Biology Exam
Characteristics of Living Things
Acquire Energy and Materials:
Plants: Use photosynthesis to acquire energy.
Equation: CO2+H2O→lightO2+C6H12O6CO2+H2OlightO2+C6H12O6 (carbon dioxide + water → oxygen + glucose).
Animals (Humans): Acquire energy through food and oxygen.
Equation: C6H12O6+O2→CO2+H2O+energyC6H12O6+O2→CO2+H2O+energy.
Energy is used for life processes like movement, digestion, and memory encoding.
Metabolism: All chemical reactions in cells that regulate energy use.
Maintain Internal Balance (Homeostasis):
Homeostasis ensures a stable internal environment (e.g., temperature, water balance, sugar levels).
Examples:
Balancing body temperature (37°C).
Regulating blood sugar (~100 mg/mL).
Maintaining blood pressure (~160/106 kPa).
Homeostasis
Definition: Maintaining a stable internal physiological state despite external changes.
Examples:
Gas Levels: Breathing and respiration.
Water and Salt Levels: Osmoregulation.
Body Temperature: Thermoregulation.
Blood pH: ~7.4.
Normal homeostasis fluctuates within a narrow range (dynamic equilibrium).
Examples of Homeostasis:
A polar bear eating seals for energy.
A caterpillar morphing into a butterfly.
A chameleon warming in the sun.
Other Key Characteristics of Living Things
Living Things Are Organized:
Cells: Basic units of life.
Multicellular organisms: Cells → tissues → organs → organ systems.
Reproduction:
Asexual: Offspring are identical to parents.
Sexual: Offspring are genetically unique (combination of gametes).
Growth and Development:
Growth: Increase in cell size/number and tissue repair.
Development: Series of changes from conception to adulthood.
Respond to Stimuli:
Reaction to environmental stimuli:
Short-term examples: Sweating (heat), squinting (brightness).
Long-term examples: Hibernation (winter).
Checklist for Living Characteristics
Acquire energy and materials.
Maintain homeostasis.
Are organized.
Reproduce.
Grow and develop.
Respond to stimuli.
What Do Cells Do for Us?
Facts About Cells:
The human body is made up of ~100 trillion cells.
Cells are small for efficient nutrient absorption and waste excretion (high surface area-to-volume ratio).
Cell Theory:
All organisms are made of one or more cells.
The cell is the basic unit of life in all living things.
All cells come from the division of preexisting cells.
Modern Cell Theory (Additional Statements):
Cells contain hereditary information (DNA).
All cells share similar chemical compositions and metabolic activities.
All life processes occur inside cells (e.g., movement, digestion).
Cell activity depends on sub-cellular structures like organelles.
Homeostasis Within Cells:
Homeostasis is maintained by the plasma membrane:
Regulates nutrient and waste exchange.
Maintains an internal environment.
Cell Membrane and Its Functions
Plasma Membrane:
Semi-permeable: Controls the movement of substances in and out of cells.
Functions:
Isolation: Separates internal from external environments (lipids in the bilayer).
Transportation: Moves substances in/out of cells (transport proteins).
Interaction: Enables communication with other cells (receptor proteins).
Membrane Components:
Proteins:
Transport Proteins: Move hydrophilic molecules (some use energy).
Receptor Proteins: Trigger cellular responses.
Recognition Proteins: Identify friendly vs. foreign cells (e.g., blood type).
Lipids:
Form a bilayer with:
Hydrophilic heads (attract water).
Hydrophobic tails (repel water).
Cholesterol strengthens membranes in animal cells.
Phospholipid Bilayer:
Composed of two layers:
Hydrophilic heads face water (inside/outside cells).
Hydrophobic tails point inward, away from water.
A Closer Look at the Plasma Membrane
Key Functions:
Isolation: Separates internal contents from the environment.
Interaction: Facilitates communication via receptor proteins.
Transportation: Regulates exchange of substances through transport proteins.
Lipids
Functions of Lipids:
Form cell membranes (phospholipids).
Provide long-term energy storage.
Insulate the body.
Protect organs.
Synthesize certain hormones (steroids).
Serve as an energy source.
Dissolve fat-soluble vitamins.
Types of Lipids:
Phospholipids:
Made of glycerol, two fatty acids, and a phosphate group.
Hydrophilic head (water-attracting) and hydrophobic tail (water-repelling).
Form the bilayer in cell membranes.
Triglycerides: Storage fats.
Steroids: Hormones like testosterone and cholesterol.
Membrane Transport
1. Passive Transport:
Moves substances across the membrane without energy, down a concentration gradient.
Examples:
Simple diffusion (small, non-polar molecules like oxygen and CO22).
Facilitated diffusion (uses transport proteins for polar or large molecules like glucose, Na++).
2. Facilitated Diffusion:
Uses channel or carrier proteins to transport substances across the membrane.
Examples:
Na++ (from salt).
Amino acids.
Glucose.
Proteins
What Are Proteins?
Proteins are essential for structural, functional, and regulatory processes in the body.
