Nervous System CNS the Brain PDF

Nervous System CNS Continued THE BRAIN  The Human Brain The Human brain is ~3 lbs. of tissue All brain functions (emotions, logic, reasoning, planning, etc.) occur within the 100 billion neurons and 10 trillion neuroglia that comprise the human brain The Brain The b...

Nervous System CNS Continued THE BRAIN  The Human Brain The Human brain is ~3 lbs. of tissue All brain functions (emotions, logic, reasoning, planning, etc.) occur within the 100 billion neurons and 10 trillion neuroglia that comprise the human brain The Brain The brain and spinal cord are both protected by connective tissue membranes called meninges, the blood brain barrier (astrocytes) and cerebrospinal fluid (CSF) The Brain – Meninges 3 layers of the meninges -- from superficial to deep: Dura mater, arachnoid mater, and pia mater. Functions of the Meninges i. Cover and protect the CNS ii. Protect blood vessels and enclose the venous sinuses iii. Contain cerebrospinal fluid iv. Form partitions in the skull The Brain – Meninges Meningitis is an inflammation of the meninges and is a serious threat to the brain since bacterial or viral meningitis can spread to the CNS. When the brain itself is inflamed it is called encephalitis. Meningitis is usually diagnosed by examining the CSF obtained via a lumbar puncture for microbes or viruses. The Brain – Meninges Cerebrospinal fluid CSF is a clear, colorless liquid that carries oxygen, glucose, and other chemicals to neurons and neuroglia and removes their wastes and toxic substances. Ependymal cells found in the choroid plexuses of each ventricle of the brain produces CSF. CSF circulates through the subarachnoid space around the brain and spinal cord.  Ventricles Produced CSF Openings connect the four ventricles (cavities) together Flowing from the 4th ventricle, CSF flows into the central canal of the spinal cord and into the subarachnoid space around the surface of the brain and spinal cord. Normal CSF volume = 80 to 150 ml (3 to 5 oz) 4 Main Parts of the Brain 1. Diencephalon – thalamus, hypothalamus, pineal gland 2. Brain stem – medulla oblongata, pons, midbrain 3. Cerebellum 4. Cerebrum – cerebral cortex (superficial gray matter) i. Frontal lobe ii. Temporal lobes iii. Parietal lobes iv. Occipital lobe v. Insula ***The limbic system consists of structures in many different regions Part of Brain Location Features Role Diencephalon 1. Thalamus 2. Hypothalmus 3. Pineal Brain stem midbrain The Brain  The Brain – Diencephalon The thalamus “RELAY STATION” serve as synaptic relay stations for peripheral sensory signals before being distributed to other regions of the brain and important integrating centres for most inputs to the cortex, and plays a key role general arousal. Fine tune body movements (with cerebellum) The thalamus is also involved in focusing attention. For example, it is responsible for filtering out extraneous sensory information. The Brain – Diencephalon The hypothalamus is and endocrine gland nd lies below the thalamus and is on the undersurface of the brain, and it contains different cell groups and pathways that form the master command centre for neural and endocrine coordination. Behaviors having to do with preservation of the individual (for example, eating and drinking) and preservation of the species (reproduction) are among the many functions of the hypothalamus. The hypothalamus lies directly above and is connected by a stalk to the pituitary gland, an important endocrine structure that the hypothalamus regulates. The Brain – Diencephalon The pineal gland has a role in regulating biological rhythms. The pineal gland secretes melatonin in low light that helps to promote sleep. The pineal gland is also involved in producing dreams. The Brain – Brainstem The Brain – Brainstem All neurons that pass through the spinal cord also pass through the brainstem. The brainstem is essential for life and is the most primitive brain region, found in all animals. The core of the brainstem contains neurons that regulate consciousness and sleep-wake cycles The midbrain contains cells that release dopamine, that acts on the basal nuclei to regulate muscle movements. The Brain – Brainstem The pons plays a role in relaying information between the cerebrum and the cerebellum to coordinate muscle movements. The pons also plays a role in the regulation of breathing. Smooths out breathing; voluntary changes to breathing The medulla oblongata is the main respiratory control centre and is also the main regulator of heart contractions (rate and force) The medulla is the centre for many reflexes, such as coughing, sneezing, and vomiting. The Brain – Cerebellum The cerebellum is located at the base of the brain plays a key role in controlling muscle movements; learning muscle movements; fine motor control, such as writing with a pen; and coordinating many muscle groups so movements are smooth, such as walking or dancing. People with cerebellar disease have clumsy uncoordinated movements. www.crescentok.com  Brain – Cerebrum The subcortical regions lie underneath the cerebral cortex and contain the basal nuclei, involved in controlling muscle movements; involved in reward, pleasure, and addiction; the amygdala, involved in emotions, memory, and social interactions; the caudate nucleus – learning and memory the corpus callosum, which connects the right and left sides of the brain. Copyright © 2016 by Nelson Education Ltd. 23 15.6 The Brain – Cerebrum Copyright © 2016 by Nelson Education Ltd. 24  15.6 The Brain – Limbic System The limbic system plays a major role in our emotions, learning, memory, and social interactions. Because the olfactory bulb is part of the limbic system, the sense of smell is highly linked to memories. It functions to protect us by reacting rapidly to stimuli: for example, getting angry and becoming aggressive, or feeling sad and wanting to cry. Our limbic system reactions are highly modified by the cerebral cortex, particularly the frontal lobe. Hippocampus is location of long-term memories. Copyright © 2016 by Nelson Education Ltd. 25 The Brain – Cerebrum The cerebrum consists of the cerebral cortex (an outer rim of gray), an internal region of cerebral white matter, and gray matter nuclei. The longitudinal fissure separates the cerebrum into right and left halves called cerebral hemispheres. Hemispheres are connected by the corpus callosum Lateral cerebral sulcus Central sulcus The Brain – Cerebrum The Brain – Cerebrum Each cerebral hemisphere has 5 lobes 4 that are named after the bones that cover them: frontal lobe, parietal lobe, temporal lobe, and occipital lobe and an insula – lies within the lateral cerebral sulcus The Brain – Cerebrum The central sulcus separates the frontal and parietal lobes. The precentral gyrus is located immediately anterior to the central sulcus (motor cortex) – The postcentral gyrus is located immediately posterior to the central sulcus (sensory cortex) The lateral cerebral sulcus separates the temporal lobe from the parietal and frontal lobes and extends inwards to the insula  Precentral gyrus Central Sulcus Postcentral gyrus Lateral Sulcus The Brain – Cerebrum The Brain – Cerebrum – Frontal lobe contains the motor cortex and premotor cortex Broca’s area is part of the frontal lobe that controls muscles involved in speaking. Parietal lobe contains the sensory cortex Temporal lobe contains the auditory cortex and associated areas that interpret sound. Occipital lobe contains the visual cortex and associated areas that interpret visual stimuli. The Brain – Cerebrum Temporal lobe contains the auditory cortex and associated areas that interpret sound. Wernicke’s area is a part of the temporal lobe that is involved in comprehension of language. Occipital lobe contains the visual cortex and associated areas that interpret visual stimuli. Insula is involved in perception of pain, gastric and bladder fullness Nerve Nerve I Olfactory VII Facial II Optic VIII Vestibulocochlear IX Glossopharyngeal III Oculomotor IV Trochlear X Vagus V Trigeminal XI Accessory VI Abducens XII Hypoglossal 12 Cranial Nerves On Old Olympus’s Towering Top A Fat Vicious Goat Vandalized A Hat Oh, Oh, Oh, To Touch And Feel Very Good Velvet, AH! Copyright © 2016 by Nelson Education Ltd.