Physiology of Metabolism
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Questions and Answers

What is the primary function of storing energy during digestion?

  • To break down large molecules into smaller ones
  • To mobilize energy when no energy intake is taking place
  • To synthesize ATP for immediate energy utilization
  • To avoid large fluctuations of glucose and other compounds (correct)

    • What is the primary site of absorption for small molecules from digestion?

  • Small intestine (correct)
  • Liver
  • Stomach
  • Large intestine

    • What is the primary energy currency utilized by cells?

  • Glucose
  • ATP (correct)
  • Protein
  • Fat

    • What is the primary function of adipose tissue?

    <p>To store energy reserves</p> Signup and view all the answers

    What can be converted into glucose and fatty acids?

    <p>Amino acids</p> Signup and view all the answers

    What is the primary site of nutrient conversion and metabolism?

    <p>Liver</p> Signup and view all the answers

    What is the primary fate of excess molecules during digestion?

    <p>Storage as glycogen and fat</p> Signup and view all the answers

    What is the primary function of non-essential amino acids?

    <p>To form glucose and fatty acids</p> Signup and view all the answers

    What is the primary byproduct of cellular respiration?

    <p>CO2 and H2O</p> Signup and view all the answers

    What is the primary function of mobilizing energy when no energy intake is taking place?

    <p>To provide energy for cellular processes</p> Signup and view all the answers

    What is the primary function of lipases in the gastrointestinal system?

    <p>To split fats into glycerol and fatty acids</p> Signup and view all the answers

    What is the end result of the oxidation of monomers in body cells?

    <p>The release of primary heat</p> Signup and view all the answers

    What is the primary purpose of metabolism in an organism?

    <p>To convert food into energy for cellular processes</p> Signup and view all the answers

    What is the principle that governs metabolism?

    <p>The Law of Conservation of Energy</p> Signup and view all the answers

    What is the term for the process of converting food into building blocks for proteins, lipids, and carbohydrates?

    <p>Assimilation</p> Signup and view all the answers

    What is the relationship between anabolism and catabolism?

    <p>Anabolism and catabolism are mutually opposite but closely related processes</p> Signup and view all the answers

    What is the term for the energy released during the breakdown of monomers in body cells?

    <p>Primary heat</p> Signup and view all the answers

    What is the role of ATP in metabolism?

    <p>To store energy for cellular processes</p> Signup and view all the answers

    What is the term for the process of converting CO2 and H2O into chemical energy?

    <p>Oxidation</p> Signup and view all the answers

    What is the purpose of assimilation processes in an organism?

    <p>To synthesize proteins and lipids</p> Signup and view all the answers

    What is the primary end product of glycolysis?

    <p>Pyruvate, water molecules, ATP, and NADH</p> Signup and view all the answers

    What is the process of building cells' components such as proteins and nucleic acids?

    <p>Assimilation</p> Signup and view all the answers

    What is the unit of energy defined as the amount of energy required to raise the temperature of 1 kg of water by 1°C?

    <p>Joule</p> Signup and view all the answers

    What is the energy used in basal metabolism composed of?

    <p>Energy used in metabolic processes and energy used by the heart, respiratory muscles, kidneys, and other organs</p> Signup and view all the answers

    What is the effect of decreased metabolic rate and lack of activity on caloric needs in geriatric animals?

    <p>Decrease caloric needs by 30% to 40%</p> Signup and view all the answers

    What is the term for the minimum amount of energy needed for maintaining life processes during the physiological resting state?

    <p>Basal metabolism</p> Signup and view all the answers

    What is the process of breaking down organic matter into simple elements?

    <p>Dissimilation</p> Signup and view all the answers

    What is the type of heat formed during assimilation?

    <p>Secondary heat</p> Signup and view all the answers

    How is the energy used in the body determined?

    <p>By the amount of heat that is released from the body</p> Signup and view all the answers

    What is the unit of energy that is consumed through eating and drinking?

    <p>Calorie</p> Signup and view all the answers

    What is the primary function of essential amino acids in the body?

    <p>To facilitate protein synthesis in muscles</p> Signup and view all the answers

    What is the consequence of a lack of even one essential amino acid in the body?

    <p>Metabolic disturbances</p> Signup and view all the answers

    What is the primary role of leucine and isoleucine in the brain?

    <p>Energy production</p> Signup and view all the answers

    What is the fate of amino acids that are not used for protein synthesis in the liver?

    <p>They are converted into fats and carbohydrates</p> Signup and view all the answers

    What is the term for proteins that contain all essential amino acids?

    <p>Complete proteins</p> Signup and view all the answers

    What is the primary function of tryptophan in the brain?

    <p>Serotonin synthesis</p> Signup and view all the answers

    What is the consequence of taking too much of an amino acid?

    <p>Deamination and formation of toxic ammonia</p> Signup and view all the answers

    What is the primary function of valine in the body?

    <p>Transfer of information in nerves and synapses</p> Signup and view all the answers

    What is the term for the process of converting amino acids into energy or building blocks for proteins, lipids, and carbohydrates?

    <p>Protein synthesis</p> Signup and view all the answers

    What is the primary role of the liver in protein exchange?

    <p>Main importance in protein exchange</p> Signup and view all the answers

    What is the primary function of proteins in the body?

