Circulation and Gas Exchange

Question 1

In animals with simple body plans, what mediates exchange between the environment and body cells?

Answer 1

a gastrovascular cavity: the primary organ of digestion and circulation in two major animal phyla: the Cnidaria (including jellyfish and corals) and Platyhelminthes (flatworms). The cavity may be extensively branched into a system of canals. In cnidarians, the gastrovascular system is also known as the coelenteron, and is commonly known as a “blind gut” or “blind sac”, since food enters and waste exits through the same orifice.

Question 2

Why do most complex animals have a circulatory system that moves fluid between cells and the organs that carry out exchange with the environment?

Answer 2

Because diffusion is slow.

Question 3

Arthropods and most molluscs have an _____ circulatory system, in which _______ bathes organs directly.

Answer 3

open, hemolymph (blood like fluid in inverts)

Question 4

Vertebrates have a _____ circulatory system, in which ______ circulates in a closed network of pumps and vessels

Answer 4

closed, blood

Question 5

Describe the parts and process of the circulatory system of vertebrates

Answer 5

parts: blood, blood vessels, 2-4 chambered heart.

blood pumped by heart ventricle passes to arteriesm then to capillaries, the site of chemical exchange with interstitial fluid. veins return blood from capillaries to an atrium, which passes blood to a ventricle.

Question 6

What marine creatures have a single heart pump? How many do air-breathing vertebrates have?

Answer 6

Fishes, rays and sharks.

2.

Question 7

What feature of hearts indicates adaptations to different environments and metabolic needs?

Answer 7

ventricle number and divisions

Question 8

Describe movement of blood through the heart.

Answer 8

Right ventricle pumps blood to the lungs, where it loads O2 and unloads Co2. Oxygen-rich blood fromt he lungs enters the heart at the left atrium and is pumped to the body tissues by the left ventricle. Blood returns to the heart through the right atrium.

Question 9

How does air reach and leave body tissues?

Answer 9

Inhaled air>alveolar spaces>alveolar capillaries>pulmonary veins>systemic arteries>systemic capillaries>body tissues

(Co2 leaves in reverse path)

Question 10

Describe the cardiac cycle

Answer 10

Systole: period of contraction
diastole: period of relaxation

Heartbeat originates in SA node of the right atrium, the impulses trigger atrial contraction, are delayed at the AV node, then cause ventricular contraction.

Question 11

What influences pacemaker activity?

Answer 11

The nervous system, hormones and body temperature.

Question 12

_____ contain one way valves

Answer 12

Veins

Question 13

Fluid leaks out of capillaries and is returned to blood by the _____, which also plays a vital role in defense against infection

Answer 13

Lymphatic system

Question 14

What is blood made of?

Answer 14

cell fragments (platelets) suspended in a liquid matrix called plasma

Question 15

What do plasma proteins influence in the blood?

Answer 15

pH, osmotic pressure, viscosity, lipid transport, immunity (antibodies), and blood clotting.

Question 16

Red blood cells transport _____

Answer 16

oxygen

Question 17

What do white blood cells do? What do platelets do?

Answer 17

Defense against microbes and foreign substances. Blooding clotting.

Question 18

What happens at all sites of gas exchange?

Answer 18

a gas undergoes net diffusion from where its partial pressure is higher to where its lower.

Question 19

Is air or water more conductive to gas exchange? Why?

Answer 19

Air, because air has more oxygen, lower density, and lower viscosity.

Question 20

What are gills?

Answer 20

Outfoldings of the body that are specialized for gas exchange in water.

Question 21

What increases the effectiveness of gas exchange across gills?

Answer 21

Ventilation and countercurrent exchange

Question 22

Describe countercurrent exchange in fish gills.

Answer 22

Fish use countercurrent exchange to maximize the amount of time their blood is exposed to water that has a higher oxygen level, even as the blood takes on more oxygen.

Countercurrent oxygen exchange means the blood flows through the gills in the opposite direction as the water flowing over the gills.

This flow pattern ensures that as the blood progresses through the gills and gains oxygen from the water, it encounters increasingly fresh water with a higher oxygen concentration that is able to continuously offload oxygen into the blood. The low-oxygen blood, which is just entering the gill, meets low-oxygen water. Since there is more oxygen in the water, the oxygen can flow from water to blood. Likewise, the high-oxygen blood, which has nearly passed the entire length of the gill, meets fresh, high-oxygen water, and oxygen continues to flow from water to blood.

Question 23

How does gas exchange occur in insects?

Answer 23

Tracheal system: a branched network of tubes that brings oxygen directly to cells.

Question 24

Which groups of animals have lungs?

Answer 24

Spiders, land snails and terrestrial vertebrates.

Question 25

In mammals, where does inahled air flow?

Answer 25

Through the pharynx into the trachea, bronchi, bronchioles, and dead-end alveoli where gas exchange occurs.

Question 26

How do amphibians ventilate their lungs?

Answer 26

Positive pressure breathing, which forces air down the trachea

Question 27

How do birds keep air flowing through their lungs?

Answer 27

They use a system of air sacs as bellows to keep it flowing in one direction

Question 28

How do mammals ventilate their lungs?

Answer 28

Through negative pressure breathing, which pulls air into the lungs. Lung volume increases as the rub muscles and diaphragm contract.

Incoming and outgoing air mix, which decreases efficiency of ventilation.

Question 29

How is the rate and depth of breathing regulated?

Answer 29

Sensors detect pH of the cerebrospinal fluid (reflecting the co2 content of the blood), and the medulla adjusts breathing rate and depth to match metabolic demands. Secondary control is exerted by sensors in the aorta and carotid arteries that monitor blood levels of oxygen as well as carbon dioxide.

Question 30

Gradients of partial pressure favor the net diffusion of _____ into the blood and _____ out. The _____ situation exists in the rest of the body.

Answer 30

Oxygen, carbon dioxide, opposite

Question 31

What are respiratory pigments?

Answer 31

Hemoglobin is an example, binds oxyegn and greatly increases the amount of oxygen that can be transported in the circulatory system.