Biology: Blood and Oxygen Transport

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Protein Structure, Properties, and Functions

• Primary structure of proteins is stabilized with peptide bonds.
• Secondary structure of proteins is stabilized ONLY with hydrogen bonds.
• Tertiary structure of proteins is stabilized with covalent or noncovalent bonds.
• Quaternary structure of proteins is stabilized mainly with noncovalent bonds and hydrophobic interactions.
• Functions of proteins in humans:
  • Transport of hormones in blood
  • Muscle contraction
  • Catalysis of reactions
• Not a function of proteins: Storing of genetic information

Protein-Ligand Interactions

• Ligand binding is highly specific and necessary for performing specific biological functions.
• Examples of protein-ligand interactions:
  • Antigen-antibody interaction
  • Hormone-receptor interaction
  • Protein-heavy metal ion interaction

Denaturation of Proteins

• Denaturation is always followed by alterations in its biological function and changes in its solubility.
• Denaturation can be induced by:
  • Adding a heavy metal salt to a protein aqueous solution
  • Adding a strong acid to a protein aqueous solution
  • Heating a protein aqueous solution

Vitamins and Enzymes

• Vitamin B5 (nicotinic acid) is a part of coenzyme NAD.
• Vitamin B6 is a part of coenzyme pyridoxal phosphate.
• Vitamin B9 (folic acid) is a part of coenzyme THF.
• Vitamin B2 (riboflavin) is a part of coenzyme FAD.
• Vitamin B1 (thiamin) is a part of coenzyme TPP.
• Vitamin B3 (panthotenic acid) is a part of coenzyme HS-CoA.
• Functions of enzyme cofactors:
  • FAD: intermediate carrier of hydrogen atoms
  • HS-CoA: intermediate carrier of acyl groups
  • NAD: intermediate carrier of hydrogen atoms
  • THF: intermediate carrier of one-carbon groups
  • Pyridoxal phosphate: intermediate carrier of amino groups
• Enzyme cofactors and their functions:
  • Pyridoxal phosphate: involved in transamination reactions
  • HS-CoA: involved in acyl transfer reactions
  • NAD: involved in redox reactions
  • THF: involved in one-carbon transfer reactions

Energy Exchange

• Aerobic dehydrogenation is catalyzed by cytochrome oxidase.
• Anaerobic dehydrogenation is catalyzed by succinate dehydrogenase.
• Dehydrogenation is a type of oxidation reaction in which electrons are removed from the substrate.
• Functions of monooxygenases:
  • Xenobiotics detoxication
  • Drugs and metabolites inactivation
• Caloric coefficients for macronutrients:
  • Carbohydrates: 4.1 kcal/g
  • Lipids: 9.3 kcal/g
  • Proteins: 4.1 kcal/g
• Daily requirements for macronutrients (according to WHO recommendations):
  • Lipids: 4.1 g/kg body weight
  • Proteins: 1 g/kg body weight
  • Carbohydrates: 1.5 g/kg body weight

Carbohydrates

• Glycogen is a homopolysaccharide.
• Sucrose is a disaccharide.
• Hialuronic acid is a heteropolysaccharide.
• Galactose is a monosaccharide.
• Lactose is a disaccharide.
• Heparin is a heteropolysaccharide.
• Metabolic pathways:
  • Glycolysis: anaerobic oxidation of glucose
  • Gluconeogenesis: synthesis of glucose from non-carbohydrate substances
  • Pentose phosphate pathway: oxidation of glucose to generate NADPH+H+
  • Glucogenesis: synthesis of glucose from non-carbohydrate substancesHere are the study notes for the text:
• Carbohydrate Metabolism*

Gluconeogenesis

• Located in liver, kidney cortex, and skeletal muscles
• Inhibitors: insulin, glucose
• Stimulators: glucagon, cortisol, adrenaline

Digestion of Carbohydrates

• Digestion of glycogen and starch in oral cavity catalyzed by amylase
• Digestion of disaccharides in small intestine catalyzed by sucrase, lactase, and maltase
• Absorption of sugars in intestinal wall by active transport, facilitated diffusion, and simple diffusion

Regulation of Blood Glucose Levels

• Hyperglycemia: blood glucose level > 6.2 mmol/l
• Hypoglycemia: blood glucose level < 2.8 mmol/l
• Normal range of blood glucose level in adults: 2.2-4.4 mmol/l
• Physiologic hyperglycemia: after meal, during physical activity, or emotional stress
• Pathologic hyperglycemia: diabetes mellitus
• Physiologic hypoglycemia: starvation, long-term physical activity
• Pathologic hypoglycemia: overdosage of insulin, Bronze disease
• Lipid Metabolism*

Types of Fatty Acids

• Saturated fatty acids: palmitic, stearic
• Monounsaturated fatty acids: oleic, palmitoleic
• Polyunsaturated fatty acids: linoleic, arachidonic

