Renal SAQs PDF

RENAL SAQs ​ Structure & functions of nephron ○​ Structure: ​ Renal corpuscle → glomerulus, bowman’s capsule, filtration membrane ​ Renal tubule → proximal convoluted tubule, loop of henle, distal convoluted tubule, collecting duct ○​...

RENAL SAQs ​ Structure & functions of nephron ○​ Structure: ​ Renal corpuscle → glomerulus, bowman’s capsule, filtration membrane ​ Renal tubule → proximal convoluted tubule, loop of henle, distal convoluted tubule, collecting duct ○​ Functions: ​ Renal corpuscle → produce filtrate ​ Proximal convoluted tubule → reabsorb water, ions & all organic nutrients ​ Loop of henle → descending limb is to reabsorb water, ascending limb is to reabsorb sodium & chloride ions ​ Distal convoluted tubule → active secretions of hydrogen, potassium ions and drugs and toxins as well as sodium absorption with water in exchange for hydrogen & potassium ions (happens under aldosterone) ​ Collecting duct → reabsorbs water in presence of ADH, reabsorbs/ secretion of sodium, potassium, hydrogen & bicarbonate ions ​ *In summary renal tubule → changes composition of filtrate, eventually forming urine through renal absorption & secretion ​ Structure and function of kidney ○​ Structure: ​ Renal corpuscle → glomerulus, bowman’s capsule, filtration membrane ​ Renal tubule → proximal convoluted tubule, loop of henle, distal convoluted tubule, collecting duct ○​ Function: ​ Excretion → removal of organic waste products from body ​ Elimination → discharge waste products into environment ​ Homeostatic regulation ​ Regulation of volume & BP ​ Regulation of plasma concentrations of electrolytes/ ions ​ Helps in stabilisation of blood pH ​ Conservation of valuable nutrients such as glucose & amino acids ​ Production of active form of vit. D & produce strong bones ​ Steps in urine formation ○​ Ultrafiltration ​ Blood enters renal arteries & splits into numerous arterioles, leading to nephron ​ Arterioles splits into network of capillaries → glomerulus ​ High blood pressure in glomerulus present due to wider afferent arteriole and narrow efferent arteriole, results in forcing out of blood plasma and small molecules into bowman’s capsule.  ​ Basement membrane of glomerular blood capillaries has very small pores therefore only allowing water and small molecules like glucose to pass through → forms the filtrate (in bowman’s capsule) ​ Blood cells, platelets & large molecules such as fats remain in glomerulus ○​ Selective reabsorption ​ PCT → most useful substances like glucose, amino acids & vitamins absorbed through walls of nephron in surrounding capillaries of PCT ​ Most sodium & chloride ions, water reabsorbed. ​ Active transport of sodium & other ions into blood stream increases water potential in nephron → water leave nephron via osmosis ○​ Tubular secretion: ​ Waste products such as urea, uric acid, hydrogen and potassium ions secreted into the tubules from the blood stream ○​ Excretion: ​ Final urine collected in collecting ducts & moves to bladder for excretion ​ Normal waste products in urine ○​ UREA: ​ Most common organic waste ​ Produced during breakdown of amino acids ​ Value of 1800mg/dl in urine after urine analysis ○​ URIC ACID: ​ Produced during breakdown of RNA (ribonucleic acid) ​ Value of 40 mg/dl in urine ○​ CREATININE: ​ Produced in skeletal muscle from breakdown of creatine phosphate ​ Value of 150 mg/dl in urine ○​ IONS & ELECTROLYTES ​ Sodium & potassium ​ Helps to maintain homeostasis via water retention. Process is controlled by hormone aldosterone → increases sodium reabsorption in renal tubules ​ Value of 147.5 mEq/l and 47.5 Eq/ml respectively ENDOCRINE SAQs ​ Structure of adrenal gland & hormones ○​ Structure ​ Outer cortex:(yellowish) ​ Zona glomerulosa (outermost layer) ○​ Produces mineralocorticoids ​ Zona fasciculata ○​ Produces glucocorticoids ​ Zona reticularis (innermost layer) ○​ Narrow band next to medulla ○​ Produces small amount of gonadocorticoids ​ Inner medulla:(reddish) ​ Produces catecholamines ○​ Hormones ​ Mineralocorticoids ​ Aldosterone ​ Glucocorticoids ​ Cortisol, corticosterone & cortisone ​ Gonadocorticoids ​ Androgens ​ Catecholamines ​ Adrenaline ​ Noradrenaline ​ Structure of pituitary glands & hormones ○​ Structure ​ Anterior pituitary lobe ​ Posterior pituitary lobe ​ Hangs from hypothalamus by infundibulum ○​ Hormones ​ Anterior pituitary lobe (7) ​ Thyroid-stimulating hormone (TSH) ​ Adrenocorticotropic hormone (ACTH) ​ Follicle-stimulating hormone (FSH) ​ Luteinizing hormone (LH) ​ Prolactin (PRL) ​ Growth hormone (GH) ​ Melanocyte-stimulating hormone (MSH) ​ Posterior pituitary lobe (2) ​ Antidiuretic hormone (ADH) ​ Oxytocin (OXT) NERVOUS SYSTEM SAQs ​ Structure of neuron ○​ Cell body ​ Large round nucleus; prominent nucleolus ​ No centrioles → cannot divide, regenerate & be replaced if lost to injury/ disease ​ Numerous mitochondria → produce energy ​ Clusters of RER & ribosomes → produce neurotransmitters & form nissl bodies; make neural tissues appear grey (gray matter) ○​ Axon hillock ​ Thickened region near axon ​ Starting point for generation of action potential ○​ Dendrites ​ Many, short, branched ​ Sensitive to stimulation ○​ Axon ​ Single & long ​ Transmits electrical signal ​ Has branches (collaterals) ending in axon terminals → communicates with other cells via synapses ​ Classification of neuron ○​ Sensory neurons ​ Afferent neurons ​ Carries info from sensory receptors to CNS ​ Has 2 types ​ Somatic sensory neuron; monitor external environment ​ Visceral sensory neuron; monitor internal environment ○​ Motor neurons ​ Efferent neurons ​ Carries instructions from CNS to effectors ​ Has 2 types: ​ Somatic motor neurons; innervate skeletal muscles ​ Visceral motor neurons; innervate cardiac, smooth muscles & glands ○​ Interneurons ​ Located in brain & spinal cord ​ Connects sensory & motor neurons ​ Responsible for distribution of sensory info & coordination of motor activity  ​ Also involved in higher functions like memory, planning & learning ​ Structure of spinal cord segment ○​ Each spinal segment have pair of: ​ Dorsal roots ​ Contains axons of sensory neuron ​ Dorsal root ganglia ​ Contains cell bodies of sensory neurons ​ Ventral roots ​ Contains axons of CNS motor neurons ​ Spinal nerves (dorsal & ventral roots join distally) ​ Mixed nerves ​ Both sensory & motor fibres ○​ Gray matter ​ Contains neuron cell bodies ​ Has projections → gray horns) ○​ Gray commissures ​ Contains axons crossing 1 side of spinal cord to other ​ Connects horns on either side of spinal cord ○​ White matter ​ Superficial ​ Divided into 3 columns containing bundles of sensory & motor nerve fibres tracts → Posterior, anterior, lateral white columns ○​ Posterior gray horn ​ Sensory nuclei ○​ Anterior gray horn ​ Somatic motor nuclei ○​ Lateral gray horn ​ Found in only thoracic & lumbar segments ​ Contains visceral (autonomic) motor nuclei ​ Structure of synapse ○​ Presynaptic neuron ​ Sending side of synapse ​ Axon terminal holds vesicles containing neurotransmitters ​ Neurotransmitters released & diffuse across synaptic cleft ○​ Postsynaptic neuron ​ Receiving side of synapse ​ Has receptors for neurotransmitters ​ Events occurring @ synaptic transmission ○​ Action potential arrives & depolarizes axon terminal  ○​ Extracellular Ca2+ enters axon terminals & triggers exocytosis of acetylcholine (ACh) ○​ ACh diffuses across synaptic cleft ○​ Ach binds to receptors & triggers depolarisation of postsynaptic membrane ○​ Ach removed by AChE (acetylcholinesterase) ​ Divisions of autonomic nervous system ○​ Sympathetic division ​ Preganglionic fibres leave thoracic & lumbar spinal segments ​ Ganglia near spinal cord ​ Short preganglionic fibres (opp of parasympathetic) ​ Long postganglionic fibres ○​ Parasympathetic division ​ Preganglionic fibres originate in brain stem & sacral spinal region ​ Ganglia located near/ within target organs ​ Long preganglionic fibres ​ Short postganglionic fibres MCQ MISTAKES ​ RENAL SYSTEM ○​ Endocrine system not involved in the process of excretion ○​ Structure resting on superior pole of each kidney → adrenal gland ○​ Medulla → inner part of kidney containing pyramid-shaped sections ○​ Prominent indentation (concave shape, notch, small hollow) on medial surface of kidney → hilum ○​ Flow of blood vessels carrying blood to kidney ​ Renal artery → interlobar artery → arcuate artery → interlobular artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillary (venous drainage) ○​ Glomerulus → knot of capillaries lies within renal corpuscle ○​ 60-65% of water & virtually all nutrients, electrolytes & plasma proteins reabsorbed into blood at → PCT ○​ Loop of henle → sodium & chloride ions actively transported out of ascending limb ○​ Amount of sodium secreted by kidneys regulated by the hormone → aldosterone ​ Action of aldosterone on nephron results in retention of sodium ions ○​ Antidiuretic hormone (ADH) → increases permeability of collecting ducts to water ○​ Angiotensin II active hormone primarily affects nephrons, CNS & adrenal glands ○​ Process of filtration driven by → blood hydrostatic pressure ​ (hydrostatic pressure → pressure exerted by blood within glomerular capillaries; forces water & small solutes through filtration membrane.) ​ (osmotic pressure → works against filtration; pulls water back into capillaries) ○​ Urea passively reabsorbed in PCT → help maintain osmotic gradient in renal medulla, important for concentrating urine ○​ Major calyces → large branches of renal pelvis ​ ENDOCRINE SYSTEM ○​ The body's response to rising insulin levels in a healthy individual is increased production of glucose. → mechanism known as -ve feedback ○​ Hormone functions ​ Stimulate synthesis of an enzyme/ structural protein not already present in cytoplasm by activating appropriate genes in cell nucleus ​ increase/ decrease rate of synthesis of particular enzyme or other protein by changing rate of transcription/ translation ​ Turn existing enzyme on/ off by changing shape and structure ○​ Male’s hormones → androgens ​ Female hormones → progesterone & oestrogen ○​ Increased levels of parathyroid hormone lead to increased levels of calcium ion in blood ○​ Parathyroid hormone: ​ Stimulates formation & secretion of calcitriol @ kidneys ​ Stimulates osteoclast activity ​ Enhance reabsorption of calcium at kidneys ○​ If thyroid gland removed, parathyroid gland stays intact thus person will still be able to maintain and produce calcium via intact parathyroid glands ○​ Alpha cells of pancreas produce glucagon whereas beta cells produce insulin ○​ Pituitary tumour; produces too much growth hormone → growth hormone affects metabolism & blood sugar by increasing it → therefore person will become hyperglycemic (high blood sugar) ○​ Parathyroid hormones increases synthesis of vitamin D ○​ Follicle cells in ovary produce large quantities of oestrogen when stimulated by FSH. ​ NERVOUS SYSTEM ○​ Function of autonomic nervous system → provides involuntary regulation of smooth muscles, cardiac muscles & glands ○​ K+ ions move out of cells during repolarisation of propagation of action potential steps ○​ Continuous propagation of action potential is relatively slow and occurs in unmyelinated axons → must move step by step along entire length of axon. ​ Saltatory propagation of action potential is much faster and occurs in myelinated axons. ​ Function of nervous system ​ Coordinating voluntary & involuntary movement activities ​ Integrating sensory info ​ Providing sensation of internal & external environments ​ Once released, neurotransmitter molecules typically produce signals in postsynaptic neurons by binding to postsynaptic receptors ​ When action potential reaches axon terminal of presynaptic neuron → depolarisation takes place & intracellular environment becomes more +vely charged ​ Effect that neurotransmitter has on postsynaptic membrane → depends on characteristics of receptors ​ Acetylcholine stored in synaptic vesicles ​ Neurotransmitters released from synaptic knobs ○​ Neurons that have one axon & one dendrite called → bipolar ○​ Neurilemma (plasma membrane surrounding schwann cell of myelinated nerve fibre and