurons in the brain as there are stars in our galaxy
• All types of neurons

  • Have dendrites, cell bodies, and an axon
• There are thought to be as many as 100 billion neurons in the brain and over 1 billion in the spinal cord
• Types of neurons

  • Sensory
  • Motor
  • Relay
• Motor neurons


  • Carry signals from the Central Nervous System (CNS) toward the organs, muscles, and glands in the body, known as efferent neurons as they carry information away from the CNS toward the PNS, can both transmit and receive messages, have short dendrites and relatively long axons, and if connected to muscle, then it is known as a motor end plate
• The junction where two neurons meet is known as a synapse
• Components of a synapse


  • Presynaptic knob
  • Synaptic cleft
  • Postsynaptic membrane
• Transmission at a synapse

  1. Electrical impulses cannot ‘jump’ across synapses

  2. 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

  3. Neurotransmitters diffuse across the synaptic cleft and temporarily bind with receptor molecules on the postsynaptic membrane

  4. This stimulates the postsynaptic neuron to generate an electrical impulse that then travels down the axon of the postsynaptic neuron

  5. The neurotransmitters are then destroyed or recycled to prevent continued stimulation of the second neuron, which could cause repeated impulses to be sent
• The relay neuron typically resembles a blob shape and is often the one most correctly identified by candidates in the exam
• Synapses that use acetylcholine (ACh) as a neurotransmitter are described as cholinergic synapses
• Compared to the nervous system, the effects of hormones are slower but they act for longer
• The pituitary gland in the brain is a ‘master gland’ which secretes several hormones into the blood in response to body conditions
• Characteristics of hormones

  • They 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
• Pituitary gland makes and secretes thyroid-stimulating hormone (TSH)


  Stimulates the thyroid to release thyroxine
• The human endocrine system is composed of glands that secrete chemicals called hormones directly into the bloodstream
• Important structures in the endocrine system

  • Pituitary gland: a ‘master gland’ making hormones such as FSH and LH
  • Pancreas: produces insulin which regulates the blood glucose level
  • 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 is controlled by the hypothalamus


  • The anterior lobe releases adrenocortical trophic hormone (ACTH), which stimulates the adrenal cortex and the release of cortisol
  • The posterior lobe releases oxytocin, which is responsible for uterus contractions during childbirth. Oxytocin helps regulate our emotional responses and pro-social behaviors
• The major endocrine glands in the body secrete hormones which circulate around the body in the bloodstream
• Hormones are synthesized and released into the bloodstream from a gland (such as the pituitary gland) and circulate in the bloodstream, having an effect on target cells
• The blood carries the hormone around the body, and when it reaches a target cell/organ it produces an effect
• Pineal Gland


  • Releases melatonin responsible for important biological rhythms, including the sleep-wake cycle
  • Receives information from the environment about the light-dark cycle which influences the production and secretion of melatonin
• Andrenal Gland

  • Divided into two parts, the adrenal medulla and adrenal cortex
  • Adrenal medulla releases adrenaline and noradrenaline which play a key role in 'fight or flight' response
  • Adrenal cortex releases cortisol which stimulates the release of glucose while suppressing the immune system
• Describe the function of the endocrine system, using at least two examples of glands and hormones
• Questions about glands and hormones will tend to ask for identification of the gland, along with a description or outline of the hormone it produces
• is controlled by the hypothalamus

  The anterior lobe releases an adrenocortical trophic hormone (ACTH), which stimulates the adrenal cortex and the release of cortisol