BIO2242 Lecture Notes - Lecture 10: Superior Vena Cava, Arthropod, Action Potential

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29 Sep 2013

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Fish have a single atrium and single ventricle. It is the exchange of chemicals, which is a passive process. If you are small with a few cell layers in contact with the water, you can uptake materials directly from the environment. Circulatory systems are needed when diffusion distances become too big. For animals that are larger, and not flat and has a tubular gut that doesn"t distribute itself through the body. Insect = large amount of fluid inside (hemocoel), but it also has a pump, and vessels. Sinus = large space where liquid goes out of the vessels, where they squish around until it gets taken up. They no longer have an open circulatory system. They have developed a fully closed on which is related to their high levels of activity. Advantage of open circulatory system is that when they have a large volume of liquid, its very hard to maintain pressure in a fast flow.

Related Questions

The Cambrian explosion is a prime example of ________________.

		mass extinction
		evolutionary stasis
		a large meteor impact
		adaptive radiation

1 points

QUESTION 2

Most animals are viviparous.

True

False

1 points

QUESTION 3

The first phylum with ganglia in their nervous system are the ________________________.

		Mollusca
		Nematoda
		Bivalvia
		Platyhelminthes

1 points

QUESTION 4

The last common ancestor of all animals was probably a _____________________.

		a unicellular worm
		multicellular algae
		flagellated protist
		multicellular fungus

1 points

QUESTION 5

You are given an unknown organism to identify. It is unicellular and heterotrophic. It is motile by use of many short extensions of the cytoplasm. It has well-developed organelles and two nuclei, one large, one small. The organism is most likely to be a ______________.

		foraminifera
		radiolarian
		ciliate
		flagellate

1 points

QUESTION 6

Which of the following organisms would you expect to have the largest surface-area-to-volume ratio? Assume that all of the following are the same total length.

		A mollusc
		A nematode
		A platyhelminth
		Not enough information to determine.

1 points

QUESTION 7

If the animal is a hermaphrodite, it is said to be _______________.

		dioecious
		eutelic
		monoecious
		trioecious

1 points

QUESTION 8

A terrestrial animal species is discovered with the following larval characteristics: exoskeleton, system of tubes for gas exchange and segmentation. A knowledgeable zoologist should predict that the adults of this species would also feature ____________.

		eight legs
		two pairs of antennae
		a sessile lifecycle
		an open circulatory system

1 points

QUESTION 9

The Phylum Echinodermata exhibits metamerism.

True

False

1 points

QUESTION 10

The existence of evolutionary trends, such as increasing body sizes among horse species, is evidence that _____.

		a larger volume-to-surface area ratio is adaptive in many mammals
		evolution generally progresses toward some goal
		evolution tends toward increased complexity or increased size
		in particular environments, similar adaptations can be beneficial to more than one species

1 points

QUESTION 11

Suppose you are a researcher fro a pest-control company and you develop a chemical that inhibits the develpment of an embryonic mosquito's endodermal cells. Which of the following would cause the pesticide to work?

		The mosquito would develop a weak exoskeleton, making it easy prey.
		The mosquito's gut would not function properly and it would starve.
		The mosquito would not have a properly functioning muscular system.
		Nothing would happen and your experiment would be a failure.

1 points

QUESTION 12

Holometabolis refers to complete metamorphosis.

True

False

1 points

QUESTION 13

Which of these conditions are always true of populations evolving due to natural selection?
Condition 1: The population must vary in traits that are heritable.
Condition 2: Some heritable traits must increase reproductive success.
Condition 3: Individuals pass on most traits that they acquire during their lifetime.

		Condition 1 only
		Condition 2 only
		Conditions 1 and 2
		Conditions 2 and 3

1 points

QUESTION 14

Scientific theories _____. 22.3

		are nearly the same things as hypotheses
		are supported by, and make sense of, many observations
		cannot be tested because the described events occurred only once
		are predictions of future events

1 points

QUESTION 15

The evolution of animal species and their diversity is a result of the evolution of new and different ways to _______________.

		reproduce
		arrange their cells into tissues
		become symmetrical
		form an embyro and establish a basic body plan

Background

Almost all animal and plant cells require oxygen and give off carbon dioxide. This is called gas exchange and it occurs by passive diffusion. Some animals do all or most of their gas exchange across their skin (for example amphibians) but they have very low metabolisms and use very little oxygen and get rid of very little carbon dioxide.

