chapter 5 the physical self

Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. RiderChapter 5

Chapter 5The Physical Self


Chapter 5: The Physical Self

• Genetic and environmental forces

• E.g., height– Average: female 5’4” male 5’9”– Can be affected by malnutrition– Catch-up growth possible

• After illness or periods of malnutrition– More short people in cold climates

• Smaller body surface for heat loss


The Endocrine SystemEndocrine System

the body’s “slow” chemical communication system

a set of glands that secrete hormones into the bloodstream


Neural and Hormonal SystemsHormones

chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another

Pituitary Gland under the influence of the hypothalamus,

the pituitary regulates growth and controls other endocrine glands


Neural and Hormonal Systems

Adrenal [ah-DREEN-el] Glands a pair of endocrine glands just above the

kidneys secrete the hormones epinephrine

(adrenaline) and norepinephrine (noradrenaline), which help to arouse the body in times of stress

• Testes secrete androgens like testosterone• Ovaries secrete estrogen and progesterone


Figure 3.22 Glands in the endocrine system produce hormones and release them into the bloodstream. This shows only some of the endocrine glands and some of their most abundant hormones.


Nervous System CellsAnatomy of a neuron

– Neurons have a variety of shapes, but they all have 3 basic parts.• A cell body that contains the nucleus and most of

the organelles.• The dendrites, widely branching structures that

receive transmissions from other neurons.• The axon, which is a single, long, thin fiber with

branches near its tip.Action Potential

a neural impulse; a brief electrical charge that travels down an axon


Neural Communication

Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. RiderChapter 5Neural Communication

Synapse [SIN-aps] junction between the axon tip of the sending neuron and

the dendrite or cell body of the receiving neuron tiny gap at this junction is called the synaptic gap or cleft

Neurotransmitters– Communication between neurons occurs at the

synapses. chemical messengers that traverse the synaptic gaps

between neurons when released by the sending neuron, neurotransmitters

travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse


Figure 3.8 The synapse is the junction of the presynaptic (message-sending) cell and the postsynaptic (message-receiving) cell. At the end of the presynaptic axon is the terminal bouton (or button), which contains many molecules of the neurotransmitter, ready for release.


Figure 5-2


Plasticity• Responsiveness to experiences

– Can be negative• Vulnerable to damage• Environmental deprivation

– Can be positive• Aids in recovery from from injury• Can compensate for each other• Can benefit from stimulation• Allows for adaptability


Brain Development 2• Critical period: late prenatal & early infancy• Lateralization (at birth)

– Left hemisphere (“thinking side”)• Sequential processing needed for

analytic reasoning, language– Right hemisphere (“emotional side”)

• Simultaneous processing needed for understanding spatial information

• Visual-motor information• Melody, pitch, sound intensity, affective

content of language– Corpus callosum connects the two


Our Divided Brain

Corpus Callosum large band of

neural fibers connects the

two brain hemispheres

carries messages between the hemispheres

Corpus callosum


Figure 3.26 The corpus callosum is a large set of axons that convey information between the two hemispheres of the cerebral cortex. (a) A midline view showing the location of the corpus callosum. (b) A horizontal section showing how each axon of the corpus callosum links one spot in the left hemisphere to a corresponding spot in the right hemisphere.

Life-Span Human Development, Fifth Edition, Carol K. Sigelman and Elizabeth A. RiderChapter 5Experience and the brain

The two halves of the brain– Work with individuals who have had the “split-

brain” operation (severing the corpus callosum) to control seizures provides evidence that the two hemispheres are highly specialized.

– The right hemisphere needs to communicate with the left in order to name the objects in its visual field.

– The left hemisphere needs the right in order to synthesize details into a whole picture (the parts of a face into a whole recognizable image).


Brain Development 3

• Never truly complete– Changes occur across lifespan

• Growth spurts in infancy, childhood and adolescence

• Full adult weight by about age 16• Processing speed increases in adolescence• Myelination continues into adulthood


Brain Development 4The Aging Brain

– Gradual and mild degeneration Elderly adults

– 5-30% fewer neurons than younger adult– Greater loss in sensory-motor areas– Plasticity still possible

Main result of age is slower processing

chapter 5 the physical self

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