Unit 3 – Area of Study 1 Mind, brain and body Pages 132-176 and 271-283

1. Chapter 4: The Central Nervous System and Chapter 5: The Peripheral Nervous SystemPart 1 – structure and function of the CNS & PNS Unit 3 – Area of Study 1 Mind, brain and body Pages 132-176 and 271-283

2. Study Design Content • the interaction between cognitive processes of the brain and its structure including: – roles of the central nervous system, peripheral nervous system (somatic and autonomic), and autonomic nervous system (sympathetic and parasympathetic) – roles of the four lobes of the cerebral cortex in the control of motor, somatosensory, visual and auditory processing in humans; primary cortex and association areas – hemispheric specialisation: the cognitive and behavioural functions of the right and left hemispheres of the cerebral cortex, non-verbal versus verbal and analytical functions – the role of the reticular activating system in selective attention and wakefulness; role of the thalamus in directing attention and switching sensory input on and off

3. The Nervous System • The human nervous system is a complex combination of neurons that enables the brain to obtain information about what is going on inside the body and to respond accordingly • Our nervous system can be organised into divisions or branches • The central nervous system (CNS) comprises the brain and spinal cord, the spinal cord connects the brain and the peripheral nervous system • The peripheral nervous system (PNS) includes all the parts of the nervous system which lie outside the CNS

4. The Nervous System

5. The Central Nervous System • The central nervous system (CNS) is one of the two major branches of the human nervous system. • The CNS is comprised of the brain and spinal cord. • The spinal cord connects the brain to the second major branch – the peripheral nervous system (PNS).

6. The Spinal Cord • The spinal cord is the cable-like column of nerves that extends from the bas of the brain to the lower back • Its major role is to receive sensory information from the body and transmit it to the brain, and receive information from the brain and relay it to the body to control muscles, glands and organs • The spinal cord consists of two major components, white matter and grey matter

7. The Spinal Cord • White matter is made up solely of axons which run the length of the spinal cord • An axon is the part of a neuron that sends information away from the soma (cell body) to other neurons or to cells in muscles or glands • Axons are covered in a white protective coating known as myelin and are located mainly in the other layers of the spinal cord • The grey matter contains cell bodies, together with their axons and dendrites, and is mainly located in the centre of the spinal cord • Dendrites are thin extensions of a neuron that receive information from other neurons and transmit it to the cell body

8. Neurons • Neurons are cells that are specialised to receive, process and/or transmit information to other cells within the body • Neurons can be broadly categorised into 3 categories depending on the primary function they perform

9. Sensory Neurons • Sensory Neurons are nerve cells that carry messages from sensory organs and receptors through nerves in the PNS, up the tracts in the spinal cord and to the brain. • Sensory neurons generally respond only to a particular type of stimulus. • Pressure Receptors – touch, pressure, pain • Temperature Receptors – hot and cold • Pain Receptors – linked to pressure & temp receptors • Taste Receptors • Smell Receptors • Sensory neurons are also known as afferent neurons because they transmit sensory information along afferent tracts in the CNS

10. Sensory Neurons

11. Motor Neurons • Motor Neurons are nerve cells that carry messages away from the brain and spinal cord towards muscles, glands and organs that enable bodily movements or glandular secretions. • Motor neurons are also known as efferent neurons as they transmit motor activity along the afferent tracts of the spinal cord • The main distinction between motor neurons and sensory neurons is the direction of the nerve impulses and what occurs at their respective destinations.

12. Motor Neurons

13. Sensory and Motor Neurons • To remember use the acronym SAME • S – Sensory • A – Afferent • M – Motor • E – Efferent • So sensory/afferent neurons carry information from sensory receptors in the PNS towards the CNS while motor/efferent neurons carry information away from the CNS to the muscles and glands • Manual Activity 8 – Building blocks of the nervous system: Learning the structure of elements of the nervous system and how they function, pg. 16

14. Interneurons • Interneurons perform the important function of making the connection between motor and sensory neurons. • Interneurons relay messages from one group of neurons to another group of neurons. • They exist only in the CNS (brain & spinal cord). • Interneurons have a single axon leaving the cell body and a single dendrite coming into the cell body from a receptor cell. • Interneurons play an important role in reflexes • Learning Activity 4.13 – Review questions, pg. 213

15. The Peripheral Nervous System • The Peripheral Nervous System (PNS) is the complete network of neurons located outside the CNS. • The PNS extends from the top of the head to the rest of the body. • The PNS has two main functions: • To carry information from the sensory organs to the CNS. • To convey information from the CNS to the muscles, organs and glands. (up to here)

16. The Peripheral Nervous System • The PNS can be subdivided into two quite distinct nervous systems, each of which have different functions: • The Somatic Nervous System • The Autonomic Nervous System

17. The Somatic Nervous System • The Somatic Nervous System has both a sensory function and a motor function. • The Somatic Nervous System, also called the Skeletal Nervous System, is the network of neurons that transmits messages from the sensory receptors to the CNS and controls voluntary movement of skeletal muscles through messages sent from the CNS.

