SBI3U Animal: Structure and Function

Why we eat

* Growth
* Most nutrients break down into smaller molecules that are used to build bone muscles and other types of cells/tissues
* New cells are produced
* Maintenance
* Damaged cells are repaired
* Dead cells are replaced
* Energy
* Fuels biological processes and physical activities
* Obtain chemical energy carried by plants and animals
* Stored in cells then released when needed

Endotherms and Ectotherms

* Endothermic (warm-blooded)
* Energy from food is used to maintain constant body temperature
* More nutrients are needed to support loss of energy
* Larger endotherms need a consume larger quantities than smaller organisms
* Ectothermic (cold-blooded)
* Do not need as much energy to maintain body temperature
* Energy comes from sources in their environment
* Energy is not wasted in heating their body
* Not as adaptable to cold environments

Metabolism and Related Notes

* Metabolism
* The total of all chemical reactions in an organism
* Anabolism + Catabolism = Metabolism
* Anabolism
* Building up complex substances from simpler substances
* Catabolism
* Breaking up complex substances into simpler substances
* Metabolic Rate
* The rate at which metabolism occurs in an organism

Metabolic Rate Trends

* Body Size
* The larger the body the more energy is required to stay alive
* Physical Activity
* Muscles burn more energy than fat
* Sex
* Males are typically larger in size and have a greater proportion of muscle mass than females of the same size, age, and fitness level
* Age
* Metabolic rate decreases with age

Food as Fuel

* Cells need energy to function
* Nutrients from food are digested and circulated throughout the body
* A nutrient is any substance that has a useful function in the body
* Calorie
* Heat required to raise the temperature of 1 gram of water by 1°C

Classification of Food

* Organic and Inorganic
* Macronutrients and Micronutrients
* Example: Complex Carbohydrates or minerals (such as calcium)

Organic vs. Inorganic

* Organic
* Produced by living organisms
* Carbohydrates, fats, proteins, vitamins
* Inorganic
* From rocks, soil, and seas
* Water and minerals

Macronutrients vs. Micronutrients

* Macronutrients
* Needed in large amounts
* Carbohydrates, Fats, Proteins
* Micronutrients
* Needed in small amounts
* Vitamins and Minerals

Carbohydrates

* Composed of carbon, hydrogen, and oxygen
* Major source of energy
* Often called “sugars”
* Ready source of glucose
* Excess stored as fat or glycogen
* Cellulose (fibre) is indigestible but important

Fats (Lipids)

* Concentrated source of energy
* Double the energy of carbs
* Made of C, H, and O but in different ratios
* Used for insulation, forming cell membranes, protecting vital organs, and increasing nerve transmission

Types of Fats

* Unsaturated Fats
* Liquid at room temperature
* Easier to digest
* E.g. olive oil and canola oil
* Saturated Fats
* Solid at room temperature
* Harder to digest
* E.g. butter and lard

Proteins

* Most abundant compound in the body
* Used throughout the body
* Structure for skin, bones, and organs
* Also enzymes and hormones
* Made of 20 amino acids
* 8 are essential (get from diet)
* Meat, eggs, milk, and fish

Micronutrients

* Not an energy source
* Consumed in small amounts
* Vitamins
* Muscle and growth function
* Often act as coenzymes
* Minerals
* Iron (blood)
* Calcium (bones)

Water

* Most abundant substance in the body
* 90% of blood plasma
* Transports all nutrients
* Forms extracellular fluid between cells
* Regulates body temperature

The Digestive System

* Digestion is the process of converting food substances to a state in which they can be absorbed by the lining of the digestive tract
* Long tube open at both ends (Gastrointestinal tract or GI tract)
* Also has accessory organs
* Nutrients absorbed, waste eliminated
* Converts food into usable form

Stages of Digestion

* Ingestion
* Digestion
* Absorption
* Egestion/Excretion

Stage 1: Ingestion

* Food enters the oral cavity (mouth)
* In humans, digestion begins in the mouth
* Salivary Glands (3 Pairs)
* Secrete Saliva

