Results for "medulla oblongata"

Know the relationship between molecular weight and rate of diffusion The rate of diffusion is inversely proportional to the molecular weight Small weight-fast diffusion; heavy weight-slow diffusion Identify RBC’s in various solution and determine tonicity Tonicity - the ability of an extracellular solution to make water move into or out of a cell by osmosis If a cell is placed in a hypertonic solution, there will be a net flow of water out of the cell, and the cell will lose volume (shrink). A solution will be hypertonic to a cell if its solute concentration is higher than that inside the cell, and the solutes cannot cross the membrane. If a cell is placed in a hypotonic solution, there will be a net flow of water into the cell, the cell will gain volume (bigger). If the solute concentration outside the cell is lower than inside the cell, then solutes cannot cross the membrane, then the solution is hypotonic to the cell. If a cell is placed in an isotonic solution, there will be no set flow of water into or out of the cell, and the cell’s volume will remain stable. If the solute concentration outside the cell is the same as inside the cell, and the solutes cannot cross the membrane, the solution is isotonic to the cell. Homeostatic feedback loop for respiratory rate, heart rate and temperature Respiratory Rate: Stimulus : The level of carbon dioxide (CO2) in the blood increases (often due to exercise or hypoventilation) . Receptors: Chemoreceptors in the medulla oblongata, carotid arteries, and aortic arch detect changes in blood pH and CO2 levels Control Center: The medulla oblongata processes this information Effectors: Respiratory muscles (diaphragm and intercostal) adjust breathing rate and depth Response: Increased respiratory rate removes CO2 and increases O2 intake, restoring normal pH and gas levels. Heart Rate: Stimulus : Changes in blood pressure, O2, CO2, or pH levels Receptors: Baroreceptors (detect blood pressure changes) in the carotid sinus and aortic arch; chemoreceptors monitor blood chemistry Control Center: The medulla oblongata (cardiac center) processes signals Effectors : The autonomic nervous system (ANS) adjusts heart rate through the sympathetic nervous system (increases heart rate) or parasympathetic nervous system (decreases heart rate) Response : Heart rate increases during low O2 or low blood pressure (to circulate oxygen) and decreases when homeostasis is restored. Temperature Regulation Stimulus: Changes in body temperature (hyperthermia or hypothermia) Receptors: Thermoreceptors in the skin and hypothalamus detect temperature fluctuations. Control Center: The hypothalamus processes this information and signals effectors Effectors and Responses: If too hot: Blood vessels dilate (vasodilation) to release heat, and sweat glands produce sweat for cooling If too cold: Blood vessels constrict (vasoconstriction) to retain heat, and shivering generates warmth. Steps of a generic homeostatic feedback loop Stimulus : A change in the internal or external environment that disrupts homeostasis (eg. temperature change, pH levels, blood sugar levels) Sensor (Receptor) : Specialized cells or receptors detect the change and send information to the control center. Control Center (Integrator): Often the brain or endocrine glands, this component processes the information from the sensors and determines the appropriate response to restore balance. Effector: This component carries out the response to the stimulus as dictated by the control center. Effectors can be muscles or glands that help to counteract the change. Response: The action taken by the effectors to restore homeostasis. This could involve increasing or decreasing a physiological process (e.g. sweating to cool down or shivering to warm up) Feedback: The results of the response are monitored. If homeostasis is restored, the system maintains its state; if not, the loop may repeat, continuing to adjust until balance is achieved. How to evaluate data to determine the set point, error, and disturbance Identify the set point The set point is the optimal level or range that the system aims to maintain. To determine the set point: Gather baseline data: Collect data over a period to understand the normal range for the variable in question (e.g. body temp., BP, blood glucose levels) Analyze Trends: Look for patterns in the data to identify the average or median value that represents the stable condition of the system. Consult Literature: Reference established physiological norms or previous studies to confirm the typical set point for the variable. Assess Disturbance A disturbance is any factor or event that causes a deviation from the set point. To evaluate disturbances: Identify External and Internal Factors: Analyze the data for any external influences (e.g. environmental changes, dietary habits) or internal changes (e.g. illness, stress) that might have impacted the variable. Quantity Disturbance: Measure the magnitude and duration of the disturbance. This can be done by comparing the data points during the disturbance against the established set point. Monitor Changes: Track how the system responds to disturbances over time to assess their impact on maintaining homeostasis. WBC types and normal distribution values/ abnormal values and what those values indicate (infections/diseases) (Never Let Monkeys Eat Bananas) Neutrophils (50-70%) - First responders to infections, especially bacterial. High levels indicate bacterial infections, inflammation, or stress. Low levels can indicate bone marrow disorders or severe infections. Lymphocytes (20-40%) - Include B cells and T cells, important for immunity. High levels can suggest viral infections or leukemia, while low levels might indicate immune deficiency. Monocytes (2-8%) - Help with cleaning up dead cells and fighting infections. High levels can be linked to chronic infections or autoimmune diseases. Eosinophils (1-4%) - Involved in allergic reactions and fighting parasites. Elevated levels may indicate allergies or parasitic infections. Basophils (0.5-1%) - Release histamine during allergic reactions. High levels might be see in allergic conditions or blood disorders. Normal WBC Count Total WBC Count: 4000-11000 cells per microliter of blood (varies slightly by lab) Leukocytosis (High WBC): Can indicate infection, inflammation, stress, or leukemia Leukopenia (Low WBC): Can result from bone marrow disorders, viral infections, or autoimmune diseases Neutrophils: Banded vs Segmented Neutrophils are the most abundant type of white blood cells and play a crucial role in fighting infections. They exist in different stages of maturation: Banded Neutrophils (“Bands”) - Immature Neutrophils Appearance: Have a curved, unsegmented nucleus (band-shaped) Normal Range: 0-6% of total WBC count (~0-700/uL) Clinical Significance: Increased Bands (Bandemia) -> Indicates an acute bacterial infection or severe stress (e.g. sepsis). The bone marrow releases immature neutrophils in response to infection. Low Bands -> Not clinically significant unless the total WBC count is low, which could suggest bone marrow suppression. Segmented Neutrophils (“Segs”) - Mature Neutrophils Appearance: Have a segmented nucleus with 2-5 lobes Normal Range: 50-70% of total WBC count (~2500-7000/uL) Clinical Significance: High Segs (Neutrophilia) -> Suggests bacterial infections, stress, chronic inflammation, or leukemia Low Segs (Neutropenia) ->Can be caused by viral infections, bone marrow disorders, chemotherapy, or autoimmune diseases. Discuss the stages of cell cycle/mitosis-which stages are longest/shortest The cell cycle is a series of events that cells go through to grow and divide. It consists of two main phases: Interphase (Longest Phase) – Preparation for division Mitosis (Shortest Phase) – Actual cell division Stages of the Cell Cycle Interphase (90% of the Cell Cycle – Longest Phase) Interphase is the period of cell growth and DNA replication. It has three subphases: G1 Phase (Gap 1) The cell grows, produces proteins, and prepares for DNA replication. Longest variable phase; some cells may stay here indefinitely (e.g., neurons in G0 phase). S Phase (Synthesis) DNA replication occurs, ensuring each daughter cell gets a complete genome. Takes about 6-8 hours in human cells. G2 Phase (Gap 2) The cell prepares for mitosis by producing proteins and organelles. Shorter than G1 but still significant in length. Mitosis: Prophase, Metaphase, Anaphase, Telophase Know proportional and inversely proportional relationships Direct (Proportional) Relationship When two quantities increase or decrease together at a constant rate, they are directly proportional. Inversely Proportional When one variable increases, the other decreases proportionally. Know relationship between molecular weight and rate of diffusion The rate of diffusion of a substance is inversely proportional to the square root of its molecular weight. Lighter molecules diffuse faster Heavier molecules diffuse slower due to greater mass. Know relationship between filtration rate and pressure of fluid or weight of fluid Filtration rate is directly proportional to the pressure or weight of the fluid driving the filtration process. Higher pressure → Higher filtration rate Lower pressure → Lower filtration rate Know why men and women blood values are different The differences in blood values between men and women are due to biological, hormonal, and physiological factors