Composed of amino acids linked by peptide bonds.
Functions of Proteins:
Structure: Keratin (hair, nails).
Regulation: Hormones like insulin.
Movement: Actin (muscles).
Transport: Hemoglobin (oxygen transport in blood).
Immunity: Antibodies.
Receptors and Membrane Channels: Cell signaling and substance transport.
Enzymes: Speed up biochemical reactions (e.g., lactase).
Key Points:
Made of 20 amino acids in living organisms.
Two types:
Fibrous (keratin, collagen).
Globular (enzymes, hemoglobin).
Osmosis
Definition: Diffusion of water across a semi-permeable membrane.
Moves from areas of high water concentration (low solute) to areas of low water concentration (high solute).
Osmotic Pressure:
Created by an unbalanced concentration of solutes.
Water moves to balance solute concentration.
Types of Solutions:
Isotonic: Equal solute concentration inside and outside the cell (normal cell shape).
Hypotonic: Lower solute concentration outside the cell.
Water flows into the cell → Cell swells.
Hypertonic: Higher solute concentration outside the cell.
Water flows out of the cell → Cell shrinks.
Active Transport
Definition: Movement of molecules against the concentration gradient (from low to high concentration).
Requires energy (ATP).
Processes:
Endocytosis: Engulfing materials into the cell.
Phagocytosis: Engulfing solids.
Pinocytosis: Engulfing liquids.
Exocytosis: Moving materials out of the cell by fusing vesicles with the plasma membrane.
Energy and Homeostasis
Energy Sources:
Glucose, fatty acids, and amino acids are broken down to release energy.
ATP (Adenosine Triphosphate):
Acts as an energy carrier (like a rechargeable battery).
Stores energy released by cellular respiration and releases it to fuel life processes.
Processes:
Photosynthesis (plants): CO2+H2O+light energy→O2+C6H12O6CO2+H2O+light energy→O2+C6H12O6.
Cellular Respiration (animals): C6H12O6+O2→CO2+H2O+energy (ATP)C6H12O6+O2→CO2+H2O+energy (ATP).
Comparison of Passive and Active Transport
Passive Transport:
No energy required.
Moves substances from high to low concentration.
Active Transport:
Requires energy (ATP).
Moves substances from low to high concentration.
Cellular Transport Questions
Diffusion: Particles move from high to low concentration until equilibrium.
Concentration Gradient: Difference in particle concentration across a space.
Equilibrium: Balanced concentration.
Cellular Respiration Formula
C6H12O6+6O2→6CO2+6H2O+ATP (energy)C6H12O6+6O2→6CO2+6H2O+ATP (energy)
Reactants: Glucose (C6H12O6C6H12O6) and oxygen (O2O2).
Products: Carbon dioxide (CO2CO2), water (H2OH2O), and energy in the form of ATP.
ATP (Adenosine Triphosphate)
Structure:
Adenine: Nitrogenous base.
Ribose: A sugar molecule.
Three phosphate groups: Key to storing and releasing energy.
Energy Storage:
Energy is stored in the bonds between the phosphate groups.
Breaking a phosphate bond releases energy, converting ATP → ADP (adenosine diphosphate) → AMP (adenosine monophosphate).
Key Notes:
ATP is a short-term energy carrier within cells.
Heat released during ATP breakdown helps maintain body temperature.
Glucose and Ribose
Glucose (C6H12O6C6H12O6):
Main source of energy for cells.
Broken down in cellular respiration to produce ATP.
Ribose:
A component of ATP.
Pentagonal sugar structure.
Polysaccharides and Energy Storage
Building Polysaccharides:
Dehydration Synthesis:
Links monosaccharides by removing water.
Creates covalent bonds between sugars.
Example: Glucose units forming glycogen.
Breaking Down Polysaccharides:
Hydrolysis:
Adds water to break bonds.
Converts polysaccharides back into monosaccharides for energy use.
ATP and Cellular Transport
Active Transport:
ATP powers the movement of substances against their concentration gradient.
Example: Sodium-potassium pump in cells.
Key Diagram Insights:
ATP donates a phosphate group to provide energy.
After energy is used, ADP and phosphate are recycled in mitochondria.
Biochemistry Key Points
Biomolecules are made of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and phosphorus (P).
Carbohydrates like glucose provide immediate energy.
Glycogen (polysaccharide) is stored in liver and muscle cells for long-term energy use.
Mechanical Digestion Notes
1. Mouth
Process: Chewing.
Uses teeth, tongue, and roof of the mouth to break food into smaller pieces for swallowing.
2. Esophagus
Process: Peristalsis.
Peristalsis involves wave-like contractions of smooth circular muscles to move the bolus (clump of food) through the esophagus to the stomach.
The cardiac sphincter prevents gastric juices from flowing back into the esophagus (avoiding heartburn).
Vomiting involves reverse peristalsis when the stomach contents need to be evacuated.
3. Stomach
Processes:
Churning: The stomach muscles physically mix the food with gastric secretions to produce chyme.
