1. The Central Nervous system
SBI4U AP

2. Agenda
Prep for Thursday’s Lab (3 Parts of the Brain – forebrain, midbrain, hindbrain)
Dissection Video
Individual/group work – looking up terms
Read pp
Chemical Synapse Activity

3. Components of the nervous system
Adapted from: Biology: A Human Perspective. Brock University: Pearson

4. The 3 Neurons of the nervous system
Functional Unit of the Nervous System – cells that are specialized for communication
Sensory Neurons: Located in the PNS. Provide input to CNS (Afferent Pathway)
Interneurons: Located in the CNS. Integrate input from PNS and influence the functioning of other neurons
Motor Neurons: Carry CNS output to all tissues and organs in body (Efferent Pathway)

5. Cerebral Spinal fluid (Csf) p. 1082
Filtered from Arterial Blood – Supplies CNS with nutrition and removes waste
Cushions Brain and Spinal Cord
Located in the central canal of spinal cord and ventricles of brain
Ependymal Cells – line the ventricles of the brain and the spinal canal. Cilia promote circulation of CSF
Grey Matter: neuron cell bodies, dendrites and unmyelinated axons
White Matter: Myelinated axons

6. Protecting the Brain Housed within the skull and surrounded by CSF
Brain is surrounded by Meninges (Dura Mater, Arachnoid, Pia Mater)
Hydrocephalus: increased accumulation of CSF can lead to pressure on the brain

7. Adult Brain
Forebrain
Midbrain
Hindbrain

8. Forebrain
Consists of:
Cerebrum
Hypothalamus
Thalamus

9. 1. Cerebrum (aka cortex)
Largest part of human brain – Divided into Two Hemispheres that are connected by the Corpus Callosum (myelinated axon fibers)
Coordinates language
Controls decision making
Produces conscious thought
Cerebrum is wrinkled to allow increased grey matter

10. Brain Lateralization
Left Hemisphere: Broca’s (frontal lobe – trouble speaking fluently) and Wernicke’s area (temporal lobe – trouble comprehending speech) reside in left cortical hemisphere (Language, Math and Logic)
Right Hemisphere: spatial relation, nonverbal thinking, face and pattern recognition

11. Phineas Gage p. 1092

12. The 4 Lobes of the Cerebrum

13. Look Up Primary Motor and Primary Sensory Cortex
Broca’s and Wernicke’s area
Try this website:

14. 2. Hypothalamus Located at the Base of the Forebrain
Links nervous system to endocrine system via interactions with the pituitary gland
Water and solute balance, temperature control, hunger center and thirst center
Suprachiasmatic nucleus (SCN)

15. 3. Thalamus Located superior (above) hypothalamus
Receiving, processing and transfer center
Example – pain, pressure and temperature changes - cannot identify where it originates from until information is relayed to cerebrum

16. Midbrain
Coordinates movements of head related to vision and hearing (e.g. turning toward sudden sound or flashing light)

17. HindBrain
Posterior (behind) to midbrain. Joins with spinal cord. Oldest, most primitive brain division
One of the most similar among animals
Consists of:
Medulla Oblongata
Pons
Cerebellum
Collectively known as the “brain stem”

18. Medulla Oblongata Connects to spinal cord
Vital automatic functions of internal organs
Respiratory center(Oxygen and carbon dioxide levels) and Cardiovascular center (heart rate and blood pressure)
Reflexes such as coughing and sneezing
All signals passing from brain stem to higher areas of the brain pass through medulla (Look up crossover)

19. Pons Latin for “bridge”
Just superior (above) and partially surrounding medulla
Connects cerebellum to higher brain centers
Aids medulla in regulating respiration

20. Cerebellum Posterior to medulla oblongata
2 hemispheres with highly folded surface like cerebrum
Coordinates basic body movements that are below the level of conscious control (e.g. ensures antagonistic muscles do not contract at the same time)
Coordinates skilled movements (e.g. shifting a car)
Receives signals from joint and muscle receptors; balance and position receptors

21. Look Up
Lateral and Longitudinal Fissures
Central Sulcus

22. Structure of a neuron

23. Neuron Structure
Cell Body: nucleus and DNA, mitochondria and other organelles
Dendrites: extensions from cell body. Receive information from receptors or other neurons
Axon: specialized to conduct electrical impulses. Originate from dendrite in sensory neuron and axon hillock in interneurons and motor neurons. Axons branch into slender extensions known as Axon Terminals. Each axon terminal has a rounded tip known as an axon bulb

24. Glia in the vertebrate Nervous system (Fig 49.3, p. 1081)

25. Glia con’t
Ependymal Cells – line the ventricles of the brain. Cilia promote circulation of CSF
Astrocytes – Located in CNS. Facilitate information transfer at Synapses. Regulate nutrition (oxygen and glucose) for neurons by regulating nearby blood vessels. In addition, astrocytes regulate extracellular concentrations of ions and neurotransmitters
Oligodendrocytes: myelinate axons in CNS
Microglia: immune cells in CNS
Schwann cells: myelinate axons in PNS

26. Synapse: How Neurons “Talk” to Each Other

27. Readings
Read 49.3, pp – 1093
Read 48.1 and 48.2, pp –1066