separating layers of myelin) of axons in PNS formed by schwann cells ○​ If person suffers stroke the type of glial cell expected to be found in increased numbers in brain affected by stroke → microglia; helps to remove dead neurons, cellular debris & damages tissue, then deal w inflammation and repair ○​ Main steps in generation of an action potential ​ A graded depolarization brings an area of an excitable membrane to threshold. ​ Sodium channel activation occurs. ​ Sodium ions enter the cell and depolarization occurs. ​ Sodium channels are inactivated. ​ Voltage-regulated potassium channels open and potassium moves out of the cell, initiating repolarization. ​ Sodium channels regain their normal properties.  ​ A temporary hyperpolarization (inside of cell more -vely charged compared to outside of cell) occurs. ○​ Effect of tetradotoxin (toxin blocking chemically activated sodium channels from opening) → neuron would be unable to propagate action potentials ​ BRAIN ○​ Diencephalon links the cerebral hemispheres with the brain stem ○​ The pons contains tracts that link cerebellum with the brain stem ○​ Cerebellar hemispheres separated by band of cortex = vermis ○​ Pia mater → highly vascular & closely adheres to surface of brain ○​ Fourth ventricle associated with pons & upper medulla ○​ Subarachnoid space → contains delicate network of collagen & elastin fibres through which cerebrospinal fluid circulates ○​ CSF function: ​ Provide cushioning for delicate neural tissues ​ Provides buoyant support for brain ​ Acts as transport medium for nutrients ○​ Excess CSF returns to venous circulation ○​ In cerebrum ​ Gray matter known as cerebral cortex ​ Gray matter is thin outer layer ​ 2 hemispheres of cerebellum connected by corpus callosum ○​ Function of hypothalamus: ​ Adjusting of activities of autonomic centres in pons & medulla ​ Regulation of body temperature ​ Behavioural drives associated w thirst centre & hunger centre ○​ Inferior border of frontal lobe marked by lateral sulcus ○​ Primary motor cortex located in precentral gyrus ○​ Cannot move right arm → stroke damage in left frontal lobe ○​ Regulation of autonomic function eg HR, BP → originates in medulla oblongata ○​ Meningeal layer adhering to surface contour of brain, extending into every fold & curve → pia mater ○​ Diagnosing bacterial & viral infections of nervous system, sample of CSF extracted for analysis from subarachnoid space. ​ Dura mater does not have CSF circulating around it ​ CSF only found in subarachnoid space below not in arachnoid mater ​ Epidural space only used for administration of epidural not extraction of CSF ○​ Small veins of brain empty into dural sinuses ​ SPINAL CORD ○​ Specialised membrane protecting spinal cord → spinal meninges ○​ Ventral root of spinal nerve contains axons of motor neurons ○​ Stretch reflex → activated when skeletal muscle shortens ○​ Spinal cord is shorter in relation to vertebral column ○​ Anterior horns of spinal cord contain somatic (relating to body as distinct from the mind) motor nuclei ○​ Only 12 pairs of cranial nerves but 31 pairs of spinal nerves ○​ Facial nerve and glossopharyngeal nerve innervates tongue for taste purposes ○​ Oculomotor nerve, Trochlear nerve and abducens nerve innervates extrinsic muscles of the eye ○​ Oculomotor nerve, facial nerve, glossopharyngeal nerve and vagus nerve contains additional parasympathetic autonomic fibres ○​ Damage of vagus nerve results in death ○​ Lateral horns of T1-L2 contains cell bodies of autonomic (voluntary/ involuntary) motor neurons ○​ Virus infecting dorsal root ganglia causes painful rash whose distribution corresponds to that of affected sensory nerve → shingles ○​ Flexor reflex → moves limb away from painful stimulus ○​ Tapered inferior end of spinal cord → conus medullaris ○​ Layer of meninges tightly bound to surface of neural tissue → pia mater ○​ Subdural space separated dura mater from arachnoid mater ○​ Epidural space contains CT & blood vessels ○​ Damage to spinal accessory nerve → dysfunction to sternocleidomastoid muscle