An undercover investigation by the BBC's Panorama is set to show how hospital care can fail the elderly.
The three-month investigation revealed patients suffering a series of indignities at Brighton's zero-rated Royal Sussex County Hospital.
In one scene a patient is left to die on her own, and in another a patient is left waiting hours to go to the toilet.
Peter Coles, boss of the NHS trust covering the hospital, said: "Clearly they are very disturbing images."
Margaret Haywood, a nurse with more than 20 years' experience, agreed to go undercover for the Panorama programme, wearing a hidden camera while working as a bank nurse at the hospital for 28 shifts on an acute medical ward.
She was joined by BBC journalist Shabnam Grewal who got a job in the ward with ISS Mediclean, a private company which has the contract to clean the hospital and serve food.
The programme has uncovered a series of failings. The ward did not keep care plans, which describe individual patient needs, and fluid charts detailing when patients have had a drink were not updated.
Hospital staff were also filmed eating patients' food.
At one point in the programme, to be aired on Wednesday on BBC1 at 9pm, cancer patient Jessie Mowitt, 86, is seen being left to die on her own.
On another occasion Ms Grewal is told off by her boss for offering a patient a special meal.
And in another scene, when a patient asks for help, a nurse replies: "No, not helping you. Sit down, please."
The patient then says: "Oh Christ, you are a bully."
Only for the nurse to say: "You're the one that is a bully, not me."
After going undercover, Ms Haywood said: "Seeing this kind of care makes me feel angry, it makes me ashamed of my profession. We're talking about basic human needs here, basic nursing care."
Peter Coles, chief executive of the Brighton and Sussex University Hospitals Trust, who was shown the tape, said: "Clearly they are very disturbing images and I was shocked to see them.
"The first thing I would like to do is to apologise on behalf of the trust to those patients and their relatives for those lapses in quality of care that were uncovered at that time."
He said a number of complaints had been received about the ward before the BBC filming had begun and an investigation was launched.
A new ward manager and a series of new procedures were introduced in March.
But the Panorama programme also filmed the ward after that date and while improvements had been made, the footage showed the hospital was still failing to fill in care plans and fluid charts.
Two thirds of patients cared for in hospital wards are over the age of 65, and with an ageing population that figure is set to rise.
Undercover Nurse - A Panorama Special on Wednesday on BBC1 at 9pm