exam 2 Flashcards
1
Q
What are the percentages of plasma and cellular elements in blood?
A
55% Plasma
45% Cellular Elements
2
Q
What is the composition of plasma in blood?
A
Plasma is mostly water and contains proteins and ions (electrolytes).
3
Q
What are the functions of plasma?
A
Plasma is a solvent that transports nutrients, wastes, gases, ions, and hormones to and from cells.
Water and ions in plasma help to stabilize body pH, solute/solvent balance, and temperature.
Proteins in plasma help with:
Solute/solvent balance
Fighting pathogens
Lipid transport
Clotting
4
Q
How is lymph transported throughout the body?
A
Flap-like openings at the ends of lymph capillaries take in interstitial fluid from tissues.
Lymph capillaries merge into larger lymph vessels.
One-way valves in lymph vessels prevent backflow of lymph.
Lymph vessels move lymph into and out of lymph nodes (which contain WBCs).
Lymph vessels carry lymph to lymphatic ducts.
Lymphatic ducts move lymph into the veins of the circulatory system.
5
Q
Where are lymph nodes in the lymphatic system and how do they work?
A
Lymph nodes are located along lymph vessels.
They act as filtering stations where white blood cells (WBCs) fight pathogens in the lymph, helping to cleanse and protect the body.
6
Q
What is the structure of arteries?
A
Arteries have a connective tissue layer for strength.
They have smooth muscle for flexibility and contraction.
Epithelial lining (endothelium) to reduce friction as blood flows.
7
Q
How does blood move into and out of arteries?
A
Heart contractions propel blood into the arteries through the aorta and other large arteries.
The muscular artery walls bulge and recoil to push blood through the arteries, into arterioles, and then into capillaries.
8
Q
What is the structure of capillaries?
A
Capillaries are the smallest blood vessels with thin walls made up of a single layer of endothelial cells.
They allow for close proximity to surrounding tissues for efficient material exchange.
9
Q
How does blood move in and out of capillaries?
A
Blood moves through capillaries due to a pressure gradient:
High pressure at the arteriole end.
Low pressure at the venule end.
Precapillary sphincters control the entrance to specific capillary networks, so not all capillaries carry blood at all times.
10
Q
How does material exchange occur between capillaries and interstitial fluid?
A
The low flow velocity in capillaries facilitates material exchange.
Red blood cells move through capillaries single file, getting closer to surrounding tissues for better oxygen diffusion.
Materials are exchanged with interstitial fluid through processes like diffusion, osmosis, and filtration.
11
Q
What are the various ways substances are exchanged between capillaries and the interstitial fluid?
A
Diffusion: Small molecules like oxygen and carbon dioxide pass through the capillary walls.
Osmosis: Movement of water across the capillary walls based on solute concentration.
Filtration: Pressure causes fluid to move out of capillaries into the interstitial fluid, while larger molecules (e.g., proteins) are retained inside the capillaries.
12
Q
How does oxygen (O₂) and carbon dioxide (CO₂) move between capillaries and interstitial fluid?
A
Oxygen (O₂) and carbon dioxide (CO₂) move in and out of capillaries by simple diffusion, following the concentration gradient from high to low concentration.
13
Q
How do white blood cells, ions, water (H₂O), sugars, and other small molecules move between capillaries and the interstitial fluid?
A
These substances move between the capillaries and the space around epithelial cells by diffusion and osmosis, traveling through the gaps between the cells.
13
Q
How do larger molecules move between capillaries and interstitial fluid?
A
Some larger molecules move via exocytosis (out of capillaries) or endocytosis (into capillaries).
14
Q
What is the function of bone marrow in the lymphatic system?
A
Bone marrow produces white blood cells (WBCs).
It is also the site of B cell differentiation.
15
Q
What is the function of the thymus in the lymphatic system?
A
The thymus is the site of T cell differentiation.
16
Q
What is the function of lymph nodes in the lymphatic system?
A
Lymph nodes are small, round organs packed with WBCs.
They fight infections by filtering lymph.