    <p>To provide structural components to tissues</p> Signup and view all the answers

    What happens to non-used protein in the body?

    <p>It is degraded and excreted in the urine</p> Signup and view all the answers

    What are the three major functional protein pools in the body?

    <p>Plasma, muscle, and visceral</p> Signup and view all the answers

    How are proteins obtained from food?

    <p>Through enzymatic digestion</p> Signup and view all the answers

    What happens to amino acids after they are absorbed into the blood?

    <p>They are transported to tissues and the liver for protein synthesis</p> Signup and view all the answers

    What is the fate of amino acids that are not used for protein synthesis?

    <p>They are converted into glucose and fatty acids</p> Signup and view all the answers

    What is the role of proteases in protein metabolism?

    <p>To break down proteins into amino acids</p> Signup and view all the answers

    What is the significance of protein turnover in the body?

    <p>It is a dynamic process that occurs constantly in tissues</p> Signup and view all the answers

    What is the purpose of phosphorylating amino acids during protein synthesis?

    <p>To prepare amino acids for transport</p> Signup and view all the answers

    What is the significance of the experiment using radioactive nitrogen-labeled amino acids?

    <p>It demonstrated the rapid turnover of proteins in certain tissues</p> Signup and view all the answers

    What percentage of their daily protein requirement do cows receive from ruminal microorganisms?

    <p>25%</p> Signup and view all the answers

    What is the function of somatotropic hormone in protein exchange?

    <p>Promotes protein formation</p> Signup and view all the answers

    Where is the protein exchange center located?

    <p>Hypothalamus</p> Signup and view all the answers

    What is the energy yield from splitting 1g of proteins?

    <p>4.1 kcal</p> Signup and view all the answers

    What type of proteins are synthesized by ruminal microorganisms?

    <p>Very high-quality proteins</p> Signup and view all the answers

    What is the function of proteins in the body?

    <p>Plastic processes, defense reactions, enzymes, transport, and energy source</p> Signup and view all the answers

    What regulates protein exchange indirectly?

    <p>All internal secretion glands</p> Signup and view all the answers

    What type of nitrogen is used by ruminal microorganisms to synthesize amino acids?

    <p>All of the above</p> Signup and view all the answers

    What is the role of insulin in protein exchange?

    <p>Promotes amino acid entering into cells</p> Signup and view all the answers

    What is the result of impaired liver function on protein metabolism?

    <p>Severely impaired protein exchange</p> Signup and view all the answers

    What is the primary metabolic fuel for monogastric animals?

    <p>Glucose</p> Signup and view all the answers

    Where is most of the glucose processed in the body?

    <p>Liver</p> Signup and view all the answers

    What is the only direct storage form of glucose in the body?

    <p>Glycogen</p> Signup and view all the answers

    What is the primary benefit of storing glucose as glycogen?

    <p>Compact storage</p> Signup and view all the answers

    Which organs use glucose as their primary energy source?

    <p>Brain, Erythrocytes, and Renal Medulla</p> Signup and view all the answers

    How does the liver regulate carbohydrate metabolism?

    <p>By storing and releasing glucose as glycogen</p> Signup and view all the answers

    What is the role of the autonomic nervous system in carbohydrate metabolism?

    <p>To transfer impulses to the liver to increase glucose synthesis</p> Signup and view all the answers

    What is the role of cortisol and growth hormone in carbohydrate metabolism?

    <p>To maintain glucose levels during prolonged starvation</p> Signup and view all the answers

    What is the primary function of glucagon in carbohydrate metabolism?

    <p>To split glycogen and release energy</p> Signup and view all the answers

    What is the primary function of insulin in carbohydrate metabolism?

    <p>To stimulate glycogenesis and increase glucose uptake</p> Signup and view all the answers

    What is the primary source of energy for the nervous system?

    <p>Glucose delivered to tissues through the blood</p> Signup and view all the answers

    What is the primary fate of carbohydrates absorbed into the bloodstream?

    <p>They are used for energetic processes and the rest is stored as glycogen</p> Signup and view all the answers

    What is the primary function of carbohydrates in the body?

    <p>To provide energy, act as a cell component, and support nerve function</p> Signup and view all the answers

    What is the primary source of glucose in the liver?

    <p>Glycerin and fatty acids from lipids</p> Signup and view all the answers

    What is the primary function of glycogen in the liver?

    <p>To act as a buffer for excess glucose</p> Signup and view all the answers

    What is the relationship between carbohydrate, lipid, and protein metabolism?

    <p>They are interconnected and interdependent</p> Signup and view all the answers

    What is the primary function of lactose?

    <p>To provide nutrients for the infant during lactation</p> Signup and view all the answers

    What is the primary fate of excess carbohydrates in the body?

    <p>They are converted into lipids and stored in adipose tissue</p> Signup and view all the answers

    What is the primary source of carbohydrates in the animal diet?

    <p>Large carbohydrate molecules like starch and cellulose</p> Signup and view all the answers

    What is the primary function of carbohydrates in muscle contractions?

    <p>To provide energy</p> Signup and view all the answers

    What type of thirst arises from lack of water in tissues?

    <p>True thirst</p> Signup and view all the answers

    What percentage of the total body mass is composed of water in adult animals?

