-two pyruvic acid molecules 

-two NADH + H+ molecules

- A net gain of two ATP molecules

-Three molecules of NADH + H+

- One molecule of FADH2

-Two molecules of CO2

-One molecule of ATP

reflects the energy the body needs to perform its most essential activities

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surface area to volume

-          As the ratio of surface area to volume increases, BMR increases

-          Males have a disproportionately high BMR

• Complete proteins that meet all the body’s amino acid needs are found in eggs, milk, milk products, meat, and fish

• Incomplete proteins are found in legumes, nuts, seeds, grains, and vegetables

-          all chemical reactions necessary to maintain life

-          Packages fatty acids to be stored and transported

-          Synthesizes plasma proteins

-          Forms nonessential amino acids

-          Converts ammonia from deamination to urea

-          Stores glucose as glycogen, and regulates blood glucose homeostasis

-          Stores vitamins, conserves iron, degrades hormones, and detoxifies substances

-          Is carried out by the electron transport proteins in the cristae of the mitochondria

-          Nutrient energy is used to pump hydrogen ions into the intermembrane space

-          A steep diffusion gradient across the membrane results

-          When hydrogen ions flow back across the membrane through ATP synthase, energy is captured and attaches phosphate groups to ADP (to make ATP)

Mechanisms of Heat Exchange

• Radiation – loss of heat in the form of infrared rays
• Conduction – transfer of heat by direct contact
• Convection – transfer of heat to the surrounding air (moving fluid or gas)
• Evaporation – heat loss due to the evaporation of water from the lungs, mouth mucosa, and skin (insensible heat loss) (only cools when sweat evaporates; if sweat doesn’t evaporate it doesn’t cool you down)

-          When the core temperature rises, the heat-loss center is activated to cause:

-          Vasodilation of cutaneous blood vessels

-          Enhanced sweating

-          Voluntary measures commonly taken to reduce body heat include:

-          Reducing activity and seeking a cooler environment

-          Wearing light-colored and loose-fitting clothing

-          Postural Changes

-          Low external temperature or low temperature of circulating blood activates heat-promoting centers of the hypothalamus to cause:

-          Vasoconstriction of cutaneous blood vessels (to retain blood at core to keep core body temperature)

-          Increased metabolic rate (thyroid hormone released to [Increase?] oxygen production)

-          Shivering

-          Enhanced thyroxine release

o   Normal heat loss processes become ineffective and elevated body temperatures depress the hypothalamus

o   This sets up a positive-feedback mechanism, sharply increasing body temperature and metabolic rate

o   This condition, called heat stroke, can be fatal if not corrected

How does thyroxin influence BMR-

-          Thyroxine increases oxygen consumption, cellular respiration, and BMR

Nitrogen balance

-          The rate of protein synthesis equals the rate of breakdown and loss

-          Positive – synthesis exceeds breakdown (normal in children and tissue repair)

-          Negative – breakdown exceeds synthesis (e.g., stress, burns, infection, or injury)

Water Balance-

-          To remain properly hydrated, water intake must equal water output

-          Water intake sources

o   Ingested fluid (60%) and solid food (30%)

o   Metabolic water or water of oxidation (10%)

Thermoregulation & Hypothalamus

• The main thermoregulation center is the preoptic region of the hypothalamus
• The heat-loss and heat-promoting centers comprise the thermoregulatory centers
• The hypothalamus:
• Receives input from thermoreceptors in the skin and core
• Responds by initiating appropriate heat-loss and heat-promoting activities 

Adrenal glands (hormones produced by adrenal cortex)- 

o   Sodium reabsorption

§  65% of sodium in filtrate is reabsorbed in the proximal tubules

§  25% is reclaimed in the loops of Henle

o   When aldosterone levels are high, all remaining Na⁺ is actively reabsorbed

o   Water follows sodium if tubule permeability has been increased with ADH

o   The renin-angiotensin mechanism triggers the release of aldosterone

o   This is mediated by the juxtaglomerular apparatus, which releases renin in response to:

§  Sympathetic nervous system stimulation

§  Decreased filtrate osmolality

§  Decreased stretch (due to decreased blood pressure)

o   Renin catalyzes the production of angiotensin II, which prompts aldosterone release

o   Adrenal cortical cells are directly stimulated to release aldosterone by elevated K⁺ levels in the ECF

o   Aldosterone brings about its effects (diminished urine output and increased blood volume) slowly

structural and functional unit of the kidney (filtration, reabsorption, secretion)

-Cell types change along the length of the nephron

-Boman’s  (glomerular capsule)