Stage 2: Digestion (1)

* Teeth chew, saliva moistens
* Enzyme in saliva (amylase) breaks down carbohydrates
* Muscular tongue pushes food back to pharynx
* Epiglottis - flap covers trachea so food does not get in
* Food stretches walls of esophagus and travels downward through waves of contractions called peristalsis

Food enters the Stomach

* Food enters the stomach as a bolus (A round ball of food that has been moistened so it can be swallowed)
* The bolus enters the stomach through the cardiac sphincter
* Stomach has extensive folds called rugae
* Layers of smooth muscle help stomach contract and break food down further

Esophagus to Stomach

* Peristaltic contractions move the food to the stomach where storage and mixing of food occurs
* Cardiac sphincter at the top and pyloric sphincter at the bottom to keep food in stomach

Stage 2: Digestion (2)

* Food moves in and out of the stomach through sphincters (circular muscles)
* The stomach contracts and relaxes to churn the food (mechanical digestion)
* Hydrochloric acid
* Breaks down food, destroys bacteria in food
* Pepsin
* Breaks down proteins into polypeptides
* Mucus
* Protects stomach lining from acid and ulcers
* Some absorption occurs in the stomach

Mechanical Digestion

* Physical breakdown of food
* Mouth (chewing) and stomach (churning)
* Movement of food
* Peristalsis
* Wave-like muscle contractions

Chemical Digestion

* In mouth, stomach, and small intestine
* Chemicals (eg. HCl) and enzymes break down complex molecules in food

When food is Present…

* Gastrin
* Nerves in stomach detect food and release the hormone gastrin into bloodstream
* Transported to gastric cells where it stimulates gastric juice release
* Gastric juice (HCl) is very acidic with a pH of 2.0
* Kills microorganisms, stops amylase, and activates pepsinogen into pepsin (its active form)

Pepsin

* The active form of pepsinogen
* Protein-digesting enzyme produced in the stomach

Stage 2: Digestion (3)

* Chyme is released into duodenum through the pyloric sphincter
* Small Intestine
* Up to 7 metres in length, 2.5 centimetres in diameter
* 3 parts
* Duodenum - enzymes added, digestion
* Jejunum - digestion, some absorption
* Ileum - majority of nutrient absorption
* Secretes the enzyme peptidase which completes the digestion of proteins

Duodenum

* First section of the small intestine
* Basic pH (alkaline)
* Neutralizes acidic chyme from stomach and inactivates pepsin back to pepsinogen

Stage 3: Absorption

* Primary site of nutrient absorption to blood
* 80% of nutrient absorption occurs here - diffusion
* Only the small intestine can absorb lipids (fats), carbohydrates, and amino acids (from proteins)
* Small intestine is lined with villi and microvilli
* Finger-like projections that increase surface area for absorption
* Villi
* Small, finger-like projections
* Microvilli
* Microscopic projections of epithelial cells

Within each villus…

* Capillary Network
* All nutrients, except fats, enter bloodstream via capillaries
* Lacteal
* Lymphatic vessel through which fats enter the circulatory system

Large Intestine (1)

* 1.5 metres in length
* AKA colon
* Primary function is to reabsorb fluids and electrolytes
* Harmless bacteria live here producing Vitamins K and B
* Any undigested food that remains is called feces
* Fecal matter is stored here before elimination through the anus

The Appendix

* Small organ attached to the caecum
* It was thought to be vestigial for a long time but now scientists believe that it may harbor small amounts of beneficial bacteria to repopulate intestinal flora after a bad diarrhea incident or antibiotic use

The Large Intestine (2)

* The small intestine and the large intestine join at the caecum with the ileocecal valve
* Large intestine = caecum + colon + rectum
* 4 parts to the colon:
* Ascending colon
* Transverse colon
* Descending colon
* Sigmoid colon

Remember… (The Digestive System)

