Brain Stem Project
- 1. The Brain Stem Ajay Naran Alyssa Pugel Catharina Son
- 2. Thalamus/Midbrain: Where is it? What does it do? Located on top of the brainstem and close to the center of the brain. Left and Right Thalamus. Receives Auditory, Somatosensory and Visual Sensory Signals Relays sensory signals to the Cerebral Cortex. Medulla and Cerebellum. Important for motor control as well. The Midbrain in the upper part of the brainstem. Relay station for auditory and visual information.
- 3. Thalamus: Neuroanatomy Made of myelinated fibers (electrically insulating material). Epithalamus (Dorsal Thalamus) - Secretion of melatonin by the pineal gland. Habenula Recieves information from the stria medullaris , and outputs to areas of the brain involving hormone secretion. The stria medullaris is a fiber bundle that the epithalamus uses to receive messages.
- 4. Thalamus: Diseases and Brain Damage Parkinson’s disease has been linked with thalamic damage because of the impairment of motor functions. Strokes involving loss of consciousness has been linked to blood clots in the thalamus. Damage can cause loss of speed for sensory reception. Mood swings.
- 5. Hypothalamus: Where is it? What does it do? The hypothalamus is located directly below the thalamus, and above the cerebellum. One of the most ancient parts of the brain. The most important function of the hypothalamus is to link the nervous and endocrine systems through the pituitary gland. Directs maintenance functions such as body temperature, dieting, and control of emotions. Coordinates circadian rhythms. “ Human Clock” of biological processes. Functioning center for some of the most important neurohormones: Serotonin, Dopamine, Norepinephrine and acetylcholine. Nerve Impulses; Helps with body movements; Fight-or-flight response; Activates muscles. Helps to maintain homeostasis. Part of the Limbic System.
- 6. Hypothalamus: Neuroanatomy Anterior (Supraoptic Region) Medial Decreased Heart Rate and Blood Pressure Oxytocin Release Neurotransmitter in the brain. Panting and Sweating. Lateral Thirst and Hunger. Tuberal (known for control of eating). Medial Hormone release Neuroendicrine Control. Lateral Thirst and Hunger Posterior (Mamillary Region) Medial Memory Increase blood pressure.
- 7. Hypothalamus: Diseases and Brain Damage Damage to the anterior hypothalamus blocks ADH production. This causes diabetes insipidus. Water loss from the kidneys. Bilateral Lesions of the tuberal region can cause hyperphagia and extreme obesity (medial) or anorexia (lateral). Many disorders are linked to the lack or overproduction of certain hormones. Insomnia Narcolepsy Excessive daytime sleepiness.
- 8. Pineal Body: Also known as the epiphysis Early in life, it is composed of a glandular structure until puberty is hit and the glandular tissue is replaced by connective tissue Descartes believed it to be the “seat of the soul” The pineal body, or pineal gland, contains many peptides and neurotransmitters but the only hormone it secretes is melatonin Melatonin apparently acts to keep a child’s body from maturing to fast because it isn’t until the levels of melatonin decrease that the hormone luteotropine, which influences sexual organs, appears. The pineal gland is about 8mm long and weighs slightly more than 0.1 gram It is deep between the two cerebral hemispheres and attached to the posterior wall of the third ventricle of the spinal cord If damage were to occur to the pineal body sexual maturation could be too early or too late and skin pigmentation may be obscured from lack of melatonin and sleep patterns may be disrupted. Melatonin Deficiency and Excess. Also known as the Epiphysis.
- 9. Pituitary Gland: Where is it? Brain Damage? The pituitary gland is a small pea sized structure at the base of the brain protruding off of the hypothalamus. It is protected by a bone cavity called the sella turica. Damage to the area can cause deficiency of pituitary functions and cause hypopituitarism. Sheehan’s Syndrome: may occur when a woman has severe uterine hemorige during childbirth, this may result in tissue death in her pituitary gland and result in hypopituitarism. Damage to the pituitary stalk or posterior pituitary gland may cause antidiuretic hormone deficiency.
- 10. Pituitary Gland: What does it do? Also called the Hypophysis. It releases hormones that influence growth There are three sections of the pituitary gland: the anterior pituitary, the posterior pituitary, and the intermediate lobe. The anterior pituitary: synthesizes and secretes important endocrine hormones. Hypothalamic hormones are secreted to the anterior lobe by ways of special capillary system called the hypothalamic-hypophyseal portal system. The posterior pituitary: stores and releases oxytocin and antidiuretic hormone (ADH, also known as vasopressin). Intermediate lobe: thin layer of cells between the anterior and posterior lobe. It produces melanocyte-stimulating hormone (MSH) although this function is usually attributed to the anterior lobe, it helps control skin pigmentation.
