SEQ SEM 2

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Questions and Answers

What is the role of the precentral gyrus?

Control movement of muscles.

What is the Brodmann area associated with the primary motor cortex?

BA 4

What is the function of the supplementary motor cortex?

To program the sequence and coordination of movement.

Where is the premotor cortex located?

Posterior parts of the superior, middle, and inferior frontal gyri. Signup and view all the answers

The frontal eye field is responsible for moving the eyes to the same side.

False Signup and view all the answers

What is impedance matching?

Transference of energy from air to fluid to overcome sound energy loss. Signup and view all the answers

What are the components of the auditory pathway?

Cochlear nerves, dorsal and ventral cochlear nuclei, trapezoid body, inferior colliculus, medial geniculate body, primary auditory cortex. Signup and view all the answers

Describe the origin and course of the corticospinal tract.

Begins at the cerebral cortex, converges in the corona radiata, passes through the posterior limb of the internal capsule, midbrain, pons, and forms a pyramid at the medulla oblongata. Signup and view all the answers

List the differences between the autonomic nervous system and the somatic nervous system.

ANS is involuntary, has two neurons per pathway, and controls smooth muscle, whereas SNS is voluntary, has one neuron per pathway, and controls skeletal muscle. Signup and view all the answers

What are the components of the diencephalon?

Thalamus, hypothalamus, epithalamus, subthalamus. Signup and view all the answers

What is the function of the thalamus?

Sensory and motor relay station. Signup and view all the answers

What is the classification of sensory receptors?

Mechanoreceptors, thermoreceptors, chemoreceptors, photoreceptors, nociceptors. Signup and view all the answers

What are the components of the reflex arc?

Receptor, sensory neuron, integration center, motor neuron, effector. Signup and view all the answers

What stimulates the activation of peripheral chemoreceptors?

Low PaO2 below 60mmHg, high PaCO2. Signup and view all the answers

What is the process of iodide trapping in thyroid hormone production?

Iodide is actively transported from blood into the follicular cell by the Na/I symporter. Signup and view all the answers

What occurs during the oxidation of iodide?

Iodide is oxidized to iodine (I2). Signup and view all the answers

Match the thyroid hormones with their respective production steps:

T3 = MIT + DIT T4 = DIT + DIT MIT = I2 + Tyrosine DIT = MIT + I2 Signup and view all the answers

What are the physiological effects of thyroid hormone on the central nervous system?

<ol> <li>Cause normal development of growth & activity of CNS, 2. Stimulate branching of dendrites, 3. Stimulated myelination, 4. Increase number of synapses.</li> </ol> Signup and view all the answers

List four clinical features of hyperthyroidism.

<ol> <li>Goiter, 2. Fatigue, 3. Tremors, 4. Bulging eyes.</li> </ol> Signup and view all the answers

List three differences between T3 and T4.

Affinity to plasma protein = T3: Less, easy to release; T4: Greater Half-life = T3: 10-24 hours; T4: 7 days Acting = T3: More rapid; T4: Slower Signup and view all the answers

What are two advantages of using radioactive iodine?

<ol> <li>Easy to administer, 2. Effective.</li> </ol> Signup and view all the answers

What is the role of enzymes in the regulation of metabolism?

All of the above Signup and view all the answers

Describe the four groups of glycolipids.

<ol> <li>Triglycerides, 2. Phospholipids, 3. Steroids, 4. Waxes.</li> </ol> Signup and view all the answers

List the steps in de novo synthesis of fatty acids.

<ol> <li>Conversion of glucose to Acetyl-CoA, 2. Acetyl-CoA converted to Malonyl-CoA, 3. Malonyl-CoA used to build up fatty acid chain by adding 2 carbon units.</li> </ol> Signup and view all the answers

List three raw materials needed in fatty acid synthesis.

<ol> <li>Acetyl-CoA, 2. Malonyl-CoA, 3. NADPH.</li> </ol> Signup and view all the answers

Describe the mechanism of suckling reflex.

