Chapter 3: Physiologic Changes

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Welcome to the Deep Dive.

Today, we're really getting into something essential, whether you're in healthcare or just want to understand, you know, how our bodies change over time.

We're doing a system by system look at the physiological shifts of aging.

And our source material, it's solid.

It's pulled right from the core geriatric nursing curriculum.

So the mission for you, the learner, is clear.

We need to nail down the difference between what's normal aging and what's actual disease.

Because honestly, those normal changes, they can sometimes hide serious problems.

Knowing that birth line is, well, it's everything.

Absolutely.

That's the crucial clinical challenge.

Aging, well, it's ongoing.

It's universal, predictable even.

But timing, that's all over the map.

Right.

Depends on heredity, your environment, how well you've maintained your health.

It varies hugely.

You see extremes like progeria, where kids look very old, or folks over 100 who are still incredibly active.

Wow.

Yeah.

So that individuality means we're talking general patterns, but these patterns, they really set the stage for how illness shows up later.

Okay, so let's do this.

We'll move through the body, starting outside in.

We'll link the changes we see structurally and functionally to how they affect lifestyle, self -image, and the care strategies you need to know.

Let's start with the biggest organ, the endocumentary system, skin, hair, nails.

Right.

So the biggest change structurally in the epidermis, it's fragility.

The source actually describes it becoming like rice paper.

Rice paper, wow.

Yeah, really delicate.

That's why older skin so easily gets bruised.

It ups the risk for trauma, for infection,

and critically, the skin's ability to repair itself.

It slows way down.

And you see it visually too, right?

The pigment changes.

Definitely.

Melanocyte activity drops overall, so the skin might look paler, but where those cells cluster, you get senile lentigo.

Age spots.

Exactly, age spots, especially in sun -exposed areas.

It's also good to know the terms for common growths.

You might see skin tags, those little flaps or seborrheic keratosis they're raised, look kind of warty, sometimes greasy.

Then deeper, in the dermis, you lose elasticity.

Hello?

Wrinkles, like crow's feet.

And functionally, the body's cooling system kind of sputters.

Swagland activity goes down.

Ah, so that's the link to heat intolerance?

Precisely.

The direct cause.

And day to day, the most common complaint you'll hear, xerosis,

chronic dry skin.

It's often worse on the lower legs, partly because circulation isn't as good down there.

Gotcha.

And okay, structurally again, that loss of subcutaneous fat.

You mentioned protection.

It's not just looks, is it?

Not at all.

It directly increases risk.

Pressure injuries become much more likely.

And hypothermia too.

Right.

You genuinely need to think about adjusting room temperatures to help maintain core body heat.

Okay, but tell me about assessing hydration.

Why can't we just pinch the forearm skin anymore for turgor?

That fat loss changes things.

It absolutely does.

Because you have less total body fluid overall and less of that subcutaneous fat, the forearm skin.

It's just not reliable.

It might tent even if the person isn't dehydrated.

Ah, misleading.

Very.

So clinically, you must check trigger gore over the sternum or maybe the forehead.

Those spots are less affected by that general fluid and fat loss.

Right.

It seems like a tiny detail, but it's huge for catching dehydration early.

That's a great clinical tip.

Okay, let's move deeper.

Under the

framework.

Musculoskeletal system.

Bones, joints, muscles.

You mentioned something kind of shocking in the PrEP calcium loss starts way earlier than most people think.

Oh, yeah.

Between ages 30 and 40.

It's not just an old age thing.

Wow.

And there's a big difference between men and women.

Huge difference.

After that point, women lose bone mass,

roughly 8 % per decade.

Only about 3%.

This gradual loss, it leads first to osteopenia, which is reduced bone mass and then osteoporosis.

Porous, fragile bones.

Exactly.

And that's what makes spontaneous fractures, especially hip fractures, so common and so dangerous.

And structurally, the spine changes too.

People actually get shorter.

They do.

The discs between the vertebrae shrink.

