Gas Exchange/Excretion

Gas Exchange


Gas Exchange

  • Exchange carbon dioxide for oxygen

  • Need respiratory surface

    • Needs to be thin for diffusion

    • Needs to be moist for diffusion

    • Needs to be in contact with gases

Large animals need a transport system

  • Need vessels 

  • Need blood with an oxygen-carrying molecule, a respiratory pigment

  • 100 mL of water can carry 0.2 mL of oxygen

  • 100 mL of blood can carry 20.0 mL of oxygen

Gas Exchange/Humans

  • Respiratory Surface = Lungs

Lungs

  • Bronchi part of respiratory system but not part of lung

  • Inflammation in the bronchi is called bronchitis

Air

  • Inhaled (breathe in):

    • 79% Nitrogen Gas

    • 20.9% oxygen

    • 0.04% carbon dioxide

    • Water

  •  Exhaled (breath out):

    • 79% Nitrogen gas

    • 16.3% oxygen (CPR)

    • 4.5% carbon dioxide

    • Water

Route of Air

  1. Nose (Nasal passages)

    1. Hair for filtration

    2. Mucus to moisten air

    3. Blood vessels to warm air

    4. Don’t get thai with mouth breathing

  2. Pharynx

  3. Larynx (Voice Box with vocal cords made of cartilage)

  4. Trachea (Windpipe)

    1. Get open by rings of cartilage 

    2. Lined with ciliated mucus membrane

      1. Causes you to cough when you breathe in debri

    3. Coughing reflex

    4. Tobacco smoke paralyzes cilia (1 cigarette = 20 minutes of paralysis)

      1. Also increases mucus production

  5. Bronchi

    1. Ringes

    2. 2

    3. Ciliated

  6. Bronchial Tubes

  7. Bronchioles

    1. No cartilage rings

    2. Tiny tubes

    3. Open into the alveoli

      1. The alveoli is covered in capillaries

  8. Alveoli

    1. Like cluster of grapes

    2. 300 million alveoli

    3. 70 square meter surface area

    4. Walls of air sacs are one cell thick

    5. Site of gas exchange

Lung Volume

  • Tidal Volume = 500 mL of air in and out during rest (3500 mL - exercise)

    • 12 breaths/min (6L/min) Rest

    • 40 breaths/min 42L/min) Exercise

  • Functional Residual Capacity = always left with 2300 mL air after breathing out

    • For emergency situations

Problems

  • Emphysema

    • Result of inhaling multiple toxins over a long period of time

    • Destruction of alveoli walls

    • Scar tissue from macrophage attack

      • Can’t expand property

    • Reduced breathing ability

      • Lack of lung volume

  • Asthma

    • Allergic reaction in bronchioles with their subsequent closing

    • Swelling around toxins and squeezing airways, making it hard to breathe

    • Treat with Epinephrine mist

  • Lung Cancer

    • Breathing in any sort of environmental toxin or debris

  • Pneumonia

    • Fluid in alveoli

      • Treatment is to try and suck out the liquid from the lungs

    • Walking pneumonia is when a person is sick, but they can still walk and preform daily functions

  • Tuberculosis

    • Coughing out blood

    • Immune attack leaves scars that thicken alveoli and affect diffusion

  • Bronchitis

    • Increase in mucus production

    • Inflammation of bronchial tissue

    • Resulting in a horse cough

Process of Inhalation (Active)

  • Rib muscles pull ribs up and out

  • Diaphragm muscle pulled down

  • Now low air pressure in chest

  • Air sucked into chest

  • Alveoli expand

Process of Exhalation (Passive)

  • Diaphragm relaxes and goes back up

  • Rib muscles relax

  • Ribs go down and in

  • Increase pressure in chest

  • Air squeezed out of lungs

Air pressure and altitude

  • A commercial airline plane are pressurized and infused with oxygen

    • If a plane door opens while in the air then the air would rush out of the plane and start pulling everything inside with it

  • High altitudes have lower air pressure than at sea level

  • High altitudes have lower concentration of oxygen compared to sea level

  • Planes are pressurized and pump oxygen into the plane

  • Nitrogen gas in blood bubbles out

  • The people who live in the Andes mountains of Peru have:

    • High red blood cell count

    • More red bone marrow

    • More developed lungs

The Bends

  • Going from one extreme air pressure to another will cause the blood cells to bang into each other making it very painful for the person

Breathing Regulation

  • Involuntary

    • Medulla tells the body to breathe in or out

  • Have Chemoreceptors in walls of arteries that detect carbon dioxide levels

  • High carbon dioxide levels in blood detected and send message to respiratory center of brain (Medulla)