Medulla Oblongata Transverse Sections

EXTERNAL AND INTERNAL STRUCTURE OF THE BRAIN STEM DR A. A. NWAKANMA THE BRAINSTEM •The brainstem is made up of the medulla oblongata, pons and midbrain •It is stalklike in shape and connects the narrow spinal cord with the expanded forebrain •Occupies the posterior cranial fossa of the skull Loading… FUNCTIONS OF BRAINSTEM •It serves as a conduit for the ascending and descending tracts connecting the spinal cord to the different parts of the higher centers in the forebrain •It contains important reflex centers associated with the control of respiration and CVS. •It is also associated with the control of consciousness •It contains important nuclei of cranial nerves II through XII EXTERNAL FEATURES OF MEDULLA OBLONGATA • The medulla oblongata connects the pons superiorly with the SC inferiorly •The junction of the medulla and SC is at the origin of the anterior and posterior roots of the first cervical nerve which corresponds approximately to the level of the foramen magnum Loading… EXTERNAL FEATURES OF MEDULLA •The medulla oblongata is piriform in shape •It has a broad superior part – open part •And a lower closed part •The central canal of the SC continues upward into the lower half of the medulla •In the upper half of the medulla it expands as the cavity of the fourth ventricle EXTERNAL FEATURES OF MEDULLA •On the ant. Surface of the medulla is the anterior median fissure which is continous inferiorly with the ant. Median fissure of the SC •On each side of the median fissure is a swelling called the pyramid EXTERNAL FEATURES OF MEDULLA •The pyramids are composed of bundles of nerve fibers, corticospinal fibers which originate in large nerve cells in the precentral gyrus of the cerebral cortex •The pyramids tapers inferiorly and majority of the descending fibers cross over to the opposite side forming the decussation of the pyramids here •The ant. External arcuate fibers are a few nerve fibers that emerge from the ant. Median fissure above the decussation and pass laterally over the medulla oblongata to enter the cerebellum EXTERNAL FEATURES OF MEDULLA •Posterolateral to the pyramids are the OLIVES which are oval elevations produced by the underlying inf. Olivary nuclei •In the groove b/w the pyramid and olive emerges the rootlets of the hypoglossal nerve •Post. To the olives are the inf. Cerebellar peduncles which connect the medulla to the cerebellum EXTERNAL FEATURES OF MEDULLA •In the groove b/w the olive and the inf. Cerebellar peduncle emerges the roots of the glossopharyngeal and vagus nerves and the cranial roots of accessory nerve •The post. Surface of the sup. Half of the medulla forms the lower part of the floor of the 4th ventricle External features of medulla •The post surface of the inf. Half continues with the post. Aspect of the SC and possesses a post. Median sulcus •On each side of the median sulcus is an elongated swelling , the Gracile tubercle produced by the underlying gracile nu. •Lat. To the gracile tubercle is the cuneate tubercle produced by the underlying cuneate nu. Loading… INTERNAL STRUCTURE OF MEDULLA •The internal structure of the medulla oblongata is usually considered at 3 levels •Level of pyramidal decussation •Level of olive •Level of sensory or lemniscal decussation T/S OF MEDULLA AT THE LEVEL OF OLIVE •This level corresponds to the floor of the 4th ventricle and the cranial n. Nuclei seen include •Hypoglossal n. • Vestibular nuclei •Dorsal nu. Of vagus •Solitary tract and its nu. •Nu. Ambigus • dorsal and ventral cochlear nu. T/S OF MEDULLA AT THE LEVEL OF OLIVE •The other masses of gray matter seen at this level include •The medial and dorsal accessory olivary nu. •Lat. Reticular nu. •Arcuate nu. •The descending tracts seen include •Pyramid •Rubrospinal tract •Spinal nu. And •Tract of trigeminal n. T/S OF MEDULLA AT THE LEVEL OF OLIVE •The ascending tracts include •Medial lemniscus lying in the middle and is L shaped •Spinothalamic T •Spinocerbellar T. •Spinotectal T. •The reticular formation and the inf. Olivary nu. Are also prominent features found at this level T/S OF THE MEDULLA AT THE LEVEL OF LEMNISCAL DECUSSATION •The level represented by this section lies a little above the level of the pyramidal decussation •The structures found at this level include •Central canal surrounded by gray matter •Medial lemniscus •The pyramids the nu. And fasciculus cuneatus •Spinal nu. Of trigeminal n. •The reticular formation T/S OF THE MEDULLA AT THE LEVEL OF LEMNISCAL DECUSSATION •Internal arcuate fibers which arise from the nu. Gracilis and cuneatus and arch forward on the medial side of the gray matter crossing in the midline to form the lemniscal or sensory decussation •Accessory cuneate nu. Lying dorsolateral to the cuneate nu. T/S OF THE MEDULLA AT THE LEVEL OF LEMNISCAL DECUSSATION •The cranial nerve nuclei seen at this level include •Hypoglossal nu. •Dorsal motor nu. Of vagus •Arcuate nu. •Nu. Of solitary tract •Nu. Ambigus •Other structures include •Lower part of inf. Olivary nu. •Lat. Reticular nu. •Arcuate nu. •Lat. & ventral spinothalamic tr. •Doral and ventral spinocerebella tr. •Spino-olivary tr. •Pyramids •Vestibulospinal tr. •Corticospinal tr. •Medial longitudinal fasciculus Connections of the Inferior Olivary Complex • The main afferents of the inferior olivary nucleus are from the cerebral cortex and from the spinal cord • The main efferents are to the cerebellar cortex. • An olivospinal tract is traditionally described, but some authorities hold that the inferior olivary nuclei do not send any fibres to the spinal cord. •The nucleus may be regarded as a relay station on the cortico-olivo-cerebellar and spino-olivo-cerebellar pathways. • The accessory olivary nuclei are connected to the cerebellum by parolivo-cerebellar fibres. THE PONS •The pons is the middle part of the brainstem •Its continuous below with the medulla oblongata and above with the midbrain •It is seperated from the cerbellum by