Tonsils and adenoids have similar functions but are larger.
17
Q
What is the function of the spleen in the lymphatic system?
A
The spleen recycles old RBCs.
It stores blood cells and platelets.
It also fights infections by filtering blood.
18
Q
What is the purpose of electrical events in the heart?
A
The electrical events in the heart coordinate the heart’s contractions to ensure that blood is pumped efficiently through the circulatory system.
The electrical signals trigger the atrial contraction and then the ventricular contraction, maintaining the rhythmic heartbeat.
19
Q
What is the structure sequence of electrical events in the heart?
A
SA node (pacemaker) – generates electrical impulses that start the heartbeat.
AV node – receives the electrical signal from the SA node and delays it slightly to allow the atria to fully contract before the ventricles.
Bundle of His – carries the electrical impulse down the septum of the heart to the bundle branches.
Bundle branches – conduct the impulse toward the Purkinje fibers.
Purkinje fibers – distribute the electrical impulse to the ventricular muscles, causing the ventricles to contract.
20
Q
What is the function of the SA node?
A
The SA node is located in the walls of the atria and acts as the pacemaker, initiating electrical impulses to start the heart’s contraction.
21
Q
What is the function of the AV node?
A
The AV node is located between the atria and ventricles.
It receives the electrical impulse from the SA node and delays it slightly to allow the atria to fully contract before the signal moves to the ventricles.
22
Q
What is the function of the Bundle of His?
A
The Bundle of His is a pathway that carries the electrical impulse from the AV node down the septum of the heart, toward the bundle branches.
23
Q
What is the function of the Bundle branches?
A
The bundle branches carry the electrical impulse toward the Purkinje fibers, spreading it to the ventricles to cause contraction.
24
What is the function of the Purkinje fibers?
The Purkinje fibers distribute the electrical impulse throughout the ventricles, triggering ventricular contraction.
25
What is an ECG (electrocardiogram) and what does it measure?
An ECG is a test that measures the electrical activity of the heart. It records the electrical impulses as they move through the heart, helping to assess the heart's rhythm and diagnose any irregularities.
26
What is the role of specialized cardiac muscle cells in the heart?
Specialized cardiac muscle cells initiate and distribute electrical signals that coordinate the contraction and relaxation of the heart, ensuring the cardiac cycle functions smoothly.
27
What is the function of the SA node in the heart?
The SA node initiates electrical impulses that set the rate of the heartbeat.
It acts as the pacemaker of the heart, sending signals to the atria to contract.
28
How do electrical impulses move throughout the atria?
The impulses from the SA node spread throughout the walls of the atria, causing them to contract and push blood into the ventricles.
29
What is the function of the AV node?
The AV node is located at the point of contact between the atria and ventricles.
It slows down the electrical impulses to allow the atria to empty and the ventricles to fill before the next contraction.
30
What role do specialized muscle fibers play in the heart?
Specialized muscle fibers help distribute electrical impulses throughout the ventricles, ensuring coordinated ventricular contraction.
31
How is blood pressure measured in humans?
Blood pressure is measured using a sphygmomanometer (blood pressure cuff).
It is recorded as two numbers:
Systolic pressure (during systole)
Diastolic pressure (during diastole)
32
What is systole in the cardiac cycle?
Systole is the contraction phase of the cardiac cycle, where the heart pumps blood out of the ventricles into the arteries.
The systolic pressure is the higher number in the blood pressure reading.
33
What is diastole in the cardiac cycle?
Diastole is the relaxation phase of the cardiac cycle, where the heart chambers relax and fill with blood.
The diastolic pressure is the lower number in the blood pressure reading.
34
What is the order of blood vessels from highest to lowest blood pressure?
Aorta
Arteries
Arterioles
Capillaries
Venules
Veins
Venae Cavae
35
Why do blood pressure differences exist in the circulatory system?
High pressure in arteries is due to their proximity to the heart’s pump and their thick muscular walls.
Low pressure in veins is due to their distance from the heart's pump and their thin walls.