-Concentrated urine good if you are dehydrated

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• Macula densa
• Tall, closely packed distal tubule cells
• Lie adjacent to JG cells
• Function as chemoreceptors or osmoreceptors (measure osmolarity of blood to see if it is too salty or dilute)
• Mesanglial cells:
• Have phagocytic and contractile properties
• Influence capillary filtration
• [image]

o   Is relatively impermeable to solutes

Is permeable to water

o   Is permeable to solutes

o   Is impermeable to water 

• Acid-base imbalance due to inadequacy of a physiological buffer system is compensated for by the other system
• The respiratory system will attempt to correct metabolic acid-base imbalances
• The kidneys will work to correct imbalances caused by respiratory disease

-          Values above 45 mm Hg signal respiratory acidosis

-          Respiratory acidosis is the most common cause of acid-base imbalance

o   Occurs when a person breathes shallowly, or gas exchange is hampered by diseases such as pneumonia, cystic fibrosis, or emphysema

-          Values below 35 mm Hg indicate respiratory alkalosis

-          Respiratory alkalosis is a common result of hyperventilation

-          Metabolic acidosis is the second most common cause of acid-base imbalance

o   Typical causes are ingestion of too much alcohol and excessive loss of bicarbonate ions

o   Other causes include accumulation of lactic acid, shock, ketosis in diabetic crisis, starvation, and kidney failure

-          Rising blood pH and bicarbonate levels indicate metabolic alkalosis

o   Typical causes are:

§  Vomiting of the acid contents of the stomach

§  Intake of excess base (e.g., from antacids)

§  Constipation, in which excessive bicarbonate is reabsorbed

ANP

(Atrial Natriuretic Peptide)

• -ANP lowers blood Na+ by:
• Acting directly on medullary ducts to inhibit Na⁺ reabsorption
• Counteracting the effects of angiotensin II
• Indirectly stimulating an increase in GFR reducing water reabsorption

-          Intracellular fluid (ICF) – about two thirds by volume, contained in cells

-          Extracellular fluid (ECF) – consists of two major subdivisions

-          Plasma – the fluid portion of the blood

-          Interstitial fluid (IF) – fluid in spaces between cells

-          Other ECF – lymph, cerebrospinal fluid, eye humors, synovial fluid, serous fluid, and gastrointestinal secretions

Hypoproteinemia

-          – low levels of plasma proteins

-          Forces fluids out of capillary beds at the arterial ends

-          Fluids fail to return at the venous ends

-          Results from protein malnutrition, liver disease, or glomerulonephritis

-          Dehydration

o   Water loss exceeds water intake and the body is in negative fluid balance

o   Causes include: hemorrhage, severe burns, prolonged vomiting or diarrhea, profuse sweating, water deprivation, and diuretic abuse

o   Signs and symptoms: cottonmouth, thirst, dry flushed skin, and oliguria

o   Prolonged dehydration may lead to weight loss, fever, and mental confusion

Other consequences include hypovolemic shock and loss of electrolytes

-          Hypotonic hydration

o   Renal insufficiency or an extraordinary amount of water ingested quickly can lead to cellular overhydration, or water intoxication

o   ECF is diluted – sodium content is normal but excess water is present

o   The resulting hyponatremia promotes net osmosis into tissue cells, causing swelling

o   These events must be quickly reversed to prevent severe metabolic disturbances, particularly in neurons

-          Edema

o   Atypical accumulation of fluid in the interstitial space, leading to tissue swelling

o   Caused by anything that increases flow of fluids out of the bloodstream or hinders their return

o   Factors that accelerate fluid loss include: 

§  Increased blood pressure, capillary permeability

§  Incompetent venous valves, localized blood vessel blockage

§  Congestive heart failure, hypertension, high blood volume

PTH

-          PTH promotes increase in calcium levels by targeting:

o   Bones – PTH activates osteoclasts to break down bone matrix

o   Small intestine – PTH enhances intestinal absorption of calcium

o   Kidneys – PTH enhances calcium reabsorption and decreases phosphate reabsorption

-          absorptive state

o   The time during and shortly after nutrient intake

-          Postabsorptive state

o   The time when the GI tract is empty

o   Energy sources are supplied by the breakdown of body reserves

-          Antidiuretic hormone (ADH) inhibits diuresis

-          This equalizes the osmolality of the filtrate and the interstitial fluid

-          In the presence of ADH, 99% of the water in filtrate is reabsorbed

-          ADH-dependent water reabsorption is called facultative water reabsorption

-          ADH is the signal to produce concentrated urine

how are alcohol and caffeine diuretics

-          Alcohol – inhibits the release of ADH

Caffeine– inhibit sodium ion reabsorption