Contents- Preface – vii
- The purpose of this book
- A quick word about expertise
Part One – Who Ages?- Introduction – 1
- A working definition
- A few ground rules
- Figure 1: Animal Cell Architecture
- Figure 2: Spotlight on the Cell
- 1. A slippery overarching definition – 7
- How Valentino died
- Science land
- Life spans
- No predictions here
- Flexibility
- Slime and punishment1
- Sponges
- Figure 3: Creatures That Don’t Die
- So what?
- The numbers
- Death decisions
- The dinner
- The rule
- The origins
- The complexity grows
- Termites
- A lesson for us
- The point
- Under the hood
- Cell replication and aging
- Cellular immortality
- Conclusions
- 2. Humanizing aging and death – 29
- Keats
- The chapter before us
- The need for a guard
- How guards work
- Figure 4: Normal Human Flora
- How the system learns about this
- Figure 5: Fighting Foreigners
- Programmed obsolescence
- The point
- Figure 6: The process of Apoptosis
- The nervous system
- Figure 7: Cellular Aging and Death
- What that was
- Apoptosis on the brain
- Why bring this up?
- The moment of death
- Antiquity
- Sometimes a great notion
- The strange case of Bruce Tucker
- The trial
- The provocation
- Of all the nerve
- The definitions
- So then what do we do?
- Conclusions
- 3. Why age at all? – 55
- Introduction
- An important question
- A framework
- The hows of natural selection
- An intersection
- Figure 8: A quick review of Natural Selection
- The ideas of Wallace
- Weismann
- An example in army ants
- But back to Weismann
- A prophesy in numbers
- The mathematics of the aging process
- Medawar
- Still more lessons from a tumor
- Taking care of business
- The hypothesis
- Cancer and reproductive fitness
- In summary
Part Two – How do we age?Introduction – 71 - 4. How the skin and hair age – 75
- Introduction
- Skin and aging
- A quick anatomy lesson
- Historical attempts at modification
- The reason for the make-up
- Wrinkle, wrinkle little star
- Other layers
- Figure 9: Why human skin wrinkles and sags
- The body overall
- Figure 10: How the face ages
- A hair-raising fortune
- Hair today, gone tomorrow
- Figure 11: What aging does to your hair
- Thinning and greying
- Graying
- The biochemistry of greying
- The motion for a change
- 5. The aging of bones, muscles and joints – 91
- Introduction
- The power of immobility
- Deep in our bones
- Figure 12: The structure of human bone
- Low-interest bones
- Figure 13: A tale of two fractures
- The role of gender
- Joint custody
- Figure 14: Three types of human joints
- Aging the joints
- Figure 15: How human joints age
- Muscles
- Muscle sprouts
- What skeletal muscles do
- The cellular connection
- What a skeletal muscle cell looks like
- Figure 16: Human skeletal muscles
- It’s what’s inside that counts
- The aging process
- An example of the toll
- What happens
- Credibility
- What do we make of appearance?
- 6. The aging of the brain – 113
- Introduction
- What we study next
- The changes
- Intelligence2
- Memory
- Sleep3
- Age-related changes
- Neural reasons
- Figure 17: How nerves talk to each other
- The synapse
- The overall characteristics
- Neuronal Fallout Model
- Neuronal Plasticity Model
- The resolution
- Of dinosaurs and neurons
- The brain stem
- The cerebellum
- Figure 18: How the brain is organized
- The diencephalon
- The limbic system and the hippocampus
- The cerebrum4
- The strange case of Phineas Gage
- Figure 19: Nerve cell survival in aging
- In summary
- Conclusions
- 7. How the heart ages – 141
- Introduction
- A chapter devoted to hearts
- A cardiac introduction
- How the pump works
- Blood vessels
- Figure 20: The structure and function of the heart
- Veins
- Aging and the vasculature
- Figure 21: How the human heart ages
- Time-out for an interesting exception
- Other reasons for aging
- Figure 22: How arteries age
- Conclusions
- 8. The aging of the lungs – 155
- Introduction
- The purpose of this chapter
- A brief tour of the human lung
- Structure and blood
- Figure 23: Lungs under the surface
- The mechanics of breathing
- A most unusual sled
- The aging process
- What happens
- Elastic recoil
- Why do we have to lose elastic recoil?