the 4th ventricle •Pons has two surfaces: •Ventral and dorsal External Features Of Ventral Surface Of Pons •The ventral surface of pons shows the following features •The ventral surface is convex and has a shallow groove in the midline called the basilar groove which lodges basillar artery •Transvesely running fibers connecting the pons to the cerebellum thru the middle cerebellar peduncle •The two roots of trigeminal nerve (sensory and motor) emerge at the jxn b/w the ventral surface of pons and middle cerebellar peduncle EXTERNAL FEATURES OF DORSAL PONS •The dorsal surface of pons shows the following features •Median sulcus in the median plane •Medial eminence – shows rounded elevation in the lower part called facial colliculus which overlies the nu. Of abducent n. •Sulcus limitans – is lat. To the medial eminence and seperates medial eminence from vestibular area T/S THROUGH CAUDAL PART OF PONS •The features seen at this level include •Medial lemniscus in the most ant. Part of the tegmentum •The facial nu. Lies post to the lat. Part of the medial lemniscus •The fibers of the facial nerve wind around the nu. Of the abducent nerve producing the facial colliculus T/S THROUGH CAUDAL PART OF PONS •The medial longitudinal fasciculus is situated beneath the floor of the 4th ventricle on either side of the midline •The medial longitudinal fasciculus is the main pathway that connects the vestibular and cochlear nuclei with the nuclei controlling the extraocular muscles (oculomotor, trochlear and abducent) •The medial vestibular nu. Is situated lat. To the abducent nu. And in close relationship to the inf. Cerebellar peduncle T/S THROUGH CAUDAL PART OF PONS •The sup. Part of the lat. And inf. Part of sup. Vestibular nu. Are found at this level •Post. And ant. Cochlear nu. Are also found at this level •The spinal nu.of trigeminal nerve and tract lie on the anteromedial aspect of the inf. Cerebellar peduncle T/S THROUGH CAUDAL PART OF PONS •The trapezoid body is made up of fibers derived from the cochlear nuclei and the nuclei of trapezoid body •They run transversely in the ant. Part of the tegmentum •The basilar part of the pons at this level contain masses of nervr cells called pontine nuclei T/S THROUGH CAUDAL PART OF PONS •The axons of these cells give origin to the transverse fibers of the pons which cross the midline and intersect the corticospinal and corticonuclear tracts breaking them up into small bundles Loading… INTERNAL STRUCTURE OF CRANIAL PART OF PONS •The internal structure of the cranial part of pons is similar to that seen at the caudal level but contains the motor and principal sensory nuclei of the trigeminal nerve •The motor nu. Of the trigeminal nerve is situated beneath the lat. Part of the 4th ventricle within the reticular formation INTERNAL STRUCTURE OF CRANIAL PART OF PONS •The principal sensory nu. Of the trigeminal nerve is situated lateral to the motor nu. •The sup. Cerebellar peduncle is situated posterolat. To the motor nu. Of trigeminal nerve EXTERNAL FEATURES OF MIDBRAIN •Midbrain measures about 2cm in length and connects the pons and cerebellum with the forebrain •The midbrain is traversed by a narrow channel – the cerebral aqueduct ( which is filled with CSF) •On the posterior surface are four rounded eminences that are divided into superior and inferior pairs •The sup. Colliculi are centers for visual reflexes while the inf. Are lower auditory centers •In the midline below the inf. Colliculi emerges the trochlear nerves EXTERNAL FEATURES OF MIDBRAIN •Each colliculi is related to a ridge called brachium •The sup. Brachium passes from the sup. Colliculus to the lat. Geniculate body and the optic tract •The inf. brachium connects the inf colliculus to the medial geniculate body EXTERNAL FEATURES OF MIDBRAIN •On the anterior aspect of the midbrain is a deep depression in the midline called the interpeduncular fossa which is bounded on either side by the crus cerebri •Many blood vessels perforate the floor of the interpeduncular fossa and this region is termed the post. Perforated substance INTERNAL STRUCTURE OF MIDBRAIN •The midbrain is divided into two parts – •An upper tectum and •A lower part called cerebral peduncles •The upper part (tectum) contains mainly the colliculi of the two sides and represents the dorsal part of the midbrain •The cerebral peduncles are subdivided by the substantia nigra into •The tegmentum and •Crus cerebri STRUCTURE OF MIDBRAIN AT OF INF. COLLICULUS •The structures seen at this level include •Crus cerebri- this contain descending fibers from different parts of the cerebral cortex •The medial 1/6 contain frontopontine fibers •The intemediate 2/3 contain corticospinal and corticonuclear fibers •The lat. 1/6 contain temporopontine fibers •Other structures include •Substantia nigra •Cerebral aqueduct : this is surrounded by the central gray matter. •Ventral to this aqueduct is the oculomotor and trochlear nerves STRUCTURE OF MIDBRAIN AT OF INF. COLLICULUS •Reticular formation b/w the substantia nigra and gray matter •Inferior colliculus •Mesocephalic nu. Of trigeminal nerve •Compact bundle of fibers lies in the tegmentum dorsomedial to the substantia nigra •This bundle consistsof the medial lemniscus, trigeminal lemniscus and spinal lemniscus •Medial longitudinal fasciculus •Superior cerebellar peduncle •Rubrospinal tract Structure of midbrain at the level of sup. colliculus •The following structures are seen at this level •Sup. Colliculus in the tectum •Red nu. In the tegmentum dorsomedial to the substantia nigra •Oculomotor nuclei near the central gray matter •Bundles of ascending fibers consisting of medial lemniscus, spinal lemniscus and trigeminal lemniscus Structure of midbrain at the level of sup. colliculus •Dorsal tegmental decussation : this consists of fibers originating in the sup. Colliculus, it crosses to the opp. Side and descend as the tectospinal tract •Ventral tegmental decussation : this originates in the red nu