    • Carbon dioxide lowers pH by interacting with the water in the blood, making carbonic acid

  • Medulla send message to diaphragm and rib muscles to increase rate and depth of breath

  • Lo pH of blood also stimulates medulla

External vs Internal Respiration

  • External

    • Gas exchange in alveoli with capillaries

  • Internal

    • Gas exchange in capillaries with body cells

Oxygen Transport

  • In lungs oxygen combines with Hemoglobin to form oxyhemoglobin

  • Oxygen goes into the Hemoglobin because air follows a concentration gradient going from high concentration in the alveoli to low concentration in the blood

  • Oxygen released in locations of low oxygen concentration

  • Carbon monoxide has greater binding ability to hemoglobin than oxygen

Carbon Dioxide Transport

  • 70% as Bicarbonate in plasma

    • CO2 + H2O →H2CO3 → H+ + HCO3-

    • The H2CO3 acts like a buffer to keep the pH of the blood constant

    • Dissociation breaks up a compound

  • 20% as carbaminohemoglobin

    • Carbon dioxide can also travel and bind to hemoglobin

    • CO2 + Hb → HbCO2

  • 10% as free CO2 in plasma 


Excreation


Excreation

  • Elimination of unabsorbed and undigested food in the form of feces is called Elimination, not Excreation

    • These materials have never entered the body cells, therefore they are NOT metabolic waste

  • Excreation is waste products from chemical reactions; it has to be metabolic waste

Metabolic Waste

  • Carbon dioxide, water (from respiration) - result of cellular respiration

  • Nitrogen Compounds: ammonia, urea, uric acid, (breakdown amino acids)

    • These are nitrogenous wastes

    • Ammonia is converted into urea by the kidneys to make peeing less painful, since ammonia is toxic

  • Mineral salts: sodium chloride, potassium sulfate (metabolism)

  • All of these waste products are poisonous in excess

Human Excretory System

  • Metabolic wastes

    • Carbon dioxide

    • Urea

      • A less toxic version of ammonia

      • Many aquatic animals don’t convert ammonia into urea because the ocean water automatically dilutes the ammonia fast

    • Water

    • Mineral Salts

Organs of Excretion

  • Lungs

  • Kidneys

  • Liver - a very important organ

  • Skin

The Liver

  • Regulated the makeup of body fluid

  • Detoxification: Liver detoxifies the blood

  • Removes harmful substances: bacteria, certain drugs, hormones, from the blood

  • Liver changes these substances into less harmful ones, which are sent to be peed out

  • Inactive forms are returned to the blood and excreted via the kidneys

  • This the only organ that can regenerate itself

  • Bile is made by the liver

    • Contains bile salts, cholesterol, part of hemoglobin (worn out red blood cells)

    • Some of these products are metabolic waste

Overworked Liver

  • Alcohol causes Cirrhosis

    • Liver becomes overgrown with excess tissue

    • Excess tissue cuts down blood flow

    • Limits amount of detoxification it can preform

    • Leads to death

Bile Cycle

  • Bile collects in gallbladder

  • Passes into small intestine

  • Emulsifies of fats

  • Bile salts are reabsorbed from small intestine into the blood

  • Return to the liver (recycling)

  • The rest of the bile is excreated through the large intestine

Liver not Working right

  • Jaundice

    • When bile is NOT excreated properly, reabsorbed hemoglobin fragments in the blood causes skin to turn yellow

      • Also causes the whites of a person’s eyes to turn yellow

    • Babies have yellow jaundice because their liver isn’t fully developed yet

      • To cure this the babies have to be put under a special warming light for 24 hours to lower the bilirubin levels

      • The cause could also be breast milk stimulating the enzymes of the liver

    • Bilirubin is the chemical that causes the skin to turn yellow and cause brain damage in excess, however it can also reduce bacterial infections

Formation of Urea

  • Amino acids are the breakdown products of proteins. We can not store excess protein

  • Breakdown occurs in the liver

From each Amino Acid

  • The amino group (NH2) is changed to Ammonia (NH3), then to Urea, which is a much less harmful version

  • Urea diffuses into the blood stream to the kidneys

  • Kidneys filter the urea and excrete as urine

  • Remainder of amino acid is changed to either: pyruvic acid, glycogen, or fat

Urinary System

  • Kidneys (2)