    <p>65%</p> Signup and view all the answers

    What is the primary mechanism by which the equilibrium of fluid compartments is maintained?

    <p>Osmoregulation</p> Signup and view all the answers

    Where are osmoreceptors located?

    <p>Hypothalamus and peripheral tissues</p> Signup and view all the answers

    What hormone intensifies water reabsorption from nephron tubules?

    <p>Antidiuretic hormone (vasopressin)</p> Signup and view all the answers

    What is the term for the fluid that lies inside the cells?

    <p>Intracellular fluid</p> Signup and view all the answers

    What is the function of baroreceptors in gastric mucosa?

    <p>Regulation of water and salt metabolism</p> Signup and view all the answers

    What is the percentage of water in the brain?

    <p>85%</p> Signup and view all the answers

    Which hormone increases the level of Na in blood?

    <p>Aldosterone</p> Signup and view all the answers

    What is the consequence of losing 20-30% of the body's water?

    <p>Death</p> Signup and view all the answers

    What is the source of metabolic water?

    <p>Oxidation of hydrogen-containing nutrients</p> Signup and view all the answers

    What is the effect of epinephrine on blood vessels of nephron tubules?

    <p>Vasoconstriction</p> Signup and view all the answers

    What is the primary function of water in the body?

    <p>All of the above</p> Signup and view all the answers

    What is the role of the hypothalamus in water and salt metabolism?

    <p>Regulation of thirst</p> Signup and view all the answers

    What is the result of decreased plasma protein concentration?

    <p>Increased filtration of fluid out of capillary tubes</p> Signup and view all the answers

    What is the term for the fluid that lies in serous cavities, such as the eyes and joints?

    <p>Transcellular fluid</p> Signup and view all the answers

    What type of receptors are located in the mouth mucosa?

    <p>Receptors for false thirst</p> Signup and view all the answers

    What is the percentage of the total amount of fluid in the body that is intravascular fluid?

    <p>5%</p> Signup and view all the answers

    What is the role of the liver in plasma protein production?

    <p>Production of plasma proteins</p> Signup and view all the answers

    What is the consequence of losing 10-11% of the body's water?

    <p>Severe dehydration with organ function problems</p> Signup and view all the answers

    What is the primary source of water lost from the body that is classified as an insensible loss?

    <p>Evaporation from the skin or respiratory tract</p> Signup and view all the answers

    How much water is needed per kilogram of dry food for pigs?

    <p>6-8 liters</p> Signup and view all the answers

    What is the result of water losses exceeding water gain in the body?

    <p>Dehydration</p> Signup and view all the answers

    Where is the central thirst center located in the brain?

    <p>Hypothalamus</p> Signup and view all the answers

    What is the hormone that stimulates thirst in response to low blood pressure?

    <p>Angiotensin II</p> Signup and view all the answers

    What is the result of water intake exceeding water output in the body?

    <p>Positive water balance</p> Signup and view all the answers

    What is the term for the abnormal accumulation of interstitial fluid accompanied by swelling?

    <p>Edema</p> Signup and view all the answers

    What is the primary stimulus of thirst in the body?

    <p>Osmoconcentration</p> Signup and view all the answers

    What is the consequence of a loss of water equal to 10% of body weight?

    <p>Severe dehydration</p> Signup and view all the answers

    What is the term for the process of rehydrating the body with not only water but also appropriate electrolytes?

    <p>Rehydration</p> Signup and view all the answers

    What is the primary function of lipids in the body?

    <p>Providing energy and acting as thermal insulator</p> Signup and view all the answers

    What are the lipids that are required by the animal body but cannot be made in sufficient quantity from other substrates?

    <p>Essential fatty acids</p> Signup and view all the answers

    What is the characteristic of lipids that makes them good electrical insulators in nerves?

    <p>Nonpolar nature</p> Signup and view all the answers

    What is the primary difference between fats and oils?

    <p>Fats have more saturated fatty acids, while oils have more unsaturated fatty acids</p> Signup and view all the answers

    What is the primary function of lipoproteins in the body?

    <p>Transporting lipids in blood</p> Signup and view all the answers

    What is the primary site of lipid storage in the body?

    <p>Adipose tissue</p> Signup and view all the answers

    What is the primary consequence of a lack of essential fatty acids?

    <p>Pathological changes in skin and hair</p> Signup and view all the answers

    What is the primary characteristic of complex (polar) lipids?

    <p>Polarity</p> Signup and view all the answers

    What is the primary function of glycerol in lipid metabolism?

    <p>Forming esters with fatty acids</p> Signup and view all the answers

    What is the primary function of waxes in the body?

    <p>Protecting skin and hair</p> Signup and view all the answers

    What is the function of wax esters with monohydroxy alcohols?

    <p>Protection and lubrication of skin</p> Signup and view all the answers

    What is the characteristic of neutral fat synthesized from carbohydrates?

    <p>Has more unsaturated fatty acids</p> Signup and view all the answers

    What is the function of phospholipids in the body?

    <p>Structural components of cell membranes and emulsifiers</p> Signup and view all the answers

    What is the role of glycolipids in the body?

    <p>Cell-cell interactions and immune responses</p> Signup and view all the answers

    What is the composition of lipoproteins?

