BIOH111. o Cell Module o Tissue Module o Integumentary system o Skeletal system o Muscle system o Nervous system o Endocrine system

Transcription

1 BIOH111 o Cell Module o Tissue Module o Integumentary system o Skeletal system o Muscle system o Nervous system o Endocrine system Endeavour College of Natural Health endeavour.edu.au 1

2 Textbook and required/recommended readings o Principles of anatomy and physiology. Tortora et al; 14 th edition: Chapter 14 Endeavour College of Natural Health endeavour.edu.au 2

3 BIOH111 NERVOUS SYSTEM MODULE o Session 15 (Lectures 23 and 24) Organisation and histology of the nervous system o Session 16 (Lectures 25 and 26) Function of neurons: conduction of nerve impulses o Session 17 (Lectures 27 and 28) CNS: Brain anatomy and function o Session 18 (Lectures 29 and 30) Sensations and special senses o Session 19 (Lectures 31 and 32) Spinal cord anatomy and physiology o Session 20 (Lectures 33 and 34) Spinal nerves and somatic sensory and motor pathways o Session 21 (Lectures 35 and 36) Autonomic nervous system: anatomy and function Endeavour College of Natural Health endeavour.edu.au 3

4 Preparation for next session o Complete any missing concepts and linking words from Session 16 o Write down any brain parts you know and functions associated with them we will learn anatomy of the brain and cranial nerves in the next session Endeavour College of Natural Health endeavour.edu.au 4

5 BIOH111 Lectures 27 and 28 CNS: Brain anatomy and function Department of Bioscience endeavour.edu.au

6 Objectives Lectures 27 and 28: Anatomy of brain: Describe structure and functions of brain parts, including cerebrum, diencephalon, brain stem and cerebellum Describe structure and function of brain supporting system, including blood-brain barrier, cerebrospinal fluid and ventricles Describe and discuss organisation, origin and function of all cranial nerves GO TO Activity 1 in your tutorial and complete the table as you progress through the brain parts and the associated cranial nerves Endeavour College of Natural Health endeavour.edu.au 6

7 FUNCTIONS OF THE BRAIN o Overall functions in sensations, memory, emotions, decision making and behavior: 1. Center for registering sensations, correlating them with one another and with stored information 2. Center for making decisions and taking action. 3. Center for intellect, emotions, behavior and memory. 4. Directs our behavior towards others. Endeavour College of Natural Health endeavour.edu.au 7

8 NERVOUS SYSTEM DIVISIONS - revision Endeavour College of Natural Health endeavour.edu.au 8

9 OVERALL STRUCTURE OF THE BRAIN + Support systems: 1. Vascular system 2. Ventricles and cerebrospinal fluid (CSF) Endeavour College of Natural Health endeavour.edu.au 10

10 BLOOD SUPPLY TO BRAIN o Arterial blood supply is branches from circle of Willis on base of brain o Vessels on surface of brain - penetrate tissue o The brain uses 20% of our bodies oxygen & glucose needs (also see sessions 19, 20, 21 and 22 in BIOB111) blood flow to an area increases with activity in that area deprivation of O 2 for 4 min results in permanent injury o Blood-brain barrier (BBB) Endeavour College of Natural Health endeavour.edu.au 11

11 BLOOD-BRAIN BARRIER (BBB) o Structure: tight junctions seal together epithelial cells, continuous basement membrane, astrocyte processes covering capillaries o Function: protection: protects neurons from some toxins and pathogen selective barrier: proteins & antibiotics can not pass but alcohol & anesthetics do o Development of medicine against major diseases (e.g. cancer) must show BBB penetration Endeavour College of Natural Health endeavour.edu.au 12

12 PROTECTIVE COVERINGS o The brain is protected and supported by: Cranial bones Cranial meninges Cerebrospinal fluid Cranial meninges: continuous with the spinal meninges; 3 membranes: dura mater, Arachnoid and Pia mater biology-forums.com Endeavour College of Natural Health endeavour.edu.au 13

13 CEREBROSPINAL FLUID (CSF) - revision o Cerebrospinal fluid (CSF) is a clear, colorless liquid that protects the brain and spinal cord against chemical and physical injuries. o Structure: Clear liquid containing glucose, proteins, & ions; ml; produced by ependymal cells; production rate same as reabsorption rate (20 ml/hour) WHY? o Functions: 1. mechanical protection: floats brain & softens impact with bony walls 2. chemical protection: optimal ionic concentrations for action potentials 3. circulation: nutrients and waste products to and from bloodstream Endeavour College of Natural Health endeavour.edu.au 14