Food is stored temporarily, chemically digested, and passed to the small intestine.
4. Liver
Produces bile, which is stored in the gallbladder and released into the small intestine.
Function of Bile: Emulsification (breaking down fats into smaller droplets for easier digestion).
5. Small Intestine
Processes:
Emulsification: Bile works here to digest fats.
Segmental Movements: Rhythmic contractions mix chyme and expose it to the absorptive surface of the intestine.
Movements mimic "sloshing water" in a tray to enhance nutrient absorption.
Chemical Digestion Notes
1. Mouth and Salivary Glands
Salivary glands secrete saliva containing salivary amylase, which begins carbohydrate digestion.
Saliva softens food into a bolus.
Breaks down polysaccharides into simpler sugars.
2. Stomach
Secretes digestive juices:
Hydrochloric acid (HCl): Breaks down the bolus into chyme and provides an acidic environment.
Pepsin: An enzyme that breaks proteins into amino acids.
Most protein digestion occurs in the stomach.
3. Pancreas
Secretes:
Trypsin: Digests proteins.
Pancreatic amylase: Breaks down polysaccharides into simpler sugars.
Lipase: Digests lipids into glycerol and fatty acids.
Sodium bicarbonate: Neutralizes stomach acid (raises pH from 2 to ~8) to allow enzymes to function.
4. Small Intestine
The duodenum is the site of most chemical digestion.
Enzymes from the pancreas act here to break down nutrients into absorbable forms.
Enzyme Summary
Trypsin: Digests proteins.
Pancreatic Amylase: Digests starch (polysaccharides).
Lipase: Breaks down lipids (fats).
Lactase: Breaks down lactose into glucose and galactose.
Maltase: Converts maltose into glucose.
Enzyme Function:
Enzymes act as organic catalysts to speed up chemical reactions (e.g., digestion).
Example: Lactase breaks lactose (a disaccharide) into glucose and galactose by hydrolysis.
Enzymes are highly specific: The "lock-and-key" model describes how an enzyme’s active site matches only specific substrates.
Enzymes and Carbohydrate Digestion
Amylase:
Found in saliva and pancreas.
Breaks down starch (a polysaccharide) into maltose (a disaccharide with two sugar rings).
Maltase:
Breaks maltose into two glucose molecules (monosaccharides), which are small enough for absorption.
Lactase:
Breaks lactose (a disaccharide) into glucose and galactose (monosaccharides).
Lactase deficiency leads to lactose intolerance, causing bacterial fermentation in the large intestine, which results in gas and abdominal pain.
Enzyme Summary
Amylase: Breaks down starch into maltose.
Maltase: Converts maltose into glucose.
Lipase: Digests lipids into glycerol and fatty acids.
Pepsin: Digests proteins into peptides.
Trypsin: Breaks peptides into smaller amino acid chains.
Peptidase: Converts peptides into single amino acids.
Absorption of Nutrients
Overview:
Nutrients must be chemically digested into small enough molecules to be absorbed into the bloodstream via the small intestine.
Absorbed nutrients are transported to cells for energy and function.
Stomach:
Small amounts of water, ions, and alcohol can be absorbed directly into the bloodstream.
Small Intestine:
Structure: Contains villi (finger-like projections) lined with microvilli to increase surface area for absorption.
Function: Most nutrient absorption occurs in the duodenum and jejunum (first sections).
Nutrients Absorbed:
Carbohydrates → Monosaccharides (e.g., glucose).
Proteins → Amino acids.
Fats → Glycerol and fatty acids.
Large Intestine:
Absorbs water and forms solid waste.
Protein Digestion
Proteins are long chains of amino acids.
Trypsin: Breaks proteins into smaller peptides.
Peptidase: Converts peptides into individual amino acids.
Amino acids are absorbed through the walls of the small intestine into the bloodstream.
Importance of Surface Area
The small intestine’s villi and microvilli provide a large surface area, enhancing nutrient absorption.
Analogy: Larger surface area is like "unfolding a sheet" to maximize contact with nutrients.
Absorption in the Small Intestine
Structure:
The inner surface of the small intestine contains villi (finger-like projections) lined with microvilli.
Villi Function: Increase surface area for nutrient absorption.
Tiny capillaries in the villi absorb most dissolved nutrients into the bloodstream.
Lacteals (part of the lymphatic system): Absorb products of fat digestion.
Nutrients Absorbed:
Capillaries: Absorb monosaccharides (glucose), amino acids, vitamins, and minerals.
Lacteals: Absorb fatty acids and glycerol.
FYI:
Daily absorption capacity of the intestines:
Several kilograms of carbohydrates.
Up to 1 kg of fat.
~500 g of protein.
~20 liters of water.
Large Intestine
Primary Functions:
Absorption of Water: Reclaims water from indigestible food matter.
Formation of Feces: Mixes leftover nutrients, bacteria, and mucus to form feces.
Feces are stored in the rectum until elimination.
Liver and Pancreas
Liver:
Produces bile, which is stored in the gallbladder and released into the small intestine for fat emulsification.