36
Which vessel type has the lowest rate of blood flow?
Capillaries have the lowest rate of flow due to their highest cross-sectional area, which causes a decrease in flow velocity.
37
Why is the blood flow velocity lowest in capillaries?
Capillaries have a high cross-sectional area, which increases the surface area for nutrient exchange and decreases the blood flow velocity.
38
What happens during diastole (relaxation phase) of the cardiac cycle?
The heart is relaxed.
Blood flows into the atria and then into the ventricles.
Semilunar valves are closed, and AV valves are open.
Duration: 0.4 seconds.
39
What happens during systole (contraction phase) of the cardiac cycle?
Atria contract, filling the ventricles completely with blood.
Duration: 0.1 seconds.
Ventricles contract, closing the AV valves and opening the semilunar valves.
Blood leaves the ventricles (AV valves close, semilunar valves open).
Duration: 0.3 seconds.
40
What happens when the ventricles relax in the cardiac cycle?
The ventricles relax, and the backflow of blood closes the semilunar valves.
This creates the "lub-dub" sound, which is the sound of the AV valves closing followed by the semilunar valves closing.
41
What are the states of contraction and relaxation in the cardiac cycle?
The atria contract (systole), pumping blood into the ventricles.
The ventricles contract (systole), pumping blood to the lungs and the rest of the body.
After contraction, both the atria and ventricles relax (diastole) to fill with blood again.
42
What happens during diastole (relaxation phase) of the cardiac cycle?
The heart is relaxed.
Blood flows into the atria from the veins and then into the ventricles.
AV valves are open, allowing blood to flow from the atria to the ventricles.
Semilunar valves are closed, preventing backflow from the arteries.
43
What happens during systole (contraction phase) of the cardiac cycle?
Atria contract, pushing blood into the ventricles.
Ventricles contract, closing the AV valves and opening the semilunar valves.
Semilunar valves allow blood to flow from the ventricles into the aorta (left ventricle) or pulmonary artery (right ventricle).
44
What is the role of the AV valves and semilunar valves during the cardiac cycle?
AV valves (atrioventricular valves) are open during diastole to allow blood flow from the atria to the ventricles, and closed during systole to prevent backflow.
Semilunar valves are closed during diastole and open during systole to allow blood to exit the ventricles.
45
What do systole and diastole mean?
Systole refers to the contraction phase of the heart cycle, when the heart chambers contract and pump blood.
Diastole refers to the relaxation phase when the heart chambers relax and fill with blood.
46
What events do the two parts of a heartbeat correspond to in the cardiac cycle?
The first part of the heartbeat (the "lub") corresponds to the closing of the AV valves at the start of systole.
The second part of the heartbeat (the "dub") corresponds to the closing of the semilunar valves at the end of systole.
47
What are the electrical events during the cardiac cycle?
Electrical signals are initiated at the SA node (pacemaker) and travel through specialized muscle fibers (AV node, Bundle of His, bundle branches, and Purkinje fibers).
These signals cause the atria to contract during systole and the ventricles to contract during systole, coordinating the heartbeat.
48
What is the function and position of the atria?
The atria are the upper chambers of the heart that receive blood.
The right atrium receives deoxygenated blood from the body.
The left atrium receives oxygenated blood from the lungs.
49
What is the function and position of the ventricles?
The ventricles are the lower chambers of the heart that pump blood out of the heart.
The right ventricle pumps deoxygenated blood to the lungs through the pulmonary artery.
The left ventricle pumps oxygenated blood to the body through the aorta.
50
What is the function, structure, and location of the AV valves?
The AV valves (atrioventricular valves) prevent the backflow of blood from the ventricles into the atria.
The right AV valve (tricuspid) is located between the right atrium and the right ventricle.
The left AV valve (bicuspid or mitral) is located between the left atrium and the left ventricle.
51
What is the function, structure, and location of the semilunar valves?
The semilunar valves prevent the backflow of blood from the arteries into the ventricles.
The right semilunar valve is the pulmonary valve, located between the right ventricle and the pulmonary artery.