- 11. Pituitary Gland: Diseases and Neuroanatomy Growth Hormone Deficiency, growth hormones can be injected only and about once every 6-7 weeks. Deficency of TSH: increased need to sleep, muscle aching, decreased mental function. A daily pill of thyroxine is used and dosage is based on blood tests. Deficency of ACTH and cortisol: most dangerous and life threatening, symptoms are often vague and may include weight loss, fatigue, weakness, depression, apathy, nausea, vomiting, anorexia and hyperpigmentation. An over exposure to cortisol creates a diseases known as Cushing’s Syndrome. It is a small cycle: the hypothalamus releases CRH (corticotropin-releasing hormone) to the pituitary which releases ACTH to the adrenals and they respond by secreting cortisol into the bloodstream.
- 12. Medulla: Where is it? Neuroanatomy? Location Lowest portion of brainstem. Connects brain and spinal cord. Above spinal cord, below the pons, in front of cerebellum. Contains both myelinated (white matter, outside) and unmyelinated (gray matter, inside) nerve fibers. Two parts: open/superior part (where dorsal surface of medulla formed by fourth ventricle), closed/inferior part (where metacoel lies within medulla).
- 13. Medulla: What does it do? Functions Controls autonomic functions . Regulating respiration/blood pressure, heart rate, digestive processes like defecation, urination, vomiting . Other activities include cardiac function: swallowing, reflexes/control of movement, relaying of somatic sensory information from internal organs, control of arousal (wakefulness and attention) and sleep. Believed to be the key to how general anesthesia works (anesthetics depress medulla so it cannot function as it normally would). Relays nerve signals between brain and spinal cord. Functions take place at all hours all day without need for input from rest of brain Origin of many cranial nerves.
- 14. Medulla: Diseases and Brain Damage Related Diseases damage can be fatal: patient would be unable to breathe, swallow or perform other basic motor functions without assistance. Snipers trained to aim for medulla because of proximity to brain stem; damage to that area causes target to collapse immediately. Destruction of medulla causes instant death.
- 15. Pons: Where is it? Neuroanatomy? Location: portion of brainstem that is superior (above/over) to the medulla; between midbrain and medulla. White matter includes tracts that conduct signals from the cerebrum to cerebellum/medulla, and tracts that carry the sensory signals to thalamus; within pons is pneumotaxic center, a nucleus in pons that regulates the change from inspiration to expiration (inhalation and exhalation).
- 16. Pons: What does it do? Functions Pons = bridge in Latin: bridge that passes information between cerebrum, cerebellum, medulla. Assists in controlling autonomic functions (monitors respiration). Levels of consciousness/sleep. Able to facilitate coordination between functions of the two sides of the body as well as those of the face and jaw. Tells jaw to chew, controls outer eye muscles that moves eyes to the side, receives taste sensations from tongue, works muscles involved in facial expressions, receives nerve impulses from sounds that enter ear/signals from cochlea, causes secretion of saliva and tears.
- 17. Pons: Diseases and Brain Damage Diseases Central Pontine Myelinosis. Also known as osmotic demyelination. Generally caused by lack of sodium in blood. Symptoms: pseudobulbar palsy (difficulty swallowing/speaking), quadriparesis (paralysis), varying levels of consciousness, coma. Little treatment available, but can be avoided by regularly checking sodium levels. Those that recover often left with stroke-like symptoms (cannot recover completely); can lead to death. Damage will result in impaired coordination in movements.
- 18. Cerebellum: Location and Neuroanatomy Also called little brain. Attached to rear of brainstem Functions: processing sensory input and coordinating movement output and balance. About the size of a baseball. Has two hemispheres and a highly folded surface. It is supposedly much older than the cerebrum (the four lobes) evolutionary wise because reptiles have cerebellum but don’t have a neocortex, which is a part of the brain found in mammals which is the top layers of the cerebral hemispheres. Contains 50% percent of the brain’s neurons.
- 19. Cerebellum: What Does it Do? Neuroanatomy? Processes Sensory Information Helps us judge time, modulate emotions, and discriminates sounds and textures. Non-verbal learning and memory. Coordinates voluntary movement. The flocculondular one is concerned with balance and equilibrium. Anterior is concerned with regulation of muscle tones. The posterior lobe - the largest part of cerebellum - "newest part of cerebellum" - it receives inputs from the cerebral cortex. Its major output is sending signals to the motor cortex and supplementary motor area.
- 20. Cerebellum: Brain Damage and Diseases An injured cerebellum can cause difficulty walking, keeping your balance, and simple voluntary movements. They become jerky and exaggerated. Incabable of developing conditioned reflexes. It is required for implicit memory formation. Ataxia : Loss of coordination of parts of the body; movement deficits of timing, force, range, and direction. Dysmetria Characteristic of cerebellar lesions; the inability to properly direct or limit motions. Medulloblastoma Most common malignant brain tumor in children (3-5 years); arises in cerebellum and has a tendency to spread throughout the CNS; cause unknown.