Ch.11-Central Nervous System Flashcards
Name the primary regions of the brain in adults.
The adult brain is divided into the cerebrum, diencephalon, brain stem, and cerebellum.
The Cerebrum is divided into large left and right cerebral hemispheres, which make up most of the brains mass.
The cerebrum surface is covered with gyro, Sulci, and fissures. Several sulci divide each hemisphere into the frontal, parietal, temporal and occipital lobes, as well as the insula which is buried deep in the lateral sulcus.
The 3 basic regions of each cerebral hemisphere include the cerebral cortex, white matter and basal nuclei.
The cerebral cortex is a thin layer of grey matter comprising the outer portion of the cerebrum and is the centre of the conscious mind.
The diencephalon is mostly made up of paired grey matter structures known as the thalamus, hypothalamus and epithalamus, it forms the central core of the forebrain.
The diencephalon is surrounded by the cerebral hemispheres and itself encloses the third ventricle.
The most superior region of the brain stem is the midbrain, with descending regions including the pons and the medulla oblongata.
The brain stem is organised similarly to the spinal cord, with deep grey matter that is surrounded by white matter fibre tracts, however the brain stem also has nuclei of grey matter that are embedded in its white matter.
Behaviours That are needed for survival emanate from the brain stem, they are automatic and highly controlled.
The cerebellum is the 2nd largest portion of the brain and appears similar to the shape of a cauliflower. It is found dorsal to the pons, medulla, and fourth ventricle.
The cerebellum protrudes under the occipital lobes of the cerebral hemisphere.
The cerebellum process inputs from the cerebral motor cortex, brain stem and sensory receptors, then regulates skeletal muscle movements for many different activities.
Describe the locations of the ventricles of the brain.
Interconnected cavities known as ventricles exist within the cerebral hemispheres and brain stem.
They are continuous with the spinal cords central canal and contain CSF.
The walls of the hollow ventricular chambers are lined by ependymal cells.
The 2 large lateral ventricles are located inside the frontal, occipital and temporal lobes.
The 3rd ventricle is under the corpus callosum in the brains midline, surrounded by the diencephalon.
The 4th ventricle is in the brain stem, and a narrow cerebral aqueduct joins it to the 3rd ventricle.
Explain the part of the brain that is connected to the pituitary gland.
Describe function of the hypothalamus.
The hypothalamus is connected to the pituitary gland.
It is the primary visceral control centre of the body.
It is crucial for homeostasis in the body, and affects nearly all body tissues.
It is located below the thalamus, capping the brain stem, and forming the inferolateral walls of the third ventricle.
Paired, small, round structures bulge anteriorly from the hypothalamus, known as mammillary bodies, which act as relay stations in the olfactory pathways.
A stalk of hypothalamic tissue know as the infundibulum lies between the mammillary bodies and the optic chiasma. The infundibulum connects the pituitary gland to the base of the hypothalamus.
The hypothalamus controls the autonomic nervous system(ANS) and endocrine system function.
It is vital for the limbic system, as it is the emotional part of the brain, it acts through ANS pathways to initiate physical expressions of emotion.
Other regulatory functions of the hypothalamus affect body temp, intake of food, water balance, thirst, and the sleep-wake cycle.
The hypothalamus is the body’s thermostat, it controls hormone secretion from the anterior pituitary gland and produces antidiuretic hormone and oxytocin.
Describe function of the thalamus.
The superolateral walls of the third ventricle are formed by the egg-shaped, bilateral nuclei of the thalamus.
This structure makes up 80% of the diencephalon and is found deep inside the brain.
The nuclei of the thalamus are interconnected(in most individuals) by an intermediate mass known as the interthalmic adhesion.
The thalamus processes and relays all incoming and outgoing information between the cerebral cortex and the spinal cord.
The thalamus mediates motor activities, sensation, cortical arousal, learning and memory.
Related impulses are organised in groups through the internal capsule of the thalamus to the correct area of the cerebral cortex and association areas. Afferent impulses reaching the thalamus are basically recognised as either pleasant or unpleasant.
Nearly all inputs ascending to the cerebral cortex are channeled through the thalamic nuclei: inputs for memory or sensory integration are projected to areas such as the pulvinar, lateral dorsal, or lateral posterior nuclei. Inputs regulating emotional and visceral function from the hypothalamus, via the anterior nuclei.
Additionally the thalamic nuclei interpret instructions aiding in direction of motor cortical activity from the cerebellum(via the ventral lateral nuclei) and the basal nuclei(via the ventral anterior nuclei).
Describe the centres that control blood pressure and respiration.
The most inferior part of the brain stem is the medulla oblongata(medulla).
Joins the spinal cord smoothly at level of the skulls foramen magnum.
Cranial nerves VIII, IX, X and XII originate from the medulla.
Plays vital role as center of autonomic reflexes required for homeostasis.
The medulla contains a cardiovascular center, which includes the cardiac centre, the vasomotor centre and respiratory centre, which are in control of blood pressure and respiration.
Specify the functions of the cerebellum.
The cerebellum processes inputs from the cerebral motor cortex, brain stem and sensory receptors.
It regulates skeletal muscle movements for many different activities such as driving a car, riding a bike, playing an instrument.
Cerebellar activity is subconscious.
Explain the layers of the meninges.
The 3 layers of membranes in the meninges are:
Dura mater(outermost layer)
Arachnoid mater
Pia mater(innermost layer)
The dura mater is made up of fibrous tough, white connective tissue.
It has many blood vessels and nerves and attaches to the inside of the cranial cavity, it also extends inward between the brain lobes to form protective partitions.
It has 2 layers of fibrous connective tissue(the periosteal and meningeal layers).
A thin, web-like arachnoid mater lies between the dura mater and the pia mater.
The thin pia mater has many blood vessels and nerves that nourish the brain and spinal cord.
It is closely aligned with the surfaces of these organs and is composed of many tiny blood vessels and delicate connective tissue.
The pia mater is bound tightly to the brain and its convolutions.