The left semilunar valve is the aortic valve, located between the left ventricle and the aorta.
52
What is the difference between the pulmonary circuit and the systemic circuit in the human circulatory system?
Pulmonary Circuit: Carries blood between the heart and the lungs for oxygenation.
Systemic Circuit: Carries oxygenated blood from the heart to the rest of the body and returns deoxygenated blood back to the heart.
53
What is the path of blood flow through the heart and pulmonary circuit?
Vena cava → right atrium → right ventricle → pulmonary trunk
Right and left pulmonary arteries → right and left lung capillaries
Right and left pulmonary veins → left atrium → left ventricle → aorta.
54
What is the path of blood flow through the systemic circuit, in terms of vessel type?
Left ventricle → aorta → arteries → arterioles → capillaries → venules → veins → each vena cava → right atrium.
55
What are the ABO blood types and the carbohydrates found on red blood cells for each type?
A: Contains carbohydrate A on red blood cells.
B: Contains carbohydrate B on red blood cells.
AB: Contains both carbohydrate A and B on red blood cells.
O: Contains neither carbohydrate A nor B on red blood cells.
56
What antibodies are produced for each ABO blood type?
A: Produces antibodies against B.
B: Produces antibodies against A.
AB: Produces neither antibody.
O: Produces both antibodies against A and B.
57
Which blood types can be safely transfused to a person with a given blood type?
A: Can receive blood from A and O.
B: Can receive blood from B and O.
AB: Can receive blood from A, B, AB, and O (universal recipient).
O: Can receive blood only from O (universal donor).
58
What is the Rh factor in blood type, and how does it affect compatibility?
The Rh factor is a protein found on red blood cells.
If present, it is labeled Rh+.
If absent, it is labeled Rh-.
The presence or absence of the Rh factor affects compatibility in blood transfusions and during pregnancy (Rh incompatibility).
59
Where are the cellular elements of blood formed?
The cellular elements of blood (RBCs, WBCs, and platelets) are formed in the bone marrow.
60
What are the characteristics of red blood cells (RBCs)?
Structure:
Lose nucleus and organelles as they mature.
Biconcave shape to increase surface area.
Function:
Transport oxygen throughout the body using hemoglobin.
Location:
Produced in the bone marrow and circulate in the blood.
Lifespan:
Live for about 3 to 4 months before being recycled.
61
What are the characteristics of platelets?
Structure:
Cell fragments with no nucleus.
Function:
Involved in blood clotting to prevent bleeding.
Location:
Produced in the bone marrow and circulate in the blood.
62
What are the characteristics of white blood cells (WBCs)?
Structure:
Larger cells with a nucleus.
Function:
Fight infections and kill pathogens.
They also play a role in immune response.
Location:
Produced in the bone marrow, but many are located in interstitial fluid and the lymphatic system.
63
How do animals facilitate gas exchange with respiratory surfaces?
Thin, moist respiratory surfaces allow for efficient gas exchange:
Thin surface allows for rapid diffusion of gases.
Moist surfaces help gases dissolve, enabling faster diffusion.
Large surface area provides more space for gas exchange between the environment and the circulatory system or directly with body tissues.
64
What is ventilation, and how does it facilitate gas exchange?
Ventilation refers to adaptations that increase the flow of air or water over respiratory surfaces, promoting continuous gas exchange.
Examples include muscles to pump air or water and the gill operculum in fish to move water over gills.
65
What are respiratory pigments, and how do they facilitate gas exchange?
Respiratory pigments are proteins that bind and transport oxygen.
For example, hemoglobin in blood binds oxygen and carries it to tissues.
Respiratory pigments allow more oxygen to be carried in the blood than would be possible if oxygen were just dissolved in plasma.
66
How do invertebrates respire directly through their outer cell layers or skin?
Small, long, thin, and/or flat invertebrates have a high ratio of respiratory surface area to body volume.
They can respire directly through their outer cell layers or skin.
This method is typically used by animals that live in water or damp places.