Additional Functions:
Filters toxins (e.g., alcohol and drugs) from the blood.
Regulates blood sugar by converting glucose into glycogen for storage.
Pancreas:
Produces enzymes (amylase, trypsin, lipase) to aid chemical digestion in the small intestine.
Hormonal Function:
Insulin: Lowers blood glucose by allowing cells to absorb it or store it as glycogen in the liver.
Glucagon: Converts stored glycogen back into glucose when blood sugar is low.
Enzyme Summary
Amylase: Digests starch into maltose.
Maltase: Breaks down maltose into glucose.
Lipase: Breaks down lipids into glycerol and fatty acids.
Pepsin: Begins protein digestion into peptides.
Trypsin and Peptidase: Break peptides into individual amino acids.
Nutrient Transport
Nutrients absorbed by capillaries are transported to cells via the bloodstream.
Fats absorbed by lacteals are transported through the lymphatic system before entering the blood.
Importance of Surface Area
The structure of villi and microvilli increases nutrient absorption by providing a large surface area.
Analogy: Like unfolding a crumpled sheet to cover more area.
The Role of the Liver and Pancreas in Blood Sugar Regulation
Homeostasis and Glucose Storage:
Glucose is essential for producing ATP (short-term energy storage).
Excess glucose is stored as glycogen in the liver for later use when blood sugar drops.
Pancreatic Hormones:
Insulin:
Released when blood glucose levels rise.
Promotes glucose uptake by cells and storage in the liver as glycogen.
Glucagon:
Released when blood glucose levels are low.
Stimulates the liver to convert glycogen into glucose, releasing it into the bloodstream.
Feedback Mechanism:
High Blood Sugar: Pancreas releases insulin → Glucose is stored or used → Blood sugar decreases to normal.
Low Blood Sugar: Pancreas releases glucagon → Glycogen is converted to glucose → Blood sugar increases to normal.
Blood Sugar Disorders
Type 1 Diabetes:
The body does not produce insulin.
Patients must inject insulin into their bloodstream.
Type 2 Diabetes:
Insulin is produced, but cells become resistant to it, preventing glucose uptake.
Often linked to poor diet, lack of exercise, and genetics.
Managed through diet, exercise, and medication.
Nutrition and the Six Essential Nutrients
Macronutrients:
Carbohydrates:
Main energy source.
Simple carbs (e.g., sugar) are digested quickly, leading to short energy bursts.
Complex carbs (e.g., pasta, bread) digest slowly, providing sustained energy.
Lipids (Fats):
Most concentrated energy source.
Unsaturated fats (e.g., avocado) are healthier than saturated fats.
Proteins:
Provide amino acids for building and repairing tissues.
Essential amino acids must be obtained through diet (e.g., meat, cheese).
Micronutrients:
Water:
Essential for chemical reactions (e.g., hydrolysis).
Regulates body temperature, lubricates joints, and removes waste.
Minerals:
Examples: Calcium (for bones) and iron (for oxygen transport in blood).
Vitamins:
Support metabolic processes and immune function.
Summary Diagram of Digestion
Mechanical Digestion:
Involves chewing, peristalsis, and churning in the stomach.
Chemical Digestion:
Carbohydrates → Monosaccharides (e.g., glucose) via enzymes like amylase and maltase.
Proteins → Amino acids via pepsin and trypsin.
Lipids → Glycerol and fatty acids via bile (emulsification) and lipase.
Absorption:
Nutrients absorbed by villi in the small intestine and transported to the bloodstream or lymphatic system.
Large Intestine:
Absorbs water and forms solid waste.
Vitamins
Types of Vitamins:
Fat-Soluble Vitamins:
Vitamins A, D, E, K.
Stored in the body's fat tissues.
Water-Soluble Vitamins:
Vitamins B and C.
Dissolve in water and are not stored in the body (excess is excreted).
Vitamins FYI:
Antioxidants:
Vitamins A, C, E, and beta-carotene act as antioxidants.
Antioxidants neutralize free radicals, reducing the risk of diseases such as cancer and heart disease.
Free radicals are harmful molecules formed by exposure to sunlight, tobacco smoke, car exhaust, and pollutants.
Minerals
Key Minerals and Their Functions:
Calcium:
Function: Builds strong bones and teeth, aids muscle and nerve activity, and helps in blood clotting.
Sources: Milk, cheese, grains, beans, hard water.
Deficiency: Leads to soft bones, teeth problems, and osteoporosis.
Sodium:
Function: Regulates nerve activity and body pH.
Sources: Table salt, vegetables, canned meat.
Deficiency: Causes dehydration.
Iron:
Function: Forms hemoglobin, which transports oxygen in the blood.
Sources: Green vegetables, liver, whole wheat bread, grains, nuts.
Deficiency: Results in low energy and anemia.
Iodine:
Function: Essential for thyroid hormone production.
Sources: Seafood, eggs, iodized salt.
Deficiency: Causes a swollen thyroid gland (goiter).