<ol> <li>Stimulation of pressure receptors in the nipple by suckling from the baby, 2. Afferent impulse to the hypothalamus, 3. Release of oxytocin from the posterior pituitary, 4. Milk ejection occurs.</li> </ol> Signup and view all the answers

What is the location of hormone receptors?

<ol> <li>In or on the surface of cell membranes, 2. In the cell cytoplasm, 3. In the nucleus.</li> </ol> Signup and view all the answers

What is the effect of insulin on blood glucose levels?

<ol> <li>Increases glucose transport and uptake to cells, 2. Promotes glycogenesis, 3. Inhibits gluconeogenesis.</li> </ol> Signup and view all the answers

Describe the hypothalamus-pituitary-gonadal axis in ovarian regulation.

<ol> <li>Hypothalamic GnRH stimulates FSH and LH secretion, 2. FSH and LH stimulate follicular growth, 3. Rising estrogen levels suppress GnRH, FSH, and LH secretion, 4. Feedback mechanisms regulate the cycle.</li> </ol> Signup and view all the answers

What occurs during the secretion of insulin from β-cells?

<ol> <li>Glucose enters β-cells, 2. ATP closes K+ channels causing depolarization, 3. Ca2+ influx triggers insulin exocytosis.</li> </ol> Signup and view all the answers

List the stages of aldosterone hormone synthesis.

<ol> <li>Cholesterol -> Progesterone -> Deoxycorticosterone -> Corticosterone -> Aldosterone.</li> </ol> Signup and view all the answers

What is the mechanism of diabetic ketoacidosis?

<ol> <li>Increased synthesis of acetoacetic acid and β-hydroxybutyric acid, 2. Starts buffering, 3. Leads to metabolic acidosis.</li> </ol> Signup and view all the answers

Describe the mechanism of action of hormones.

<ol> <li>Hormone binds to specific receptors, 2. Activation, 3. Signal transduction, 4. Amplification, 5. Cellular response, 6. Termination.</li> </ol> Signup and view all the answers

Describe the sequence of events during excitation-contraction coupling.

<ol> <li>Action potential enters adjacent cell 2. Voltage-gated ion channel opens, Ca2+ enter cell 3. Ca2+ induces Ca2+ release through RyR 4. Local release causes Ca2+ sparks 5. Summed Ca2+ sparks create Ca2+ signal 6. Ca2+ ion bind to troponin to initiate contraction 7. Relaxation occurs when Ca2+ unbinds from troponin 8. Ca2+ pumped back into SR for storage 9. Ca2+ is exchanged with Na+ by NCX antiporter 10. Na+ gradient is maintained by Na+K+ATPase.</li> </ol> Signup and view all the answers

Describe the sequence of events that occur during neuromuscular transmission.

<ol> <li>Action potential arrives at the motor neuron/axon 2. Opening of voltage-gated calcium channel 3. Calcium ion influx to the terminal 4. Fusion of vesicles to presynaptic membrane 5. Triggers an increase in exocytosis - release ACh into the cleft 6. Acetylcholine binds with the nicotinic acetylcholine receptor (postsynaptic) at the junctional fold of motor end plate 7. Opening of ligand gated channel – increased Na+ conductance 8. End plate potential is generated 9. Exceeds the threshold causing action potential generated over muscle fibre surface and along T-tubules 10. Muscle contraction occurs.</li> </ol> Signup and view all the answers

What are the four mechanical properties of skeletal muscle related to contractility?

<ol> <li>Refers to muscular stiffening followed by death 2. Shortening of muscle tissue and stiffening of body parts 3. Muscle cell membrane becomes more permeable to Ca2+ 4. Intracellular Ca2+ increases.</li> </ol> Signup and view all the answers

Briefly explain rigor mortis.

<ol> <li>Muscles stiffen after death due to a lack of ATP 2. Ca2+ binds to troponin C and cross-bridge occurs 3. After death, cross-bridge will lock muscles in place.</li> </ol> Signup and view all the answers

Describe the sliding filament theory of skeletal muscle contraction.