- Figure 24: The aging lung
- 9. What happens to the digestion – 167
- Introduction
- The next section
- The oral phase of digestion
- How it ages
- Figure 25: How to digest a chocolate torte
- What happens next?
- Does it age?
- Figure 26: How the digestive system ages
- On to the small intestine
- How it ages
- The organs that help the small intestine
- Aging in the liver and pancreas
- The colon
- But does it age?
- The kidneys
- Do kidneys age?
- Figure 27: Changes in elimination
- Let’s not leave the bladder out
- Taken together
- 10. How the senses age – 185
- Introduction
- The power of living
- The eyes have it
- Figure 28: Eyes and Human Vision
- The aging of the eye
- The effect of vision
- Figure 29: How Vision Changes with Age
- We are all hear
- Figure 30: Ears and Human Hearing
- For those who have ears
- I sit and watch as ears go by
- Figure 31: How hearing changes with age
- Days of wine and roses
- A matter of taste
- How it ages
- Figure 32: The aging of taste
- For whom the smell tolls
- Figure 33: Smell: Anatomy and function
- How does our sense of smell age?
- A touching reminder
- The biology of touch
- How to make sense of this
- 11. The aging of the reproductive system – 209
- Introduction
- This section
- What happens to women
… The anatomy - How the system ages
- Figure 34: The role of estrogen in the female anatomy
- A many-faceted event
- What does it do to sexual activity?
- Sexual interest
- Figure 35: The changes of menopause
- What happens to men
- What happens to testicles
- As the sperm turns
- Semen production
- Figure 36: Aging and male sexuality
- Erections and sexual activity
- So what?
- Conclusions
Part Three – Why do we age?- Introduction – 225
- 12. A tale of two theories – 229
- Introduction
- Two theories about aging
- Error Accumulation
- Genetic Program Activation
- A hard-cell setting
- Figure 37: The Anatomy of the Nucleus of a Human Cell
- So how does a gene make a protein?
- Figure 38: The Genetic Code
- Activation
- Developing answers
- Figure 39: A genetic problem solved
- Selective activation
- Crowded runways
- Figure 40: How genes are turned on
- Promoters
- Popcorn-strung Christmas ornaments
- The role of histones
- Stopping a prickly gene
- Conclusions
- 13. Error accumulation – 249
- Introduction
- This chapter
- The power of electrons
- Radical formation
- Tiny toxic dumps
- Figure 41: Free Radical Formation
- Figure 42: Radical Damage
- Relevance to the section
- The culprit
- A heat-shocked lawyer
- A heat-shocked gene
- Figure 43: The Heat Shock Response
- The heat-shock genes and aging
- Error accumulation
- The process of communication
- Figure 44: How DNA Ages
- But what about age-related errors?
- One last gasp of biochemistry
- Conclusions
- Figure 45: The Aging of Proteins in Human Cells
- The prescience of playwrights
- 14. Programmed death – 271
- Introduction
- This section
- A genetic basis
- Cellular timing
- Figure 46: The Molecular Clock of Aging
- Genetic programs and stupid thieves
- The aging process
- The first gene – fos
- Coal-driven people
- Other genes
- The bcl-2 gene
- Figure 47: The Genes of Life and Death
- Death in the Philippines
- The subject of aging
- As the worm turns
- A human program
- Conclusions
- 15. Winding back the clock – 293
- Introduction
- An introduction to the section
- The role of exercise in extending longevity
- Skin
- Skeletal muscles
- Bone
- Joints
- Heart, blood and lungs
- The effects of diet
- The role of anti-oxidants in extending longevity
- Cognitive abilities
- The role of hormones in extending longevity
- Does this mean anything for humans?
- In summary
- 16. Conclusions – 311
- Introduction
- The Merlins of the 20th Century
- But seriously, folks
- The end of The Clock of Ages
Further Reading – 317
Index – 327
In-Page Footnotes
Footnote 1: This is the first of many irritating section headings that, while feebly witty, obscure the meaning of the section heading as an aide memoire.
Text Colour Conventions (see disclaimer)
- Blue: Text by me; © Theo Todman, 2021
- Mauve: Text by correspondent(s) or other author(s); © the author(s)