Over time, you can lose up to two inches in height by age 70.

And that contributes to kyphosis.

That sort of stooped or hunchback appearance.

Right.

And at the same time, muscle mass and tone decrease.

That's

often made worse by less activity.

And in men, lower testosterone plays a role too.

So what does that muscle change mean clinically?

Fatigue, mainly.

The muscles have less glycogen stored up, so even a little bit of exertion.

It leads to lactic acid buildup really quickly.

The person just feels wiped out almost immediately.

Oh, and another thing, because you have proportionally more fat tissue compared to muscle, it actually changes how drugs get absorbed and metabolized.

Something you really have to consider for dosing and toxicity.

Good point.

Okay.

Joints.

Let's talk arthritis.

Big topic.

We need to differentiate the main types.

Right.

So rheumatoid arthritis, RA, that's the autoimmune one.

It's systemic, causes inflammation.

You get flares.

Okay.

Then you have osteoarthritis, OA.

It's degenerative.

Wear and tear, basically.

Often hits the weight bearing joints, knees, hips, linked to obesity overuse.

And importantly, the sore stress is this.

OA is not considered a normal part of aging, even though it's super common.

Not normal, just common.

Got it.

And there's gout too.

Yes.

Gouty arthritis.

That's different again.

Caused by uric acid crystals building up in the joints.

Okay.

Moving inward again.

Vital systems.

Let's talk breathing the respiratory system.

What happens there?

Well, the main theme is rigidity.

The system just loses its flexibility.

You get calcification of the cartilage connecting the ribs.

So the rib cage itself gets stiff.

Exactly.

Less pliable.

Plus the cilia, those little hairs that clear debris, they decrease.

Nucous membranes get drier.

And overall, the lung tissue itself has less elastic recoil.

Doesn't snap back as well after you breathe in.

So a stiff box and less springy lungs.

That sounds like it would reduce capacity.

It does, significantly.

And if someone also has kyphosis, that stooped posture,

it restricts chest movement even more.

That rigidity and loss of elasticity.

It makes gas exchange less efficient.

And it also means secretions, you know, mucus tend to pool in the lower parts of the lungs.

That increases the risk for things like adlectasis or infection.

Ah, infection risk again.

Huge risk.

Older adults are much more vulnerable to severe respiratory infections, flu, COVID -19 pneumonia.

But here's that masking effect we keep talking about.

Let me guess they might not show the usual signs.

Bingo.

Because their immune response is altered, an older person with serious bacterial pneumonia might not have a high fever.

They might not have that spike in white blood cells, the leukocytosis.

That's scary.

It is.

And add to that, a weaker gag reflex makes aspiration pneumonia inhaling food or fluid into the lungs a much bigger risk too.

That muted response pattern is definitely sticking with me.

Okay, let's shift to the heart.

Cardiovascular system.

The body's engine.

Does it weaken like other muscles?

Actually, no.

Unlike skeletal muscle, the heart muscle itself typically does an atrophy.

In fact, the left ventricular wall, the main pumping chamber, often gets a little thicker.

It hypertrophies slightly.

Why?

To compensate.

It's working harder against vessels that have lost tone and offer more resistance.

Interesting.

What about the electrical side?

That each is two.

The pacemaker cells in the SA node, the natural pacemaker, they decrease in So the risk of arrhythmias, irregular heartbeats, goes up.

And functionally, older adults maintain their cardiac output, the amount of blood pumped per minute differently.

How so?

Instead of jacking up their heart rate, like younger people might under stress, they often increase the stroke volume, the amount of blood pumped per beat.

It's just a different compensation mechanism.

Okay.

And the blood vessels themselves.

They lose elasticity too, become stiffer.

This makes it harder for blood to return from the limbs, which is why you see more dependent edema swelling in the legs and feet, plus varicose veins, even hemorrhoids.

Right.

And the big functional issue, especially related to falls, is orthostatic hypotension.

That dizziness when you stand up too fast?

