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BS Respiratory and Skin Systems


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How does a eukaryotes acquire oxygen to perform what?
Acquire by simple diffusion of oxygen to perform oxidative phosphorylation
4 tasks performed by the respiratory system
1. Diffusion between cells and the environment
2. pH regulation
3. Thermoregulation - breathing results in significant heat loss.
4. Protection from disease and particulate matter - lungs provide large moist surface w/macrophages
What enzyme convert CO2 to carbonic acid?
RBC enzyme carbonic anhydrase
How is pH of blood increased?
When CO2 is exhaled by lungs, amount of carbonic acid in blood is decreased.
**results in pH increase, blood becomes more alkaline (more basic).
How does hyperventilation (too much breathing) affect the body?
causes alkalinization of the blood, aka respiratory alkalosis.
**hypoventilation--> acidification of the blood (respiratory acidosis)
What organ regulates pH over a period of hours to days?
The pathway of respiratory tract
nose --> nasopharynx(open space behind the nose) --> pharynx(throat) --> larynx --> trachea --> bronchi(plates of cartilage) --> bronchioles --> alveolar ducts --> alveoli (walls one cell thick except around capillaries. Sites of gas exchange).
3 functions of larynx
1. made of cartilage; keeps the airway open.
2. contains epiglottis that seals the trachea during swallowing.
3. contains vocal cords, which partially block airflow and vibrate producing sound
1 mm wide and contain no cartilage. Their walls are made of smoooth muscle, thus diameters are regulated to adjust airflow.
Columnar epithelial (ep) cells
Too thick for gas exchange. Known as the conduction zone. Goblet cells secrete a layer of mucus.
Mucociliary escalator
Cilia in ep cells of upper respiratory tract sweep mucus (containing foreign matters) toward the pharynx. Mucus swallowed or coughed out.
Simple squamous epithelium
A single layer of thin squamous ep cells that lines gas-exchanging surfaces and permits rapid diffusion
What protects alvioli
Since mucus will interfere the gas exchange, alveolar macrophages patrol and engulf foreign matters
1. What is surface tension?
2. What causes it?
1. The force causing wet hydrophilic surfaces to stick together in presence of air
2. the tendency of water molecules to clump together
Surface active substance that coats alvioli and reduces surface tension that could collapse alvioli. A mixture of phospholipids, proteins, and ions secreted by cuboidal ep cells.
Pulmonary ventilation
Circulation of air into/out of lungs to continually replace gases in alveoli with the atmosphere
1. Parietal pleura
2. Visceral pleura
3. Pleural space
4. Pleural pressure
pleura: two membranes that surround the lung.
1. lines the inside of the chest cavity
2. lines the lungs
3. between the 2 space
4. pressure in the pleural space. Pleural pressure is negative, thus lungs expand along w/ the chest. 2 pleural membranes are drawn tightly together by a vacuum.
2 functions of pleural pressure
1. Negative pressure keeps the outer surface of lungs drawn out against chest wall.
2. A thin layer of fluid between 2 pleura helps hold lungs and chest wall together thru surface tension.
During inspiration, what happens to intercostal muscles?
They contract, pulling the ribs upward and expanding the chest cavity along with diaphragm.
**inspiration: active process; muscle contraction occurs
What happens during expiration when muscles relax?
The elastic recoil of lungs draws the chest cavity inward, reducing the volume of lungs and forcing air out
6 steps in inspiration
1. Diaphragm expands
2. Volume of the chest cavity expands
3. Pleural pressure decreases, becoming more negative
4. Lungs expand outward
5. Pressure in the alveoli becomes negative
6. Air enters the lungs and the alveoli
At the beginning of inspiration, what happens to pleural pressure?
Decreases, sucking the lungs open
When is alveolar pressure exactly 0?
1. At the end of a resting expiration, air neither enters nor leaves lungs, until another inspiration begins.
2. Instantly just after inspiration and before expiration begins
What happens if there's a hole in visceral pleura and inhaled air flows into pleural cavity?
Causes lung to collapse, because negative pleural pressure is the only force opposing lung collapse. Inspiration not possible.
Measurement of the volume of air entering lungs at the various stages of respiration
1. Tidal Volume (TV)
2. Residual Volume (RV)
amount of air that
1. moves in/out of lungs w/ normal light breathing and is equal to about 10% of the total volume of lungs.
2. remains in lungs after the strongest possible expiration.
1. Expiratory Reserve Volume (ERV)
2. Inspiratory Reserve Volume (IRV)
Volume of air that can be
1. expired after a passive resting expiration
2. inspired after a relaxed inspiration
1. Functional Residual Capacity (FRC)
2. Inspiratory Capacity (IC)
Volume of air
1. left in the lung after a resting expiration
2. which can be inhaled after a resting expiration
1. Vital Capacity (VC)
2. Total Lung Capacity (TLC)
1. Maximum amount of air that can be foreced out of the lungs after first taking the deepest possible breath.
2. Vital capacity (VC) + Residual Volume (RV)
If lungs don't tend to contract, what happens to the pleural space?
The vacuum in pleural space will be lessened (becomes more +).
