Lecture 3: Circulation And Gas Exchange

Front 1

What is a single circulatory system?

Back 1

The heart consists of two champs: an atrium and a ventricle. The blood passes through the heart once in each complete circuit through the body. Blood entering the heart collects in the atrium before transfer to the ventricle, where blood is pumped to the capillary beds in the gills.

Front 2

What is a double circulatory system?

Back 2

In animals with double circulation, the pumps for the twi circuits are combined into a single organ, the heart. One pump, the right side of the heart, delivers oxygen-poor blood to the capillary beds of the gas exchange tissues (lungs), where this is a net movement of O2 into the blood and of CO2 out of the blood.

Front 3

Complete this statement:

Gas diffusion increases with _________ and decreases with ____________.

Back 3

1) Increased with surface area

2) Decreases with distance

Example: Fish Gills which have large surface area and small distance.

Front 4

What is counter current exchange?

Back 4

The exchange of asubstance or heat between two fluids flowingin opposite directions. For example, blood ina fish gill flows in the opposite direction ofwater passing over the gill, maximizing diffu-sion of oxygen into and carbon dioxide out ofthe blood.

Front 5

What are lungs?

Back 5

Unlike tracheal systems, which branch throughout the insect's body, lungs are localized respiratory organs. Representing an infolding of the body surface, they are typically subdivided into numerous pockets.

Front 6

Major components of the mammalian lung

Back 6

* Nasal Cavity

* Pharynx - separated food and air channels

* Larynx - leads air to the direction of the lungs

* Trachea - Mucus protector

* Bronchus - leads oxygen to either side of lungs

* Bronchiole - small tubes within the bronchus

Front 7

Specifically, where does gas exchange happen in mammals?

Back 7

Gas exchange occurs in the alveoli, air sacs clustered at the tips of the tiniest bronchioles. They have a LARGE surface area and small distance

Front 8

What are the tissues aligning the lungs?

Back 8

They are epithelial tissues and are very thin in order to breathe.

Front 9

Why do white bloods cells circulate the alveoli?

Back 9

Lacking cilia or significant air currents to remove par-ticles from their surface, alveoli are highly susceptible tocontamination. White blood cells patrol the alveoli, engulf-ing foreign particles. However, if too much particulate mat-ter reaches the alveoli, the defenses can be overwhelmed,leading to inflammation and irreversible damage. For ex-ample, particulates from cigarette smoke that enter alveolican cause a permanent reduction in lung capacity.

Front 10

Why don't alveoli collapse under high surface tension?

Back 10

It turns out that alveoli produce a mixtureof phospholipids and proteins called surfactant, for surface-active agent, which coats the alveoli and reduces surfacetension.

Premature babies lack this important protein and are given artificial ones to help them survive.

Front 11

What are the basic three (3) components of a circulatory system?

Back 11

1) A circulatory fluid

2) A set of interconnecting vessels

3) A muscular pump

Front 12

What is an open circulatory system?

Back 12

In an opencirculatory system, the circulatory fluid, called hemolymph,is also the interstitial fluid that bathes body cells. Heart contraction pumps thehemolymph through the circulatory vessels into interconnected sinuses, spaces surrounding the organs. Within the sinuses, chemical exchange occurs between thehemolymph and body cells.

Front 13

What is a closed circulatory system?

Back 13

In a closed circulatory system, a circulatory fluid calledblood is confined to vessels and is distinct from the interstitial fluid. One or more hearts pump bloodinto large vessels that branch into smaller ones that infiltratethe organs. Chemical exchange occurs between the blood and the interstitial fluid, as well as between the interstitialfluid and body cells.

Front 14

What is advantageous of a closed circulatory system? And of an open circulatory system?

Back 14

1) The benefits of closed circulatory systems include relatively high blood pressure, which enables the effective delivery of O2, and nutrients to the cells of larger and more active animals.

2) The lower hydrostatic pressures typically associated with open circulatory systems makes them less costly than closed systems terms of energy expenditure.