* As digested matter passes through the colon, any excess water is absorbed back into the body
* Vitamins and ions are absorbed with the water
* Rectum holds solid waste until time for elimination through the anus

Stage 4: Egestion/Excretion

* Occurs in the large intestine
* Main components of feces
* Cellulose
* Living and dead bacteria
* Water
* Toxic wastes are removed
* People who eat less cellulose have fewer bowel movements and are at risk of colon cancer

Accessory Organs of the Digestive System

* Salivary Glands
* Parotid Glands
* Sublingual Glands
* Submandibular Glands
* Liver
* Gallbladder
* Pancreas

Salivary Glands

* Parotid glands secrete watery fluid that contains salivary amylase
* Other two glands produce slippery mucus to help swallow food bolus

Liver

* Second largest organ in the body
* Produces bile
* Emulsifies fats
* Filters the blood
* Extracts toxins and prepares nutrients for circulation
* Stores glucose as glycogen
* Regulates metabolism (blood sugar levels)

Gallbladder

* Receives, stores, and concentrates bile from liver
* When fats enter duodenum, duodenum releases hormone CCK
* CCK signals the gallbladder to secrete bile to duodenum to emulsify fats

Pancreas

* Finger/leaf shaped organ that cradles below and behind the stomach
* Secretes hormones and enzymes
* Acidity of chyme entering small intestine from stomach signals duodenum to secrete hormone secretin
* Secretin stimulates the pancreas to release sodium bicarbonate
* Other pancreatic digestive enzymes:
* Lipases (break down fats)
* Proteases (break down proteins)
* Carbohydrases (break down carbohydrates)
* Secretes insulin and glucagon hormones to regulate blood sugar levels

Homeostasis

* Maintenance of steady internal state
* Maintained through negative feedback loops
* Example: Insulin regulates blood sugar levels
* Normal levels between 4-6 mmol/L
* Blood sugar levels increase (e.g. after a meal)
* Pancreas releases insulin
* Uptake in glucose from blood to cell
* Blood sugar levels decrease (e.g. skipped a meal)
* Pancreas releases glucagon
* Glucagon causes liver to release glucose into bloodstream

Enzymes

* Pepsin
* Produced by stomach
* Active in stomach
* Only when pH is low
* Acts upon proteins
* Bile
* Produced by liver
* Present in gallbladder and active in small intestine
* Acts upon carbohydrates
* Amylase
* Produced by salivary glands
* Present/active in mouth/saliva
* Acts upon starches
* Hydrochloric acid
* Produced by stomach
* Present/active in stomach
* Provides proper pH for pepsin (to break down proteins)
* Lipases, Proteases, and Carbohydrases
* Produced by pancreas
* Present/active in small intestine
* Act upon fats, proteins, and carbohydrates

Chron’s Disease

* Chronic inflammatory bowel disease
* Most common in the small/large intestine
* Causes:
* Possible hereditary link to autoimmune disease (25%)
* Possible bacterial or viral infection
* Symptoms
* Abdominal pain
* Intestinal bleeding
* Diarrhea
* Nausea and vomiting
* Loss of appetite
* Weight loss
* Fever
* Diagnosis
* Barium X-ray
* Colonoscopy
* Treatment
* No cure
* Medication to control inflammation or associated problems
* Avoidance of “trigger foods”
* Removal of blocked segments

Stomach (Gastric) Cancer

* Cancer of tissues lining stomach
* Exact cause unknown
* Risk factors:
* H. Pylori Infection
* Smoking
* Poor diet
* Symptoms
* Nausea and vomiting
* Heartburn and indigestion
* Fatigue
* Stomach pain
* Feeling full after eating little
* Diagnosis
* Barium swallow x-ray
* Endoscopy or biopsy
* CT scans
* Treatment
* Radiation therapy or chemotherapy
* To shrink tumour
* Gastrectomy
* Partial or total removal

