Chapter 42: Circulation and Gases Flashcards
Respiratory System
how ventilation and diffusion at the respiratory surface are accomplished
Collection of cells tissues and organs responsible for gas exchange
Skin in some animals, in most species located in specialized organ like lungs, gills, or tracheae
Circulatory System
responsible for moving O2, CO2, and other materials around the body
Many cases, involved muscular heart rate propels special liquid transport tissue through the body
Lungs of Snails and spiders
simple lungs, air movement takes places via diffusion only
Vertebrate Lungs
actively ventilate lungs by pumping air via muscular contractions
Two mechanisms of lung structure
positive pressure ventilation, used by frogs
Two mechanisms of lung structure
positive pressure ventilation, used by frogs
negative pressure ventilation, used by humans and other mammals
Boyle’s Law
volume goes down, pressure goes up (vice versa)
Two steps involved: inhalation and exhalation
Inhalation
Diaphragm moves down, pressure in chest cavity is lowered
This causes the lungs to expand and air to move in
Exhalation
Diaphragm relaxes, chest cavity decreases and air is exhaled
Passive process! Driven by elastic recoil of lungs and chest walls, diaphragm and rib muscles relax
**energy demanding/active during exercise
How do vertebrate lungs work?
Air enters body through the mouth and nose
Trachea carries inhaled air to narrow tubes called bronchi
Bronchi: they branch off into even narrower tubes called bronchioles
Lung: organ of ventilation
Examples: animals, such as fished, amphibians, reptiles, birds and mammals
Lungs can vary in structure! BUT they all have these structures in general
Frog and Amphibian Lungs
lung is simple sac lined with blood vessels
Mammalian lungs
divided into tiny sacs called alveoli
Alveoli
greatly increase the surface area for gas exchange; provide an interface between air and blood (0.2 micrometers) that consists of:
* Thin aqueous film
* Layer of epithelial cells
* ECM: extracellular matrix material
* Wall of a capillary
Humans have approx. 150 million alveoli
Oxygen process in red blood cells
Red blood cells use hemoglobin to carry Oxygen: Oxygen loads onto hemoglobin; Hemoglobin carries up to 4 oxygen molecules
Up to 1 billion oxygen molecules;250 million or so hemoglobin molecules per RBC
Oxygen unloads once the RBCs get to capillaries in systemic tissues
Dalton’s Law of partial pressures
gases are transported and unload on tissues; Oxygen unloads into tissues because oxygen is consumed there
CO2 generated in tissues and loads into blood
each gas has its own partial pressure (fraction of total pressure)
Partial pressure of oxygen (PO2 – fraction of oxygen in the gas) is lower in the tissues than in the lungs
Flow from high to low, (A PRESSURE GRADIENT)
o Moves from high PO2 to low PO2
o Moves from low PCO2 to high PCO2
Functions of Circulatory system
Transport:
O2 and nutrients to tissues (in arterial blood) CO2 and wastes away from tissues for elimination
Regulation
o Hormone transport
o Temperature regulation: Radiate heat to the environment to cool off, storing it to keep warm
Protection
o Blood clotting: Seals up gas in circulatory system
o Immune defense
materials in blood
plasma, RBCs, WBCs, platelets, blood vessels
Plasma
liquid portion -> 55%
o Contains ions, electrolytes, various nutrients, various wastes, various hormones, various proteins, etc.
Red blood cells
erythrocytes, O2 and CO2 transport
White blood cells
leukocytes, immune response
Platelets
blood clotting
Blood vessels
Blood leaves heart through arteries which branch into arterioles, which branch into very thin capillaries
Blood returns to the heart from tissues through venules, that lead to veins
Capillaries
small spaces closest to tissues of cells to transport oxygen
made up of nucleus, endothelial cells, and basement membrane
Change from veins to capillaries happens in capillary beds
Veins and arteries
contain fibrous, muscle, and elastic tissue, as well as endothelium
muscle tissue and fibrous tissue in arteries quite thick compared to veins
vein tissue levels all quite thin
Process of blood in blood vessels
Arteries and arterioles: Carry blood from heart to tissues
Smooth muscle vasoconstricts which slows/decreases blood flow
Smooth muscle vasodilates, which increases blood flow
Capillaries: Arterioles divide into capillaries in systemic tissue, for gas exchange
Venules and veins: Collect blood from capillaries, return to heart; Much less smooth muscle; pressure low
Why is there one way blood flow through veins?