<ol> <li>Actin filaments slide toward the center of the sarcomere 2. Myosin remains stationary 3. Myosin head binds to its binding site on actin - crossbridge 4. Thin filament slides toward each other 5. During contraction, the sarcomere shortens, thick and thin filaments overlap 6. Causes the whole muscle to contract.</li> </ol> Signup and view all the answers

What is the role of calcium ions in skeletal muscle contraction and relaxation?

<ol> <li>Cause release of Ca2+ from SR 2. Bind to troponin 3. Cause conformational changes in troponin-tropomyosin complex 4. Expose the myosin binding site.</li> </ol> Signup and view all the answers

State 2 roles of ATP during muscle contraction.

<ol> <li>To break the cross-bridge 2. To transport Ca2+ back to SR.</li> </ol> Signup and view all the answers

Describe calcium homeostasis.

<ol> <li>Vitamin D 2. Parathyroid hormone.</li> </ol> Signup and view all the answers

Describe the steps of glycogenolysis.

<ol> <li>Shortening of chains - glycogen phosphorylase cleaves a(1-4) glycosidic bond 2. Removal of branches - block of 3 glucose transferred to other branch, remove a(1,6) linkages and glucose unit released 3. Conversion of G1P to G6P - released into bloodstream to maintain blood glucose level.</li> </ol> Signup and view all the answers

Add a note on the regulation of glycogenolysis.

<ol> <li>Hormonal (phosphorylation/dephosphorylation) - glycogen phosphorylase is active if phosphorylated, causes secretion of glucagon/epinephrine in low BGL/stress & exercise 2. Allosteric (by effector muscle) - allows rapid effect hormone-mediated covalent regulation.</li> </ol> Signup and view all the answers

State the joints of the lower limb.

Hip, knee, ankle, and joint of foot. Signup and view all the answers

Describe the hip joint articulation.

<ol> <li>Between head of femur and acetabulum of pelvic bone 2. Ball and socket & synovial joint 3. Articular surface of hip joint - lunate surface of acetabulum and head of femur - transverse acetabular ligament.</li> </ol> Signup and view all the answers

Describe the knee joint articulation.

<ol> <li>Hinge joint – synovial 2. Flexion-extension, small degree of rotation 3. Have medial & lateral menisci, which act as shock absorbers.</li> </ol> Signup and view all the answers

Describe the ankle joint articulation.

<ol> <li>Hinge synovial joint 2. Dorsiflex and plantarflex of the foot.</li> </ol> Signup and view all the answers

Describe the role of uncouplers in oxidative phosphorylation.

<ol> <li>Compounds that uncouple the ETC and phosphorylation 2. Causes electron transfer to proceed at rapid rates without establishing a proton gradient 3. Heat is produced rather than ATP.</li> </ol> Signup and view all the answers

List 4 uncouplers of oxidative phosphorylation.

<ol> <li>2,4-Dinitrophenol 2. Gramicidin 3. Valinomycin 4. Salicylates.</li> </ol> Signup and view all the answers

Describe the peripheral chemoreceptors in the respiratory system.

They are located at the carotid bodies and aortic arch, contain glomus cells, respond to low PaO2, high PaCO2, and low arterial pH, release catecholamines, excite nerve endings, and increase ventilation. Signup and view all the answers

Match the following structures with their respective functions related to peripheral chemoreceptors:

Glomus cells = Stimulated by low PaO2, high PaCO2, and low arterial pH Afferent nerves = Transmit signals to increase ventilation Catecholamines = Released by glomus cells K+ channel = Sensitive to O2 levels, closes during hypoxia Signup and view all the answers

Explain the mechanism in peripheral chemoreceptors.

Hypoxia causes closure of O2 sensitive K+ channels, leading to depolarization of glomus cells, opening of voltage-gated Ca2+ channels, Ca2+ influx, and release of neurotransmitter dopamine, resulting in nerve stimulation and increased ventilation. Signup and view all the answers

List the medullary respiratory centers.

Dorsal respiratory group (DRG) and Ventral respiratory group (VRG). Signup and view all the answers

List the pontine respiratory centers.