    <p>Lipids and proteins</p> Signup and view all the answers

    What is the function of cholesterol in the body?

    <p>Structural component of cell membranes</p> Signup and view all the answers

    What is the result of hydrolysis of simple and compound lipids?

    <p>Formation of fatty acids and glycerol</p> Signup and view all the answers

    What is the function of lipases in the gastrointestinal system?

    <p>Breakdown of lipids</p> Signup and view all the answers

    What is the function of surfactant in the lungs?

    <p>Lowering of surface tension</p> Signup and view all the answers

    What is the characteristic of complex lipids?

    <p>High molecular weight and esters of fatty acids and alcohols</p> Signup and view all the answers

    What happens when the balance of acetyl-CoA with oxaloacetate is interfered with?

    <p>Ketones are formed</p> Signup and view all the answers

    How much water is formed when 100g of fat is burned?

    <p>107g of water</p> Signup and view all the answers

    What is the significance of a camel's hump?

    <p>It stores water</p> Signup and view all the answers

    Where is the regulatory center of lipid metabolism located?

    <p>Hypothalamus</p> Signup and view all the answers

    What is the role of the brain cortex in lipid metabolism?

    <p>It plays a very important role</p> Signup and view all the answers

    What happens to fatty tissues during stress?

    <p>They are broken down</p> Signup and view all the answers

    Why do fatty tissues need insulin?

    <p>To use glucose as an energy source</p> Signup and view all the answers

    What is involved in lipid metabolism?

    <p>All internal secretion glands</p> Signup and view all the answers

    What is characteristic of animals during hibernation?

    <p>They can survive without water for a long time</p> Signup and view all the answers

    What is the significance of water in lipid metabolism?

    <p>It is very significant</p> Signup and view all the answers

    What is the primary function of cholesterol in the body?

    <p>To synthesize steroid and sex hormones</p> Signup and view all the answers

    What is the role of bile acids in lipid absorption?

    <p>To form a complex with fatty acids for absorption</p> Signup and view all the answers

    What is the primary source of oxalacetate in the body?

    <p>Glucose, glycogen</p> Signup and view all the answers

    What is the significance of the phrase 'Fats burn in a carbohydrate flame'?

    <p>Fats require carbohydrates to be oxidized and produce energy</p> Signup and view all the answers

    What is the primary role of saturated fatty acids in the body?

    <p>To participate in the synthesis of milk fat</p> Signup and view all the answers

    What is the fate of fatty acids that are not used for energy production?

    <p>They are stored as triglycerides</p> Signup and view all the answers

    What is the primary function of lipases in the body?

    <p>To break down triglycerides into glycerol and fatty acids</p> Signup and view all the answers

    What is the primary role of omega-3 fatty acids in the body?

    <p>To decrease the levels of cholesterol in the blood</p> Signup and view all the answers

    What is the primary site of fatty acid synthesis in the body?

    <p>Liver, adipose tissues, and mammary glands</p> Signup and view all the answers

    What is the consequence of a lack of carbohydrates in the body?

    <p>Decreased energy production from fats</p> Signup and view all the answers

    What percentage of heat loss occurs through radiation?

    <p>55-65%</p> Signup and view all the answers

    Where are thermoreceptors mainly located in the skin?

    <p>Outer layer of dermis</p> Signup and view all the answers

    What is the term for the process of converting CO2 and H2O into chemical energy?

    <p>Photosynthesis</p> Signup and view all the answers

    What is the primary function of the hypothalamus in thermoregulation?

    <p>Sensing heat and cold temperatures</p> Signup and view all the answers

    What is the percentage of heat loss through evaporation?

    <p>30%</p> Signup and view all the answers

    What is the primary function of the autonomic nervous system in thermoregulation?

    <p>Responding to thermal stimuli</p> Signup and view all the answers

    What is the term for the minimum amount of energy needed for maintaining life processes during the physiological resting state?

    <p>Basal metabolic rate</p> Signup and view all the answers

    What happens to the activity of the hypothalamus when it is cold?

    <p>Increases</p> Signup and view all the answers

    What is the primary function of brown fat in newborns?

    <p>Heat production</p> Signup and view all the answers

    What is the result of a body temperature drop below 34°C?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of fever or pyrexia?

    <p>To kill bacteria and inhibit viruses</p> Signup and view all the answers

    What is the term for the regulation of heat production and heat release?

    <p>Thermoregulation</p> Signup and view all the answers

    What is the method that measures mid- and long-wave infrared radiation emitted by all objects and converts it to temperature?

    <p>Thermography</p> Signup and view all the answers

    What is the consequence of a body temperature above 45°C?

    <p>Fatal brain damage</p> Signup and view all the answers

    What is the term for a temporary reduction in body temperature, e.g., in bats and hummingbirds?

    <p>Torpor</p> Signup and view all the answers

    What is the term for the internal body part that maintains a relatively constant temperature?

    <p>Internal body part</p> Signup and view all the answers

    What is the primary mechanism for heat transfer in the body?

    <p>Convection through the bloodstream</p> Signup and view all the answers

    Why are humans more susceptible to sunburns?

    <p>Cold sensations are felt faster than warmth sensations</p> Signup and view all the answers

    What is the main difference in heat tolerance between cattle and pigs?