Example organisms: Sponges, flatworms, and cnidarians.
67
How do aquatic invertebrates use gills for respiration?
Gills have a highly folded structure, increasing their surface area.
Body fluids flow inside the gills, allowing gas exchange between the water and the organism.
This method is used by aquatic invertebrates to extract oxygen from water.
Example organisms: Mollusks (e.g., clams, snails) and crustaceans (e.g., crabs, lobsters).
68
How do insects use the tracheal system for respiration?
Insects respire through openings (called spiracles) on the body surface that take air in and let it out.
The air is moved through a system of branched tubes (tracheae) that distribute oxygen directly to tissues.
This system is used for internal gas exchange in insects.
Example organisms: Insects (e.g., grasshoppers, flies).
69
What are the special conditions for each method of respiration in invertebrates?
Direct respiration through outer skin or cell layers:
Used by small, long, thin, or flat animals with a high surface area to volume ratio.
Typically occurs in moist environments or aquatic habitats.
Gills:
Used by aquatic invertebrates to exchange gases in water.
Gills must be highly folded to increase surface area.
Tracheal system:
Used by terrestrial insects for internal gas exchange.
Spiracles and branched tubes carry oxygen to tissues.
70
How do fish use gills for respiration?
Fish gills extract oxygen from water as it flows over the gill filaments.
The gill filaments contain blood capillaries that allow gas exchange: oxygen from the water enters the blood, and carbon dioxide from the blood is expelled into the water.
71
What is the concept of countercurrent exchange, and how does it affect respiration through gills?
Countercurrent exchange refers to the opposite flow of water and blood:
Water flows over the gills in the opposite direction of blood flow in the capillaries.
This maximizes oxygen transfer because it maintains a concentration gradient between water and blood, ensuring oxygen moves into the blood and carbon dioxide moves out.
72
What is the path of air flow in the human respiratory system from the external environment to the alveoli?
Nose/Nasal cavity:
Hairs filter air.
Air is warmed and moistened before entering the respiratory system.
Pharynx:
Passage for air to the larynx.
The epiglottis is a tissue flap that covers the larynx when swallowing to prevent food from entering the airway.
Larynx:
Contains vocal cords.
Air moving over the vocal cords causes them to vibrate, producing sound.
Trachea:
A rigid tube that carries air to the bronchi.
Bronchi:
Two main branches that lead to the left and right lungs.
Bronchioles:
Smaller tubes that further divide into the lungs.
Alveoli:
Tiny air sacs where gas exchange occurs between the air and blood.
73
What is the function and composition of the nose/nasal cavity?
The nose and nasal cavity filter, warm, and moisten the air before it enters the lungs.
Hairs in the nasal cavity help filter out large particles from the air.
74
What is the function of the pharynx in the human respiratory system?
The pharynx is a passage for air to travel from the nose to the larynx.
The epiglottis, a tissue flap in the pharynx, covers the larynx during swallowing to prevent food from entering the airway.
75
What is the function of the larynx in the human respiratory system?
The larynx contains the vocal cords, which vibrate when air passes over them, producing sound.
It serves as the passageway between the pharynx and trachea.
76
What is the function and structure of the trachea?
The trachea is a rigid tube that carries air from the larynx to the bronchi.
It is lined with cilia and mucus that trap debris and prevent it from entering the lungs.
77
What is the function of the bronchi?
The bronchi are the two main branches that carry air from the trachea into the left and right lungs.
They further divide into smaller bronchioles that lead to the alveoli.
78
What are the alveoli, and what is their function?
The alveoli are tiny air sacs at the end of the bronchioles where gas exchange occurs.
Oxygen from the air diffuses into the blood, and carbon dioxide from the blood is expelled into the air.
79
What does it mean for a gas to have partial pressure?
Partial pressure refers to the pressure exerted by a single gas in a mixture of gases.
Each gas in the air contributes a portion of the total air pressure, called its partial pressure.
80
How does the movement of gases relate to their partial pressure?
Gases move by diffusion from areas of high partial pressure to areas of low partial pressure.