Functions of Lipids

• Energy storage
• Structural components of cell membranes
• Sources of energy during starvation
• Can be used as second messengers

Lipid Transport

• Exogenous lipids transported from intestine to tissues by chylomicrons
• Endogenous lipids transported from liver to peripheral tissues by VLDL, IDL, and LDL
• Reverse transport of cholesterol from peripheral tissues to liver by HDL

Regulation of Lipid Metabolism

• Lipolysis in adipose tissue stimulated by glucagon, adrenaline, and cortisol
• Lipogenesis in adipose tissue stimulated by insulin

Atherosclerosis

• Atherogenicity coefficient: (total cholesterol - HDL cholesterol) / HDL cholesterol
• High risk of atherosclerosis development: atherogenicity coefficient > 3.5
• Protein and Amino Acid Metabolism*

Essential Amino Acids

• Phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, lysine, leucine

Nitrogen Balance

• Positive nitrogen balance: during growth, pregnancy, and after surgery
• Negative nitrogen balance: during starvation, fever, and after trauma
• Nitrogen equilibrium: during normal adult life

Transamination Reactions

• Transfer of amino group from amino acid to ketoacid
• Cofactor: pyridoxal phosphate

Urea Cycle

• Location: liver mitochondria and cytosol
• Function: detoxification of ammonia
• Enzymes: carbamoylphosphate synthase I, ornithine transcarbamoylase, arginase

Biogenic Amines

• Synthesis: from amino acids
• Inactivation: by methylation, transamination, and oxidative deamination

Let me know if you'd like me to continue!### Hormones and their Functions

• Glucagon is a hormone of the pancreatic gland
• Tyroxin is a hormone of the thyroid gland
• Adrenalin is a hormone of the medulla of suprarenal glands
• Somatotropin is a hormone of the hypothalamus

Synthesis of Hormones

• Cortisol, Aldosteron, and Testosteron are synthesised in the cortex of suprarenal glands
• Somatostatin, Insulin, and Glucagon are synthesised in the pancreatic gland
• Growth hormone, Thyreotropic hormone, and ACTH are synthesised in the pituitary gland
• Somatotropin is synthesised in the hypothalamus
• Calcitonin is synthesised in the thyreoid gland
• Calcitriol is not synthesised in the thyreoid gland

Classification of Hormones

• Hormones of peptide nature include Glucagon, Growth hormone, Insulin, and Thyreotropin
• Hormones of protein nature include Adrenalin, Thyroxine, Insulin, and Somatotropin
• Hormones - derivatives of aminoacids - include Adrenalin, Melatonin, T3, and T4
• Steroid hormones include Aldosteron, Cortisol, Calcitriol, and Testosteron

Receptors of Hormones

• Hormones that have receptors in the outer cell membrane include Insulin, Glucagon, and Thyreotropin
• Hormones that have receptors inside cells (in cytosole or nucleus) include Thyroxine, Cortisol, and Aldosteron
• Hormones that act on receptors in the nucleus include Thyroxine and Cortisol
• Hormones that act on receptors in the outer cell membrane include Adrenalin and Glucagon

Inactivation of Hormones

• Insulin is inactivated by Oxidative deamination and conjugation
• Adrenalin is inactivated by Oxidative deamination and methylation
• Glucagon is inactivated by Oxidative deamination

Regulation of Metabolic Processes

• Aldosteron and Vasopressin regulate exchange of water and minerals
• Testosteron and Estradiol regulate reproductive functions
• Calcitriol and Calcitonin regulate exchange of calcium and phosphates
• Glucagon and Cortisol regulate glucose metabolism

Biochemistry of Blood, Liver, Kidney, and Connective Tissue

• Erythrocytes lack several metabolic pathways, including protein biosynthesis on ribosomes and DNA replication
• 2,3-bisphosphoglycerate decreases Hb affinity to oxygen
• MetHb is a variant of Hb which can not transport oxygen in blood
• ATP in red blood cells is used mainly for active transport
• Increase of affinity and rate of O2 binding to Hb is a result of positive cooperative effect

Kidney and Liver Functions

• Kidney is the main organ producing Erythropoetin
• Hepatocytes produce VLDL and HDL
• Glucokinase in hepatocytes has kinetic properties of high value of Km and is not inhibited by glucose-6-phosphate
• Direct bilirubin can not be found in urine of patients with hemolytical jaundice

Connective Tissue

• Fibronectin is a polydomain protein with main function of integrative
• Collagen synthesis requires ascorbic acid and produces desmosin after degradation
• Elastin is a protein responsible for elasticity of tissues and consists of single polypeptide chain
• Glycosaminoglycans found in extracellular matrix of humans include Chondroitinsulphates, Dermatansulphates, and Keratansulphates