Cirrhosis

* Scarring of the liver
* Leads to loss of liver function
* Caused by chronic damage to liver (e.g. hepatitis and alcoholism)
* Symptoms
* Fatigue
* Loss of appetite
* Easy bruising and bleeding
* Nausea and vomiting
* Fluid retention in abdominal region
* Diagnosis
* Blood tests
* Ultrasound
* Liver biopsy
* CT or MRI scan
* Treatment
* Damage cannot be reversed
* Avoidance of alcohol
* Liver transplant

Blood Vessels

* Arteries
* Thick-walled vessels that always carry oxygenated blood away from the heart
* Veins
* Thin-walled vessels that always carry deoxygenated blood towards the heart
* Arteries→Arterioles→Capillaries→Venules→Veins

Arteries

* Transports blood under pressure
* Blood moves in a pulse-like wave throughout the circulatory system
* Arterioles
* Have smaller diameter than arteries and are less elastic
* Contraction and relaxation of arteries is the major determinant of the overall blood pressure

Capillaries

* Narrowest of all blood vessels
* RBCs travel in a single file
* Branching of the capillaries increases surface area for diffusion
* Connects the arterial and venous systems

Veins

* Thinner walls, larger diameter, less muscle than arteries, and they contain valves
* Contains 70% of total blood volume
* Most veins must work against gravity
* Allow one-way flow of blood
* Contraction of skeletal muscles moves blood toward heart
* If veins are constantly stretched, they will lose their elasticity and varicose veins will form

The Heart

* Size of your fist
* Hardest-working muscle in the body
* Contains 4 chambers
* Left and right atria (receiving chambers)
* Left and right ventricles (delivery chambers)
* The left and right sides of the right are separated by a muscular septum
* The heart is protected by the ribcage, sternum, and spine

Pathways of Blood

* Pulmonary Circuit
* Pumps blood to lungs
* Right side of the heart
* Low-pressure system
* Systemic Circuit
* Pumps blood to the rest of the body
* Left side of the heart
* High-pressure system

Pulmonary Circuit

Vena Cava (Superior & Inferior)→Right Atrium→Tricuspid Valve/Right AV Valve→Right Ventricle→Pulmonary Semilunar Valve→Pulmonary Trunk→Pulmonary Arteries→Lungs’ Capillaries→Pulmonary Veins→Left Atrium

Systemic Circuit

Left Atrium→Bicuspid Valve/Left AV Valve/Matrial Valve→Left Ventricle→Aortic Semilunar Valve→Aorta→Smaller Systemic Arteries→Arterioles→Capillaries→Venules→Veins→Vena Cava (Superior & Inferior)→Right Atrium

Coronary Circulation

* Delivers oxygenated blood directly to the heart
* Consists of the left and right coronary arteries

Cardiac Contractions

* The heart’s intrinsic contractions are maintained by the sinoatrial (SA) node in the right atrium
* The nerves can control the strength and rate of the heart’s contractions
* The SA node passes the signal through the atrioventricular (AV) node
* There is a 0.1 second delay the AV node before the signal travels to the ventricles
* The signal travels to the ventricles via the Perkinje fibres and the Bundle of His
* The signal delay cause the atria to contract simultaneously before the ventricles

Specialization of Cardiac Muscle

The rhythmic contractions of the heart are due to special characteristics of cardiac muscle cells

Coronary Artery Disease

* Plaque buildup in coronary arteries


* Prevents the heart from oxygen-rich blood
* Causes/Risk Factors
* Smoking and Alcoholism
* High Blood Pressure
* High Blood Cholesterol
* Stress
* Diabetes
* Obesity
* Lack of Physical Activity
* Age, Gender, and Family History
* Symptoms
* Shortness of Breath
* Angina
* Diagnosis
* Electrocardiogram
* Echocardiogram
* Chest X-ray
* Blood tests
* Treatment
* Angioplasty
* Coronary Artery Bypass Surgery
* Medications
* Decrease blood pressure, blood cholesterol, etc.
* Lifestyle Changes
* Increase physical activity and focus on healthy diet