Pneumotaxic center and Apneustic center. Signup and view all the answers

Explain the Herring-Breuer reflex.

It is a reflex involving pulmonary stretch receptors that prevents over-inflation of the lung by inhibiting inspiratory neurons in the DRG and VRG, leading to an increased respiratory rate. Signup and view all the answers

Describe the right lung.

The right lung has four impressions on the mediastinal surface and specific relations to the hilum. Signup and view all the answers

Describe the HCO3- buffer system in acid-base homeostasis.

The HCO3- buffer system helps maintain pH balance by neutralizing acids in the blood. Signup and view all the answers

Briefly describe the nasal septum regarding its structure, arterial supply, and innervation.

The nasal septum is a cartilage and bone structure that divides the nasal cavity, supplied by the sphenopalatine artery and innervated by the nasopalatine nerve. Signup and view all the answers

What are the types of anti-asthma drugs and their respective functions?

Leukotriene modifiers Signup and view all the answers

What are the benefits of oral route drug administration?

Oral administration is convenient, non-invasive, and generally safer with fewer complications compared to other routes. Signup and view all the answers

Define bronchopulmonary segment.

A bronchopulmonary segment is a functionally independent region of the lung supplied by a specific bronchus and its accompanying blood vessels. Signup and view all the answers

List the names of bronchopulmonary segments.

Right lung: Upper lobe (3 segments), Middle lobe (2 segments), Lower lobe (5 segments); Left lung: Upper lobe (4 segments), Lower lobe (5 segments). Signup and view all the answers

What is the position of pulmonary vessels and bronchus in bronchopulmonary segments?

Pulmonary vessels and bronchus are positioned at the hilum and follow a specific branching pattern within each segment. Signup and view all the answers

What is the significance of bronchopulmonary segments?

Bronchopulmonary segments allow for the understanding of lung function and aid in surgical interventions. Signup and view all the answers

Describe the applied anatomy of bronchopulmonary segments.

Knowledge of segments assists in surgical resections, such as lobectomies, and targeting specific areas for disease. Signup and view all the answers

State three predisposing factors of tuberculosis (TB).

Immunosuppression, poverty, and close living conditions. Signup and view all the answers

Describe the formation of granuloma.

Granulomas form in response to chronic inflammation, characterized by macrophages clustering and transforming into epithelioid cells, often surrounded by lymphocytes. Signup and view all the answers

What is the function of CD4 T cells in tuberculosis?

CD4 T cells help orchestrate the immune response against TB by activating macrophages. Signup and view all the answers

Describe the oxygen dissociation curve.

The oxygen dissociation curve shows how hemoglobin saturation changes with varying oxygen pressures, illustrating its affinity for oxygen. Signup and view all the answers

Define hypercapnia.

Hypercapnia is an increase in carbon dioxide (CO2) levels in the blood. Signup and view all the answers

Define hypercarbia.

Hypercarbia refers to elevated CO2 levels in the bloodstream, synonymous with hypercapnia. Signup and view all the answers

Define the Bohr effect.

The Bohr effect describes how increased CO2 and decreased pH reduce hemoglobin's oxygen affinity, facilitating oxygen release to tissues. Signup and view all the answers

Which types of cartilage are found in the larynx?

Hyaline cartilage Signup and view all the answers

What roles do the recurrent laryngeal nerves and external laryngeal nerves have?

The recurrent laryngeal nerve supplies motor function to all intrinsic muscles except the cricothyroid, which is supplied by the external laryngeal nerve. Signup and view all the answers

What happens when the recurrent laryngeal nerve is cut during thyroidectomy?

The affected vocal cord becomes fixed in a paramedian position, leading to hoarseness of voice. Signup and view all the answers

What happens if both recurrent laryngeal nerves are cut?

Both vocal cords become fixed in a paramedian position, resulting in aphonia and difficulty in respiration. Signup and view all the answers

Describe Semon's law regarding recurrent laryngeal nerve paralysis.