Medulla Oblongata

1. Medulla oblongata

Components and Functions of the Medulla Oblongata and Pons

Medulla Oblongata

3.2: Cenbral Lobes, Basal Nuclei, Diencephalon, Limbic System, Midbrain, Pons, Medulla Oblongata, & Cerebellum

Medulla oblongata

Nervous System is the body's decision and communication center. It is divided into two major divisions.- Central and Peripheral Nervous System. Central Nervous System It is made of the brain and the spinal cord. The brain is divided intro three parts: forebrain, midbrain and hindbrain. 1. Forebrain-consists of the cerebrum. thalamus and hypothalamus (part of the limbic system). 1. Cerebrum-or cortex is the largest part of the human brain. Associated with higher brain function such as thoughts and actions. It is divided into four sections: 1. Frontal Lobe-reasoning, planning, part of speech, movement, emotions and problem solving. 2. Temporal Love - associated with perception and recognition of auditory stimuli, memory and speech 3. Occipital Lobe- associated with visual processing. 4. Parietal Lobe associated with movement, orientation, recognition, perception of stimuli. 1. Right Hemisphere - is associated with creativity. 2. Left Hemisphere- is for logical abilities. 2. Limbic System often referred to as the "emotional brain". It is found buried within the cerebrum. 1. Thalamus-is a large mass of grey matter deeply situated in the forebrain; almost all sensory information enters this structure. 2. Hypothalamus - is involved in functions including homeostasis, emotion, thirst, hunger, arcadian rhythms and control of autonomic nervous system. It also controls the pituitary gland. 2. Midbrain consists of tectum and tegmentum. Also called mesencephalon, it involves functions such as vision, hearing, eye movement, and body movement. 3. Hindbrain consists of cerebellum, pons and medulla (brain stem). 1. Cerebellum-or the "little brain". Associated with regulation and coordination of movement, posture and balance. 2. Pons-it is involved in motor control and sensory analysis. It has parts that are important for the level of consciousness and for sleep. 3. Brain Stem (Medulla Oblongata)-underneath the limbic system, this structure is responsible for breathing. heartbeat, blood pressure, etc

Opt 113 final: brainstem (overview, medulla oblongata)

Medulla Oblongata (Bulbus)

Chapter 7: Biological Bases: The Brain and Nervous System