Potassium:
Function: Supports nerve and muscle activity.
Sources: Meats, grains, milk, fruits, green vegetables.
Deficiency: Causes weak muscles.
Phosphorus:
Function: Important for teeth and bone formation, blood pH balance, and enzyme function.
Sources: Meats, fish, dairy products, grains.
Deficiency: Leads to poor bone and teeth development.
Circulatory and Respiratory System
Blood is made up of 4 components
Plasma (Water)
Red Blood Cells (RBC)
White Blood Cells
Palatlets
Plasma (The Liquid Part)
Mostly contains water
It has the color of straws?
it Contains and Transports
Nutrients, Gases, Waste, Proteins, Hormones
Red Blood Cells
It carries oxygen through a protein called hemoglobin.
it appears cherry red when binded to oxygen.
It appears dark red when exposed to oxygen.
it appears blue under the skin
A LACK OF IRON CAN LEAD TO ANEMIA
formed in the bone marrow
White Blood Cells
Protects and fights off the bad guy ( Microbes )
<1% of the blood cellular components
derived from :
cells that originate in bone marrow
spleen
Thymus
Lymph nodes
Platlets
Derrived from the blood cells in the bone marrow
THEY PLAY AN IMPORTANT ROLE IN CLOTTING
Blood Types
ABO Blood Groups:
Blood types are determined by antigens (proteins) on the surface of red blood cells.
Blood Types:
A: Has A antigens and anti-B antibodies.
B: Has B antigens and anti-A antibodies.
AB: Has both A and B antigens, no antibodies (universal recipient).
O: No antigens, has both anti-A and anti-B antibodies (universal donor).
Antigens and Antibodies:
Antigens: Act as labels to signal what belongs in the body.
Antibodies: Proteins in plasma that attack foreign antigens.
Clumping (Agglutination):
Occurs when antibodies bind to foreign antigens, forming clusters.
Example: Mixing incompatible blood types causes clumping, which is dangerous.
Rh Factor (Rhesus Blood Group)
Rh Antigen:
Rh-positive (Rh⁺): Has the Rh antigen (e.g., A⁺, B⁺).
Rh-negative (Rh⁻): Lacks the Rh antigen (e.g., A⁻, B⁻).
Clumping with Rh Factor:
Anti-Rh antibodies attack Rh antigens if they detect a foreign Rh factor.
Blood Typing
Blood Typing Process:
Blood is tested with antibodies (Anti-A, Anti-B, Anti-Rh) to identify the antigens present.
Clumping with a specific antibody indicates the presence of that antigen.
Examples:
A blood sample clumps with Anti-A and Anti-Rh → Blood type = A⁺.
A blood sample clumps with Anti-B only → Blood type = B⁻.
Blood Donation and Compatibility
Universal Donor and Recipient:
Universal Donor: Type O⁻ (no antigens to trigger a reaction).
Universal Recipient: Type AB⁺ (has all antigens and no antibodies to attack).
Donation Rules:
Donors must match the recipient’s antibodies to avoid clumping.
Example: A⁺ can donate to A⁺ and AB⁺; O⁻ can donate to any blood type.
Quick Reference Chart for Blood Donation
Who Can Donate to Whom:
A⁺ → A⁺, AB⁺
A⁻ → A⁻, A⁺, AB⁻, AB⁺
O⁺ → O⁺, A⁺, B⁺, AB⁺
O⁻ → All types (universal donor)
B⁺ → B⁺, AB⁺
B⁻ → B⁻, B⁺, AB⁻, AB⁺
AB⁺ → AB⁺ (universal recipient)
AB⁻ → AB⁻, AB⁺
Key Components of the Circulatory System
Fluid: Blood – carries oxygen, nutrients, and waste.
Channels: Blood vessels – arteries, veins, and capillaries.
Pump: Heart – drives blood flow in two closed loops:
Pulmonary loop: Blood flows from the heart to the lungs and back.
Systemic loop: Blood flows from the heart to the rest of the body and back.
Blood Vessels
Arteries:
Direction: Carry blood away from the heart.
Characteristics:
Thick, elastic walls to handle high pressure.
Expand and contract with blood flow.
Oxygen Content:
In systemic circulation: Oxygenated.
In pulmonary circulation: Deoxygenated.
Capillaries:
Direction: Connect arteries to veins.
Characteristics:
Smallest vessels (7 microns in diameter).
Thin walls allow exchange of gases, nutrients, and waste.
Oxygen Content:
Exchange both oxygen and carbon dioxide.
Veins:
Direction: Carry blood back to the heart.
Characteristics:
Thinner walls than arteries.
Contain one-way valves to prevent backflow.
Carry a larger blood volume (up to 70% of total blood).
Oxygen Content:
In systemic circulation: Deoxygenated.
In pulmonary circulation: Oxygenated.
Important Blood Vessels
Pulmonary Artery:
Carries deoxygenated blood from the heart to the lungs.
Pulmonary Vein:
Carries oxygenated blood from the lungs to the heart.
Aorta:
Largest artery, carries oxygenated blood from the heart to the body.