    <p>Cattle are able to pant more effectively than pigs</p> Signup and view all the answers

    What is the primary mechanism for heat loss in birds?

    <p>Evaporation through the air sacs</p> Signup and view all the answers

    What is the effect of high humidity on evaporation in animals?

    <p>It decreases the rate of evaporation</p> Signup and view all the answers

    What is the primary function of arteriovenous anastomoses in the body?

    <p>To increase blood flow to the skin</p> Signup and view all the answers

    What is the primary mechanism for non-shivering thermogenesis in animals?

    <p>Increased production of thyroid hormones</p> Signup and view all the answers

    What is the primary function of brown fat in the body?

    <p>To produce heat through metabolism</p> Signup and view all the answers

    What is the primary reason why homeothermic animals need to maintain a high metabolic rate in cold weather?

    <p>To maintain a constant body temperature</p> Signup and view all the answers

    Which type of animals have a constant body temperature in the summer, but it decreases in the winter?

    <p>Heterothermic animals</p> Signup and view all the answers

    What is the range of daily fluctuations in internal body temperature?

    <p>1°C</p> Signup and view all the answers

    What is the primary function of heat production in the body?

    <p>To regulate body temperature</p> Signup and view all the answers

    Which part of the body is divided into superficial and internal parts based on thermoregulation?

    <p>Body</p> Signup and view all the answers

    What is the primary mechanism by which poikilothermic animals regulate their body temperature?

    <p>Behavioral adaptations</p> Signup and view all the answers

    Why do older animals have a lower body temperature?

    <p>Due to decreased metabolic rate</p> Signup and view all the answers

    What is the primary function of the internal body part in thermoregulation?

    <p>To maintain a constant body temperature</p> Signup and view all the answers

    What is the primary advantage of using thermography to monitor animal health?

    <p>It can measure temperature distribution over a large area.</p> Signup and view all the answers

    What is a disadvantage of using special ear tag sensors to monitor animal health?

    <p>They may not be as accurate as other methods.</p> Signup and view all the answers

    What is an advantage of using infrared lamps to warm animals in case of hypothermia?

    <p>They can be targeted to specific areas.</p> Signup and view all the answers

    What is a disadvantage of using electric heating mats to warm animals in case of hypothermia?

    <p>They can cause burns if not properly monitored.</p> Signup and view all the answers

    What is an advantage of using clothing to warm animals in case of hypothermia?

    <p>It provides insulation.</p> Signup and view all the answers

    What is a disadvantage of using rubber gloves with warm water to warm animals in case of hypothermia?

    <p>They require frequent reheating of water.</p> Signup and view all the answers

    What is an advantage of using warm air to warm animals in case of hypothermia?

    <p>It is quick and effective.</p> Signup and view all the answers

    What is a disadvantage of using oral thermometry to monitor animal health?

    <p>It may not be as accurate as other methods.</p> Signup and view all the answers

    Study Notes

    Physiology of Metabolism

    • In the gastrointestinal system, polymers are broken down into monomers:
      • Proteases: proteins into amino acids
      • Lipases: fats into glycerol and fatty acids
      • Amylases: carbohydrates into monosaccharides
    • Monomers can be:
      • Converted into central metabolites (pyruvates, Acetyl-CoA, etc.) or oxidized to CO2 and H2O, releasing chemical energy
      • Used to form substances (assimilated) such as glycogen, protein, and triglycerides, with energy supplied by ATP and secondary heat released

    Metabolism

    • Metabolism is the sum of physical and chemical processes in an organism
    • Main purposes of metabolism:
      • Converting food to energy for cellular processes
      • Converting food to building blocks for proteins, lipids, nucleic acids, and some carbohydrates
      • Eliminating nitrogenous wastes
    • Metabolism involves various biochemical reactions that transform one form of energy into another
    • Any molecule synthesized or utilized in metabolism is a physically recognizable form of energy
    • Metabolism follows the Law of Conservation of Energy
    • Metabolism consists of two opposite but closely related processes:
      • Anabolism (assimilation): building cells' components, consuming energy
      • Catabolism (dissimilation): breaking down organic matter, releasing energy

    Factors Affecting Metabolism Rate

    • Feeding
    • Physical activity
    • Environmental temperature
    • Age
    • Gender
    • Body mass
    • Functional state of the nervous system (stress, rest, etc.)

    Basal Metabolism

    • Minimum amount of energy needed for maintaining life processes during physiological resting state
    • Depends on:
      • Gender, age, body mass, sleep or awake state, body temperature
    • Evaluated and compared by amount of heat in kilocalories (kcal) per 1kg of body weight
    • Energy consumption per 1kg of body weight is higher in smaller animals than in larger animals

    Energy

    • Use of energy in the body is determined by the amount of heat released
    • Calories: units of energy consumed through eating and drinking, and expended through physical activity
    • Joule: unit of energy, defined as the amount required to raise the temperature of 1kg of water by 1°C
    • Energy is needed by cells continuously, but only supplied to the body while food is digested
    • The body must store energy during digestion and mobilize energy when no intake occurs

    Protein Metabolism

    • Proteins are essential for life-supporting processes, containing nitrogen, and are a source of protein (P).
    • Proteins are constantly synthesized and broken down in tissues, and they are components of all body cells.

