A&P 1 - Chapter 12
Temporal Lobe Discuss the function of the auditory cortex, auditory association area and the olfactory cortex
Function of: Auditory cortex: It receives nerve impulses from the ear (pitch, loudness, and location) of sound origin. Auditory association area: It allows us to determine and process exactly what it is we hear (a word, a scream, music, thunder, etc.). Memories of sound heard in the past are stored here. Olfactory cortex: It receives messages from smell receptors in the nasal mucosa.
Occipital Lobe Discuss the function of the primary visual cortex and visual association areas
Function of: Visual cortex: It receives visual messages from the retina of the eye. Visual association areas: It uses past visual experiences to analyze and interpret visual stimuli, and recognition of images.
Insula Discuss the function of the vestibular cortex, gustatory cortex and visceral sensory areas
Function of: Vestibular cortex: It regulates equilibrium and is located primary in the insula and partially in the parietal lobe. Gustatory cortex: It processes the sense of taste. Visceral sensory areas: It is the conscious perception of visceral stimuli.
Meninges Name the layers of the meninges (superficial to deep) and give a brief description and function of each layer
From superficial to deep: Dura mater: "Tough mother" - the outermost layer of meninges and sits right underneath the skull (or vertebra in the spine) and is the thickest/strongest layer Arachnoid mater: "Middle layer" - Weblike extensions (called arachnoid trabecule) that gives it a spiderweb-like appearance. The subarachnoid space (between the arachnoid mater and pia mater). The cerebrospinal fluid is located here and adds an additional cushioning layer within the skull and vertebral column. Pia mater: "Innermost layer" - Thinnest and most delicate of the meninges. Clings tightly to the brain. It is well vascularized and can help bring nourishment to the underlying cells of the brain and spinal cord.
Brain Anatomy Define contralateral and ipsilateral and be able to use the terms correctly when discussing brain and spinal cord anatomy and function
Ipsilateral: Occurring on the same side of the body. Contralateral: Occurring on the opposite side of the body. This term is used frequently when we talk about the nervous system. - If we need to kick with our left leg, our right frontal lobe in our brain will control the muscles of the left side of the body
Blood Brain Barrier Where in the central nervous system is the blood brain barrier absent
It is absent in some areas (vomiting center and the hypothalamus, where it is necessary to monitor the chemical composition of the blood).
The Brainstem Medulla Oblongata - note the functions of the medulla oblongata and pyramids
Medulla Oblongata: (location: Inferior to the pons. Joins spinal cord at foramen magnum, allows brain to communicate with spinal cord) Function: Cardiac center controls HR, vasoconstriction and vasodilation of blood vessels (BP). Respiratory centers control rate of breathing. Also controls, vomiting, swallowing, coughing, sneezing and mediates responses that maintain equilibrium. Works with the hypothalamus in regulating some of these processes.
Parietal Lobe Explain what sensation and somatosensory means
Sensation: the ability to be aware of a sensory stimuli. Somatosensory: Body sensations
Parietal Lobe Locate the primary somatosensory cortex and discuss its function. Identify the central sulcus and postcentral gyrus. What does the sensory homunculus demonstrate
Sensory homunculus demonstrates the body being represented spatially and upside down according to the site of stimulus input, and the right hemisphere receives input from the left side of the body. The amount of sensory cortex devoted to a particular body region is related to that region's sensitivity (that is, to how many receptors it has), not its size. In humans, the face (especially the lips) and fingertips are the most sensitive body areas, so these regions are the largest parts of the somatosensory homunculus.
Brain Anatomy Locate the corpus callosum and name its function
An important band of neurons which will allow the left side of the brain to communicate with the right side of the brain. It acts as a bridge for information to travel between the left and right hemispheres.
List and explain the four structures that protect the brain and spinal cord
Bones: the bones of the skull and vertebral column provide a hard protective shell encasing the brain and spinal cord. Meninges: Located right underneath the bones of the skull and vertebral column. The meninges are three layers of connective tissue coverings that wrap and support the brain and spinal cord. Cerebrospinal fluid: A watery cushion inside of the brain and spinal cord The Blood Brain Barrier: A filtering barrier that protects the neurons from potential toxins in the bloodstream.
The Brainstem Name the structures of the brainstem and discuss each structures function
Brain Stem: Controls automatic behaviors necessary for survival. 10 of the 12 pairs of cranial nerves will exit off the brain from here. Reticular formation: located throughout brain stem. Contains the Reticular Activating System (RAS) which plays a crucial role in consciousness.
Brain Anatomy Explain the difference between white and grey matter of the brain. For white matter explain how association fibers, commissural fibers and projection fibers connect different parts of the brain and spinal cord.
Cerebral cortex: 2-4mm superficial layer of grey matter and is 40% of the mass of the brain. It is the site of the conscious mind: awareness, sensory perception, voluntary motor initiation, communication, memory storage, and understanding. Cerebral white matter: It is myelinated, and composed of large bundles of myelinated axons called tracts. It serves as fast communicating pathways so that different parts of CNS can talk to one another. - Commissural fibers: allow left and right hemispheres to talk to one another (ex. Corpus callosum) - Association fibers: Connect different parts of the brain within the same hemisphere and allows them to communicate with each other (ex. Occipital lobe communicating with frontal lobe) - Projection fibers: Run vertically, allows cerebral cortex to talk to brain stem and spinal cord, and vice versa.
