PSY 3128 Lecture Notes - Lecture 9: Chemoreceptor, Hearing Aid, Functional Magnetic Resonance Imaging
5 Jun 2018
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Immune System
A process known as immune senescence occurs throughout the aging process. The two primary types of immune
lymphocytes are T cells and B cells, both of which are involved in destroying bodily invaders known as antigens. In
immune senescence, these cells fail to develop properly and lose their ability to perform effectively, causing older
adults to be less resistant to infections (Grubeck-Loebenstein, 2010). Thus, although children are more likely to
develop influenza infection during seasonal flu season, the mortality occurs almost entirely among older adults unless
the flu viruses were ones to which they were exposed as children or young adults.
Central Nervous System
i. Neuronal Fallout Model: the hypothesis that individuals progressively lose brain tissue over the life span
because neurons do not have the ability to replace themselves when they die.
a. The data to support neuronal fallout model came primarily from autopsy studies in which
neuroanatomists counted the number of neurons in the brains of people of different ages.
ii. In the absence of disease the aging brain maintains much of its function and structure.
iii. The Plasticity Model: proposes that the neurons that remain alive are able to take over the function of
those that die. Many of these new findings supporting this model were due to brain scanning methods.
a. Electroencephalogram (EEG): measures electrical activity in the brain and demonstrates brain
waves. This is used for epilepsy, sleep disorders, or tumors.
b. Computed Axial Tomography (CAT or CT scan): provides a cross slice of the brain by evaluating
fluid filled areas of the brain. This is used when clinicians are looking for structural damage.
c. Magnetic Resonance Imaging (MRI) is brain imaging method that uses radio waves to construct a
picture of living brain based on the water content of various tissues. The person is placed inside a
device that contains a powerful electromagnet – nuclei in hydrogen atoms to transmit
electromagnetic energy.
d. Functional Magnetic Resonance Imaging (fMRI) is a type of scan that can e used to show changes
in the brain over the course of a mental activity. Researchers are increasingly using fMRIs to
understand the brain areas involved in the processing of information, giving an inside look at age
differences in cognition.
Hippocampus and Aging: typically used for consolidating memories.
- Becomes smaller with increasing age, although this decline is more pronounced in abnormal aging such
as in Alzheimers disease
White Matter Hyperintensites (WMH): aging associated with changes. Abnormalities are thought to be made up of
parts of deteriorating neurons. Their presence appears to interfere with long term memory because they disrupt the
integrity of the white matter.
Sleep
- It is a myth that people need less sleep as they age.
- Sleep problems in middle and later life relate in part to lifestyle and physiology
- They spend more time in bed relative to their sleep than younger adults
- Become more morning people
- Older adults tested at non-optimal hours are more disproportionately affected than younger adults.
Temperature Control
Dysthermia – hyper or hypothermia.
- High death rates because older people cannot regulate their body temperature.
- In less extreme conditions, older adults can adjust their internal bodily temperature
- Sweat output is reduced causing their core temperature to rise
Sensation and Perception
Vision: most people require some form of corrective glasses by the time they reach their 50s and 60s.
i. Presbyopia is the loss of ability to focus vision on near objects, and is the primary culprit for the need
for reading glasses. This is caused by a hardening and thickening of the lenses. These changes mean the
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