Superior and Inferior Vena Cava:
Largest veins, return deoxygenated blood from the body to the heart.
Specific Vessels and Flow
Renal Artery and Vein:
Artery: Oxygenated blood to the kidneys.
Vein: Deoxygenated blood from the kidneys to the heart.
Hepatic Artery and Vein:
Artery: Oxygenated blood to the liver.
Vein: Deoxygenated blood from the liver to the heart.
Carotid Arteries:
Deliver oxygenated blood to the upper body and brain.
Heart Chambers and Blood Flow
Deoxygenated Blood Pathway:
Superior/Inferior Vena Cava → Right Atrium → Right Ventricle → Pulmonary Artery → Lungs.
Oxygenated Blood Pathway:
Pulmonary Veins → Left Atrium → Left Ventricle → Aorta → Body.
Capillaries in the Lungs:
Gas exchange occurs: Blood becomes oxygenated and releases carbon dioxide.
Circulatory System Notes
Key Components of the Circulatory System
Fluid: Blood
Carries oxygen, nutrients, hormones, and waste products throughout the body.
Channels: Blood vessels
Types: Arteries, veins, and capillaries.
Pump: Heart
Drives blood flow in two loops:
Pulmonary Loop: Heart → Lungs → Heart.
Systemic Loop: Heart → Body → Heart.
Blood Vessels
Arteries:
Function: Carry blood away from the heart.
Characteristics:
Thick and elastic walls to handle high pressure.
Largest artery: Aorta (25mm diameter).
Oxygen Content:
Oxygenated in systemic circulation.
Deoxygenated in pulmonary circulation (going to the lungs).
Capillaries:
Function: Connect arteries to veins, enabling exchange of substances.
Characteristics:
Smallest blood vessels (~7 microns in diameter).
Thin walls for exchange of gases, nutrients, and waste between blood and cells.
Oxygen Content: Can carry both oxygenated and deoxygenated blood, depending on location.
Veins:
Function: Carry blood back to the heart.
Characteristics:
Thin walls with one-way valves to prevent backflow.
Carry a larger blood volume (70% of total blood).
Oxygen Content:
Deoxygenated in systemic circulation (to the heart).
Oxygenated in pulmonary circulation (from lungs).
Important Blood Vessels
Pulmonary Artery:
Carries deoxygenated blood from the heart to the lungs.
Pulmonary Vein:
Carries oxygenated blood from the lungs to the heart.
Aorta:
Largest artery, carries oxygenated blood from the heart to the body.
Superior and Inferior Vena Cava:
Largest veins, return deoxygenated blood from the body to the heart.
Famous Circulatory Pathways
Pulmonary Circuit:
Deoxygenated Blood Path:
Superior/Inferior Vena Cava → Right Atrium → Right Ventricle → Pulmonary Artery → Lungs.
Oxygenated Blood Path:
Pulmonary Vein → Left Atrium → Left Ventricle → Aorta → Body.
Other Key Vessels:
Renal Artery and Vein:
Renal Artery: Carries oxygenated blood to the kidneys.
Renal Vein: Carries deoxygenated blood from the kidneys to the heart.
Hepatic Artery and Vein:
Hepatic Artery: Carries oxygenated blood to the liver.
Hepatic Vein: Carries deoxygenated blood from the liver to the heart.
Carotid Arteries:
Carry oxygenated blood to the brain and upper body.
Blood Flow and Oxygenation
Oxygen Exchange:
Lungs: Blood picks up oxygen and releases carbon dioxide in the capillaries.
Tissues: Oxygen is delivered to cells, and carbon dioxide is absorbed into the blood.
Chambers of the Heart:
Right Atrium → Right Ventricle → Pulmonary Artery → Lungs (deoxygenated).
Pulmonary Veins → Left Atrium → Left Ventricle → Aorta → Body (oxygenated).
Fun Facts:
Blood vessels laid end-to-end could circle the Earth 2.5 times.
The heart pumps blood approximately 1,000 times per da
Part 1: Anatomy of the Respiratory System
Nostrils and Nasal Passages:
Filter, moisten, and warm the air before it reaches the lungs.
Oral Cavity:
Allows air intake, especially during exercise.
Pharynx (Throat):
Collects air from the nose and mouth, directing it to the trachea.
Epiglottis:
A flap that prevents food from entering the trachea during swallowing.
Larynx (Voice Box):
Contains vocal cords that vibrate to produce sound.
Trachea (Windpipe):
Main airway leading to the lungs.
Lined with cilia to trap and move dust and germs.
Bronchi and Bronchioles:
Trachea divides into left and right bronchi, which branch further into bronchioles, ending in alveoli.
Alveoli:
Tiny air sacs where gas exchange occurs.
Diaphragm:
A muscle that separates the chest cavity from the abdominal cavity.
Contraction allows inhalation; relaxation enables exhalation.
Breathing and Gas Exchange
Inhalation:
Diaphragm contracts and moves down, increasing lung volume.