It states that a slow-growing tumor compresses the recurrent laryngeal nerve causing paralysis of abductors first, followed by other muscles. Signup and view all the answers

Study Notes

Excitation-Contraction Coupling

Action potential travels along adjacent muscle cells.
Voltage-gated calcium channels open, allowing Ca2+ entry into the cell.
Ca2+ release is induced via Ryanodine receptors (RyR) on the sarcoplasmic reticulum (SR).
Localized Ca2+ release generates Ca2+ sparks.
Summation of these sparks produces a cellular Ca2+ signal.
Calcium binds to troponin, initiating muscle contraction.
Muscle relaxation occurs when Ca2+ detaches from troponin.
Ca2+ is actively pumped back into SR for storage, requiring ATP.
Na+/Ca2+ exchange occurs via NCX antiporter.
Na+ gradient maintained by Na+/K+ ATPase.

Neuromuscular Transmission

Action potential reaches the motor neuron, triggering voltage-gated Ca2+ channels.
Calcium influx into the terminal promotes vesicle fusion and exocytosis of acetylcholine (ACh).
ACh binds to nicotinic receptors on the motor end plate, increasing Na+ conductance.
End plate potential is generated, leading to action potential in muscle fibers.
Muscle contraction is initiated following action potential propagation.

Mechanical Properties of Skeletal Muscle

Rigor mortis happens post-mortem due to muscle stiffening from lack of ATP.
Muscle cells become highly permeable to Ca2+, causing contractions despite death.
Ca2+ binds to troponin, establishing cross-bridge interactions.

Sliding Filament Theory

Actin filaments slide toward the center of sarcomere during contraction, while myosin heads pivot.
Myosin heads attach to binding sites on actin, forming strong cross-bridges.
During contraction, sarcomere shortens, increasing overlap of thick and thin filaments.

Role of Calcium in Muscle Contraction and Relaxation

Calcium triggers release from the sarcoplasmic reticulum.
It binds to troponin, exposing myosin-binding sites on actin.
This leads to muscle contraction, while removal of calcium results in relaxation.

Role of ATP in Muscle Contraction

ATP is necessary for cross-bridge detachment between actin and myosin.
It is also required for Ca2+ transport back into the sarcoplasmic reticulum.
ATP maintains resting membrane potential and sustains cross-bridge cycling as long as binding sites remain open.

Calcium Homeostasis

Vitamin D plays a crucial role in maintaining calcium levels.
Parathyroid hormone regulates calcium release and storage in bones.

Glycogenolysis Steps

Glycogen phosphorylase cleaves α(1-4) bonds for glycogen chain shortening.
Branches are removed by transferring glucose units and breaking α(1,6) linkages.
Glucose-1-phosphate (G1P) is converted to glucose-6-phosphate (G6P) for bloodstream release to maintain glucose levels.

Regulation of Glycogenolysis

Hormonal regulation occurs via phosphorylation; glycogen phosphorylase is activated by phosphorylation.
Glucagon and epinephrine are secreted during low blood glucose levels or stress.
Allosteric regulation allows rapid hormonal effects on glycogen metabolism.

Lower Limb Joints

Key joints include hip, knee, ankle, and foot joints.
Hip joint: ball-and-socket articulation; strengthened by iliofemoral, pubofemoral, and ischiofemoral ligaments, with blood supply from medial/lateral circumflex arteries.
Knee joint: hinge joint; features medial/lateral menisci; supported by ligaments preventing excessive movement.
Ankle joint: hinge joint allowing dorsiflexion and plantarflexion, stabilized by medial and lateral deltoid ligaments.
Foot joints: plane synovial joints facilitating inversion and eversion; supported by talocalcaneonavicular and metatarsophalangeal joints.

Motor Unit

A motor unit consists of a motor neuron and the muscle fibers it innervates.

Chemiosmotic Theory in Oxidative Phosphorylation

Electron transport chain functions as a proton pump, creating an electrochemical gradient.
Uncouplers disrupt ATP synthesis while allowing electron transport to occur without proton gradient formation, producing heat instead of ATP.
Uncouplers include 2,4-Dinitrophenol, Gramicidin, Valinomycin, and Salicylates.

