chapter 10 basic human physiology

• the study of the body's functions inits normal human condition
• 1. physical 2. mechanical 3. biochemical

independent cells which form tissues

• water
• food stuff (glucose, amino acids, and fatty acids)
• oxygen

• 1. heat
• 2. acidity
• 3. biochemical reactions
• 4. metabolism

A. One of the primary functions of the human body is to maintain a relatively even state of temperature, acid load, oxygenation, blood glucose, and so on, for internal life processes

state of physiologic equilibrium

body's process to attain internal equilibrium

• A. Cell wall membrane
• 1. Outside of the cell
• 2. Porous semipermeable dual layer lipid-protein matrix

• 1. Internal fluid
• 2. Primarily water and organelles
• 3. Subunits with a specific cellular function(s)

• 1. Center of cell
• 2. First organelle
• 3. Contains chromosomes and DNA
• a. Blueprints for cellular production and reproduction

• 1. Outside the nucleus
• 2. Inside the cytoplasm
• 3. Tiny sacs that contain enzymes which can break down proteins

chromosomes

• 2. Inside the mitochondria, glucose is transformed into the energy source adenosine triphosphate (ATP)
• a. Used to power the rest of the cell's functions
• i. Nicknamed the cell's "powerhouse
• b. Body must maintain complex set of conditions to work properly

• 1. To make adaptations to the constantly changing conditions that exist within
• the body, cells need energy
• a. Adenosine triphosphate (ATP)

• cell changes glucose into pyruvate acid, which is in
• turn convened into lactic acid by an enzyme (i.e., lactate dehydrogenase)
• a. Relatively inefficient (only yields two ATP, or about 2% of the energy
• available from glucose if oxygen were to be used, 1 00 times faster than
• aerobic metabolism)
• b. Cells that need quick energy in a short amount of time (i.e., skeletal
• muscles) use anaerobic metabolism
• c. Blood cells (erythrocytes) that carry oxygen cannot use the oxygen they
• carry
• i. Depend on anaerobic metabolism and save the oxygen for the cells
• of the body instead
• d. Can release 619 kCal of heat
• i. Comparable to aerobic metabolism
• ii. Can keep the body warm while not requu-ing complex interactions

• body uses eight different enzymes to divide glucose, a
• process called glycolysis (glycol- -"sugar"; -lysis - "to divide"), to create
• pyruvate
• a. Pyruvate and oxygen enter into the citric acid or Krebs cycle
• i. Complex series of changes facilitated by enzymes
• ii. There they undergo a process that creates ATP
• b. End result of this chemical reaction creates carbon dioxide (C02), water
• (H20), energy (in the form ofATP), and heat from the carbohydrate

• 1. When abundant, glucose not needed immediately is stored in the liver and muscles as a dual molecule called glycogen (glycol- - "sugar ; "gen — "create")
• a. When glucose levels fall, the body liberates some glucose from these stores
• b. These two bonded glucose molecules (glycogen) are broken down by an enzyme called glucagon into individual glucose molecules
• c. In the absence of other readily available glucose stores, the body can use other food sources to create glucose (i.e., gluconeogenesis)
• 2.
• Process of aerobic metabolism is dependent upon many organ systems
• working together in synchrony in order to be effective

• A. Body is primarily made up of water
• 1. 50% to 55% of total body weight (TBW) in women
• 2. 55% to 60% of TBW in men
• B. Water is intracellular and extracellular
• 1. Majority of body water is intracellular (35% to 40%
• 2. Extracellular fluids include:
• a. Interstitial fluid: fluid between cells (16% TBW)
• b. Intravascular fluid: fluid found in blood
• i. Primarily plasma (4% TBW)
• C. Anatomists referred to spaces
• 1. First: fluid inside the cells
• 2. Second: fluid in the bloodstream
• 3. Third: volume of blood in between cells

• constant movement of fluids between compartments
• 1. Fluids can move from outside to inside the cells and from compartment to compartment by diffusion or osmosis
• a. Amount is controlled by pressure behind fluids or salts/proteins in the
• fluid of the other compartment

• 1. Hydrostatic pressure:
• pressure created by the force behind the volume of water

dramatic fluid buildup in the tissues

a balanced solution

• fluid has more water and less salt (electrolytes)
• than the solution on the other side of a semipermeable membrane or has less
• water and more salt then the solution

force similar to osmotic pressure created by proteins

• most common intravascular protein
• Principally made in the liver

Whenever colloidal osmotic pressure (COP) is low fluid leaks from the intravascular space and into the interstitial space

• A. Enzymes within the cells operate best in a narrow temperature range of 98.6°F
• +/- 1°F
• 1. All endothermic (i.e., warm-blooded) animals create heat during cellular
• metabolism
• a. Used to maintain a relatively constant core temperature
• 2. At least 90% of all cellular metabolism is used to maintain that heat production
• a. Leaves little for other life processes

too much heat builds up in the body's core

too little heat

regulates body temperature

• one of the most effective heat-dissipating mechanisms that the body has
• I. Controlled by the parasympathetic nervous system
• 2. Surface capillaries under the skin react to dissipate the heat
• a. Causes skin to act as a massive radiator to allow heat to dissipate by conduction, convection, and radiation
• 3. If the body should start to cool, then the hypothalamus can either increase
• heat production by causing shivering, an involuntary contraction of muscles, and/or by vasoconstriction