18. The Somatic Nervous System • Therefore the Somatic Nervous System allows you to – • Feel any sensations from your external environment. • Make any voluntary movements or actions to respond to your external environment. • Paraplegics and Quadriplegics have had their spinal cord severed at a certain point allowing no neural information to pass through the somatic nervous system below the severed cord. • Learning Activity 5.1– Review questions, pg. 273

19. The Autonomic Nervous System • The Autonomic Nervous System (ANS) is a network of neurons that connects the CNS to all the body’s internal muscles, organs and glands. • When you are suddenly frightened – your heart rate and breathing rate increases, your pupils dilate and goosebumbs appear. The Autonomic Nervous System is responsible for all of these events occurring.

20. The Autonomic Nervous System • The term autonomic means automatic, independentorself governing. • Regardless of our awareness or alertness, the ANS keeps the vital organs and systems of our body functioning, thus maintaining our survival. • This occurs automatically without our conscious control.

21. The Autonomic Nervous System • The ANS modulates (modifies or changes) the activity of visceral muscles, organs and glands. • The ANS receives constant neural activity from the CNS by either increasing or decreasing messages to bring about changes in the body. • While most of the actions controlled by the ANS are not within our control, there are a few responses of the ANS that we can voluntarily control – blinking, heart rate and breathing rate.

22. The Autonomic Nervous System • In India, it has been reported that Yogis (Hindu holy men) can change their heart rate from 75 bpm, to 300 bpm or 50 bpm. • People who aren’t Yogis can also learn to control various autonomic responses using a technique called Biofeedback Training. • Box 5.1 – Keeping the body alive pg. 275 • Learning Activity 5.3– Review questions, pg. 275 • Learning Activity 5.4– Distinguishing between the SNS and the ANS, pg. 276

23. Divisions of the ANS • Most muscles, organs and glands receive messages from two sets of neurons from two distinct divisions of the ANS. • The Sympathetic division is responsible for increasing the activity of muscles, glands and organs in times of vigorous activity, stress or threat. • The Parasympathetic branch is responsible for decreasing the activity of muscles, glands and organs and keeping the body functioning at a normal rate.

24. Divisions of the ANS • When you play a game or sport, the sympathetic nervous system speeds up your heart rate, increases metabolism and induces sweating in order for you to perform to your maximum. • When you stop playing, the parasympathetic nervous system slows your heart and breathing rate, to help the body return to its normal state. • While the sympathetic and parasympathetic nervous systems are both active at the same time, one system usually predominates over the other at any given time.

25. The Sympathetic Nervous System • The sympathetic nervous system originates in the spinal cord, and enhances survival by providing an immediate response, in a split second, to any kind of emergency. • In an emergency situation, the sympathetic nervous system sends a message to the adrenal glands to secrete the hormones adrenalin and noradrenalin. • These hormones are released into the bloodstream and activate muscles organs and glands for preparation of the potential emergency.

26. The Sympathetic Nervous System • The results of these hormones include: • Increased heart rate and blood pressure, • Increased breathing rate, • Increased pupil size, • Increased sweat production, • Decreased digestion, • Heightened senses (ie: goosebumps, see p136)

27. The Parasympathetic Nervous System • The parasympathetic nervous system has the effect of counterbalancing the activities of the sympathetic nervous system. • The parasympathetic nervous system has three main functions: • It keeps the systems of the body functioning efficiently. • It helps maintain a constant internal environment. • It restores the body to a state of calm after vigorous or strenuous activity.