Neck and Carotid Triangle

Triangle of neck boundaries includes sternocleidomastoid muscle, mandible, and midline.
Carotid triangle contains carotid artery and associated vessels, particularly important for circulatory function.

Cubital Fossa

Boundaries and contents related to the elbow joint, crucial for arm movement and function.

Brachial Plexus

Formed by spinal nerves C5-T1; involved in innervating upper limb muscles.
Divides into roots, trunks, divisions, cords, and branches facilitating upper limb movement.### Differences Between T3 and T4
T3 has a lower affinity to plasma proteins compared to T4, making T3 easier to release.
T3 has a shorter half-life of 10-24 hours, whereas T4 has a half-life of about 7 days.
T3 acts more rapidly than T4, which has a slower action.

Iodides

Iodides inhibit hormone release.

Advantages of Radioactive Iodine

Easy to administer.
Effective treatment option.
Painless procedure.

Drugs Used in Thyroid Storm Treatment

Propranolol (a beta blocker).
Iodide.

Regulation of Blood Glucose

In fasting state, glycogenolysis breaks down glycogen into glucose, gluconeogenesis produces glucose from non-carbohydrate sources, and lipolysis breaks down triglycerides into free fatty acids and glycerol.
Insulin facilitates glucose uptake in tissues to prevent excessive blood glucose levels.
In post-prandial state, insulin is secreted in response to elevated blood glucose levels, stimulating glucose uptake and lipogenesis.

Role of Enzymes in Metabolism Regulation

Enzyme cascades amplify regulatory signals by activating multiple enzymes.
Product inhibition occurs when high product concentrations inhibit enzyme activity.
Sub-cellular compartmentalization depends on the availability of substrates regulated by cell membranes.
Allosteric interactions involve enzymes binding to activators or inhibitors to modulate pathway activity.
Feedback inhibition reduces the activity of a regulatory enzyme when the end product binds to it.

Groups of Glycolipids

Triglycerides.
Phospholipids.
Steroids.
Waxes.

Steps in De Novo Synthesis of Fatty Acids

Conversion of glucose to Acetyl-CoA.
Conversion of Acetyl-CoA to Malonyl-CoA.
Malonyl-CoA builds fatty acid chains by adding 2-carbon units, leading to long-chain fatty acid and triglyceride formation.

Raw Materials Needed for Fatty Acid Synthesis

Acetyl-CoA.
Malonyl-CoA.
NADPH.

Mechanism of Suckling Reflex

Pressure receptors in the nipple are stimulated by suckling.
Afferent impulses travel to the hypothalamus, activating the release of oxytocin from the posterior pituitary.
Oxytocin stimulates breast contractions for milk ejection.
Positive feedback continues until suckling stops.

Location of Hormone Receptors

In or on the cell membrane.
In the cytoplasm.
In the nucleus.

Mechanism of Hormone Action

Hormone binds to a specific receptor, activating it and triggering signal transduction.
Amplification of the signal leads to a cellular response, followed by termination of the signal.

Effect of Insulin on Blood Glucose

Increases glucose transport and uptake into cells.
Promotes glycogenesis and inhibits gluconeogenesis.
Stimulates fatty acid synthesis and inhibits lipolysis.
Facilitates amino acid uptake and increases protein synthesis.

Hypothalamus-Pituitary-Gonadal Axis in Ovarian Function Regulation

GnRH from the hypothalamus stimulates FSH and LH secretion.
FSH and LH stimulate follicular growth and estrogen release.
Rising estrogen levels suppress GnRH, FSH, and LH, creating a feedback loop.
Sudden LH surge triggers ovulation, leading to corpus luteum formation.

Insulin Secretion Mechanism by Islets of Langerhans

Glucose is taken up by beta cells through GLUT2.
Glycolysis of glucose produces ATP, leading to the closure of ATP-sensitive K+ channels.
Membrane depolarization opens voltage-sensitive Ca2+ channels, increasing intracellular calcium and stimulating insulin secretion via exocytosis.