Exactly.

The circulation just responds more slowly to changes in position.

Stand up quickly, blood pressure drops, you feel dizzy, lightheaded, maybe even faint.

Critical safety issue.

Now, heart disease presentation.

You mentioned silent MI.

Yes.

A myocardial infarction and a heart attack.

In older adults, you can't just rely on looking for that classic crushing chest pain.

The symptoms are often way more subtle or atypical.

Like what?

Sudden shortness of brenitistinia, acute confusion,

unexplained fainting, syncope, sometimes just vague stomach upset or GI distress can be really tricky.

And linking this to the bigger picture, high blood pressure, essential hypertension,

it's incredibly common over 70 % people over 65 have it.

Wow.

And we should also mention peripheral vascular disease signs.

Definitely.

Intermittent quadrication, that's cramping pain in the legs, usually the calves, that comes on with walking and goes away with rest.

It's an early warning sign of narrowed arteries in the legs.

These are serious symptoms, but sometimes they get brushed off as just slowing down.

Okay.

Let's touch on the immune system itself.

Hematopoietic and lymphatic systems.

There's a specific term for the changes there.

Yes.

Immunosness.

It basically means the immune system changes in ways that aren't helpful.

It becomes less effective.

You see more immature T -cells, for example, meaning the body is slower to recognize and fight off new threats, new pathogens.

Okay.

Third time's the charm for this pattern then, because the immune response is weaker.

The classic signs of infection might be missing or delayed.

No fever with pneumonia, like we said, maybe no burning pain, dysuria with a urinary tract infection.

You just can't rely on those typical symptoms as reassurance.

The infection risk is high, period.

Got it.

Assume risk even without classic signs.

Okay.

Gee, I tracked.

What happens there?

Well, in the mouth, gums might recede, enamel can soften, teeth might loosen, though losing teeth itself isn't considered normal aging.

Functionally, that depressed gag reflex pops up again, big aspiration risk.

Right.

And the muscle tone at the bottom of the esophagus, the lower esophageal sphincter, it decreases.

That's what leads to acid reflux, heartburn.

And further down, peristalsis, the muscle waves that move food along, that slows down, predictable constipation risk.

Okay.

And when dealing with things like ulcers,

does presentation change here too?

It often does.

Instead of that classic sharp pain in the upper abdomen, older adults might just complain of more general abdominal discomfort, maybe loss of appetite, weight loss, just feeling less active.

And way down low, diverticulosis, those little pouches in the colon wall, they're almost universal by age 80.

It only needs intervention if they get inflamed, which is diverticulitis.

Okay.

Lastly in this section, the urinary system.

This sounds critical for safety.

Absolutely.

The kidneys take a hit.

By age 70, they've lost about a third of their filtering efficiency.

That means the GFR, the glomerular filtration rate, goes down significantly.

And the big implication there is?

Drugs, impaired drug clearance.

Medications hang around in the system longer at higher concentrations.

The risk of drug toxicity just skyrockets.

You have to be incredibly careful with dosages.

Huge point for medication safety.

What about the bladder itself?

It changes too.

Capacity shrinks.

Someone might feel the urge to void when there's only a hundred milliliters of Rahu in there.

Hence the frequency and urgency issues.

Exactly.

And the bladder muscle, the detrusor, can become overactive, contributing to that urgency.

Plus, loss of general muscle tone can lead to incomplete emptying, retention, or dribbling.

And for men, there's the prostate factor.

Right.

After age 60, enlargement of the prostate gland, either benign, BPH, or potentially cancer, is really common.

And because the urethra runs right through it, an enlarged prostate physically squeezes the urethra.

That causes trouble starting the stream, hesitancy, and a weaker flow.

All right.

Let's move to the command center.

The nervous system and cognition.

What are the baseline changes in the brain itself?

Well, there's some physical atrophy.

The brain actually shrinks slightly in size and weight.

You see about a three percent reduction in cortical volume per decade from age 50 to 90.

