SS3 FIRST TERM SCHEME OF WORK. BIOLOGY WK1: Nervous co-ordination WK2: Regulation of internal environment. WK3: Sense organs WK4: Reproductive systems in animals WK5:Reproductive systems in plants WK6:Reproductive behaviours WK7: Development of new organisms WK8:Fruits WK9:Variation in population WK10:Adaptation for survival. NERVOUS CO-ORDINATION. Introduction: -Nervous co-ordination is the transfer of messages round the body of an organism by means of nerves. -Nervous system is made up of nerve cells or neurones. -It transmit the impulses to the other specialised cells Called effectors,which are capable of producing an appropriate response. COMPONENTS AND ORGANISATION OF NERVOUS. -It is made up of two main parts: a. The central nervous system (CNS) b. The peripheral nervous system (PNS) - The central nervous system analyses information and initiate responses - The peripheral nervous system gathers information and carries the response signal. - Some responses are involuntary, others are voluntary. THE CENTRAL NERVOUS SYSTEM - The central nervous system consists of: a. Spinal cord b. Brain enclosed in the skull. -The brain integrates information from many internal and external sense organs, stores information and acts as the main command centre, sending instruction through the spinal cord to muscles and organs throughout the body. -The spinal cord acts as a relay centre between the brain, peripheral sense -The brain integrates information from many internal and external sense organs, stores information and acts as the main command centre, sending instruction through the spinal cord to muscles and organs throughout the body. -The spinal cord acts as a relay centre between the brain, peripheral sense organs and the peripheral effectors. SPINAL CORD -The spinal cord is a long tubular structure which extends from the medulla oblongata to the tail region. -It is protected by the vertebral column. -Contains inner grey matter and outer white matter. -Has nerves along which impulses travel to and from the brain. -All the cell bodies in the spinal cord are found in the ganglia. -It is the seat of reflex actions. -The centre of the spinal cord is made up of a small canal(spinal canal). The canal contains cerebrospinal fluid. FUNCTIONS OF THE SPINAL CORD -The centre of reflex action, e.g sneezing, jerking of the knee, blinking of the eyes. -Transmit impulses to and from the brain. THE MAMMALIAN BRAIN The three main regions of the brain are: -The fore brain: consists of the Cerebrum and the olfactory lobe. -The mid brain: consists of the optic lobes,. The thalami and the hypothalamus are situated there. -The hind brain: consists of the cerebellum and the medulla oblongata. CEREBRUM This is of two halves: -The right cerebral hemisphere. -The left cerebral hemisphere. The two halves are connected by a band of fibres called the corpus callosum which keeps each of hemisphere informed of the others activities. -There are four distinct lobes of a cerebral hemisphere: a. Frontal. b. b. Parietal. c. c. Temporal. d. d. Occipital. Cerebral cortex is the most active region of the cerebrum. It is located on its outer layer and composed of grey matter. THALAMI -These are two ovoid structures attachedto the back of the fore brain. -They receive sensory information from various parts of the nervous system, integrating it and pasing itunto the relevant regions of the cerebral cortex. HYPOTHALAMUS -This is located below the brain. -It is the coordinating and control centre for the autonomic nervous system. -It plays an important role in homeostasis. CEREBELLUM Has three parts. -A central part -Two lateral cerebellar hemispheres. The two lateral cerebellar hemispheres are connected by a broad band of fibres called Pons varolii. MEDULLA OBLONGATA It is the posterior end of the brain that continues with the spinal cord. ASSIGNMENT: -State the functions of the parts of the brain. -Make a well labeled drawing of the cross section of the following: a. spinal cord. b. Human brain. c.Ventral view of the Brain of rabbit.