It is not allowed to bring books and notes. Answers can be written in English or Danish.

Transkript

1 1 Exams 15. April 2005 Cellular and Integrative Physiology The set consists of 7 pages. It is not allowed to bring books and notes. Answers can be written in English or Danish. There are 5 main questions in this set. Choose and answer only 4 questions of your choice. Only 4 will be marked. The numbers in parentheses after each question indicate their value, that is, how much they will contribute to the evaluation. The maximum number of points attainable is by answering 4 questions. Eksamen den 15. april 2005 Cellulær og Integrativ Fysiologi Sættet indeholder 7 sider. Der må ikke medbringes bøger og noter. Svarene kan være på engelsk eller dansk. Det er 5 hovedspørgsmål i sættet. Besvar kun 4 spørgsmål efter eget valg. Kun 4 spørgsmål bliver bedømt. Tallet i parentes efter opgavens nummer angiver opgavens vægtning, dvs. hvor meget bedømmelsen betyder for det samlede resultat. Man kan få maximum 100 point for 4 spørgsmål.

2 2 DANSK SÆT Spørgsmål 1 Delprocesser på vejen fra præ-synaptisk aktionspotentiale til aktivering af NMDA receptoren ved igangsætning af LTP. (total 25 point) a) Beskriv membranprocesserne under dannelse af et aktionspotentiale frem til frigørelse af glutamat (12 point). b) Hvordan bidrager AMPA receptoren til aktivering af NMDA receptoren (5 point)? c) Hvilke ioner bærer strøm gennem den aktiverede NMDA receptor? Hvordan kan man bestemme vendepotentialet (reversal potential) for ionstrømmen gennem receptoren (8 point)? Spørgsmål 2 Eksokrin sekretion (total 25 point) a) De store spytkirtler er komplekse eksokrine kirtler, som secernerer hypoton spyt. Forklar hvad navnene eksokrin og hypoton væske betyder. (3 point) b) Hvilke hovedkomponenter indeholder spyt og hvilke funktioner har det? (3 point) c) Benævn de anatomiske hovedkomponenter i spytkirtlerne og beskriv/tegn epiteltransportører, som er ansvarlige for sekretions- og/eller absorptionsprocesser i disse dele. (9 point) d) Forklar, hvordan koncentrationen af de væsentligste ioner i spyt afhænger af sekretionshastigheden. (5 point) e) Hvordan er spytsekretionen reguleret? (5 point)

3 3 Spørgsmål 3 Arbejds-inducerede tilpasninger (total 25 point) Figuren viser typiske ændringer i forskellige parametre over en 24 ugers periode med udholdenhedstræning efterfulgt at 6 uger uden træning. a) Beskriv figuren. Dette skal omfatte ændringernes størrelse og tidsforløbet af ændringerne. (7 point). b) Beskriv mulige underliggende molekylære mekanismer, der kan forklare ændringerne i citronsyrecyklus-enzymer ( TCA-cyklus ) i skeletmuskulaturen som følge af perioden med udholdenhedstræning. (7 point). c) Hvad er den primære årsag til de ændringer, der sker i den maximale iltoptagelseshastighed over perioden med udholdenhedstræning og i den efterfølgende periode uden træning. (3 point). d) Forklar den funktionelle betydning af ændringerne i antal kapillærer i skeletmuskulaturen over perioden med udholdenhedstræning. (4 point). e) Glukokortikoider som kortisol regulerer gentransskription af visse gener. Beskriv hvordan glukokortikoider signalerer fra overfladen af cellen til de bestemte gener i cellekernen. (4 point).