Adrenal Gland Hormones

Medulla produces norepinephrine (NE) and epinephrine (E) classified as catecholamines.
Cortex produces aldosterone (mineralocorticoid), cortisol (glucocorticoid), and androgens (sex hormones).

Aldosterone Synthesis and Effects

Synthesized through a sequence converting cholesterol to aldosterone.
Regulates blood pressure by activating RAAS, increasing sodium and water reabsorption in kidneys, and managing potassium levels.

Process of Ketogenesis

Production of ketones occurs during periods of low insulin or fasting, increasing acetoacetate and β-hydroxybutyric acid.
Leads to metabolic acidosis due to the accumulation of ketone bodies.

Synaptic Transmission

Synapse connects neurons, categorized into chemical, electrical, and mixed types.
Presynaptic depolarization triggers calcium influx, neurotransmitter release, and binding to postsynaptic receptors.

Differences Between EPSP and IPSP

EPSP causes depolarization, increasing likelihood of action potential firing; IPSP causes hyperpolarization, decreasing likelihood of firing.
EPSP opens sodium or calcium channels; IPSP opens chloride or potassium channels.

Properties of Synapse

Unidirectional flow of signals.
Synaptic delay occurs during transmission.
Summation occurs either temporally or spatially, affecting transmission intensity.

Auditory Pathway Description

Sound waves are directed through the ear structure to stimulate hair cells in the cochlea.
Afferent cochlear nerves transmit signals to the medulla, then to higher processing centers in the brain.

Impedance Matching Mechanism

Overcomes sound energy loss transitioning from air to fluid; involves the area difference between the tympanic membrane and oval window to enhance sound transfer efficiency.### Auditory Pathway
Bending towards the kinocilium opens K+ channels, leading to depolarization and generation of action potentials.
Bending away from the kinocilium closes K+ channels, causing hyperpolarization and no action potential, which results in no sound perception.
Depolarization opens Ca2+ channels in the presynaptic hair cells.
Calcium influx triggers the release of neurotransmitters, producing an excitatory postsynaptic potential (EPSP).
Action potentials propagate via afferent cochlear nerves to the auditory cortex, enabling sound perception.

Corticospinal Tract

Originates from the cerebral cortex.
Fibers converge in the corona radiata and traverse the posterior limb of the internal capsule (IC).
Fibers near the genu innervate cervical regions; those further down innervate lumbar and sacral levels.
Passes through the middle third of the crus cerebri in the midbrain.
Corticospinal tract breaks into bundles within the pons forming pontine nuclei.
At the medulla oblongata, these fibers form the pyramids.
Fibers cross the midline at the decussation of the pyramids to form the lateral corticospinal tract (LCST).
LCST enters the lateral white column of the spinal cord and terminates at the anterior gray horn in cervical, thoracic, lumbar, and sacral regions.
Uncrossed fibers form the anterior corticospinal tract (ACST), which enters the anterior white column, crosses at the anterior white commissure, and terminates in the anterior gray horn.

Lateral Spinothalamic Tract

Axons enter the spinal cord through the dorsal root ganglion.
Ascend or descend 1-2 segments via the tract of Lissauer.
First-order axons synapse in the posterior gray column.
Second-order axons cross at the anterior white commissure and ascend as the lateral spinothalamic tract (LSPT).
LSPT passes through the brainstem, alongside the anterior spinothalamic tract and spinotectal tract, forming the spinal lemniscus.
Ascends through the posterior part of the pons and the tegmentum of the midbrain.
Second-order neurons synapse in the ventral posterolateral nucleus (VPL) of the thalamus.
Third-order neurons project to the somatosensory area in the postcentral gyrus via the posterior limb of the internal capsule and corona radiata.

Anterior Spinothalamic Tract

Axons enter the spinal cord through the posterior root ganglion.
Ascends or descends 1-2 segments through the post-lateral tract of Lissauer.
Axons synapse with second-order neurons in the posterior gray column.
Second-order axons cross to the anterior gray horn and anterior white commissure.
Ascend in the anterolateral white column as the anterior spinothalamic tract (ASPT).
Travels through the medulla oblongata, accompanying LSPT and spinotectal to form the spinal lemniscus.
Ascends through the pons and tegmentum of the midbrain.
Synapses with third-order neurons in the VPL of the thalamus, proceeding to the postcentral gyrus.

