A&P 2 Chapter 11

Cerebellum

1. The cerebellum is made up of two hemispheres connected by a vermis. 2. A thin layer of gray matter called the cerebellar cortex lies outside a core of white matter. 3. The cerebellum communicates with other parts of the central nervous system through cerebellar peduncles. 4. The cerebellum functions to integrate sensory information about the position of body parts and coordinates skeletal muscle activity and maintains posture.

reflexes

1. reflexes are automatic, subconscious responses to stimuli that help maintain homeostatsis ( heart rate, blood pressure) and carry out automatic respinses (vomiting, sneezing, swallowing) 2 the knee jerk reflex (patellar tendon reflex) is an example of a monosynaptic reflex 3. the withdrawl reflexs involves sensory neurons, interneurons and moroe neurons

functions of the spinal cord

1. spinal cord has 2 major functions: a)transmit imoulses to and from the brain b) house the spinal reflexes 2.tracts carrtying sensory information to the brain are called ascending tracts; descending tracts carry motor information from the brain 3. the names that identify nerve tracts identify the origin and termination of the fibers in the tract 4. many spinal reflexes also pass through the spinal cord

Hemisphere Dominance

a. Both cerebral hemispheres function in receiving and analyzing sensory input and sending motor impulses to the opposite side of the body. b. Most people exhibit hemisphere dominance for the language-related activities of speech, writing, and reading. e. The basal ganglia are masses of gray matter located deep within the cerebral hemispheres that relay motor impulses from the cerebrum and help to control motor activities by producing inhibitory dopamine. f. Basal ganglia include the caudate nucleus, the putamen, and the globus pallidus.

Functional Regions of the Cerebral Cortex

a. The functional areas of the brain overlap, but the cortex can generally be divided into motor, sensory, and association areas. b. The primary motor areas lie in the frontal lobes, anterior to the central sulcus and in its anterior wall.

Epilepsy

•The brain fires out of control •In the past certain kinds of epilepsy could not be controlled •In extreme circumstances extreme measures were taken... Extreme measures.... •Doctors performed a corpus callostomy •Partially cutting the corpus callosum •Reducing the traffic between neurons •And reducing the symptoms of epilepsy

structure of the spinal cord

- consists of 31 segments each of which gives rise to a pair of spinal - a cervical enlargement give rise to nerves leading to the upper limbs and a lumbar enlargement give rise to the lower limbs -anterior median fissure and posterior median sulcus divide the cord into 2 halves - white matter is myelinated nerve fibers surround a butterfly shape of gray matter housing interneurons - central canal contains cerebrospinal fluid

ventricles

-are continuouswith central canal of spinal column -and the subarachnoid space of meninges -csf is made by choroid plexus

four ventricles that are interconnected

-two lateral ventricles in cerebral hemispheres -third ventricle in midline beneath corpus callosum - fourth ventricle in brainstem

Brain Stem

1. The brain stem, consisting of the midbrain, pons, and medulla oblongata, lies at the base of the cerebrum, and connects the brain to the spinal cord.

Structure of the Cerebrum

1. The cerebrum is the largest portion of the mature brain, consisting of two cerebral hemispheres. 2. A deep ridge of nerve fibers called the corpus callosum connects the hemispheres. 3. The surface of the brain is marked by convolutions, sulci, and fissures. 4. The lobes of the brain are named according to the bones they underlie and include the frontal lobe, parietal lobe, temporal lobe, occipital lobe, and insula. 5. A thin layer of gray matter, the cerebral cortex, lies on the outside of the cerebrum and contains 75% of the cell bodies in the nervous system. 6. Beneath the cortex lies a mass of white matter made up of myelinated nerve fibers connecting the cell bodies of the cortex with the rest of the nervous system.

Diencephalon

1. The diencephalon lies above the brain stem and contains the thalamus and hypothalamus. 2. Other portions of the diencephalon are the optic tracts and optic chiasma, the infundibulum (attachment for the pituitary), the posterior pituitary, mammillary bodies, and the pineal gland. 3. The thalamus functions in sorting and directing sensory information arriving from other parts of the nervous system, performing the services of both messenger and editor. 4. The hypothalamus maintains homeostasis by regulating a wide variety of visceral activities and by linking the endocrine system with the nervous system. a. The hypothalamus regulates heart rate and arterial blood pressure, body temperature, water and electrolyte balance, hunger and body weight, movements and secretions of the digestive tract, growth and reproduction, and sleep and wakefulness.

the brain

A. The brain is the largest, most complex portion of the nervous system, containing 100 billion multipolar neurons. B. The brain can be divided into the cerebrum (largest portion and associated with higher mental functions), the diencephalon (processes sensory input), the cerebellum (coordinates muscular activity), and the brain stem (coordinates and regulates visceral activities).

Functions of the Cerebrum

The cerebrum provides higher brain functions, such as interpretation of sensory input, initiating voluntary muscular movements, memory, and integrating information for reasoning.

Functional Regions of the Cerebral Cortex

a. The functional areas of the brain overlap, but the cortex can generally be divided into motor, sensory, and association areas. b. The primary motor areas lie in the frontal lobes, anterior to the central sulcus and in its anterior wall. c. Broca's area, anterior to the primary motor cortex, coordinates muscular activity to make speech possible. d. Above Broca's area is the frontal eye field that controls the voluntary movements of the eyes and eyelids. e. The sensory areas are located in several areas of the cerebrum and interpret sensory input, producing feelings or sensations. f. Sensory areas for sight lie within the occipital lobe. g. Sensory and motor fibers alike cross over in the spinal cord or brain stem so centers in the right hemisphere are interpreting or controlling the left side of the body, and vice versa. h. The various association areas of the brain analyze and interpret sensory impulses and function in reasoning, judgment, emotions, verbalizing ideas, and storing memory. I. Association areas of the frontal lobe control a number of higher intellectual processes. j. A general interpretive area is found at the junction of the parietal, temporal, and occipital lobes, and plays the primary role in complex thought processing.

Medulla Oblongata

a. The medulla oblongata transmits all ascending and descending impulses between the brain and spinal cord. b. The medulla oblongata also houses nuclei that control visceral functions, including the cardiac center that controls heart rate, the vasomotor center for blood pressure control, and the respiratory center that works, along with the pons, to control the rate and depth of breathing.

Midbrain

a. The midbrain, located between the diencephalon and pons, contains bundles of myelinated nerve fibers that convey impulses to and from higher parts of the brain, and masses of gray matter that serve as reflex centers. b. The midbrain contains centers for auditory and visual reflexes.

Pons

a. The pons, lying between the midbrain and medulla oblongata, transmits impulses between the brain and spinal cord, and contains centers that regulate the rate and depth of breathing.

Reticular Formation

a. Throughout the brain stem, hypothalamus, cerebrum, cerebellum, and basal ganglia, is a complex network of nerve fibers connecting tiny islands of gray matter; this network is the reticular formation. b. Decreased activity in the reticular formation results in sleep; increased activity results in wakefulness. c. The reticular formation filters incoming sensory impulses.

spinal cord

begins at the base of the brain and extends as a slender cord to the level of the intervertebral disk between the first and second lumbar vertebrae

3 layers of meninges

dura mater arachnoid pia mater

Meninges

the brain and spinal cord are surrounded by membranes called meninges that lie between the bone and the soft tissues