Leukemia

* Bone Marrow Cancer: Abnormal WBC overproduction
* WBCs do not die properly
* Bone Marrow Overcrowding
* Reduced RBC, platelet production
* Causes/Risk Factors
* Radiation/Chemotherapy
* Benzene Exposure
* Smoking
* Symptoms
* Swollen, pain-free lymph nodes
* Bleeding and bruising easily
* Fevers and night sweats
* Frequent infections
* Fatigue
* Unexplained weight loss
* Diagnosis
* Physical Exam
* Swollen lymph nodes, spleen, liver
* Blood Test
* High WBCs and/or Low hemoglobin and platelets
* Bone Marrow Biopsy
* Treatment
* Bone Marrow Transplant
* Chemotherapy
* Radiation Therapy
* Stem Cell Transplant

Marfan’s Syndrome

* Heritable disease that affects connective tissue
* 25% of all cases are a result of a spontaneous mutation
* Symptoms
* Tall and Slender
* Retinal Displacement
* Aortic Dilation
* Easily puncturable leading to sudden death
* Leaky Heart Valves
* Heart murmour
* Diagnosis
* Physical Exam
* Genetic Analysis
* Rarely Completed
* Treatment
* Skeletal: Orthopedic Braces and Surgery
* Vision: Surgery and Glasses
* Heart: Medications, Valve Replacements, Aortic Repair

The Cardiac Cycle

* A continuous cycle of contraction and relaxation
* Systole
* Heart Contraction
* Diastole
* Heart Relaxation

Systole

* Atria contract to further fill the ventricles
* The Tricuspid and Bicuspid valves forced closed due to an increase in ventricular pressure
* Ventricles contract to force blood from the heart
* Right Ventricle→(Open Pulmonary Semilunar Valve)→Pulmonary Trunk→Pulmonary Arteries
* Left Ventricle→(Open Aortic Semilunar Valve)→Aorta
* Blood pressure is increased (120 mm Hg)

Diastole

* Blood enters all four chambers:
* Pulmonary Veins→Left Atrium
* Vena Cava (Superior & Inferior)→Right Atrium


* The Tricuspid and Bicuspid Valves are open, allowing blood to flow into the left and right ventricles
* The Pulmonary and Aortic Semilunar Valves close due to a decrease in ventricular pressure
* Blood pressure is reduced (80 mm Hg)

Lub Dub

* Heart valves open and close at different times to ensure blood flows in the proper direction
* “**Lub**:” Tricuspid and Bicuspid valves close (Beginning of systole)
* “**Dub**:” Pulmonary and Aortic Semilunar valves close (End of Systole)

Some Common Causes of High Blood Pressure

* Generally these cause blood vessels to get narrow and/or your heart to beat faster
* Some examples:
* Poor diet
* Kidney and hormone problems, diabetes, and high cholesterol
* Family history or genetic predisposition
* Lack of physical activity
* Older age
* Being overweight or obese
* Some medicines
* Tobacco and/or alcohol use
* Stress

Blood Pressure

* Larger Arteries
* Blood Pressure: High
* Velocity: High
* Total Area: Low
* Smaller Arteries
* Blood Pressure: Slightly lower than larger arteries
* Velocity: Slightly lower than larger arteries
* Total Area: Slightly higher than larger arteries
* Arterioles:
* Blood Pressure: Lower than smaller arteries
* Velocity: Lower than smaller arteries
* Total Area: Higher than smaller arteries
* Capillaries
* Blood Pressure: Low
* Velocity: Very low
* Total Area: Highest
* Venules
* Blood Pressure: Low
* Velocity: Low
* Total Area: High
* Veins
* Blood Pressure: Low
* Velocity: Moderate
* Total Area: Low