On the other hand humans (and other mammals) have very high metabolic requirements and we canât rely on gas exchange over the limited 1.5 to 2.0 square meters of our skin to get enough oxygen in and carbon dioxide out fast enough. Our gas exchange takes place across a very thin membrane in the Alveoli of the lung and the gas exchange surface in humans is estimated to be between 50 and 100 square meters, or between 25 and 67 times our skin surface area.

Our lungs provide a huge surface for gas exchange but they are a dead-end system. Once the oxygen in the lungs is used up it needs to be replenished and carbon dioxide builds up in the air spaces in the lungs and needs to get out. This is where the diaphragm and a few of the skeletal muscles become important. In its relaxed state the diaphragm is at its longest and the space in the thoracic cavity (and the lungs) is small. When the diaphragm contracts it shortens, which increases the volume of the thoracic cavity (and the lungs). The increase in size means the pressure is lower in the lungs than outside so air comes into the lungs (inhalation). As the diaphragm relaxes, the lungs decrease in size enough that the pressure inside the lungs is higher than the external air pressure so air comes out (exhalation).

Introduction

In this lab you will be building a model of a lung and experimenting with different ways to breath.

Supplies:

In the Lab Kit

One round 9" balloon (one lung, we donât need two for this)
medium-sized plastic bag large enough to fit over bottom end of bottle (diaphragm)
medium-size, thin rubber band

You supply

plastic 2-liter soda bottle with bottom cut off (thoracic cavity)

Tape (optional)

Directions:

1. Insert the balloon through the open bottom of a modified 2-liter soda bottle and up over the neck of the bottle. Pull the end of the balloon over the edges of the neck of the bottle. The balloon is held open by the neck of the bottle.

2. Place the plastic bag over the bottom (open) end of the 2-liter bottle and use the rubber band to hold it in place. This will serve as the diaphragm. To inflate the lung, blow into the balloon just before you fasten the rubber band. You can also wrap tape over the edges of the plastic bag to minimize air leaks

3. Grasp the bottom of the plastic bag and pull it down and push it up. Watch as the "lungs" (the balloon) expand and contract as you do this. The balloon has to change size because the air space between the balloon and bottle must remain constant. (Well, it would if the seal around the plastic bag and bottle were perfect).

You may block the "trachea" (the neck of the bottle) so that the air supply is cut off and watch as nothing happens when the "diaphragm" is pushed in and out.

This model isnât perfect. None of the joints are air tight as they would be in a real thoracic cavity. Pull the âdiaphragm down and watch the lungs expand . If you hold it in place, the lungs will collapse again over time. This is because of leaks and is not how real lungs work. Pushing the diaphragm in and pulling it out over and over does give you an idea of how lungs work. As the diaphragm tightens, contracts (pull down on the plastic bag) the lungs fill with air. As the diaphragm relaxes (push up on the plastic bag) air is expelled from the lungs .

There are several different ways we breath, i.e. expand our thoracic cavity so that our lungs can expand. You have just made a demonstration model of the diaphragm at work. You can also use your rib cage to expand and contract so that you can inhale and exhale. There are muscles between and around your ribcage which you can use to change the size of your thoracic cavity.

This is approximately what your model of a lung will look like.

Answer the questions on the Report Page

Report Page Name

1. Put a hand on your lower ribcage and try moving your ribs out and in. Does air also move in and out?

2. Someone with an upper back or neck injury may not have the options of using diaphragm or ribs to breath. They can learn to use the clavicle and the muscles attached to expand their thoracic cavity a small amount and breathe independently for short periods of time. Put your hand on you clavicle and try to raise and lower just that bone without using your diaphragm or your ribs. It isnât easy but you should be able to get a little air into and out of your lungs this way. How effective do you think this way of breathing is?

3. When you take a really deep breath you use all these muscle groups to help. Take a really deep breath and notice that your ribs expand, your lower abdomen comes out (a sign that the diaphragm has contracted) and your shoulders lift a little (the upper chest and clavicle are working). Now take a relaxed breath. Only your abdomen should go in and out. The movement of your abdomen is a result of the contracting diaphragm pushing on the contents of your âgutâ which forces your abdomen to push out.

Do you breath in or out when your diaphragm contracts?\

4. If a hole were poked in your thoracic wall (the wall of the pop bottle â the hole should be at least the diameter of a pencil)

a. what would happen when you tried to breath? (This is a pneumothorax).

b. Is the space between the balloon and plastic bottle still required to remain constant?

5. Would it be possible to live with a paralyzed diaphragm? Explain your answer.

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BIO2242 Lecture Notes - Lecture 10: Superior Vena Cava, Arthropod, Action Potential

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