The juxtamedullary cells detect reduced renal blood flow and convert prorenin to renin…renin converts angiotensinogen to angiotensin I, then angiotensin converting enzymes split that to angiotensin II, which stimulates the secretion of aldosterone…and what the fuck does aldosterone do?

He threw down the textbook in disgust. Endocrinology was so logical, why did it not stick? Hormones triggered hormones triggered actions, which suppressed more hormones and started a negative feedback chain. It made sense. So why could he never remember what they actually did?

He gave a heavy sigh. Piles of notes and unfinished work were looming ominously over him. He had planned on completing endocrinology today, but he was stuck in the hormones. Before he could stop himself, he sighed again.

‘That’s two sighs in less than two minutes. Going well?’

Looking over to her, he was amused again by her revision techniques. She was surrounded by textbooks with fluorescent tags of different colours labelling carefully highlighted paragraphs that corresponded to flash cards and diagrams. His own revision was scattered over leaves of paper and each topic was stuffed into a different folder. It had seemed adequate, now he wasn’t so sure.

‘Fucking hormones!’ he exploded. ‘They all sound the same and…oh, I can’t do this anymore.’

Although he couldn’t yet hear her, he could see her shoulders shaking as she tried to smother her laughter. Damn, the jolting was causing her breasts to bounce temptingly inside her shirt. That really wasn’t helping…

He was beginning to suspect that revising with Amy had not been a wise choice. He was finding it hard enough to focus anyway without his cock twitching at every move she made. He could smell her perfume when she tossed her hair back over her shoulders. When she had stretched across to borrow his copy of Kumar and Clark, her shirt had opened just enough to give him a tantalising glimpse of the curve of her breast, hidden behind pale blue lace. And she kept making these adorable subconscious noises when she was working. God, this was such a bad idea. He sighed again, this time from a different sort of frustration.

‘OK, that’s it!’ She put down her own work and turned to face him. ‘You need a new strategy. What are you doing at the moment?’

‘The renin-angiotensin system. I can sort of remember the pathway, but the actions…’ He grimaced.

‘You’re thinking about it like a textbook, that’s not how you work.’

He looked at her strangely. How did she know how he worked?

‘You need to think more practically. You’ve got the axis, right?’ 

He nodded.

‘So think like a doctor, not a scientist! Ramipril inhibits the angiotensin converting enzymes, blocking conversion of angiotensin I to II, and is used to treat hypertension, so you just need to remember that increasing blood pressure is an endpoint of the pathway, OK? And spironolactone blocks aldosterone and we use that as a diuretic, so what does that mean aldosterone does? Fluid retention…easy!’

He starred at her. Somewhat blankly.

‘How do you do that? How do you know that?’ He dragged his hands through his hair in a gesture of defeat. ‘And how are you still able to work? This is killing me!’

‘Stop complaining and get back to it. Either that or have a break, you’re bugging me.’ A small smile flashed across her face and his stomach jumped again. ‘Go on, go have a wank or something.’

He looked incredulously at her. Did she really just say that? What…what did she mean?

‘Oh, come on! Don’t look at me like that.’ She quickly spoke before he had time to respond. ‘You must have had a masturbation break when revising? Hot and fast expulsion of energy to reinvigorate you? More fun and effective than a dance break? You’ve never done that?’

 ‘No, I’ve never done that!’

She’d turned away from him again, her attention apparently focussed on her work, but she wasn’t writing anything any more. The pen in her hand was trembling slightly, hinting at an inner tension. Neither of them moved or spoke for longer than felt natural.

‘Well, you’re missing out. It’s very effective.’ She finally broke the silence before it became truly uncomfortable. ‘I do it all the time.’

‘Show me.’

Now it was her turn to look incredulous. Her head flicked around to look at him, eyes wide in surprise. For a moment, he was terrified that he had seriously overstepped his bounds. That he’d misunderstood why she always gravitated towards him on nights out, why she looked at him the way she did when he was around, why she’d asked him over to help her revise when clearly he was the one who needed help.

Then she smiled the sexiest and most wicked smile he had ever seen. It lit up her face and sent a hot bolt of lust straight down into his cock.

‘What did you say?’

‘You heard…show me.’

Without breaking eye contact, she stood and, with a small wiggle of her hips, let her knickers fall to the floor. He could barely breathe. Stepping out of them, she walked over to the armchair directly opposite him and sat down. She slowly spread her knees and allowed her skirt to ride up her thighs. Her cunt was already glistening and swollen, and he couldn’t tear his eyes away. She licked her index finger to moisten it before reaching down and running it up between her folds. She shivered at even this briefest touch and, as she took her finger back into her mouth to taste herself, he was unable to suppress a moan of need.

She began stroking herself with more purpose. With her index and ring fingers on either side of her cunt, holding her labia slightly apart, her middle finger slid up and down, teasing her opening and circling her clit. As he watched, her face became flushed and her breath more ragged. This may be the hottest thing he had ever seen, she was absolutely incredible. The speed of her movements increased and, slipping her fingers deep inside her for a moment, she closed her eyes and leaned back into the chair, gasping slightly and shifting her pelvis to push her hips up. She began gripping her thigh with her other hand, caressing the muscles that occasionally twitched beneath her touch. She was focussing on her clit alone now with faster and firmer circles, moaning softly and arching her back.

Suddenly, and wonderfully, her whole body tensed and she began curling her toes up against the carpet. Her fingers were rubbing at her clit in a more frenzied manner until, with a long, breathy moan, she came, her body shuddering and flexing against the chair.

She lay still for a few moments until her body became quiet and she could stop panting. The whole performance, if it could be called that, had lasted less than 5 minutes. She opened her eyes, shook herself, straightened up her skirt and went back to the sofa, re-opening her textbook.

‘There! All set to start work again.’

‘Oh, I don’t think so!’

He had been on his feet and moving towards her even before she’d sat back down. Pulling her up and into his arms, he kissed her and felt his blood surge as she hungrily, eagerly kissed him back. They fell backwards into the sofa, knocking papers and stationery everywhere and rolling onto the floor.

‘No, this isn’t nearly good enough. I’ve waited too long for this not to do it properly.’

Picking her up, he started to carry her through to his bedroom.

‘But what about the exams?!’ She laughed, gesturing back towards the scattered notes.

‘Right now, I couldn’t care less. And anyway, this was all your idea…’