Cerebral Dominance and Lateralization What is cerebral dominance? Which hemisphere is dominant in most people. Explain how and give examples of how the right and left cerebrum have specialized functions
Cerebral dominance: It indicates the side of the brain which is dominant for language. - 90% of people are left hemisphere dominant (results in most people being right handed) - 10% of people have their roles reversed which often results in left-handedness Left hemisphere: has control over language (speech, writing reading, math, and logic) Right hemisphere: has control over visual spatial skills, motor tasks, emotion, artistic, and musical skills
The Brainstem Midbrain - note the functions of the midbrain, corpora quadrigemina (superior and inferior colliculi)
Midbrain: (location: between the diencephalon and the pons) Contains: Cerebral and cerebellar peduncles that contain motor tracts and attach cerebral hemispheres and cerebellum to the brain stem. Substantia nigra that produces neurotransmitter dopamine, which will be used by the basal nuclei. Corpora Quadrigemina is composed of the superior and inferior colliculi. These areas help with auditory and visual reflexes. Function: Visual reflex centers (blinking, focusing, pupil dilation and constriction, tracking moving objects with your eye), found in the superior colliculi region of the midbrain Auditory relay centers and auditory reflexes (jumping when you hear a loud sound, turning your head towards a sound), found in the inferior colliculi region of the midbrain
Frontal Lobe Locate the primary motor cortex and discuss its function. Identify the central sulcus and precentral gyrus. What does the motor homunculus demonstrate
Motor homunculus demonstrates the body is represented upside down—with the head at the inferolateral part of the pre-central gyrus, and the toes at the superomedial end. Most of the neurons in these gyri control muscles in body areas having the most precise motor control—that is, the face, tongue, and hands. Consequently, these regions are disproportionately large in the caricature-like.
The Brainstem Pons - note the functions of the pons
Pons: (location: between midbrain and medulla oblongata - it links cerebellum with midbrain, diencephalon, cerebrum, and spinal cord) Function: Help maintain normal rhythm/depth of breathing, and relay impulses between the motor cortex and the cerebellum. The pons is also home to the structures known as the cerebellar peduncles. There are three of them and they are responsible for routing information regarding movement into and out of the cerebellum and motor cortex of the cerebrum. Cerebellar Peduncles: - Superior Cerebellar Peduncle - Function: Sends motor instructions from the Cerebellum to the Motor Cortex in the Cerebrum - Middle Cerebellar Peduncle - Function: Advises the Cerebellum on voluntary muscle movements initiated by the Motor Cortex of the Cerebrum - Inferior Cerebellar Peduncle - Function: Sensory information regarding equilibrium and balance enters the Cerebellum for motor coordination design by the Cerebellum
Frontal Lobe Locate and discuss the function of the premotor cortex, Broca's area and Frontal Eye Field
Premotor cortex: learned motor skills of a repetitious mature (tying shoes and riding a bike) Broca's area: Motor speech area, usually only in left hemisphere. This area directs the muscles of speech production. Damage here will cause a person to have difficulty forming words (understanding/comprehension of written and spoken words will usually be normal) Frontal eye field: this is the area of the frontal lobe that controls the eye movements.
The Diencephalon Name the structures of the diencephalon and discuss each structure's function
Thalamus: (location: forms wall of the third ventricle and composes 80% of the diencephalon) It sorts and processes incoming sensory information and relay it to the appropriate lobe of the cerebral hemisphere for final processing. It is the "gateway to the cerebral cortex." If a sensation is worthy of further processing, it will relay that information to the appropriate lobe (ex: touch sensations get routed to the parietal lobe) Also sorts and relays impulses from the hypothalamus for regulation of emotion and visceral function. Relay impulses from the cerebellum and basal nuclei to help direct the motor cortex in the frontal lobe Mediates sensation, cortical arousal, learning, and memory. Works with the limbic system to generate emotions Hypothalamus: (location: below the thalamus. Will connect to the pituitary gland via the infundibulum) Regulates lots of basic life-sustaining activities. Autonomic (involuntary) control center of blood pressure/BP, heart rate/HR, digestion, pupil dilation), emotional responses, body temperature regulation, hunger and thirst, sleep/wake cycles (circadian rhythms), metabolism. Coordinates nervous and endocrine (hormone) activities and release. Epithalamus: (location: Forms roof of third ventricle) It contains the pineal gland. The pineal gland releases the hormone melatonin, used in the sleep/wake cycle.
Blood Brain Barrier Explain the structure of the basement membrane
The basement membrane of the endothelial cells forms the last part of the blood brain barrier. It contains enzymes that destroy certain chemicals (such as epinephrine and norepinephrine) that would otherwise activate brain neurons.
Blood Brain Barrier What are the weaknesses/limitations of the blood brain barrier
The epithelial cells in the capillary wall are continuous with one another and joined by tight junctions. This means that there are no large openings of gaps between epithelial cells for substances to easily escape the bloodstream and travel to nearby neurons. It is a selective barrier: - It allows nutrients to move by facilitated diffusion - It allows any fat-soluble substances to pass, including alcohol, nicotine, and anesthetics
Parietal Lobe Discuss the function of the somatosensory association cortex
The major function of this area is to integrate sensory inputs (temperature, pressure, and so forth) relayed to it via the primary somatosensory cortex to produce an understanding of an object being felt: its size, texture, and the relationship of its parts. For example, when you reach into your pocket, your somatosensory association cortex draws upon stored memories of past sensory experiences to perceive the objects you feel as coins or keys. Someone with damage to this area could not recognize these objects without looking at them.