• I. Fever is actually beneficial to the healing process at many levels
• 2. Hypothalamus controls mean body temperature
• a. During an infection, poisons from the bacteria (i.e., endotoxins), stimulate chemical mediators to affect the hypothalamus
• i. Reset hypothalamus thermostat and cause body temperature to raise
• ii. These pyrogens (fever producers) therefore create a pyrexia (Greek—fever) which makes the environment hostile to bacteria
• iii. Also moves the oxyhemoglobin dissociation curve to the right, improving oxygen off loading to the cells
• iv. Metabolism at the site also increasesStress

• 1. Stress: constantly changing conditions cause the body to respond in effort to
• regain homeostasis
• 2. Stressors: Hans Selye
• a. Rats physiologic response was not limited to injections only but to cold and injury as well
• 3. General adaptation syndrome stages
• a. Alarm stage: body responds to stressor
• b. Resistance: body attempts to regain homeostasis
• c. Exhaustion or recovery: exhaustion occurs when the body's response is insufficient to meet the challenge of the stressor

stress that overcomes the body's innate defenses, and leads to exhaustion

daily stress that essentially keeps body defenses on guard for larger stress threats

• 1. Autonomic nervous system controls the moment-to-moment functions of most of the organs within the body
• a. Two divisions: sympathetic (the accelerator) and parasympathetic (the brake) nervous systems
• b. Effects of the parasympathetic system can be grossly characterized as the "feed and breed" regulation of the organs
• c. The sympathetic nervous system is reactive, stimulated by stressors, and promotes protection of the body

• chemical messengers
• a. Neurons do not physically contact the organs that they innervate
• b. Neurons are separated by a gap (i.e., synapse)
• c. Nervous signal is transmitted across this synapse by a neurotransmitter to awaiting chemical receptors across the synapse called neuroreceptors

transmission of a nervous signal using adrenalined.

• i.'" An electrical stimulus releases norepinephrine from storage in
• pockets, or vesicles, within the neuron that travel to the synapse
• ii. Norepinephrine travels across the synapse to occupy neuroreceptors on the next neuron
• ill. Cause increased permeability of the affected neuron
• iv. Creates an electrical transference across the cell wall membrane that propagates the nervous signal or stimulates the affected organ
• e. Parasympathetic nerve uses acetylcholine

• transmission of a nervous signal using acetylcholine as the neurotransmitter at the motor endplate
• f There are different neurotransmitters in the different portions of the
• nervous system throughout the body
• 3. Neuroreceptors

nicotinic and muscarinic receptors

• alpha receptors and beta receptors
• i. Type one and type two

• 1. Two effects of stress:
• a. Initially, the sympathetic nervous system stimulates the medulla of the
• adrenal glands, an endocrine organ, to secrete the hormone, adrenaline
• i. Circulating adrenaline then goes to the liver and muscles where it
• stimulates glycolysis ofglucogen stores and liberates glucose into
• the bloodstream
• b. Simultaneously, sympathetic nervous system stimulates the release of
• corticotrophin-releasing factor (CRF) from the hypothalamus
• i. CRF stimulates the pituitary gjand to release several important
• stress hormones
• a) Vasopressin is a powerful vasopressor, a chemical that
• causes vasoconstriction particularly on the arterioles
• b) Cortisol is a glucocorticoid hormone that stimulates the
• production ofglucogen from amino acids and fatty acids
• contained in lipids, a process called glyconeogenesis

• 1.
• Major organs are directly innervated by the nerve fibers of the autonomic
• nervous system
• a. Hypothalamus acts through the pituitary gland and then the adrenal
• gland to modulate the immune response
• 2. Important function of the immune system may b to alert other organs of an impending systemic threat
• a. Done through the release of inflammatory mediatore (e.g., interferon)

• A. Atrophy
• I. Reduction of cells
• a. Physiologic: loss of cells as a result of normal changes.
• b. Pathologic: loss of cells as a result of a disease
• i. Neuromuscular disease or diseases affecting muscles directlyIX.

• Hypertrophy
• 1. An increase in either the weight or functional capacity of a tissue or organ beyond what is nonnal
• a. Example: bodybuilder who undergoes resistance training to create
• enlarged, or hypertrophied, biceps muscles
• C. Cell replacement

replacement of one adult cell type with another type of adult cell

• abnormal increase in the number of cells due to frequent cell
• division/reproduction which causes the tissue or organ to increase in size
• a. May be physiologic, compensatory, or pathologic

1. Too many new, or immature, cells that are not functional

• 1. Process of planned cell death
• a. To prevent intrinsic biochemical errors from accumulating within a cell, or to simply replace old worn out or senescent cells, all cells are
• programmed to commit suicide
• b. Maintains a relatively even number of cells among rapidly dividing
• cells
• c. Removes damaged cells
• 2. May also be a pathological condition when it is stimulated by DNA damage caused by oxygen-free radicals