Wow.

Neurotransmitter function can also be impaired.

Serotonin levels might decrease, which could make people more vulnerable to depression.

And functionally, the biggest thing you notice is just slowing.

Slow reactions.

Yep.

Motor responses, reflexes, they all become more sluggish.

This is why complex coordination tasks like, say, navigating heavy traffic while driving become much more challenging.

Makes sense.

Okay.

Movement disorders.

Parkinson's is a big one.

Birds and disease.

Yeah.

It's progressive degenerative caused by the loss of neurons that produce dopamine.

The classic signs usually start on one side, a tremor when the limb is at rest, muscle rigidity, that flat mask -like facial expression, and a distinctive shuffling gait, sometimes called festinating gait.

And cognition can be affected, too.

It can.

Up to half of people with Parkinson's eventually develop dementia, which we call Parkinson's disease dementia or PDD.

Okay.

Let's talk about dementia more broadly.

What's the starting point?

First, define it.

Dementia is the overall term for a permanent, usually progressive, organic mental disorder that affects cognitive function.

But crucially, before diagnosing dementia, you have to rule out reversible causes.

Like what?

Things like hypothyroidism, vitamin B12 deficiency, sometimes even depression can mimic dementia symptoms.

Always rule those out first.

Good point.

So the most common type of actual dementia is Alzheimer's.

By far.

Alzheimer's disease, AD.

Pathologically,

it's linked to those beta amyloid plaques and neurofibrillary tangles you hear about.

Age is the single biggest risk factor.

By age 85, the prevalence is really high, maybe around 35%.

Are there specific genes?

There are some rare deterministic genes, but mostly we talk about risk factor genes like APOE4.

Having that gene increases your risk but doesn't guarantee you'll get AD.

Okay.

Are there other major types of dementia besides Alzheimer's?

Yes.

Vascular dementia is important.

It tends to have a more sudden onset, often follows a stroke or a series of mini strokes, TIAs.

The decline happens in steps rather than gradually.

TIAs, those are the warning signs.

Transient ischemic attacks, yeah.

Brief episodes where blood flow to the brain is interrupted.

Symptoms like blurred vision, weakness, trouble speaking.

There are serious warnings of a potential major stroke.

And you mentioned Lewy bodies.

Right.

Dementia with Lewy bodies or DLB.

This one's characterized by the dementia symptoms plus prominent visual hallucinations and often motor symptoms that look a lot like Parkinson's.

It really shows how interconnected brain functions are.

Okay.

So we've gone from the skin all the way to the brain.

These changes are systemic, pervasive.

It really brings us back to that core mission you mentioned.

Because there are so many predictable, normal changes happening across all these systems, the older adult's body just responds differently when something acute goes wrong.

Serious illness often presents in atypical ways.

Muted symptoms?

Muted, ambiguous, sometimes just completely unexpected symptoms.

That's why your comprehensive knowledge of that normal baseline, the fragile skin, the stiff rib cage, the slower kidney function, the quiet immune response, it's the absolutely essential foundation.

It's the only way you can reliably spot when something is truly wrong and intervene effectively.

So knowing the normal is key to seeing the abnormal.

Precisely.

And here's something to really chew on, a final thought.

Our understanding of the aging body,

it's still rapidly evolving.

Think about this.

It wasn't that long ago that scientists discovered lymphatic vessels actually exist in the brain's outer membranes, the meninges.

For decades, we thought the brain didn't have that kind of waste clearance system.

Finding those vessels fundamentally changes how we think about brain health, waste removal, and maybe even diseases like Alzheimer's.

Right.

So if we're still uncovering basic anatomy like that, imagine how quickly our approaches to managing and maybe one day curing age -related diseases could change based on new knowledge.

It's a fascinating point.

Knowledge about aging is definitely not static.

It's a constant journey of discovery.

Indeed it is.

We really encourage you to keep diving deep into your source material.

Keep learning.

Thanks so much for joining us for this deep dive today.