14 EPENDYMAL CELLS - revision synapticplasticity.wix.com o Structure: columnar cells with apical cilia o Functions: form epithelial membrane lining cerebral cavities & central canal produce cerebrospinal fluid (CSF) Endeavour College of Natural Health endeavour.edu.au 15

15 VENTRICLES o CSF filled cavities within the brain; 4 total: lateral ventricles (2): located in each hemisphere of the cerebrum; separated by the septum pellucidum third ventricle: narrow cavity along the midline superior to the hypothalamus and between the right and left halves of the thalamus fourth ventricle: between the brain stem and the cerebellum Endeavour College of Natural Health endeavour.edu.au 16

16 OVERALL STRUCTURE OF THE BRAIN + Support systems: 1. Cerebrospinal fluid (CSF) 2. Vascular system Endeavour College of Natural Health endeavour.edu.au 19

17 Cranial nerves Endeavour College of Natural Health endeavour.edu.au 20

18 THE CEREBRUM STRUCTURE o Largest part of the brain; 2 layers and 2 cranial nerves (I and II): 1. Cerebral cortex; surface layer; gray matter 2-4 mm thick and contains billions of neurons. gyri (convolutions): deep grooves called fissures + shallower sulci 2. Cerebral white matter tracts that connect parts of the brain with itself and other parts of the nervous system Endeavour College of Natural Health endeavour.edu.au 21

19 THE CEREBRUM STRUCTURE o Divided into 2 hemispheres (right and left halves): separated by the longitudinal fissure internally connected by the corpus callosum, a bundle of transverse white fibers longitudinal fissure o Each hemisphere divided in 4 lobes: separated by the fissures and sulci Frontal, parietal, occipital and temporal Insula: fifth part, hidden Endeavour College of Natural Health endeavour.edu.au 22

20 CEREBRAL WHITE MATTER Diffusion tensor imaging o Under the cortex consists of myelinated axons running in three principal directions: 1. Association fibers (tracts) connect and transmit nerve impulses between gyri in the same hemisphere. 2. Commissural fibers (tracts) connect gyri in one cerebral hemisphere to the corresponding gyri in the opposite hemisphere; corpus callosum, anterior commissure and posterior commissure 3. Projection fibers (tracts) form ascending and descending tracts; transmit impulses from the cerebrum to other parts of the brain and spinal cord Endeavour College of Natural Health endeavour.edu.au 23

21 I - Olfactory Nerve sensory nerve o Begins in cerebrum o Extends from olfactory mucosa of nasal cavity to olfactory bulb o Function: controls sense of smell Endeavour College of Natural Health endeavour.edu.au 24

22 II - Optic Nerve sensory nerve o Begins in cerebrum o Connects to retina o Function: controls vision Endeavour College of Natural Health endeavour.edu.au 25

23 STRUCTURE-FUNCTION RELATIONSHIP OF THE CEREBRUM 1. Center for registering sensations, correlating them with one another and with stored information SENSORY AREAS 2. Integrative functions such as memory, emotions, reasoning, will, judgment, personality traits, and intelligence; directing our behavior towards others - ASSOCIATION AREAS 3. Center for making decisions and taking action MOTOR AREAS Endeavour College of Natural Health endeavour.edu.au 26

24 SENSORY AREAS Endeavour College of Natural Health endeavour.edu.au 27

25 ASSOCIATION AREAS o o o o o o Somatosensory area: integrate & interpret Visual association area: recognize & evaluate Auditory association area (Wernicke s): words become speech Gnostic area: integrate all senses & respond Premotor area: learned skilled movements (e.g. typing) Frontal eye field: scanning eye movements (e.g. phone book) Endeavour College of Natural Health endeavour.edu.au 28

26 MOTOR AREAS Broca s speech area Endeavour College of Natural Health endeavour.edu.au 29

27 For interest only Hemispheric lateralisation functional asymmetry of hemispheres o Each hemisphere is not exactly alike and has functional specialisations o Some neural functions tend to be dominated by one side or the other o Lateralisation can however be unique to the individual o The science of lateralisation has been oversimplified to infer that the L) side is more analytical and the R) side is more creative o Generally language and speech processing is represented in the L) hemisphere however in L) handed people it is less lateralised Endeavour College of Natural Health endeavour.edu.au 30

28 o Structure: paired masses of gray matter in each cerebral hemisphere; 3 nuclei: globus pallidus, putamen and caudate nucleus globus pallidus+putamen= lentiform nucleus; located lateral to the thalamus lentiform nucleus+caudate nucleus=corpus striatum o Function: 1. control large automatic movements of skeletal muscles 2. help initiate and terminate some cognitive processes BASAL NUCLEI What part of a neuron constitutes grey matter? Endeavour College of Natural Health endeavour.edu.au 32

