How many sweat glands does the average person have?
The average person has 2.6 million sweat glands in the dermis layer of their skin.
Describe the sweat gland.
the sweat gland is a long, coiled, hollow tube of cells. The coiled part in the dermis is where sweat is produced, and the long portion is a duct that connects the gland to the opening or pore on the skin's outer surface
How is sweat made?
Sweat can be made in response to nerve stimulation, hot air temperature, and/or exercise. When the sweat gland is stimulated, the cells secrete a fluid (primary secretion) This fluid travels from the coiled portion up through the straight duct.
How does sweating cool you down?
To convert water from a liquid to a vapor, it takes a certain amount of heat called the heat of vaporization. if you can produce one liter of sweat, which is equal to 1 kg (density of water is 1 kg/l) in one hour, then 540,000 calories of heat can be removed from your body. A major factor that influences the rate of evaporation is the relative humidity of the air around you.
What is defined as high altitude?
defined on the following scale High (8,000 - 12,000 feet), Very High (12,000 - 18,000 feet), and Extremely High (18,000+ feet). Most people can go up to 8,000 feet with minimal effect.
What causes altitude sickness?
The concentration of oxygen at sea level is about 21% and the barometric pressure averages 760 mmHg. As altitude increases, the concentration remains the same but the number of oxygen molecules per breath is reduced. Since the amount of oxygen required for activity is the same, the body must adjust to having less oxygen. In addition, for reasons not entirely understood, high altitude and lower air pressure causes fluid to leak from the capillaries which can cause fluid build-up in both the lungs and the brain.
What changes take place in the body to allow it to acclimatize to high altitudes?
The depth of respiration increases.
Pressure in pulmonary arteries is increased, "forcing" blood into portions of the lung which are normally not used during sea level breathing.
The body produces more red blood cells to carry oxygen,
The body produces more of a particular enzyme that facilitates
the release of oxygen from hemoglobin to the body tissues.
Genetic changes which favor survival of a population in a stressful environment are called:
increase in basal metabolic rate in a cold climate, sweating in a warm environment, increase in capillaries in a high-altitude environment are all examples of:
Vasodilation and reduced urine volume are adjustments to:
Melanin has been linked to the regulation of:
Human adaptations for life in a warm climate, as seen in the Nilote, include:
The study of bones is called:
The process of turning cartilage into bone is called:
growth by virtue of an increase in intercellular material.
the enlargement of an organ or tissue caused by an increase in the reproduction rate of its cells, often as an initial stage in the development of cancer.
Menarche refers to the onset of:
Anthropometry is the study of:
measurements of the human body
Secular trend refers to:
a tendency for succeeding generations to, on the average, mature faster and grow larger
Nongenetic changes which aid in survival are called:
is the temperature at which the body must begin to combat a lowering of body temperature due to cold air temperature.
T or F? The use of bottled oxygen at high altitude is an example of an acclimatory adjustment.
This is an example of a behavioral adjustment. Acclimatory adjustments involve actual physiological changes.
T or F? The only major skin pigment is melanin.
The amount of heat that can be lost from an object by radiation depends on
the ratio of surface area to volume
The specialization and differentiation of cells into different tissues and organs is termed:
T or F? The bone age of an individual can be determined by examining an x-ray for bone density.
False. The bone age is determined by the fusion of growth plates.
T or F? The development of two sets of teeth is unique to humans.
The development of two sets of teeth is characteristic of mammals as a group.
T or F? An example of variation due to developmental adjustment is individuals who grow up at high altitudes having larger chest circumference.
The life span of a species is defined as:
the theoretical maximum age determined by genetics.
What is meant by the term adjustment?
an adjustment is a nongenetic change that allows humans to survive in stressful environments.
In what way does the concept of adjustment differ from the concept of adaptation?
Adjustments are reversible. In contrast, adaptations are genetic changes that are not reversible. Adaptation refers to changes in gene frequencies resulting from selective pressures and results in a greater fitness of the population in its ecological niche.
What physiological changes take place during puberty?
puberty is an event in the life cycle that includes rapid increases in stature, the development of the sex organs, and the development of secondary sexual characteristics.
What are the main differences between a human male and a human female skeleton?
the male skull is characterized by a less rounded forehead, heavier zygomatic arches, larger teeth, squared orbits and larger supraorbital tori. The other major skeletal differences are largely in the pelvis as the female pelvis is adapted for child-bearing. The female pelvis is characterized by a U-shaped and broader subpubic angle, a smaller acetabulum, a larger, wider and shallower sciatic notch, and an elliptical pelvic outlet.
Which is the more common blood allele worldwide, A or B?
Within the same species of warm-blooded animal, those living in colder areas tend to, when compared to those living in warmer areas:
A) be taller
B) have less mass
C) have shorter limbs
D) have thinner hair or fur
C) Have shorter limbs
Allen's rule and Bergmann's rule describe variation among:
A) all animals
B) all vertebrates
D) humans only
A discontinuous distribution is one in which:
a trait shows little or no gradation in frequencies between adjacent populations
An anthropologist studying a trait finds that for every 250 miles covered, the frequency of the trait increases by 5 percent. She has discovered a
The distribution of both skin color and body build show a:
High frequencies of the blood allele B are found in:
The cephalic index refers to the relative proportions of:
head length to head breadth.
In Stanley Garn's classification, Australians are a:
Folk taxonomies are:
classifications which are parts of specific cultural traditions
The major differences among human groups are differences in:
The short and stocky body type as seen in the Inuit (Eskimo) is an example of ________ rule.
In a clinal distribution, frequencies show a __________.
T or F? The selective pressure acting on the ABO blood system may be that people with blood types O and B are resistant to smallpox.
T or F? Genetic diseases, such as Tay-Sachs disease and sickle-cell anemia are found with equal frequency in all populations.
False. Genetic diseases are often more frequent in some populations than in others.
T or F? Body modifications, including deformation of bones, can be the result of cultural traditions.
T or F? Linnaeus classified all humans as Homo sapiens and then divided the human species into four subspecies based on skin color and geographical location.
T or F? Blood type frequencies are often used in human classification because large geographical areas fall into clearly defined categories.
False. Blood type frequencies were used because blood types are easy to determine, are not affected by the environment, and the mechanisms of inheritance are known. However, clearly defined categories do not always emerge.
T or F? The average genetic differences between geographically separated human populations are fewer than the genetic differences within a single population.
The assertion that there are pure races is no longer true today, but was probably true a hundred years ago.
False. There are no biological races among Homo sapiens, now or in the past.
What three rules describe variation among mammals?
Gloger's rule, Bergmann's rule, and Allen's rule
What is Gloger's rule?
more heavily pigmented forms tend to be found near the equator and lighter forms away from the equator
What is Bergmann's rule?
populations with less bulk are found near the equator while those with greater bulk are found further away from the equator
What is Allen's rule?
populations living nearer the equator tend to have body parts that protrude more and to have longer limbs than those populations farther away from the equator
What are the difficulties in using skin color to categorize human groups?
the precise genetic mechanisms of skin color are not known, skin color can be strongly influenced by environmental and cultural factors, and skin color distribution is largely clinal.
How does Jared Diamond explain the development of colonial Empires in Eurasia and not in Africa or South America?
the more extensive development of agriculture in Europe, the greater availability of domesticatable plants and animals on Europe, and the East-West orientation of the European continent, which enabled domesticated plants and animals to spread more rapidly.