Air flows into the lungs (nose/mouth → trachea → bronchi → alveoli).
Exhalation:
Diaphragm relaxes and moves up, reducing lung volume.
Air is expelled (alveoli → bronchioles → trachea → nose/mouth).
External Respiration:
Location: Alveoli and capillaries in the lungs.
Process:
Oxygen diffuses into the blood.
Carbon dioxide diffuses out of the blood into the lungs.
Internal Respiration:
Location: Capillaries and cells throughout the body.
Process:
Oxygen diffuses into cells from the blood.
Carbon dioxide diffuses into the blood from cells.
Cellular Respiration:
Occurs in mitochondria.
Equation: Oxygen + Glucose → ATP (energy) + Carbon dioxide (waste) + Water.
What is Excretion?
The removal of waste products made during metabolic processes from the body.
These wastes include substances that can be toxic if not removed (e.g., carbon dioxide, urea).
Excretory System Overview
Digestive System:
Removes solid waste (feces) left over from digestion.
Not considered metabolic waste.
Respiratory System:
Removes carbon dioxide (CO₂) and carbonic acid from cellular respiration.
Maintains pH balance in the body.
Urinary System:
Removes urine (containing water, salts, and urea).
Helps with osmoregulation (water/salt balance).
Integumentary System:
Removes sweat (water, salts, and urea).
Assists in thermoregulation (body temperature control).
Body’s Metabolic Wastes
Wastes from Cellular Respiration:
Chemical Equation:
Oxygen + Glucose → Carbon Dioxide + Water + ATP
(O₂ + C₆H₁₂O₆ → CO₂ + H₂O + ATP)Excretory Organs:
CO₂: Lungs.
Water: Skin (sweat), kidneys (urine), and lungs (exhalation).
Mineral Salts:
Remain after digestion of minerals like calcium, potassium, and sodium.
Excretory Organs: Skin (sweat) and kidneys (urine).
Nitrogenous Wastes:
Produced when proteins are broken down into amino acids.
Ammonia (NH₃):
Highly toxic waste.
Converted into urea in the liver by combining ammonia with carbon dioxide.
Urea is then transported to the kidneys for excretion in urine.
Excretory Organs:
Liver (processes ammonia).
Kidneys (excrete urea in urine).
The Liver's Role in Excretion
Processes ammonia (NH₃):
Converts ammonia into urea (less toxic).
Urea is transported via blood to the kidneys.
The liver also detoxifies harmful substances (e.g., drugs and alcohol).
Summary Table: Waste Products and Excretory Organs
waste | origin | OriginExcretory Organs |
Carbon Dioxide | Cellular respiration | Lungs |
Water | Cellular respiration, digestion | Skin, kidneys, lungs |
Ammonia | Protein digestion | Liver |
Urea | Processed ammonia | Kidneys |
Mineral Salts | Digestion (minerals) | Skin, kidneys |
Key Notes on Homeostasis
Respiratory System:
Maintains pH balance by regulating CO₂ levels in the blood.
Urinary System:
Regulates water and salt balance (osmoregulation).
Integumentary System:
Controls body temperature through sweating.
Function: Removes waste products (e.g., urea) from the body and regulates water and electrolyte balance.
Components:
Kidneys:
Filter blood to produce urine.
Maintain water and electrolyte balance.
Ureters:
Tubes that transport urine from the kidneys to the bladder.
Bladder:
Muscular organ that stores urine until excretion.
Urethra:
Tube through which urine exits the body.
Bladder FYIs
The bladder is a hollow, stretchable organ located in the pelvic floor.
Capacity:
Holds 300–500 mL of urine, though the urge to urinate begins at ~150 mL.
Sphincters:
Internal Urinary Sphincter:
Located between the bladder and urethra; involuntary control.
External Urinary Sphincter:
Voluntary control; strengthens with pelvic floor exercises.
Differences Between Male and Female Urinary Tracts
FeatureFemaleMale | ||
External Sphincter | Made of three muscles, supports vaginal functions (e.g., childbirth). | Prevents urine and semen from mixing during ejaculation. |
Urethra | Shorter, exits between the clitoris and vagina, prone to bladder infections. | Longer, exits at the tip of the penis; carries both urine and semen. |
Anatomy of the Kidney
Layers:
Renal Cortex: Outer layer; houses the glomeruli and Bowman's capsules.
Renal Medulla: Middle layer; contains nephron loops, darker due to high capillary density.
Renal Pelvis: Funnel-like structure that collects urine from the kidney.
Blood Flow Through Kidney:
Blood enters via renal artery.
Travels through smaller arterioles to glomerulus.
Exits through renal vein after filtration.
Nephron Structure (Basic Unit of the Kidney)
Bowman’s Capsule:
Surrounds the glomerulus.
Filters blood to form the initial filtrate (water, salts, waste).
Proximal Convoluted Tubule:
Reabsorbs nutrients (e.g., glucose, amino acids).
Loop of Henle:
Concentrates urine by reabsorbing water and salts.