Pulmonary (alveolar) capillaries
Many branches of pumonary artery carrying deoxygenated blood toward lungs
Each alveolus is
Surrounded by a few tiny capillaries, wide enough to permit the passage of RBCs and diffusion of gases between blood and alveolus.
How does increase in left atrial pressure affect the respiration?
Has very little effect on the pulmonary circulation b/c pulmonary veins can dilate, accomodating excess blood.
What happens if the pressure in the left atrium increases above a certain level?
The pressure wil increase in pulmonary capillaries.
Pulmonary edema
Fluid in the lungs resulting from increased blood pressure. Normally, the lymphatic system prevents pulmonary edema from developing by carrying interstitial fluid out of lungs
Properties of lung
1. large surface area. Goal: to allow O2 from atmosphere diffuse into pulmonary capillaries & CO2 diffusion from blood to alveolar gas.
What happens in alveolar capillaries?
O2 & CO2 diffuse between alveolar air and blood.
What's the driving force for the pulmonary gas exchange?
THe difference in partial pressure between alveolar gas and blood.
**partial pressure describes the amount of gases carried in bloodstream.
What 3 barriers should gases pass for diffusion to occur?
1. Across the alveolar epithelium
2. Thruough the interstitial liquid
3. Across the capillary endothelium.
**The 3 barriers form respiratory membrane.
What drives the net diffusion of oxygen into the blood?
The oxygen pressure gradient between alveolar air and blood as blood passes thru the alveolar capillaries.
Atmospheric & arterial PO2, PCO2, and PH2O
Pressure of O2, CO2, H2O
What controls breathing and how is it done?
Respiratory control center in medulla of brain stem involuntarily directs breathing.
Stretch receptors in lungs
Stimulated by the mechanical stretching of lung tissues, they inhibit further excitatory signals from the respiratory center to muscles involved in inspiration. So basically, they inhibit inspiration.
3 principal chemical stimuli that affect respiration
1. Increased PCO2
2. Decreased pH via carbonic anhydrase (increases respiratory rate)
3. Decreased PO2 (secondary stimulus). Increases respiratory rate)
What 2 special autonomic sensory organs monitor the chemical stimuli that affect respiration?
1. Peripheral chemoreceptors located in aortic and carotid arteries
2. Central chemoreceptors in medullary respiratory control center (located in central nervous system)
1. What is Bronchoconstriction?
2. Its function?
3. What controls it?
1. Contraction of smooth muscle in walls of bronchi/bronchioles.
2. Prevents irritants from entering the passageways.
3. Determined by parasympathetic nerves releasing ACh.
1. What causes bronchoconstriction?
2. What counteracts this?
1. Histamine from allergy attack.
2. Epinephrine opposes this by increasing ventilation by causing airway to relax (bronchodilation)
What's in 'inhalers' carried by patients with asthma?
Epinephrine, antihistamines
Irritant receptors in lungs
trigger coughing and/or bronchoconstriction when chemicals detected.
3 functions of skin
1. Protects from pathogens
2. Prevents excessive evaporation of water
3. Regulates body temp
Order of the skin layer
Epidermis --> dermis --> subcutaneous tissue (hypodermis)
**Hypodermis: a protective insulating layer of fat
1. Epidermis
2. What replenishes it?
1. Composed of stratified (multi-layers) squamous epithelial cells. Constantly sloughed off & replenished.
2. Mitosis of cells in stratum basale, deepest part of epidermis
How does epidermis provide a strong protective structure?
New daughter cells in stratum basale will be pushed farther outward by continued mitosis below, and old cells on the surface will flake away.
A process of old stratified squamous cells becoming surrounded by a thick coating of tough hydrophobic protein keratin. Makes skin waterproof.
A pigment produced by specialized cells in epidermis called melanocytes that absorb UV light of the sun to prevent damage to underlying tissues
5 things dermis contains
1. blood vessels nourishing derm/epiderm (epidermis has no blood vessels)
2. sensory receptors conveying information to central nervous system.
3. sudoriferous (sweat) glands
4. sebaceous (oil) glands
5. hair folicles
**Hairs consist of dead ep cells bound tightly together
1. What is sudoriferous gland?
2. What does sweat contain?
3. To what hormone are sweat glands responsive to?
A tube-like structure that originates from dermis to a sweat pore on the surface.
3. Water, electrolytes, & urea
4. Aldosterone (helps conserve Na+; thus the body does not waste much salt during excessive sweating)
4 only strategies to cope with cold weather and conserve heat.
1. Contraction of skeletal muscles that produces heat whether voluntary or involuntary (shivering)
2. Skin insulation so that heat generated by metabolism is conserved.
3. Constriction of blood in dermis that minimizes heat loss by conduction. Aka cutaneous vasoconstriction
4. Contrivances such as clothing
How does cutaneous vasoconstriction occur?
It occurs
1. in response to cold weather
2. upon activation of sympathetic nervous system
2 mechanisms that dissipate excess heat
1. Sweating, allowing heat loss by evaporation
2. Dilation of blood vessels in dermis (cutaneous vasodilation) resulting in heat loss by conduction.

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