29 OVERALL STRUCTURE OF THE BRAIN Endeavour College of Natural Health endeavour.edu.au 33

30 o Structure: consists of numerous nuclei structured in 3 parts: 1. Thalamus 2. Hypothalamus 3. Epithalamus 4. Subthalamus o Surrounds 3 rd ventricle; almost completely surrounded by cerebrum DIENCEPHALON o Function: variety of sensory and motor processing between higher and lower brain centers Endeavour College of Natural Health endeavour.edu.au 34

31 THALAMUS o Structure: ~80% of diencephalon; paired oval masses of grey matter (i.e. nuclei); seven major groups of thalamic nuclei on each side o Functions: 1. serves as relay stations for all sensory impulses, except smell, to the cerebral cortex 2. registers conscious recognition of pain and temperature and some awareness of light touch and pressure 3. role in awareness and the acquisition of knowledge Endeavour College of Natural Health endeavour.edu.au 35

32 HYPOTHALAMUS o Structure: dozen or so nuclei arranged in 4 groups: mammillary, tuberal, supraoptic and preoptic o Functions: Major regulator of body homeostasis: 1. controls the ANS 2. produces hormones 3. regulates emotional and behavioral patterns 4. regulates eating and drinking 5. controls body temperature 6. regulates circadian rhythms and states of consciousness Endeavour College of Natural Health endeavour.edu.au 36

33 EPITHALAMUS o Structure: contains pineal gland and the habenular nuclei o Functions: 1. regulates circadian rhythms - pineal gland secretes melatonin 2. regulates olfaction (emotional responses to odors) (habenular nuclei) 3. Makes cerebrospinal fluid (choroid plexus) Endeavour College of Natural Health endeavour.edu.au 37

34 o Structure: tracts and the paired subthalamic nuclei SUBTHALAMUS o Function: control of body movements o Overall movement control: subthalamic nuclei + red nucleus and substantia nigra (midbrain) + basal ganglia + cerebellum + cerebrum Endeavour College of Natural Health endeavour.edu.au 38

35 CIRCUMVENTRICULAR ORGANS o Structure: part of the hypothalamus, pineal gland, pituitary gland, and a few other nearby structures; no bloodbrain barrier o Functions: 1. coordinate homeostatic activities of the endocrine and nervous systems 2. monitor chemical changes in the blood Holes in capillary walls = permeability Endeavour College of Natural Health endeavour.edu.au 39

36 OVERALL STRUCTURE OF THE BRAIN Endeavour College of Natural Health endeavour.edu.au 40

37 MIDBRAIN o Structure: 1 inch in length; both nuclei and tracts: Anterior part: Cerebral peduncles - clusters of motor & sensory tracts; Red nucleus-- rich blood supply & ironcontaining pigment Posterior part: Tectum nuclei that are part of reflex arcs; Substantia nigra Nuclei for nerves III and IV o Functions: coordinates visual and auditory reflexes; helps control subconscious muscle activity Endeavour College of Natural Health endeavour.edu.au 41

38 III = Oculomotor Nerve motor nerve o Begins in midbrain o Functions: raising of eyelids; accommodation for near vision (changing shape of lens during reading); constriction of pupil Endeavour College of Natural Health endeavour.edu.au 42

39 IV = Trochlear Nerve motor nerve o Begins in midbrain o Function: controls eye muscle Endeavour College of Natural Health endeavour.edu.au 43

40 PONS o Structure: 1 inch long; connects the spinal cord with the brain and links parts of the brain with one another using tracts; both nuclei and tracts dorsal region: white matter left/right tracts connecting cortex of 2 hemispheres Ventral region: ascending sensory and descending motor tracts; nuclei and cranial nerves V-VII (plus vestibular branch of VIII) o Function: helps control breathing Endeavour College of Natural Health endeavour.edu.au 44

41 V = Trigeminal Nerve sensory and motor nerve o Begins in pons o Functions: o Sensory portion touch, pain, & temperature receptors of the face o Motor portion muscles of mastication Endeavour College of Natural Health endeavour.edu.au 45

42 VI = Abducens Nerve motor nerve o Begins in pons o Function: controls eye muscle Endeavour College of Natural Health endeavour.edu.au 46

43 o Begins in pons VII = Facial Nerve sensory and motor nerve o Functions: o Sensory portion controls taste buds on anterior 2/3 s of tongue o Motor portion facial muscles salivary & nasal and oral mucous glands & tears Endeavour College of Natural Health endeavour.edu.au 47