Altitude & Oxygen

* Altitude increases, oxygen concentration decreases
* Body temporarily increases blood pressure & heart rate
* Adaptation occurs over a couple of days
* Body produces hemoglobin and red blood cells
* Enhanced oxygen-carrying capacity

Altitude Training

* Athletes live and train at high altitudes before events
* Increases red blood cell mass and hemoglobin
* Enhanced oxygen-carrying capacity in blood

Cellular Respiration

* Extra energy boosts aerobic cellular respiration
* Improves VO2 max
* Delays lactic acid production, soreness, & fatigue
* Some athletes attempt blood doping
* Inject extra red blood cells before events

Blood Doping

* Athlete donates a pint or two of their own blood
* Blood is placed in centrifuge and spins at high speeds
* Red blood cells (oxygen carriers) forced to bottom
* Liquid part (plasma) drawn off and re-injected into athlete
* Red blood cells stored (sometimes frozen)
* Day before competition, stored red blood cells are re-injected
* Improves blood’s oxygen-carrying capacity

Components of Blood

* Blood Plasma
* 55% of total blood volume
* Cellular Components
* 45% of total blood volume
* Buffy Coat
* White Blood Cells
* Platelets
* Red Blood Cells

Blood Plasma

* Yellowish liquid component of blood
* Holds blood cells in suspension
* Carries cells, carbon dioxide, and proteins
* 55% of total blood volume

Erythrocytes: Red Blood Cells

* Produced by bone marrow, stored in spleen
* Constantly destroyed and replaced
* Distinct biconcave shape
* Flattened disc, pinched centre
* Flexible for travelling through blood vessels
* No nucleus
* No mitochondria
* Contains special hemoglobin molecule

Hemoglobin

* Complex protein: 4 protein chains, central iron-containing heme group
* Iron: Gives red blood cells red colour
* Iron’s function: Binds with oxygen, oxgenates blood
* Oxygen’s carrying capacity: 4 oxygen molecules per hemoglobin molecule
* Iron recycling: Occurs in bone marrow

Leukocytes: White Blood Cells

* Produced in bone marrow
* Larger than red blood cells, fewer in number
* Amoeboid shape
* Contain nucleus and lysosomes
* Part of the body’s immune response system
* Detect and defend against infection and disease
* Lysosomes: Digest foreign bacteria
* Pus formation: At the site of infection
* Pus Components: Living and dead white blood cells, bacteria
* Pus as natural “soap”
* WBC increase: Indication of body fighting infection

Leukemia

* Cancer of white blood cells
* Excess white blood cells in bone marrow
* Bone marrow unable to make other blood cells
* Can leave bone marrow, travel into bloodstream, and affect other organs

Platelets

* Fragments of special cells from bone marrow
* Important for circulatory system repair
* Form blood clots

Blood Clotting

* Detects damaged blood vessels, bursts, and releases adhesive chemicals
* Platelets stick together at the site of damage
* Chemical reactions create strand-like fibrin molecules, form mesh (blood clot)
* Prevents blood loss, hold vessel wound together
* Clot supports wound until new tissue grows

Hemophilia

Absence of clotting proteins in an individual

The Respiratory System

* Respiration
* The exchange of oxygen and carbon dioxide between an individual and their environment
* The respiratory system supplies oxygen to body cells and removes carbon dioxide

Components of Respiration

1. Ventilation (Breathing)
2. External Respiration
3. Internal Respiration
4. Cellular Respiration

Ventilation (Breathing)

1. Inhalation: Oxygen is taken in from the external environment
2. Exhalation: Carbon dioxide is removed from the internal environment

* Inhaled
* 78% Nitrogen
* 21% Oxygen
* 0.03% Carbon Dioxide
* Exhaled
* 78% Nitrogen
* 16% Oxygen
* 5% Carbon Dioxide

External Respiration

* Gas exchange between the alveoli and the blood vessels (pulmonary capillaries)
* Alveoli must be moist to allow for diffusion
* Oxygen diffuses into capillaries and carbon dioxide diffuses out to alveoli
* The blood carries the oxygen from the lungs to the body cells

