Animal: Lecture 5 Flashcards
Diffusion is only rapid over..?
Diffusion is only rapid over short distances.
Molecules move randomly?
Molecules move randomly due to their kinetic energy.
What does random movement cause?
Random movement causes a new flow from an area of high concentration to an area of low concentration.
Rate of diffusion proportional to distance?
Rate of diffusion is inversely proportional to distance.
- further distance = slower rate
- shorter distance = faster rate
Water example?
a. Crystal of due is placed in water
b. Diffusion of water and dye molecules occurs
c. Equal distribution of molecules results.
Movement of particles is always?
Movement is random, but will always even out.
- always moves from high to low.
Diffusion is also affected by?
Diffusion across a surface is also affected by the area of the surface (ex. cell membrane)
Rate of diffusion, surface area, and distance?
Rate of diffusion and surface area are proportional to one another.
Rate of diffusion and distance are inversely proportional to one another.
To maximize diffusion rate, exchange surfaces should have..?
A large surface area and be thin.
Cells must do what with the environment?
Each cell in a multicellular organism must exchange molecules with the environment.
- Molecules include nutrients, gases, and water, which must be brought in
- Waste must be able to get out.
How many strategies are there for allowing the exchange of molecules with the environment?
There are two different strategies that allow animals to need to be able to bring things in and out.
Staying small strategy?
Some animals have a body size and shape that keeps most cells in contact with the environment (environment might be the lining of the gut or outside of the organism).
- these are SMALL animals
Planaria and flatworm?
Small and flat shape of them allows them to exchange nutrients so that almost all cells are in contact with the environment.
- This means that there is no need for a circulatory or respiratory systems.
- they are abosolutely tiny (~7mm)
Large animals?
Animals with many cell layers require a circulatory system to transport materials between all the body cells and the organs that exchange those materials with the environment.
Note: materials only need to diffuse over short distances as they enter or exit the circulatory system. By the time that blood reaches the cels, they are really small in distance - therefore exchanges can occur over small distances.
How is the circulatory system connected to everything else?
The circulatory system is connected to everything else, and transports materials all throughout the body.
Animals exhibit variation in their circulatory systems… but have what?
Animals exhibit much variation in their circulatory systems, but all have three basic components.
What are the three basic components that all have?
- A circulatory fluid
- Set of interconnecting vessels
- A muscular pump.
Circulatory fluids ?
- Blood in a closed circulatory system (closed means enclosed in the vessels). Ex. Mammals, birds, earthworms, fishes, octopi.
- Hemolymph in an open circulatory system (mix of open cavities with organs and closed vessels that carry it around the body). Ex. crabs, insects, spiders.
Se of interconnecting fluids?
They bring fluids parts of the body.
Muscular pump?
Ex. heart - pumps fluid for circulation
Open system?
Everything is open in cavities. Hemolymph is in the sinuses surrounding the organs. They’re are smaller pores, which open into sinus cavities. Then, they exchange fluid.
Closed system?
Heart pumps blood into the vessels and through them and capillaries in a closed loop. All blood is contained in the vessels and nutrients have to cross the interstitial fluid to move from one area to another.
Double circuit?
There are two circuits of flow to and from the heart.
- Pulmonary: leads to lungs and allows blood to become oxygenated.
- Systemic: leads to the body and allows the bodily mechanisms to function.
Blood mixing?
Oxygenated and deoxygenated blood do not mix within the heart. This is very important as it keeps use healthy.
Blood circuit in heart?
- Deoxygenated blood returning from the systemic circuit enters via the superior (head) vena cava and the inferior (legs) vena cava.
- The blood flows into the right atrium.
- When the right atrium contracts, blood is pushed into the right ventricle.
- When the right ventricle contracts, blood is pushed into the pulmonary arteries, sending it to the lungs.
- Oxygenated blood returns from the pulmonary circuit and enters via the pulmonary veins.
- The blood flows into the left atrium
- When the left atrium contracts, blood is pushed into the left ventricle.
- When the left ventricle contracts, blood is pushed into the aorta (largest artery) sending it to the systemic circuit (brain, limbs, etc.)
Veins and arteries?
Veins ~> toward heart
Arteries ~> away from heart
What are valves?
Valves ensure unidirectional flow of blood through the heart by closing to prevent back flow.
- There are two kinds of valves!
Atrioventricular (AV) valves?
Separate the atria from the ventricles and prevent backflow into atria when the atria relax and ventricles contract
Semilunar valves?
They look like half-moons. Separate ventricles from the arteries and prevent backflow into the ventricles when the ventricles relax
The cardiac cycle?
Right and left happen at the same time.
1. Atrial and ventricular diastole (0.4)
2. Atrial systole and ventricular diastole (0.1)
3. Ventricular systole and atrial diastole to push blood out of the arteries (0.3)
Diastole and Systole?
Diastole = relaxation
Systole = contraction
Blood vessel structure…?
Reflects their functions.
Artery components and why they are the way they are?
They have three layers of tissues:
1. Endothelium
2. Smooth muscle
3. Connective tissue
- The layers are thicker on arteries than veins.
- They are thicker to withstand pressures that help them stay firm.
- Speed slows down as we progress from artery to capillaries.
Capillary components?
Made up of two “layers”
1. Endothelium
2. Basa lamina (membrane)
- Allows easy diffusion of nutrients and gases
- Has to slow down here
- Causes pressure to decrease greatly.
Vein components and why they are the way they are?