28. The autonomic nervous system

29. The Autonomic Nervous System • Learning Activity 5.5– Review questions, pg. 279 • Learning Activity 5.6– Sympathetic VS Parasympathetic, pg. 279 • Learning Activity 5.7– Summarising the Activities of the Sympathetic and Parasympathetic Nervous Systems, pg. 280 (handout) • Manual Activity 7 – Fight or flight! – Learning the physiological systems involved in arousal through the use of diagrams • Chapter 5 Test, pg. 282-285

30. The Brain • The human brain is encased in a hard protective skull and weighs about 1.5kg. • It has the consistency of firm jelly and is covered by a strong plastic like membrane. • The brain contains over one billion neurons and over one trillion synaptic connections.

31. The Brain • Neuropsychologists often describe the brain as having three main regions: • The Hindbrain, • The Midbrain, • The Forebrain

32. The Cerebral Cortex • The cerebral cortex is one of the most easily recognised parts of the brain • It is recognisable as the folded outer layer or covering of the cerebral hemispheres of the brain • The cerebral cortex is largely involved with: • information-processing activities, • language, • speech, • learning, • memory, • thinking, • problem solving • the control of sensory and motor abilities.

33. The Cerebral Cortex • It is believed that the size of a species’ cerebral cortex is linked to intellectual ability.

34. The Cerebral Cortex • In terms of function, the cerebral cortex has three main parts: • The various sensory areas (which receives information about vision, smell and sound) • The motor cortex (which transmits information about bodily movements) • The association cortex (which integrates sensory and motor information) • Learning Activity 4.1 – Review questions pg. 180

35. Cerebral Hemispheres • The cerebral cortex is described as having two halves. • The cerebral hemispheres are two almost symmetrical brain structures that appear to be separated by a deep groove (known as the longitudinal fissure). • These hemispheres appear to be separated completely, but they are joined in the midbrain by a structure called the corpus callosum.

36. Cerebral Hemispheres

37. Cerebral Hemispheres • The cerebral hemispheres is described as having inverted functions. • This means that sensory and motor information in the right side of the body is controlled by the left cerebral hemisphere. • Sensory and motor information in the left side of the body is controlled by the right cerebral hemisphere.

38. Corpus Callosum • The corpus callosum is a strand, or ‘bridge’, of nerve tissue that connects the left and right cerebral hemispheres and serves as the main communication pathway between them. • Its function is one of a ‘cross-over’ station for neural messages between the two cerebral hemispheres.

39. Learning Activity 2 – Review questions pg. 182 Corpus Callosum

40. Four Lobes of the Cerebral Cortex • The cerebral cortex covering each hemisphere can be divided into four anatomical regions. • These cortical lobes are called: • The frontal lobes • The parietal lobes • The occipital lobes • The temporal lobes

41. Four Lobes of the Cerebral Cortex

42. Four Lobes of the Cerebral Cortex • Each cortical lobe has areas that specialise in receiving and processing sensory or motor information. • There are also association areas that integrate sensory, motor and other information for complex mental processes.

43. Four Lobes of the Cerebral Cortex

44. The Frontal Lobe

45. The Frontal Lobe • The frontal lobe is the largest of all lobes and occupies the front half of the brain. • The primary motor cortex is located at the rear of the frontal lobes. The PMC controls voluntary movements. • Stimulation in the left hemisphere of the PMC will trigger movements of body parts in the right side of the body and vice versa.

46. The Primary Motor Cortex

47. The Primary Motor Cortex • Figure 4.12– The primary motor cortex, pg. 185 • The primary motor cortex is mapped so that a specific area of the cortex controls a specific part of parts of the body • The amount of area in the cortex devoted to a specific part demonstrates the amount of finesse or control given to movement in that part of the body • Areas with great precision such as fingers are allocated a much greater cortex area than parts which have less control such as toes • Learning Activity 4.3 – Mapping the primary motor cortices, pg. 185 • Learning Activity 4.4 – Applying your knowledge of the primary motor cortex, pg. 185

48. The Frontal Lobe • In the forward section of the frontal lobes is the association area responsible for higher mental functions such as judging, planning and initiative. • The frontal lobes are also involved with expression of characteristics such as personality and emotional behviour. • Possibly the best case to support this, is that of the case of Phineas Gage. • Box 4.1 – Case study: damage to the frontal lobes of Phineas Gage

49. Broca’s Area • Broca’s area is located in the frontal lobe of the left hemisphere and is thought to be responsible for articulate speech. • In particular, Broca’s area is involved with the movement of the muscles required to speak (ie coordination of lips, jaw, tongue and vocal cords). • Broca’s area is also concerned with the meaning of words, the structure of sentences and specific parts of speech.

50. Broca’s Area