Front 15

What is an advantage of double circulatory system?

Back 15

* High blood pressure

* No mixing of oxygenated and de-oxygenated blood

Front 16

What and why is the amphibian double circulatory system different than the mammalian double circulatory system?

Back 16

The amphibian system has three heart chambers instead of four: two atriums and one central ventricle. A ridge within the ventricle diverts most (about 90%) ofthe oxygen-rich blood from the left atrium into the systemic circuit (the body) and most of the oxygen-poor blood fromthe right atrium into the pulmocutaneous circuit (lungs). Whena frog is underwater, the incomplete division of the ventricle allows the frog to adjust its circulation, shuttingoff most blood flow to its temporarily ineffective lungs.Blood flow continues to the skin, which acts as the solesite of gas exchange while the frog is submerged.

Hint 16

Front 17

What and why is the reptilian double circulatory system different?

Back 17

In alligators, caimans, and other crocodilians, the ventricles are divided by a complete septum, but the pulmonary and systemic circuits connect where the arteries exitthe heart. This connection allows arterial valves to shuntblood flow away from the lungs temporarily, such aswhen the animal is underwater. (So when the blood goes from the right atrium to the right ventricle to the right pulmonary artery, there is another possible connection for the blood to skip the pulmonary artery completely and go to the systemic system.

Hint 17

Front 18

In your own words, describe the flow of the mammalian circulatory system.

Back 18

Front 19

What is systole vs diastole?

Back 19

The heart contracts and relaxes in a rhythmic cycle.When it contracts, it pumps blood; when it relaxes, itschambers fill with blood. One complete sequence of pumping and filling is referred to as the cardiac cycle. Thecontraction phase of the cycle is called systole, and the relaxation phase is called diastole

Front 20

What is cardiac output and what two factors determine it?

Back 20

The volume of blood each ventricle pumps per minute is the cardiac output. Two factors determine cardiac output: the rate of contraction, or heart rate (number of beats per minute), and the stroke volume, the amount of blood pumped by a ventricle in a single contraction.

Front 21

What is the pacemaker of the heart?

Back 21

The sinoatrial node (SA) is the pacemaker of the heart. They are a group of auto rhythmic cells located in the wall of the right atrium, near where the superior vena cava enters the heart.

Front 22

What regulates the pacemaker?

Back 22

1) The sympathetic division speeds up the pacemaker

2) The parasympathetic division slows down the pacemaker

Front 23

What is the difference between arteries, veins, and capillaries?

Back 23

1) Arteries move blood away from the heart.

2) Veins move blood towards the heart.

3) Capillaries - microscopic vessels that infiltrate tissues

Hint 23

Front 24

What are capillary beds?

Back 24

Networksof capillaries, called capillary beds, infiltrate tissues, passingwithin a few cell diameters of every cell in the body. Acrossthe thin walls of capillaries, chemicals, including dissolvedgases, are exchanged by diffusion between the blood andthe interstitial fluid around the tissue cells. At their “down-stream” end, capillaries converge into venules, and venulesconverge into veins, the vessels that carry blood back to theheart.

Front 25

What is the interrelationship of cross-sectional area of blood vessels, blood flow velocity, and blood pressure?

Back 25

As aresult of an increase in total cross-sectional area, blood flow velocitydecreases markedly in the arterioles and is lowest in the capillaries.Blood pressure, the main force driving blood from the heart to thecapillaries, is highest in the aorta and other arteries.

Front 26

What are erythrocytes?

Back 26

Erythrocytes are red bloods cells. Their function is O2 transport. Mammalian red blood cells leaves more space for hemoglobin, the iron-containing protein that transports O2.

Front 27

What causes pH of the blood to go down and what does the body do to fix it?

Back 27

Too much CO2 in the blood causes blood's pH to go down. Sensors in the blood vessels will sense this acidity and send a signal to the Medulla oblongata which in turn will send a signal to the diaphragm and rib muscle to breathe more deeply and to increase rate. This will bring the CO2 level down.