    Types of Proteins

    • Proteins can be classified into two categories: animal and plant proteins.
    • The human and animal body has no protein reserves, and all proteins are functional, either part of tissue structures or metabolic systems.

    Protein Pools

    • The body has three major functional protein pools:
      • Plasma proteins and plasma amino acids
      • Muscle protein
      • Visceral (abdominal organs) protein

    Transfer and Synthesis of Proteins

    • Proteins obtained from food are split into amino acids with the help of enzymes.
    • Amino acids are then phosphorylated and absorbed into the blood, and transported to tissues and the liver.
    • In tissues, amino acids are synthesized into tissue-specific proteins.
    • Amino acids are also obtained from the decomposition of cell proteins.

    Amino Acids

    • All proteins are made of 20-25 amino acids (AmAc).
    • The body can transform one AmAc into another, which is needed at a particular moment.
    • Irreplaceable or essential amino acids must be obtained from food, while replaceable amino acids can be synthesized in the body.

    Essential Amino Acids

    • In adult animals, essential amino acids include:
      • Leucine (Leu)
      • Isoleucine (Ile)
      • Lysine (Lys)
      • Methionine (Met)
      • Phenylalanine (Phe)
      • Tryptophan (Trp)
      • Valine (Val)
      • Threonine (Thr)
      • Taurine
    • In newborn animals, additional essential amino acids include:
      • Histidine (His)
      • Arginine (Arg)

    Replaceable Amino Acids

    • Replaceable amino acids can be synthesized in the body from other amino acids.

    The Role of Essential Amino Acids

    • Metabolic disturbances can be caused by a lack of even one essential amino acid.
    • Essential amino acids have specific roles in the body, such as:
      • Taurine: stabilizes neuron membrane excitability, critical for normal vision, digestion, heart muscle function, and immune system.
      • Tryptophan: takes part in synthesis of group B vitamins, transforms into serotonin in the brain.
      • Leucine: used for energy production in the brain, essential for liver function.
      • Valine: needed for nerve transfer and synapses, promotes muscle coordination and emotional balance.

    Protein Synthesis

    • Proteins are synthesized from amino acids in tissues.
    • Amino acids that are not used for protein synthesis are deaminated and used for energetic processes or synthesis of fats and carbohydrates.

    Protein Exchange

    • Liver is of main importance in protein exchange.
    • Impaired liver functions lead to impaired protein exchange.
    • Growing animals and animals during lactation require well-balanced food due to increased protein formation.

    The Value of Proteins

    • The value of proteins is determined by the presence of all irreplaceable amino acids.
    • Proteins that contain all essential amino acids are called complete or whole proteins.
    • Proteins that do not contain all essential amino acids are called incomplete proteins.

    The Role of the Liver in Protein Metabolism

    • The liver plays a key role in protein metabolism.
    • Liver dysfunction severely impairs protein exchange.

    Protein Particularities in Ruminants

    • Ruminants, such as cows, receive about 25% of their daily protein requirement from ruminal microorganisms.
    • Ruminal microorganisms can synthesize all irreplaceable amino acids using other amino acids, urea nitrogen, ammonia nitrogen, and simple non-protein nitrogen compounds.

    The Use of Proteins

    • Proteins are used for:
      • Plastic processes related to animal growth and development
      • Defense reactions, such as immune substances and antibodies
      • Enzymes and hormones
      • Transporting other chemical substances
      • Serving as an energy source

    Neural Regulation of Protein Exchange

    • Protein exchange is regulated by the protein exchange center, located in the hypothalamus.
    • Humoral regulation of protein exchange involves direct and indirect actions of various hormones.

    Carbohydrates in the Diet

    • Small carbohydrate molecules in the diet: monosaccharides (glucose) and disaccharides (lactose, sucrose)
    • Large carbohydrate molecules in the diet: polysaccharides (starch, glycogen, cellulose)

    Carbohydrates in the Body

    • Three most prominent carbohydrates in the body: glucose (monosaccharide), glycogen (polysaccharide), and lactose (disaccharide)

    Importance of Carbohydrates

    • Energy source for the body
    • Component of glycoproteins
    • Provides energy for muscle contractions and relaxation
    • Necessary for myocardium function
    • Essential for nervous system function, with almost no glucose reserves in the brain

    Carbohydrate Metabolism

    • Carbohydrates are broken down into monosaccharides (glucose) in the digestive tract
    • Glucose is absorbed into the blood and distributed to the body, with the liver and muscles storing it as glycogen
    • Glycogen can be synthesized from glucose, glycerin, fatty acids, amino acids, and volatile fatty acids

    Cellular Metabolism of Carbohydrates

    • Glucose is the primary metabolic fuel for non-herbivores
    • In herbivores, cellulose is the primary carbohydrate intake
    • Ruminants convert carbohydrates to volatile fatty acids in the forestomach
    • Monogastric herbivores convert carbohydrates to volatile fatty acids in the large intestine

    Glucose Processing in the Liver

    • The liver processes most of the glucose received via the portal vein
    • Glucose is stored as glycogen in the liver and muscles
    • Excess glucose is converted to lipids and stored in adipose tissue

    Benefits of Glycogen Storage

    • Glycogen is a large, insoluble molecule that does not affect osmotic balance
    • It is compact, allowing for efficient energy storage
    • Glycogen is easily broken down for energy

