Inside a small, white-walled room, a tall, raven-haired woman covers a series of questions. Have you come into contact with anyone with hepatitis? Have you been outside the United States in the past 12 months? Have you been in jail or prison for more than 72 hours? Any recent tattoos or piercings?

Maybe it’s just my nerves, but I feel a little like I am being cross-examined – like I’ve done something wrong. Only I’m trying to do something good.

Good, I soon learn, doesn’t appropriately describe the practice of giving blood. A better word: vital.

Every three seconds someone needs a blood transfusion. When it comes to heart surgery, hemophilia treatments, or those suffering from sickle cell disease, donated blood is fundamental in the purest sense of the word – life-saving simply doesn’t happen without it. Prosthetic limbs can replace a lost arm or leg. Skin can be grafted from other places on a person’s body. Even the heart can be replaced by way of a synthetic heart or pacemaker. Yet there is no such thing as synthetic blood, no way to borrow it from elsewhere in our systems, no substitute for the real thing.

Though nearly 5 million Americans need a blood transfusion each year, only 3 out of every 100 Americans give blood. That helps make the demand daunting – more than 38,000 donations are needed every day in the U.S. alone.

In Monterey County, the need reaches about 7,200 pints annually – enough to fill a Deuce Bigelow-size aquarium – which translates to nearly 20 donations a day for Community Hospital of the Monterey Peninsula’s Blood Center.

Unfortunately, as CHOMP flebotomy technician Elizabeth Chavez reports, an average of about 12-15 people donate daily. Fortunately, the Blood Center’s Bloodmobile helps make up the gap.

“We were 100 percent self-sufficient in 2010,” says Nancy Shammas, donor recruiter for The Blood Center. “We collected enough blood locally to cover our needs. Our community really steps up when we experience high usage and need to replenish.”

The initially unnerving interview process – which includes blood pressure, temperature, pulse and blood checks – goes fast. (It also doubles as a check up: The other day, Chavez detected an irregular pulse in a donor that led to life-saving coronary bypass surgery.)

From there, donation is surprisingly simple. For the understandably needle-averse, the use of lidocaine, a local anesthetic, numbs the location and, if you’re looking away, makes it almost impossible to know when the needle enters. A pint drains in about 10 minutes.

The staff at The Blood Center, meanwhile, couldn’t be more pleasant and polite. A technician stays your side and is genuinely concerned with how you feel after the donation, extending a selection of snacks and juices to keep blood sugar levels up. Today it’s carrot cake and cranberry juice that help restore my loss of fluid. I’m free to continue on with my day as normal, with the caveat that I should hold off on strenuous activity for 24 hours.

The blood has its own itinerary. It is spun in a centrifuge to separate the red blood cells and plasma and sent out for secondary testing; by separating its components, the Blood Center ensures one pint can be used twice. Then the vacuum packs are refrigerated and used by the Community Hospital within 42 days.

Two large guestbooks, filled with signatures and notes from donors over the past several years, reveal that many who donate feel as if it’s the least they can do. “Had some extra, thought I’d share,” reads one scribble. “It’s a small gift that I can give and will be a large gift to those who get it,” reads another.

Those thinking about donating have plenty of relatively convenient opportunities beyond the Blood Center, which is open Monday through Friday. Nearly 12 times a month, Nancy Shammas plans events at local businesses, organizations and high schools where the blood center’s Blood Mobile parks and awaits potential donors; groups can also request a visit. An upcoming St. Patrick’s Day promotion offers a pint for a pint – but probably not the kind of pint you’re assuming (it’s ice cream).

Shammas speaks for anyone who has received a blood transfusion that helped them to live past the hospital doors:

“I think people who donate are very altruistic,” she says. “Some people feel like if they can donate, they will.”

The Blood Center, 576 Hartnell St. in Monterey, is open 8:30am-4pm Tuesday, Wednesday and Friday and 10:30am-6pm Monday and Thursday. Call 625-4814 or visit www.CHOMP.org for an appointment, or to schedule a visit to your business.