exam2

Nutrient

any ingested chemical used for growth, repair, or maintenance of the body

Macronutrients

must be consumed in relatively large quantities

Water

a macronutrient required for various bodily functions

Carbohydrates

a macronutrient that serves as a source of fuel once broken down into monomer form (monosaccharide)

Lipids

a macronutrient that includes triglycerides, fatty acids, phospholipids, steroids, and glycolipids

Proteins

a macronutrient with functions including muscle contraction and structural components

Micronutrients

only small quantities are required, including vitamins and minerals

Essential Nutrients

must be consumed as our bodies cannot create these nutrients (e.g., carbohydrates, water, sodium)

Nonessential Nutrients

can be produced by the body (e.g., Vitamin D, Vitamin K)

RDA

required daily amount, which is 130 g for carbohydrates

Brain glucose consumption

the brain alone consumes about 120 g of glucose per day

Triglycerides

dietary fat that serves as energy storage

Fatty acids

source of energy; precursor to triglycerides

Phospholipids

component of cellular membranes

Steroids

cholesterol used to develop steroid hormones

Glycolipids

signaling molecules for cellular recognition

Vitamins

small dietary organic compounds that are necessary for metabolism

Water-soluble vitamins

absorbed with water in the small intestine and quickly excreted by kidneys; not stored

Vitamin C

promotes hemoglobin synthesis, collagen synthesis, and sound connective tissue structure

B vitamins

assist enzymes by transferring electrons from one metabolic reaction to another

Fat-soluble vitamins

absorbed with dietary lipids

Vitamin A

component of visual pigments

Vitamin D

promotes calcium and phosphorus absorption and bone mineralization

Vitamin K

essential for prothrombin synthesis and blood clotting

Minerals

inorganic elements that plants extract from soil or water and introduce into the food web

Major minerals

required in large amounts (>100mg/day)

Trace minerals

required in small quantities (<100mg/day)

Metabolism

the sum of all chemical reactions in the body

Catabolism

reactions that break bonds in large molecules to make small molecules

Anabolism

reactions that create bonds between small molecules to make larger molecules

Enzymes

chemical catalysts that increase the reaction rate and increase number of products created per second

Coenzymes

non-protein molecules that help enzymes carry out the reactions by assisting in the transfer of electrons

Anaerobic respiration

occurs in the absence of oxygen and produces small amounts of energy

Aerobic respiration

occurs in the presence of oxygen and produces 30-32 ATP per glucose molecule

Glycolysis

the first step in both anaerobic and aerobic respiration that splits a glucose molecule into two molecules of pyruvate

Krebs Cycle

a series of reactions that processes citric acid and produces CO2, NADH, FADH2, and ATP

Electron Transport Chain

a series of compounds that oxidize the coenzymes to continue the transfer of electrons and produce ATP

Glycogenolysis

Breakdown of glycogen from glucose; occurs when glucose and ATP are low and cells need energy; stimulated by glucagon and epinephrine.

Gluconeogenesis

Synthesis of glucose from non-carbohydrates such as glycerol and amino acids; occurs chiefly in the liver, and can occur in the kidneys if necessary.

Glycogenesis

Taking excess glucose to form storage glycogen.

Lipogenesis

Synthesis of fat from other types of molecules (e.g., amino acids, fatty acids).

Lipolysis

Breaking down fat for fuel; triglycerides hydrolyzed to glycerol and fatty acids; fatty acids can be used in the Acetyl-CoA.

Protein Catabolism

Degradation of skeletal muscle; amino acids first must be deaminated (removal of −NH2).

Keto acid

What remains after deamination of amino acids; can be converted into pyruvate, Acetyl-CoA, or other acids of the Krebs Cycle.

Protein Anabolism

Building of proteins; process involving DNA, mRNA, tRNA, and ribosomes; stimulated by growth hormone, thyroid hormone, and insulin.

Transcription

The process of synthesizing RNA from DNA.

Translation

The process where ribosomes read RNA to synthesize proteins in the correct order of amino acids.

Metabolic Rate

Your metabolism changes from hour to hour; depends on how long it has been since your last meal.

Absorptive (Fed) State

About 4 hours during and after a meal; nutrients are plentiful and are being absorbed to meet energy needs or stored if in excess.

Postabsorptive (Fasting) State

Prevails in the late morning, late afternoon, and overnight; stomach and intestines are empty, and nutrients are not sufficient; body's energy needs are met from stored fuels.

