Homeostasis and Thermoregulation Quiz

Homeostasis

• The body maintains a stable internal environment, called homeostasis, through dynamic equilibrium.
• A set point is the specific value that homeostasis aims to maintain. Examples include body temperature and blood sugar levels.
• Negative feedback loops are self-regulating systems that inhibit further production in response to an increased output, maintaining balance.
• For instance, sweating cools the body down, preventing excessive temperature rise.

Thermoregulation

• The body regulates its internal temperature through thermoregulation.
• Endotherms, such as humans, maintain a constant body temperature regardless of the environment.
• Ectotherms, like reptiles, rely on external heat sources to regulate their temperature.
• Fever is a higher homeostatic equilibrium temperature, which makes the body less hospitable to bacteria and boosts cellular activity to fight infections.
• Pyrogens are substances that trigger fever by resetting the hypothalamus’s “thermostat”.

Digestion

• Humans are heterotrophs, relying on other organisms for food.
• Our cells need essential nutrients like amino acids, lipids, nucleotides, and simple sugars.
• We consume macromolecules, which are broken down into simpler components: fats, carbohydrates, and proteins.
• The GI tract, the path of digestion, includes the oral cavity, esophagus, stomach, small intestine, large intestine, rectum, and anus.
• Mastication (chewing) begins the mechanical breakdown of food.
• The salivary glands produce lipase (fat digestion) and amylase (starch digestion).

Accessory Organs

• Accessory organs assist digestion: salivary glands, liver, pancreas, and gallbladder.
• The liver, the largest internal organ, plays a vital role in fat digestion and blood detoxification. It produces bile.
• The gallbladder stores bile and produces bile salts.
• The pancreas secretes bicarbonate to neutralize acidic chyme and various enzymes: trypsin (protein digestion), amylase (carbohydrate digestion), and lipase (fat digestion).

Essential Nutrients

• Essential nutrients must be obtained from food as our bodies cannot produce them.

Energy Considerations

• Metabolism encompasses all chemical reactions in cells, including energy-consuming and energy-generating processes.
• ATP (adenosine triphosphate) serves as the primary energy currency in cells.
• Photosynthesis is a key process: 6CO2 + 6H2O → C6H12O6 + 6O2.

Metabolic Pathways

• Metabolic pathways are sequences of chemical reactions that modify molecules step-by-step.
• Anabolic pathways build polymers from monomers.
• Catabolic pathways break down polymers into monomers.
• Enzymes are proteins that catalyze specific reactions in metabolism. For example, amylase breaks down starches.

Thermodynamics

• Thermodynamics studies energy and energy transfer within physical matter.
• A system refers to the matter involved in energy transfer.
• Surroundings encompasses everything outside the system.
• Biological organisms are open systems, exchanging energy with their surroundings.
• The First Law of Thermodynamics (Conservation of Energy) states that the total energy in the universe remains constant.
• The Second Law of Thermodynamics states that energy transfers always produce some heat.

Energy Forms

• Heat energy is energy transferred as non-work.
• Potential energy represents the capacity to do work.
• Kinetic energy is the energy of motion.
• Activation energy is the minimum energy required for chemical reactions to occur.

Cellular Respiration

• Cellular respiration converts energy from nutrients into ATP and releases waste products.
• It involves Glycolysis, transition reaction cycle, Krebs Cycle (citric acid cycle), and the electron transport chain.
• Fermentation occurs when oxygen is absent.

Glycolysis

• Glycolysis converts glucose into pyruvate, producing ATP and NADH. This is vital for energy production.

Blood

• Blood is a connective tissue for nutrient and cell transport, waste removal, and hormone distribution. It plays a crucial role in maintaining homeostasis.
• It’s composed of plasma and formed elements: red blood cells (RBCs), white blood cells (WBCs), and platelets.

Red Blood Cells

• Red blood cells (RBCs), also called erythrocytes, are the most abundant formed elements.
• Hematopoiesis is the process by which RBCs are made in the red bone marrow.
• Their primary function is to transport oxygen from the lungs to tissues and carry about 24% of carbon dioxide waste back to the lungs.
• RBCs lack mitochondria and rely on fermentation for energy.
• Their short lifespan (115 days) is due to the absence of endoplasmic reticulum, preventing them from producing repair proteins.
• Hemoglobin, a protein with iron, carries oxygen and consists of four globin chains.