Flap of tissue/valve to prevent blood from going wrong direction
Contraction of skeletal muscle helps propel blood through veins
Valves prevent back-up of blood, even with low blood pressure in veins; it can only move toward heart
Thermoregulation in blood
Body uses Precapillary sphincters:
can contract, diverts blood away from skin; More blood in the veins than capillary; Decrease in heat loos across epidermis; Traps more heat in body (when it is cold out)
Reynaud’s syndrom
Individual experiences extreme contraction of precapillary sphincters
Experience painful cold in what is considered normal cold temperatures (40 degrees)
Fish Circulatory/Respiratory system
Fish experiences gas exchange across gills (since they do not have lungs like mammals/humans do)
Fish has single atrium; Differ to other organisms
Amphibian, reptile, bird, and mammalian circulation
Evolution toward two circuits, based upon environmental constraints; Two circuits based on pressure put on capillaries (Wants to be able to handle pressures in their heart and bodies from environment)
pulmonary and systemic
Pulmonary circulation
oxygenate blood, Associated with right side of heart
Blood enters right atrium on return from body; Blood enters right ventricle; Blood pumped to lungs from right ventricle
Systemic circulation
oxygenate body; Associated with left side of heart
Blood returns to left atrium from lunsg; Blood enters left ventricle; Blood pumped to body from left ventricle; Back to pulmonary circulation
Fish circulation and respiratory system
Have Gills
1 circuit; 2-chambered heart
1 atria, 1 ventricle
Amphibian circulation and respiratory systems
2 circuits, Gas exchange in lungs, Gas exchange in body
2 circuits not completely separate
1 ventricle, 2 atria
Atria fills ventricles on one side, another atria fills another side; Still only connected to one ventricle
Mix of oxygenated and deoxogyenated blood (since they get some oxygen through their skin)
The circulatory systems of turtles, lizards, and snakes
2 circuits
3 chambered heart
1 ventricle, 2 atria
Mammalian, Crocodile and bird heart systems
2 cirucits: Left atria, left ventricle, out to right atria, right ventricle out to left again
4 chambered heart: 2 atria, 2 ventricles
**extra “purple” vein for crocodiles for purpose of extra carbon dioxide getting to stomach, to synthesize stomach acids(such as carbonic acid) from bones they consume
Circulation directions of mammals and birds
Right atrium -> right ventricle -> lungs ->
Left atrium -> left ventricle -> body (returns to right atrium/step 1 after this
Electrical Excitation and Contraction of Heart
Action potentials in heart cause contraction
Sinoatrial (SA) node: group of pacemaker cells that generate spontaneous action potentials
Atrioventricular (AV) node: receives input/signals from SA node
(Passes it to ventricles; If SA node is injured, can take over responsibility to some degree)
Pattern of Depolarization in electrical activation of heart
SA node in atrium
Action potential spreads over atria; atria contract
Signal goes to AV node, Signal spreads to ventricles to create ventricle contraction; Ventricles relax
**EKG/ECG used to record this, detects fluctuations
NOT ACTION POTENTIALS; Total activity of entire heart through muscle, skin, and bone
Cardiac Output
How much blood is moved out of the heart over time
Blood volume pumped per minute
Combo of heart rate and stroke volume
CO = HR x SV
Stroke Volume
blood kicked out with each heart beat; blood volume per beat of heart
Volume of blood in ventricle
o Determines blood ejected from ventricle
Strength of contraction
o Determines blood ejected from ventricle
(**Sympathetic increases force of contraction)
2 factors coincide, but not the same
Heart rate
Determined by number of A.P.s at SA node
Trachycardia
abnormally fast HR
Greater than 100 BPM at rest (like when sitting taking notes)
Bradycardia
abnormally slow HR, Less than 45-50 BPM at rest (sitting taking notes)
Normal during sleep
Blood Pressure
Measured as systolic vs diastolic
Systolic/diastolic -> average 110/70
Systolic pressure: During contraction
Diastolic pressure: Pressure between heartbeats
Atrial blood pressure
Depends on cardiac output and resistance to flow
Cardiac output: example of blood volume and HR
Resistance to flow: due to vasoconstriction!
Unhealthy diet can cause constriction
Prevalent cardiovascular diseases
Hypertension ( caused possibly by Obesity, Smoking, Stress, Others)
Atherosclerosis: accumulation of fatty materials and cellular debris (from Smoking, high cholesterol, genetics; Can lead to hypertension)
Can be many relationships between diseases such as these