Absorptive State

During this state, glucose is readily available for ATP synthesis.

Excess glucose

Absorbed by liver to form glycogen or fat.

Fats

Lipoprotein lipase removes fats from chylomicrons for uptake by tissues.

Primary energy substrates

Fats are primary energy substrates for hepatocytes, adipocytes, and muscle cells.

Amino acids

Most pass through the liver and go on to other cells for protein synthesis.

Regulation of the Absorptive State

Regulated by insulin that is secreted in response to elevated blood glucose and amino acid levels.

Insulin

Secreted by beta cells of the pancreas.

Uptake of glucose

Stimulates the uptake of glucose by nearly all cells, except neurons, kidney cells, and erythrocytes.

Postabsorptive State

Postabsorptive state regulates plasma glucose concentration to be between about 90 to 100 mg/dL (normal range).

Stored fuels

Nutrients are low or insufficient, so stored fuels are used.

Brain fuel source

Especially critical to the brain as glucose is its primary source of fuel.

Glycogen reserves

Glucose is drawn from glycogen reserves or synthesized from other compounds (gluconeogenesis).

Liver glycogen storage

Liver usually stores enough glycogen to support 4 hours of postabsorptive metabolism before gluconeogenesis occurs.

Adipocytes and hepatocytes

Break down fat and convert glycerol to glucose.

Proteins as fuel

Used as fuel when glycogen and fat reserves are depleted; muscle protein use first.

Regulation of the Postabsorptive State

Regulated mainly by sympathetic nervous system and glucagon.

Glucagon

Increases blood glucose levels; secreted by alpha cells of the pancreas.

Sympathoadrenal system

Especially under the conditions of injury, fear, anger, and other forms of stress.

Thermoregulation

Achieved via several negative feedback loops.

Hypothalamus

Preoptic area of hypothalamus is the body's thermostat.

Kidneys

Filter blood and excrete toxic metabolic wastes.

Metabolic waste

Waste substance produced by the body.

Urea formation

Proteins → amino acids → NH2 removed → forms ammonia, liver converts ammonia to urea.

Blood Urea Nitrogen (BUN)

Level of nitrogenous waste in blood.

Normal concentration of blood urea

10-20 mg/dL

Azotemia

Elevated BUN may indicate renal insufficiency

Uremia

Diarrhea, vomiting, dyspnea, and cardiac arrythmia symptoms stemming from toxicity of nitrogenous wastes; treatment includes Hemodialysis or organ transplant.

Kidney position

Lie against posterior abdominal wall at level of T12-L3.

Right kidney position

Slightly lower due to large right lobe of liver.

Rib 12

Crosses the middle of the left kidney.

Kidney structures

Retroperitoneal along with ureters, urinary bladder, renal artery and vein, and adrenal glands.

Kidney size

About the size of a bar of bath soap.

Renal parenchyma

Two zones: outer renal cortex and inner renal medulla.

Renal columns

Extensions of the cortex that project inward toward sinus.

Renal pyramid

6 to 10 with broad base facing cortex and renal papilla facing sinus.

Minor calyx

Cup that nestles the papilla of each pyramid; collects its urine.

Major calyx

Formed by convergence of 2 or 3 minor calyces.

Renal pelvis

Formed by convergence of 2 or 3 major calyces.

Ureter

A tubular continuation of the pelvis that drains urine down to the urinary bladder.

Nephron

Functional unit of the kidney; each kidney has about 1.2 million nephrons.

Renal corpuscle

Filters the blood plasma.

Renal tubule

Long, coiled tube that converts the filtrate into urine.

Glomerulus

Network of capillaries.

Glomerular (Bowman) Capsule

Capsule surrounding the glomerulus; consists of parietal and visceral layers.

Capsular space

Separates the two layers of the glomerular capsule.

Renal (uriniferous) tubule

Duct leading away from the glomerular capsule.

Collecting duct

Receives fluid from many nephrons; not a part of the renal tubule.

Urine formation stages

Kidneys convert blood plasma to urine in four stages: Glomerular filtration, Tubular Reabsorption, Tubular Secretion, Water conservation.

Glomerular filtration

Water and some solutes in the blood plasma pass from the capillaries of the glomerulus into the capsular space.

Filtration membrane

3 barriers through which fluid passes: Endothelium of glomerular capillaries, Basement membrane, Filtration slits.