Platelets

• Platelets, also called thrombocytes, are essential for repairing damaged blood vessels.
• They work alongside proteins like fibrin to block ruptured blood vessels and prevent further blood loss.

Blood Functions

• Blood performs crucial functions, including transportation, defense, heat distribution, and homeostasis.
• It carries nutrients and gases to cells, and waste products from cells to the liver and kidneys for excretion.
• Blood also distributes hormones from endocrine glands throughout the body.

Blood Composition

• Hematoctrit tests measure the percentages of RBCs, WBCs, platelets, and plasma in blood.
• The buffy coat, a thin layer between plasma and RBCs, contains WBCs and platelets (approximately 1% of the sample).
• During a hematocrit test, blood is spun in a centrifuge, separating the heavier RBCs at the bottom, lighter plasma at the top, and the buffy coat in between. Normal values are roughly 37-52% RBCs, 1% WBCs and platelets, and the remaining is plasma.

Hemoglobin

• Hemoglobin, a pigment, changes color depending on oxygen saturation. Bright red blood indicates high oxygen levels, while dusky, bluer blood indicates lower oxygen levels.

Blood Temperature

• Normal blood temperature is 100.4°F.

Blood Volume

• Males have 5-6 liters of blood, while females have 4-5 liters.

Blood pH

• Normal blood pH is 7.35–7.45. A lower pH indicates acidemia, and a higher pH indicates alkalemia.

Plasma Proteins

• Plasma proteins include albumin, globulins, and fibrinogen.

Albumin

• Albumin, the most abundant plasma protein, is produced in the liver, serving as a binding protein for transporting fatty acids and steroid hormones.
• It contributes to blood osmotic pressure.

Globulins

• Globulins, the second most abundant plasma protein, are produced by specialized plasma cells (a type of B cell).
• There are three main subgroups: alpha, beta, and gamma. Alpha and beta globulins transport iron, lipids, and fat-soluble vitamins.
• Gamma globulins, also known as immunoglobulins or antibodies, are involved in the immune response.

Fibrinogen

• Fibrinogen, the least abundant plasma protein, is produced in the liver and plays a crucial role in blood clotting.

Blood Type

• Blood cells have specific glycoprotein markers called antigens (agglutinogens) – types A and B.

Heart

• The heart is a hollow muscular organ that pumps blood throughout the body through blood vessels.

Heart Conduction System

• The SA node (sinoatrial node) is the heart’s pacemaker, initiating electrical activity that triggers heart contractions.
• The AV node (atrioventricular node) conducts electrical impulses from the SA node to the AV bundle.
• The AV bundle (atrioventricular bundle) carries impulses from the AV node to the Purkinje fibers in the ventricles.
• The Purkinje fibers transmit impulses from the AV bundle to the ventricular walls, ensuring coordinated contractions.
• Understanding the pathway of conduction through the heart is crucial.

Electrocardiogram (ECG/EKG)

• An ECG records electrical changes in the myocardium during the cardiac cycle.
• Electrodes are used to detect electrical activity.
• Deflections represent deviations from a baseline.
• ECG waves are labeled: P, Q, R, S, T. Knowing how to identify these waves is important for interpreting heart function.

Blood Vessels

• Blood vessels are tubular structures carrying blood throughout the body.
• They have three layers: tunica externa (outer), tunica media (middle, primarily smooth muscle cells), and tunica intima (inner).
• The lumen is the opening in the vessel where blood flows.

Vascular Changes

• Vasodilation is the expansion of blood vessels.
• Vasoconstriction is the narrowing of blood vessels.

Types of Blood Vessels

• There are five main types of blood vessels: arteries, veins, arterioles, venules, and capillaries.

Arteries

• Arteries are strong, elastic vessels that transport blood away from the heart at high pressure.

Veins

• Veins are less muscularized than arteries and transport blood back to the heart at lower pressure.
• Veins have valves to prevent backflow of blood, aided by surrounding skeletal muscle contractions.

Arterioles

• Arterioles are smaller subdivisions of arteries, branching into finer vessels.

Venules

• Venules are microscopic vessels that merge to form veins.

Capillaries

• Capillaries are microscopic channels that supply blood to tissues.
• Gas exchange occurs between capillaries and surrounding cells and interstitial fluid.

Test your understanding of homeostasis and thermoregulation in the human body. This quiz covers key concepts such as negative feedback loops, set points, and the differences between endotherms and ectotherms. Dive into the mechanisms that keep our internal environment stable and how our body responds to temperature changes.