Human Health and Physiology

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Human Health and Physiology

• a. Homeostasis maintenance of the internal
  environment at a level that allows normal
  functioning to continue. What must be maintained?

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• -O2 CO2 concentrating (gas exchange)
• -body temp (thermoregulation)-(cellular resp.)
• -Water Balance (osmoregulation)
• -Blood pH
• -Blood Glucose

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• B. Many of the above processes are regulated by
  enzymes so if the pH, temp, salinity or substrate
  concentrations are altered enzyme activity
  homeostatic controls may raise or lower or stop

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• C. One method of control is negative feedback a
  change in one variable is counteracted by an
  opposite change to bring it back to normal
• Ex Preferred body temp 37 but exercise and
  convert more sugar into ATP, body temp. increases
  so, vasodilate, sweat, and hairs lay flat
• Ex Blood sugar level up insulin is produced to
  bring it down

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Digestion

• Why Digest? By hydrolysis large units are
  degraded into simple ones
• Absorption by small intestine villi is easier
• Dissolution into blood for travel is achieved
• Ex. Starches to Monosaccharide

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• B. How do enzymes fit in? enzymes are required to
  degrade polymers, they also increase the rate of
  digestion therefore help create a more stable
  system- most enzymes prefer a 37 degree Celsius
  environment

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• C. Since most foods contain one or more of the
  following carbohydrate, protein, fat enzymes
  generally fall into 3 categories

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• Amylase produced in salivary glands digests
  starch into maltose prefers pH 7
• Proteases ex pepsin produced by stomach glands
  digests proteins into simple polypeptides
  prefers pH 2

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• 3. Lipase produced by the pancreas digests
  lipids into glycerol and fatty acids prefer
  alkaline (above 7) pH

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• D. Digesting/ed food follows a set path
• Mouth? esophagus ?stomach ?small intestine ?
  large intestine ? ANUS (bye-bye)
• But the liver, pancreas and gall bladder all play
  supporting roles
• by coordinating hormone release

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• E. Major Players
• 1. stomach muscular organ with an acidic
  environment main place protein is degraded,
  particles of food are greatly reduced in size

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• 2. Small Intestine secrets enzymes for degrading
  lipids and receives smaller particles from the
  stomach so they can be absorbed. Particles are
  absorbed as they pass from the intestinal wall
  lined w/ villi into capillaries. Absorption may
  involve osmosis, simple or facilitated diffusion,
  active transport, vesicle mediated transport

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• 3. Large Intestine main function is to absorb
  water and prepare waste

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• F.1. Villi folded, finger-like projections on
  the inner wall of the small intestine
• 2. Structure each villus contains capillaries
  and a lymph vessel
• 3. Capillaries branch from the artery and supply
  the intestine w/ oxygen while they receive simple
  sugars and amino acids to the liver via the
  hepatic portal vein

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• 4. Lymph Vessels absorb fats which are shuttled
  to the lymphatic system

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