Edexcel IAL Biology A-level: Kidneys and Osmoregulation Flashcards PDF

Edexcel IAL Biology A-level 7.18-7.22 - The Kidneys, Osmoregulation and DNA Control Flashcards PMT Education is licensed under https://bit.ly/pmt-cc This work by https://bit.ly/pmt-edu-cc CC BY-NC-ND 4.0...

Edexcel IAL Biology A-level 7.18-7.22 - The Kidneys, Osmoregulation and DNA Control Flashcards PMT Education is licensed under https://bit.ly/pmt-cc This work by https://bit.ly/pmt-edu-cc CC BY-NC-ND 4.0 https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the gross structure of a mammalian kidney https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the gross structure of a mammalian kidney Fibrous capsule: protects kidney Cortex: outer region consists of Bowman’s capsules, convoluted tubules, blood vessels Medulla: inner region consists of collecting ducts, loops of Henle, blood vessels https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the structure of a nephron A: Glomerulus B: Bowman’s capsule C: Proximal convoluted tubule D: Collecting duct E: Afferent arteriole F: Efferent arteriole G: Loop of Henle H: Distal convoluted tubule https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the blood vessels associated with a nephron https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the blood vessels associated with a nephron Wide afferent arteriole from renal artery enters renal capsule & forms glomerulus: branched knot of capillaries which combine to form narrow efferent arteriole Efferent arteriole branches to form capillary network that surrounds tubules https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the histology of the kidney https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the histology of the kidney 1: Glomerulum 2: Proximal tubule 3: Distal tubule Image source: Uwe Gille, CC BY-SA 3.0 https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the sections of a nephron https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the sections of a nephron Bowman’s capsule at start of nephron: cup-shaped, surrounds glomerulus, inner layer of podocytes Proximal convoluted tubule (PCT): series of loops surrounded by capillaries, walls made of epithelial cells with microvilli Loop of Henle: hairpin loop that extends from cortex into medulla Distal convoluted tubule : similar to PCT but fewer capillaries Collecting duct: DCT from several nephrons empty into collecting duct, which leads into pelvis of kidney https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is deamination? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is deamination? The removal of the amino group in an amino acid https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is urea? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is urea? A waste molecule produced in the liver as a product of amino acid breakdown which is excreted in urine https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the process of ultrafiltration https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the process of ultrafiltration Occurs in Bowman’s capsule High hydrostatic pressure in glomerulus forces small molecules (urea, water, glucose, mineral ions) out of capillary fenestrations AGAINST osmotic gradient Basement membrane acts as filter. Blood cells & large molecules e.g. proteins remain in capillary https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How are cells of the Bowman’s capsule adapted for ultrafiltration? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How are cells of the Bowman’s capsule adapted for ultrafiltration? Fenestrations between epithelial cells of capillaries Fluid can pass between and under folded membrane of podocytes https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc State what happens during selective reabsorption and where it occurs https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc State what happens during selective reabsorption and where it occurs Useful molecules from glomerular filtrate e.g. glucose are reabsorbed into the blood Occurs in proximal convoluted tubule https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Outline the transport processes involved in selective reabsorption https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Outline the transport processes involved in selective reabsorption https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How does the kidney produce urine? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How does the kidney produce urine? After selective reabsorption, filtrate passes through Loop of Henle, which acts as countercurrent multiplier and then through distal convoluted tubule, where water and mineral ions are reabsorbed. More water is reabsorbed in collecting duct. Remaining fluid (urine) contains only waste materials & water https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What happens in the loop of Henle? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What happens in the loop of Henle? 1. Active transport of Na+ & Cl- out of ascending limb 2. Water potential of interstitial fluid decreases 3. Osmosis of water out of descending limb (ascending limb is impermeable to water) 4. Water potential of filtrate decreases going down descending limb: lowest in medullary region, highest at top of ascending limb https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is the pituitary gland? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is the pituitary gland? An endocrine gland found in the brain which secretes many regulatory hormones into the bloodstream. These hormones either have their own effects or stimulate other glands to secrete hormones. The pituitary gland is important in osmoregulation as it secretes antidiuretic hormone (ADH). https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is antidiuretic hormone (ADH)? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What is antidiuretic hormone (ADH)? A hormone secreted by the posterior pituitary gland which decreases water loss in urine by increasing the water reuptake capacity of the collecting duct https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What are aquaporins? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What are aquaporins? A type of intrinsic membrane protein channel which allows water to pass across membranes https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How does ADH increase water reuptake in the collecting duct? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How does ADH increase water reuptake in the collecting duct? - ADH is secreted by the posterior pituitary gland and it binds to receptors cell membrane receptors on the collecting duct cells - This triggers an intracellular signalling cascade which results in the exocytosis of vesicles which contain aquaporins embedded in their membranes - These aquaporins then become part of the plasma membrane after exocytosis https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the process of ADH secretion by the pituitary gland https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Describe the process of ADH secretion by the pituitary gland - Osmoreceptors in the hypothalamus detect a low blood water content and generate an action potential - This action potential travels down the pituitary stalk to the pituitary gland - The pituitary gland then secretes ADH into the bloodstream https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What are transcription factors? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc What are transcription factors? Proteins which bind to regulatory regions of DNA and control DNA transcription. They can turn genes on or off https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How can peptide hormones affect DNA transcription? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How can peptide hormones affect DNA transcription? By binding to extracellular receptors which produce changes within cells which are brought about by intracellular signalling cascades https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Why must peptide hormones bind to extracellular receptors? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Why must peptide hormones bind to extracellular receptors? Peptide hormones are hydrophilic and so cannot pass through the plasma membrane https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How can steroid hormones affect DNA transcription? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How can steroid hormones affect DNA transcription? They can diffuse into the nucleus and bind to nuclear or cytoplasmic receptors which can directly alter DNA transcription by binding to regulatory sections https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Give one example of a peptide hormone https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Give one example of a peptide hormone Insulin is a peptide hormone which binds to membrane bound insulin receptors. It is secreted by the beta cells of the pancreas and it regulates blood glucose concentration https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Give one example of a steroid hormone https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc Give one example of a steroid hormone Testosterone is an example of a steroid hormone which binds to a nuclear receptor called the androgen receptor which acts as a transcription factor. It is secreted by the testes and it is the primary male sex hormone involved in the development of male sex organs https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How do transcription factors work? https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc How do transcription factors work? Transcription factors bind to DNA and either promote or inhibit transcription by either blocking or enhancing the activity RNA polymerase https://bit.ly/pmt-cc https://bit.ly/pmt-edu https://bit.ly/pmt-cc