Internal Respiration

* Gas exchange between the blood and the body cells
* Oxygen diffuses out of the blood and carbon dioxide diffuses in
* Allows for cellular respiration to occur

Cellular Respiration

* Occurs in the mitochondria of every cell
* Cells produce ATP (energy) when glucose breaks down in the presence of oxygen
* Byproducts include water and carbon dioxide
* C6H12O6 + O2 → H2O + CO2 + ATP

Anatomy of the Respiratory System

* Nose (Nares)
* Nasal & Oral Cavities
* Pharynx
* Larynx
* Trachea
* Lungs
* Bronchi & Bronchioles
* Alveoli
* Diaphragm

Nasal & Oral Cavities

* Air enters through the nares (nostrils)
* Warmed (capillaries), Filtered (cilia), and moistened
* Inhaling through the mouth misses some steps

Pharynx

* Common path for air and food (throat)
* Branches into the esophagus and the trachea

Larynx

* Vocal chords for sound production, breathing, and swallowing

Trachea

* Connects the pharynx to the lungs
* Rings of cartilage protect the tube from collapsing
* Divides into a bronchus on each side

Lungs

* Joined to the trachea by two bronchi
* The bronchi divide into smaller bronchioles
* Each bronchiole ends in an alveolar sac

Alveoli

* Tiny, hollow air sacs
* One cell thick
* Surrounded by capillary system
* Functional unit sof the respiratory system
* Where gas exchange occurs
* Increases surface area

Diaphragm

* Large, dome-shaped sheet of skeletal muscle (voluntary muscle)
* Under the ribs, separates the thoracic cavity (heart and lungs) from the abdominal cavity (all other organs)
* Essential to breathing

Inhalation

* Diaphragm and intercostal muscles contract
* Ribs move up and out, chest cavity enlarges, and pressure decreases
* Air rushes in from higher pressure environment

Exhalation

* Diaphragm and intercostal muscles relax
* Ribs compress, chest cavity gets smaller, and pressure increases
* Air escapes to lower pressure environment

Breathing

* Involuntary inhalation & exhalation
* Delivers oxygen to alveoli and removes carbon dioxide
* Medulla Oblongata
* Brain region that controls breathing

Gas Exchange

Occurs between the alveoli and the capillaries due to concentration differences

Control of Breathing

* Chemoreceptors detect change in blood pH
* Blood high in CO2 has lower than normal pH
* Drop in pH causes Medulla Oblongata to stimulate breathing

Oxygen Transport

* Oxygen is carried by hemoglobin in red blood cells
* Hemoglobin picks up oxygen in high concentration areas
* Hemoglobin releases oxygen in low concentration areas
* Oxygen binds with hemoglobin via hydrogen bonds
* oxygen + hemoglobin → oxyhemoglobin

Carbon Dioxide Transport

* Carbon dioxide is carried as bicarbonate ions in blood
* Red blood cells pick up carbon dioxide in high concentration areas
* Carbon dioxide converted to bicarbonate in red blood cells
* Bicarbonate converted back to carbon dioxide in low concentration areas
* Carbon dioxide released from red blood cells
* carbon dioxide + water → carbonic acid
* Some carbon dioxide is carried by hemoglobin as carboxyhemoglobin
* Some carbon dioxide dissolves in blood plasma

Human Lung Capacity

* Influenced by many factors:
* Age
* Sex
* Body Position
* Strength of diaphragm
* Strength of chest muscles


* The average human breathes 12-20 times per minute

Measurements

* Tidal Volume: The amount of air inhaled and exhaled in a normal breath
* Inspiratory Reserve Volume: The amount of air inhaled after a normal inhalation
* Expiratory Reserve Volume: The amount of air forcefully exhaled after a normal exhalation
* Vital Capacity: The maximum amount of air that can be exhaled
* Residual Volume: The amount of air remaining in the lungs after a forceful exhalation