Distal Convoluted Tubule:
Regulates potassium, sodium, and pH levels.
Collecting Duct:
Final structure where urine is formed and directed to the renal pelvis.
Regions:
Cortex: Outer layer, brown/smooth, houses nephrons.
Medulla: Inner layer, purple, packed with capillaries.
Renal Pelvis: Collects urine before ureter transport.
Nephron Functions
Filtration: Blood filtered in Bowman's capsule.
Reabsorption: Essential substances (glucose, amino acids) reabsorbed in the proximal tubule.
Secretion: Unwanted materials secreted into the nephron.
Excretion: Waste products exit as urine.
Key Structures of a Nephron
Glomerulus: Capillary bed for filtration.
Bowman's Capsule: Collects filtrate.
Proximal/Distal Convoluted Tubules: Sites of reabsorption/secretion.
Loop of Henle: Concentrates urine.
Collecting Duct: Final concentration and transport of urine.
Homeostasis and Hormonal Control
ADH (Antidiuretic Hormone):
Role: Increases water reabsorption in kidneys.
Trigger: Dehydration (low blood volume/high osmolarity).
Effect: Produces concentrated urine and conserves water.
Aldosterone:
Role: Promotes reabsorption of sodium and water in nephron.
Trigger: Low blood pressure or volume.
Effect: Increases blood pressure and volume.
Negative Feedback Mechanism Examples
Scenario 1: Dehydration
Receptor: Osmoreceptors detect high osmolarity.
Control Center: Hypothalamus signals release of ADH.
Effector: Kidneys reabsorb more water, reducing urine output.
Scenario 2: Overhydration
Receptor: Osmoreceptors detect low osmolarity.
Control Center: Hypothalamus inhibits ADH release.
Effector: Kidneys excrete more water, increasing urine output.
Blood Pressure Regulation
Key Hormone: Aldosterone from adrenal glands.
Mechanism:
Low Blood Pressure: Triggers aldosterone release, increasing sodium/water reabsorption.
High Blood Pressure: Inhibits aldosterone, reducing water reabsorption.
Pathogens Overview
Viruses:
Not alive, require host cells to replicate.
Examples: COVID-19, Influenza, Chickenpox, Herpes.
Antibiotics are ineffective.
Bacteria:
Single-celled organisms, some beneficial (probiotics), others harmful (pathogenic).
Examples of diseases: Strep throat, E. coli food poisoning, Chlamydia, Gonorrhea.
Treated with antibiotics (though antibiotic resistance is a concern).
Fungi:
Can overgrow and harm humans.
Examples: Athlete’s foot, Ringworm, Toenail fungus.
Parasites:
Live off a host; often seen in tropical areas.
Examples: Malaria, Tapeworms, Lyme disease.
Pathogen Spread
Transmission through:
Sexual transmission (e.g., STIs).
Blood (e.g., Hepatitis).
Food and water (e.g., Salmonella).
Vectors (e.g., mosquitoes in malaria).
Immune System Defense Mechanisms
Non-Specific Defense:
First Line (Barriers):
Skin, mucus, earwax, tears.
Prevent pathogens from entering the body.
Second Line (Internal):
White blood cells (Phagocytes): Engulf and destroy pathogens.
Inflammation: Histamines increase blood flow to affected areas, bringing white blood cells.
Fever: Slows down pathogen reproduction.
Specific Defense:
Third Line (Adaptive Immunity):
Humoral Immunity:
B cells produce antibodies specific to pathogens.
Memory B cells retain information for future infections.
Cell-Mediated Immunity:
T cells target infected cells and destroy them.
Important Points on Immunity
Vaccination: Triggers adaptive immunity by introducing antigens to create memory cells.
Active Immunity: Developed by exposure to pathogens or vaccines.
Antibodies: Bind to pathogens to mark them for destruction.
Why do we have a nervous system?
Protects us by helping us respond to pain, danger, or external changes.
Maintains homeostasis by sending signals throughout the body.
Components of the Nervous System:
Central Nervous System (CNS): Includes the brain and spinal cord.
Peripheral Nervous System (PNS): Nerves that connect the CNS to the rest of the body.
Stimulus and Response:
Stimulus: A change in the environment that triggers a reaction (e.g., bright light, dehydration).
Response: The action taken to adapt to the stimulus (e.g., sweating, pupil contraction).
Organization:
CNS: Processes and interprets sensory data and initiates responses.
PNS:
Sensory nerves: Carry information to the CNS.
Motor nerves: Carry signals from the CNS to muscles and glands.
Divided into:
Somatic System: Controls voluntary actions.
Autonomic System: Controls involuntary actions like breathing and digestion.
Sympathetic: Activates "fight or flight."
Parasympathetic: Promotes "rest and digest."
Reflexes:
Reflex Arc Process:
Stimulus (e.g., touching a hot object).
Sensory neuron sends signal to spinal cord.
Interneuron processes the signal in the CNS.
Motor neuron sends the response to the muscle.
Muscle contracts, pulling away from danger.
Reflexes are automatic and protect the body from harm.