    Organs that Use Glucose as the Predominant Energy Source

    • Brain
    • Erythrocytes
    • Renal medulla
    • Skeletal muscle (under aerobic conditions)
    • Fetal metabolism during gestation
    • Lactose synthesis during lactation

    Neuro-Humoral Regulation of Carbohydrate Metabolism

    • The liver is the main depot of carbohydrates
    • Muscles are the main consumers of glucose
    • The kidneys excrete excess glucose
    • The nervous system and hormones regulate carbohydrate metabolism

    Regulation of Carbohydrate Metabolism

    • Direct regulation: decreased glucose levels stimulate the "sugar" center, which increases glucose synthesis in the liver
    • Indirect regulation: insulin stimulates glycogenesis, while glucagon, epinephrine, and glucocorticoids break down glycogen and release glucose
    • Other hormones involved: cortisol, growth hormone, and glucagon

    Water Metabolism

    • Water forms the major part of body fluids, acts as a solvent, and participates in enzymatic reactions, thermoregulation, and digestive processes.
    • Water also moisturizes air in the respiratory tract, mucous membranes, and acts as a lubricant for joints and a shock absorber for organs.

    Water in the Body

    • The human body is composed of approximately 65% water, with newborns having around 75-80% water content.
    • Water distribution varies across different organs, with the brain having 85% water, heart having 80%, and blood having 83%.
    • Bones have a lower water content, around 20%.
    • Losing 10-11% of water leads to severe dehydration and organ function problems, while losing 20-30% of water can be fatal.

    Fluid Compartments

    • The body maintains equilibrium of fluid compartments through osmoregulation.
    • Extracellular fluid (ECF) makes up 20% of the total fluid, with 5% being intravascular fluid and the rest being lymphatic and interstitial fluid.
    • Intracellular fluid (ICF) accounts for 40% of the total fluid, located within cells.
    • Transcellular fluid (TCF) is a small, variable amount found in serous cavities.

    Water Gain and Loss

    • Water can be gained through drinking, food, and metabolic water (via oxidation of hydrogen-containing nutrients).
    • The body loses water through insensible loss (evaporation from skin and respiratory tract) and sensible loss (urine, feces, and body secretions).
    • Water needs vary across different animal species, with pigs requiring 6-8 liters/kg of dry food, cows requiring 4-6 liters/kg, and horses and sheep requiring 2-3 liters/kg.

    Water Balance in the Body

    • Water balance is achieved when water intake equals water output.
    • Negative water balance occurs when water loss exceeds water gain, leading to dehydration.
    • Dehydration can occur due to inadequate drinking water, diarrhea, vomiting, or excessive sweating.
    • A skin fold test can check for dehydration.

    Dehydration

    • Dehydration develops when water losses exceed water gain, causing the body to lose water from the extracellular fluid compartment first, followed by a shift from intracellular to extracellular fluid.
    • A loss of 10% of body weight is considered severe for most animals.
    • Dehydration leads to the depletion of water and electrolytes, requiring rehydration with both water and electrolytes.

    Regulation of Water Balance

    • The kidneys conserve water when water losses exceed water gain.
    • The thirst mechanism is triggered by the hypothalamus, which is stimulated by an increase in osmoconcentration (loss of water and increased salt concentration).
    • Angiotensin II, a kidney hormone, also stimulates thirst in response to low blood pressure.

    Positive Water Balance

    • Positive water balance occurs when water intake exceeds output, leading to excess water storage in the body.
    • This can result in edema, an abnormal accumulation of interstitial fluid accompanied by swelling.

    Edema

    • Factors that contribute to edema include increased capillary pressure, increased capillary permeability, decreased plasma protein concentration, and obstruction of lymphatic vessels.
    • Heart failure can lead to increased capillary pressures and edema due to increased venous pressure.

    Neural Regulation of Water and Salt Metabolism

    • Receptors involved in water and salt metabolism regulation include:
      • Osmoreceptors in the hypothalamus and tissues
      • Baroreceptors in the gastric mucosa
      • Volume receptors in blood vessels
    • "True" thirst arises from lack of water in tissues, whereas "false" thirst arises from dryness of the mouth and throat.

    Humoral Regulation of Water and Salt Metabolism

    • Antidiuretic hormone (vasopressin) from the neurohypophysis intensifies water reabsorption from nephron tubules, leading to water retention in the body.
    • Aldosterone from the adrenal gland cortex intensifies Na reabsorption from nephron tubules, increasing blood Na levels.
    • Epinephrine from the adrenal gland medulla narrows blood vessels of nephron tubules, decreasing filtration and urine output, thereby retaining water in the body.

    Lipid Metabolism

    • Lipids comprise a group of naturally occurring molecules, including fats, sterols, phospholipids, and others, made up of glycerol and fatty acids.

    Properties of Lipids

    • Lipids are relatively insoluble in water and soluble in nonpolar solvents such as ether, chloroform, benzole, and acetone.
    • Lipids are stored in adipose tissue, serve as thermal insulators, and are nonpolar lipids that serve as electrical insulators in nerves.