    • The adrenal glands sit right on top of the kidneys

  • Bladder

    • Females have smaller bladders than males

  • Urethra

  • Ureters

Kidneys

  • Bean shaped

  • Located in posterior aspect of the abdomen, just below the diaphragm

  • Function: 

    • Removes waste of cellular metabolism from the blood

    • Regulate the concentrations of the substances found in body fluids including water, salts

    • Maintain homeostasis

Structure of Kidneys

  • Cortex

    • Outer part

    • Blood is filtered by size

      • Larger particles are kept in the blood

  • Medulla

    • Middle part

    • Made of tubes called collecting ducts

    • Carry filtered substances and filtrate to pelvis

      • Smaller substances are now flowing inside the bloodstream

  • Pelvis: inner region

    • Cavity connected to the ureter

    • Urine formed from filtrate drains from pelvis into ureter

    • Directly connected to blood vessels

Nephrons

  • Kidney contains 1.25 million nephrons

  • Filters waste from the blood

  • Part is in cortex, remainder is in medulla

Parts of Nephron

  • Glomerulus: a group of capillaries that form a tight ball

    • Plasma leaks out and becomes a filtrate 

    • The tightness creates pressure

  • Bowman’s capsule: a double walled cup shaped structure surrounding the glomerulus

    • Captures all the filtrate

  • Proximal Renal Tubule

    • Most things get reabsorbed here

  • Loop of Henle: middle section of the that forms a loop

    • Water reabsorption with the help of salt pumping creating a hypertonic environment

    • Extends into the medulla region of kidneys

    • Filtrate enters distal renal tubule

  • Distal convoluted tubule

    • Water and Salt, Calcium reabsorption

  • Collecting Duct

    • Some urea reabsorption

    • More water reabsorption

    • Many collecting ducts fuse

    • Urine exits out Ureter of Kidney

    • Site of ADH action

Filtration at Bowman’s Capsule

  • Pressure pushed out “filtrate”

  • Large substances (Proteins, cells, etc) do not enter Bowman’s capsule

  • Filtrate includes: water, urea, glucose, amino acids, and various salts

  • Filtrate moves in Proximal Renal Tubule

    • Closer to Bowman’s capsule

    • Place where most of the nephron process takes place

  • Chemicals leave the tube and goes into the capillaries for the blood vessels to reabsorb them

  • The rest of the toxins will be peed out

  • The Loop of Henle goes into the medulla region

    • This is where salt will be released into the bloodstream to create a hypertonic environment causing the water to exit the nephron

  • The solutes go the to the collecting ducts

Kidney Threshold Level

  • If the concentration of a substance in the blood is greater than a certain level: it is not reabsorbed

  • The excess remains in the Urine

Imbalance in Homeostasis

  • Blood sugar level of a person who has diabetes is so high that not all the glucose in the filtrate can return to the blood

  • Glucose in the Urine

Urine

  • The fluid remains in the tubules: water, urea, various salts

  • Substances that crystalize out of the Urine: kidney stones

    • The result of too much Vitamin C

    • The pointed ends of the kidney stones scrapes the ureters

  • Dialysis

    • Checkup on the kidneys

Ureters

  • Bring urine to urinary bladder

  • Urine exits through urethra

Lungs

  • Lungs are considered part of the excretory system because they get rid of carbon dioxide and water in the form of vapor

Skin

  • Excretes small amount of urea and salts in sweat

  • Structure

    • Two Layers

      • Epidermis: outer layer

        • Tightly packed epithelial cells

        • Made up of dead skin cells

        • Deepest portion is rapidly dividing

        • As they push farther and farther from Dermis, they receive less and less nourishment

        • Before dying, they produce Keratin: tough water proof protein

        • Wears away, replaced by new cells

        • Protects Dermis

      • Dermis

        • Made of elastic connective tissues

        • Binds to the muscle and bone beneath it

        • Contains: blood vessels, lymph vessels, nerves, sensory receptors, sebaceous glands, sweat glands, hair follicles

          • Sebaceous Glands

            • Produce oily secretion that provide a protective coating to the skin and hair keeping them soft and pliable

          • Sweat glands

            • Made of coiled tubes that open to the surface through pores

            • Sweat is release through these pores

      • Subcutaneous Layer

        • Adipose (fat-storing) cells

Heat Loss

  • Blood vessels in the skin open wider, when the person is hot

  • Increases the blood flow through the skin’s capillaries (flush)

  • Allows more heat to be given off to the air

  • Sweat begins to evaporate: cooling the body

Heat Retained

  • Blood vessels in the skin narrow

    • Causes cramping

  • Blood sweats less