44 MEDULLA OBLONGATA o Structure: continuation of spinal cord; white matter; contains all ascending sensory tracts and all descending motor tracts between spinal cord and brain Dorsal surface (anterior aspect): Pyramids - white matter protrusions; olive olivary nucleus Ventral surface (posterior aspect): Nuclei of 5 cranial nerves o Functions: 1. Cardiovascular center: force & rate of heart beat, diameter of blood vessels 2. Respiratory center: sets basic rhythm of breathing 3. Information in & out of cerebellum 4. Reflex centers for coughing, sneezing, swallowing etc. Endeavour College of Natural Health endeavour.edu.au 48

45 o Structure: Pyramids: large corticospinal tracts ; pass from cerebrum to the spinal cord Olive: nuclei that receive input from midbrain and send signal to cerebellum o Decussation of pyramids left/right structural crossover Pyramids & olive If they are tracts what part of the neuron do they contain? And if they are white, what does that mean for these pyramids? o Function: control voluntary movement of limbs and trunk (pyramids) and learning of new motor skills (olive) Endeavour College of Natural Health endeavour.edu.au 49

46 RETICULAR FORMATION o Structure: scattered nuclei in medulla, pons & midbrain o Function: o Reticular activating system alerts cerebral cortex to sensory signals (sound of alarm, flash light, smoke or intruder) to awaken from sleep maintains consciousness & helps keep you awake with stimuli from ears, eyes, skin and muscles o Motor function is involved with maintaining muscle tone psychneuro.wordpress.com Endeavour College of Natural Health endeavour.edu.au 50

47 VIII = Vestibulocochlear Nerve sensory nerve o Cochlear branch begins in medulla receptors in cochlea Function: hearing o Vestibular branch begins in pons receptors in vestibular apparatus Function: sense of balance vertigo (feeling of rotation) ataxia (lack of coordination) Endeavour College of Natural Health endeavour.edu.au 51

48 IX = Glossopharyngeal Nerve sensory & motor nerve o Begins in medulla o Receptors in mouth throat and salivary gland o Function: controls taste (sensory), tongue and pharynx (sensory & motor) Endeavour College of Natural Health endeavour.edu.au 52

49 o Begins in medulla X = Vagus Nerve sensory and motor nerve o Receptors in viscera o Function: - controls cardiac muscle and smooth muscle of the viscera - controls secretion of digestive fluids Endeavour College of Natural Health endeavour.edu.au 53

50 o Cranial portion Begins in medulla XI = Accessory Nerve motor nerve Function: controls skeletal muscles of throat & soft palate o Spinal portion Begins in cervical spinal cord Function: controls sternocleidomastoid and Trapezius muscles (swallowing) Endeavour College of Natural Health endeavour.edu.au 54

51 XII = Hypoglossal Nerve primarily motor nerve o Begins in medulla o Function: controls muscles of tongue during speech and swallowing Endeavour College of Natural Health endeavour.edu.au 55

52 Cranial nerves VIII-XII Endeavour College of Natural Health endeavour.edu.au 56

53 OVERALL STRUCTURE OF THE BRAIN Endeavour College of Natural Health endeavour.edu.au 57

54 CEREBELLUM o Structure: 2 cerebellar hemispheres and vermis (transverse fissure); hemisphere consists of: Grey matter cerebellar cortex, folia and central nuclei White matter arbor vitae o Functions: correct voluntary muscle contraction and posture based on sensory data from body about actual movements sense of equilibrium Endeavour College of Natural Health endeavour.edu.au 58

55 LIMBIC SYSTEM o Structure: limbic system is found in the cerebral hemispheres and diencephalon. Blausen.com staff. "Blausen gallery 2014". Wikiversity Journal of Medicine. DOI: /wjm/ ISSN o Function: emotional aspects of behavior and memory, and is associated with pleasure and pain. Endeavour College of Natural Health endeavour.edu.au 59

56 Recap of Session 17 Central nervous system contains brain and the spinal cord Brain is divided into different parts (e.g. cerebrum and cerebellum) Cerebrum contains important areas for receiving (sensory), interpreting (association) and actioning (motor) sensations Cranial nerves can be motor or sensory or motor and sensory and originate in different brain parts Endeavour College of Natural Health endeavour.edu.au 60

57 Preparation for next session o Complete any missing concepts and linking words from Session 17 o Review: plasma membrane and receptors neuron structure and function structural neuron classification sensory area of cerebrum Endeavour College of Natural Health endeavour.edu.au 61