    Classes of Lipids

    • Simple (neutral) lipids
    • Complex (polar) lipids
    • Precursor and derived lipids (neutral)

    Simple Lipids

    • Fats and oils: esters of fatty acids with glycerol
    • Waxes: esters of fatty acids with high molecular weight monohydroxy alcohols
    • Fats (triglycerides): solid at room temperature, with more long-chain fatty acids and more saturated fatty acids
    • Oils (triglycerols): liquid at room temperature, with relatively short-chain fatty acids and more unsaturated fatty acids

    Complex Lipids

    • Phospholipids: lipids containing fatty acids, alcohol, and phosphoric acid residue
    • Glycolipids (glycosphingolipids): lipids containing fatty acid, sphingosine, and carbohydrate
    • Other complex lipids: lipids such as sulfolipids and aminolipids, including lipoproteins

    Phospholipids

    • Structure: glycerol + 2 fatty acids + phosphate group
    • Physiological significance: structural components of cell membranes, emulsifiers, and involved in lipid absorption and transport

    Glycolipids

    • Functions: cell-cell interactions, immune responses, and determining blood group

    Lipoproteins

    • Lipids + proteins
    • Structural lipoproteins: widely distributed in tissues, present in cellular and subcellular membranes
    • Transport lipoproteins: present in blood plasma, composed of apolipoprotein and different types of lipids

    Types of Lipoproteins

    • Chylomicrons (1-2% protein, 98-99% lipid)
    • VLDL (7-10% protein, 90-93% lipid)
    • LDL (10-20% protein, 80-90% lipid)
    • HDL (35-55% protein, 45-65% lipid)

    Precursor and Derived Lipids

    • Derived lipids: produced from simple and compound lipids through hydrolysis
    • Include fatty acids, glycerol, cholesterol, steroid hormones, fatty aldehydes, and fat-soluble vitamins (A, D, E, K)

    Cholesterol

    • Essential for health, composing around 35% of lipids in animal cell membranes
    • Precursor of steroid and sex hormones, bile acids, and vitamin D

    Essential Fatty Acids

    • Omega 6 and Omega 3
    • Found in fish, shellfish, soybean oil, rapeseed oil, corn oil, sunflower oil, olive oil, peanuts, and almonds
    • Advisable to take 30% of daily requirements of kcal from fats, with 5% being essential fatty acids

    Thermoregulation

    • Thermoregulation is the body's ability to maintain a relatively constant internal temperature through heat production and heat loss.
    • A constant body temperature is necessary for normal metabolic processes, as enzymes work only within certain temperature limits.

    Types of Thermoregulation

    • Homeothermic (Endothermic) Animals: mammals and birds, maintain constant body temperature despite different environmental temperatures.
    • Heterothermic Animals: animals that have a constant body temperature in the summer, but it decreases in the winter (e.g., bears, hedgehogs, badgers).
    • Poikilothermic (Ectothermic) Animals: animals that have a body temperature that varies depending on the surrounding temperature (e.g., fish, reptiles, amphibians).

    Body Temperature Regulation

    • The body is divided into two parts: superficial body (shell) part and internal body (core) part.
    • The superficial body part temperature changes depending on environmental factors, while the internal body part maintains a relatively constant temperature.
    • Daily fluctuations in body temperature can be up to 1°C, and vary depending on factors such as eating, physical work, and sleep.

    Heat Production and Loss

    • Heat production: chemical thermoregulation, which occurs through muscle activity, liver metabolism, and gastrointestinal tract metabolism.
    • Heat loss: physical thermoregulation, which occurs through evaporation, convection, radiation, and conduction.
    • Radiation is the main form of heat loss, accounting for 55-65% of heat loss.

    Regulation of Thermoregulation

    • Neural Regulation: involves the hypothalamus, cerebral cortex, and autonomic nervous system.
    • Humoral Regulation: involves the endocrine system and stress hormones.
    • Behavioral Regulation: involves conscious and unconscious behaviors, such as changing body posture or seeking shade.

    Thermoreceptors

    • Krause End Bulbs: sensitive to low temperatures, located in the outer layer of dermis.
    • Ruffini Endings: sensitive to increases in temperature, located deeper in the dermis.
    • Thermoreceptors: located in the CNS, skin, and internal organs, respond to changes in temperature.

    Heat Transfer in the Body

    • Heat is transferred through the body by blood, which is a poor conductor of heat.
    • Arterioles and arteriovenous anastomoses play a crucial role in heat transfer.

    Responses to Extremes of Heat

    • Panting and sweating are responses to heat stress, and are influenced by humidity and temperature.
    • Different species have varying abilities to withstand extreme temperatures, such as cattle and sheep being more tolerant of heat.

    Keeping Warm in the Extremities

    • Arterioles and veins are located close together, allowing for heat transfer from arterial to venous blood.
    • Shivering is a mechanism to produce heat, and can be increased in response to cold stress.
    • Non-shivering thermogenesis is a mechanism to increase heat production without shivering, achieved through increased thyroid hormone production.

    Thermoregulation in Practice

    • Thermometry is the measurement of temperature, and is essential in assessing the health status of animals.
    • Different methods of thermometry, such as rectal thermometry, non-contact thermometry, and thermochips, have their own advantages and disadvantages.

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    Quiz about the process of metabolism in the human body, covering the breakdown of macromolecules into monomers and their conversion into energy.

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