Autonomic Nervous System (ANS)

Divided into sympathetic and parasympathetic systems.
Autonomic nervous system controls smooth muscle, glands, and viscera; somatic nervous system controls skeletal muscle.
ANS operates involuntarily whereas SNS functions voluntarily.
ANS sensory input is subconscious; SNS input is consciously perceived.
ANS consists of a two-neuron system while SNS has one neuron.
ANS uses acetylcholine and norepinephrine; SNS primarily uses acetylcholine.

Diencephalon Components

Comprised of thalamus, hypothalamus, epithalamus, and subthalamus.
Thalamus serves as a sensory and motor relay station.
Anatomical classification of thalamic nuclei:
- Anterior group: Anterior nucleus
- Medial group: Medial dorsal nucleus
- Lateral group: Contains ventral tier (VA, VL, VP) and dorsal tier (LD, LP, pulvinar)
- Geniculate body: Medial (MG) and Lateral (LG) geniculate nuclei.

Hypothalamus Nuclei

Divided into preoptic, supraoptic, tuberal, and mammillary regions.
Preoptic nucleus regulates reproductive behaviors; supraoptic nuclei manage water balance.

Sensory Receptors

Defined as specialized cells responding to specific stimuli.
Classifications include photoreceptors (e.g., rods and cones), mechanoreceptors (e.g., touch receptors), thermoreceptors (temperature), and chemoreceptors (taste and smell).
Characteristics of receptors include specificity, adaptability, sensitivity, and transduction capability.

Reflexes

Reflexes are involuntary responses to specific stimuli.
Components of the reflex arc include the receptor, sensory neuron, integration center, motor neuron, and effector.
Flexor withdrawal reflex protects the body from harmful stimuli by automatically withdrawing a limb.

Olfactory Transduction Pathway

Odorant molecules bind to olfactory receptors.
Receptor activation leads to G-protein signaling cascade.
Adenylate cyclase converts ATP to cAMP, resulting in ion channel opening.
Sodium influx causes depolarization, generating action potentials.
Signal transmits along the axon of the olfactory sensory neuron to the olfactory bulb for processing.

Chemical Regulation of Respiration

The brainstem regulates respiration based on sensory input regarding PCO2, arterial pH, and PO2 levels.
Central chemoreceptors respond to changes in CSF pH, stimulating increased ventilation when pH drops.
Peripheral chemoreceptors located in carotid and aortic bodies detect decreased PaO2, increased PaCO2, and decreased arterial pH and release catecholamines to increase ventilation.

Medullary and Pontine Respiratory Centers

Medullary centers include the dorsal respiratory group (DRG) and Ventral respiratory group (VRG).
Pontine centers consist of the pneumotaxic center and apneustic center, which help regulate normal breathing rhythms.

HCO3- Buffer System in Acid-Base Homeostasis

Composed of carbonic acid and bicarbonate ions, crucial for maintaining pH balance in extracellular fluid (ECF).
Activated rapidly to counteract fluctuations in acid-base levels.
Primarily regulated through respiratory and renal mechanisms.

Bronchopulmonary Segment

Defined as a functional division of the lung containing bronchi and blood vessels.
Comprised of distinct named segments, each supplied by its own bronchus and blood vessel, allowing for localized treatment in pulmonary medicine.

Tuberculosis (TB) Factors and Immune Response

Predisposing factors for TB include compromised immune systems, environmental exposure, and genetic predisposition.
Granuloma formation serves as an immune response to isolate the infection, typically involving CD4 T cells which help coordinate the immune response.

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This quiz focuses on the sequence of events during excitation-contraction coupling, essential for understanding muscle function. Test your knowledge about the action potential, ion channels, and calcium signaling in muscle cells. Perfect for exam preparation!