Made up of three layers:
1. Endothelium
2. Smooth muscle
3. Connective tissue
- Lines the inside of the vessel
- A lot thinner because not much pressure
- Large because it’s better to do it one go.
- Flow has rot speed up here, which is very possible with this structure.
How does area change from aorta to venae cavae?
Increased branching increases area: capillaries have greater area than arteries and veins.
- Looks like a bell curve
How does velocity change from aorta to venae cave?
Same volume of fluid flows more slowly through a greater area: velocity is slowest within the capillaries.
- This facilitates the rate of diffusion
- Can’t be too fast at capillaries for gas exchange.
How does pressure change from aorta to venae cavae?
The increase in area in the capillaries causes pressure to drop off. Blood is not re-pressurized until it returns to the heart.
What is blood flow regulated y?
Blood flow is regulated by nerve impulses, hormones, and local chemicals that affect arteriole diameter and pre-capillary sphincters.
Relaxed vs contracted sphincters?
Relaxed: blood flow can spread to capillaries (all of them).
Contracted: blood flow is direct, as sphincters are closing off some capillaries.
How many capillaries are active at any given time?
At any one time, only about 5-10% of the body’s capillaries have blood flowing through them.
What allows for the exchange of materials between blood and interstitial fluid?
Thin capillary walls and slow blood velocity allow for exchange of materials between blood and
interstitial fluid. Items from the capillaries have to cross the interstitial fluid to get to body cells (a short distance is advantageous).
Blood is a…?
Blood is a tissue consisting of cells suspended in a liquid called plasma.
55% of blood is..?
Plasma makes up 55% of the blood. Plasma consists of:
- Water
- Ions
- Proteins
- Nutrients, metabolites, and wastes
45% of blood is..?
Cellular elements make up 45% of blood. Cellular elements include:
- Erythrocytes (red blood cells)
- Leukocytes (white blood cells)
- Platelets
Circulatory systems require energy and materials to build and run…. so why didn’t all animals just stay small/simple?
A. Larger animals with circulatory systems exchange materials more
efficiently than small/simple animals
B. Increasing size and complexity allows animals to exploit new niches
C. Bigger is always better!
ANSWER: B
During the fight or flight response, in which organs would you expect the hormone epinephrine to constrict the arterioles and pre-capillary sphincters?
A. Brain
B. Intestine
C. Skeletal muscle
D. Skin
E. Lungs
ANSWER: B and D
What are respiratory surfaces specialized for..?
Respiratory surfaces are specialized for gas exchange.
Ex. Gills, tracheae, and lungs
Gills, tracheae and lungs all have?
- Very large surface areas
* Greater than rest of body exterior (e.g., 50x greater than skin in humans) - Very thin exchange surfaces
* A single epithelial layer (allows easy diffusion)
Respiratory media vary in..?
Respiratory media vary in their O2 concentration.
Respiratory media (source of O2):
- Air has a high concentration of O2 (21%)
- Water has a much lower concentration of O2 (<1%)
Animals obtaining from different respiratory media?
Animals that obtain O2 from water need to be much more efficient than animals that obtain O2 from air
– 80% vs. 25%
Gills efficiency?
Gills are efficient at extracting O2 but are unsuitable in terrestrial environments
Respiratory surfaces must be..?
Respiratory surfaces must be moist
Respiratory surfaces of terrestrial
animals are enclosed within the
body to prevent excess water loss
– E.g., Tracheae and Lungs
Mammalian Respiratory System?
- Pharynx
- Larynx
- Trachea (large tube)
- Bronchus/Bronchi (two smaller tubes)
- Bronchiole (smallest branches)
- Diaphragm (controls when we inhale and exhale)
- Alveoli (where the gas exchange occurs and blood becomes oxygenated) are covered in capillaries that supply the deoxygenated blood.
Red blood cells are packed with what protein..?
Red blood cells are packed with the protein hemoglobin.
- This is why the circulatory and respiratory systems are linked!
O2 binds to hemoglobin?
O2 has a natural tendency to bind to hemoglobin for transport in red blood cells.
Process O2 binding to hemoglobin?
Oxygen from lungs goes through cell membrane, attaches themselves to the hemoglobin and can then be transported throughout the body.
Oxygen is released to tissue cells
- when going through respiration there is a hostile (hot and acidic) environment. This change released O2 from hemoglobin, which causes the necessary drop off off the O2 to cells that need it.
Shape and mechanics of hemoglobin?
Hemoglobin has our oxygen binding sites which will hold 4 O2.
- They have iron built in as well, which is why we need to maintain our iron levels for effective blood flow.
Red blood cells are also important for CO2 transport?
CO2 (waste of cellular respiration) produced in body cells travels:
1. bound to amino acids of hemoglobin (23%)
2. in blood plasma as CO2 (7%)
3. In blood plasma as bicarbonate
(HCO3-) (70%)
CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+
Process of loading and unloading respiratory gases?
- Inhaled air
- Alveolar spaces
- Pulmonary veins
- Systemic arteries
- Body tissue
- Systemic veins
- Pulmonary arteries
- Exhaled air
Circulatory systems are necessary?
Circulatory systems are necessary because diffusion is only rapid over very short distances.
Circulatory systems consist of? q
Circulatory systems consist of a pump, vessels, and a circulatory fluid; most vertebrates have double circulation (systemic and pulmonary)
Blood vessel structure reflects?
The function.
Exchange surfaces tend to..?
Exchange surfaces tend to be thin and have a large surface area.
Hemoglobin is..?
Hemoglobin is the blood protein that transports O2 (as well as some CO2).