4 4 Spørgsmål 4 Syre-base balance (total 25 point) a) Hvad er det normale ph i henholdsvis arterielt og venøst blod? (2 point) b) Hvilke organer er ansvarlige for regulering af blodets syre-base balance? (2 point) c) Hvad er blodets vigtigste buffer system? (2 point) d) Hvilke parametre skal kendes for at kunne beregne blodets ph, og hvilken ligning kan benyttes hertil? (4 point) e) Nyren reabsorberer stort set alt filtreret HCO 3 -. Hvilket nefron segment er hovedansvarlig for denne reabsorption? (2 point) f) HCO 3 - reabsorption i dette segment er koblet til den aktive reabsorption af Na +. Beskriv de cellulære mekanismer involveret i HCO 3 - reabsorption i nefron segmentet. (5 point) g) Hvad forstås ved henholdsvis respiratorisk og metabolsk alkalose? Hvorledes kan disse tilstande opstå? (4 point) h) Karakterisér kort de kemoreceptorer, der detekterer alkalose. (4 point) Spørgsmål 5 Fysiologi af aldosterone (total 25 point) a) Hvilken type hormon er aldosteron og hvor syntetiseres det? (2 point) b) Beskriv 3 forskellige måder, hvorpå aldosteronsekretionen reguleres. (8 point) c) Hvilke organer påvirkes af aldosteron? (3 point) d) Hvordan virker aldosteron på cellulært niveau? (9 point) e) Hvad er den endelige effekt af aldosteron på organ- og helkrops-niveau? (3 point)

5 5 ENGLISH SET Question 1 Membrane processes from the pre-synaptic action potential to activation of the NMDA receptor during initiation of LTP. (total 25 points) a) Describe the membrane processes during generation of an action potential leading to release of glutamate (12 points). b) How does the AMPA receptor contribute to activation of the NMDA receptor (5 points)? c) Which ions carry the current through the activated NMDA receptor? How is it possible to record the reversal potential for the current through the receptor (8 points)? Question 2 Exocrine secretion (total 25 points) a) Major salivary glands are compound exocrine glands that secrete hypotonic saliva. Explain what the terms exocrine and hypotonic fluid mean? (3 points) b) What are the main components of saliva and what are the functions of saliva? (3 points) c) What are the major anatomical parts of salivary glands? Describe/draw epithelial transporters that are responsible for secretion and/or absorptive processes in these parts. (9 points) d) Explain how the concentration of major ions in saliva varies with the secretory rate. (5 points) e) How is salivary secretion regulated? (5 points)

6 6 Question 3 Exercise-induced adaptations (total 25 points) The figure shows typical changes in various parameters occurring over a 24 week period of endurance training followed by 6 weeks without training. a) Describe the figure. Include the magnitude of the changes and the time course of the changes. (7 points). b) Describe possible underlying molecular mechanisms explaining the changes in citric acid cycle (TCA cycle) enzymes in skeletal muscle over the period with endurance exercise training. (7 points). c) What is the main cause of the changes in maximal oxygen uptake over the period with endurance exercise training and over the following period without training? (3 points). d) Explain the functional importance of an increased number of capillaries in skeletal muscle with endurance exercise training. (4 points). e) Glucocorticoids like cortisol regulate gene transcription. Describe how glucocorticoids signal from the surface of the cell to the target gene in the nucleus. (4 points).

7 7 Question 4 Acid-base balance (total 25 points) a) What is the normal ph of arterial and venous blood? (2 points) b) Which organ are responsible for regulating the acid-base balance of the blood? (2 points) c) What is the most important buffering system in the blood? (2 points) d) Which parameters are employed for calculation of blood ph, and which equation may be used for this calculation? (4 points) e) The kidney reabsorbs virtually all filtered HCO 3 -. Which nephron segment is mainly responsible for this reabsorption? (2 points) f) The reabsorption of HCO 3 - by this segment is coupled to the active reabsorption of Na +. Describe the cellular mechanisms involved in HCO 3 - reabsorption by this segment. (5 points) g) What is respiratory and metabolic alkalosis? How can these anomalies arise? (4 points) h) Characterize briefly the chemoreceptors that detect alkalosis. (4 points) Question 5 Physiology of aldosterone (total 25 points) a) What type of hormone is aldosterone and where is it produced? (2 points) b) Describe 3 different modes that regulate aldosterone secretion. (8 points) c) Which organs does aldosterone affect? (3 points) d) What is the cellular action of aldosterone? (9 points) e) What is the end point of the aldosterone action on the organ and whole body level? (3 points)