This occurs until equilibrium is reached, where the partial pressures are balanced.
81
How is oxygen moved from the alveoli into the blood?
Oxygen (O₂) diffuses from the alveoli (where the oxygen partial pressure is high) into the surrounding blood capillaries (where the oxygen partial pressure is lower).
82
How is oxygen transported in the blood after it enters?
Hemoglobin in red blood cells binds to almost all of the oxygen in the blood, forming oxyhemoglobin.
The oxygen is then transported throughout the body via the bloodstream.
83
How does hemoglobin release oxygen to body cells?
As the blood reaches body tissues, the oxygen partial pressure in the tissues is lower than in the blood.
This causes hemoglobin to release the oxygen, allowing it to diffuse into the body cells.
84
How is carbon dioxide (CO₂) moved from body cells to the blood?
Carbon dioxide (CO₂) diffuses from the body cells (where the CO₂ partial pressure is high) into the blood (where the CO₂ partial pressure is lower) due to the partial pressure gradient.
85
How is most carbon dioxide (CO₂) transported in the blood?
Most CO₂ is converted to bicarbonate ions (HCO₃⁻) in red blood cells through a reaction catalyzed by the enzyme carbonic anhydrase.
Hemoglobin binds to hydrogen ions (H⁺) produced in this reaction to minimize blood pH changes.
86
How does carbon dioxide move from the blood to the alveoli?
When the blood reaches the lung capillaries, the bicarbonate ions are converted back to carbon dioxide (CO₂) and hydrogen ions (H⁺).
CO₂ then diffuses into the alveoli where the CO₂ partial pressure is lower.
87
How does carbon dioxide transport affect the pH of blood?
The conversion of CO₂ to bicarbonate ions in the blood helps buffer the blood and maintain pH.
When hemoglobin binds to hydrogen ions (H⁺), it helps minimize changes in blood pH, preventing it from becoming too acidic.
88
How does inhalation occur in terms of diaphragm, rib muscles, lung volume, lung air pressure, and air movement?
Diaphragm and rib muscles contract.
This causes an increase in lung volume.
As the lung volume increases, lung air pressure decreases.
Air moves into the lungs from high to low pressure, allowing air to enter.
89
How does exhalation occur in terms of diaphragm, rib muscles, lung volume, lung air pressure, and air movement?
Diaphragm and rib muscles relax.
This causes a decrease in lung volume.
As lung volume decreases, lung air pressure increases.
Air moves out of the lungs from high to low pressure, expelling air.
90
What part of the brain contains the breathing control centers?
The medulla oblongata in the brain contains the breathing control centers.
91
What do the breathing control centers in the medulla oblongata do?
The breathing control centers regulate the rate and depth of breathing by sending signals to the diaphragm and rib muscles based on the levels of gases in the blood.
92
What chemicals are monitored to adjust breathing rate, and where does this monitoring occur?
The concentrations of CO₂, H⁺ ions (due to CO₂ concentration), and O₂ are monitored.
Nerve cell receptors in the aorta and carotid arteries detect these concentrations and send signals to the brain.
93
How does the brain adjust the breathing rate under different conditions?
High CO₂, high H⁺ (or low O₂) concentrations cause the brain to increase breathing rate until normal levels are reached.
Low CO₂, low H⁺ (or high O₂) concentrations cause the brain to decrease breathing rate to maintain homeostasis.
94
What is the difference between closed circulatory systems and open circulatory systems?
Closed circulatory systems:
Blood is always contained within vessels or the heart.
The blood is kept separate from interstitial fluid.
Found in vertebrates and some invertebrates (e.g., earthworms).
The circulatory fluid is blood, which is distinct from other body fluids.
Open circulatory systems:
Circulatory fluid (called hemolymph) flows out of open-ended vessels and sometimes into sinuses surrounding organs.
There is no distinction between blood and interstitial fluid.
Found in most mollusks and arthropods (e.g., insects, crabs).
95
What is the composition of the circulatory fluid in closed circulatory systems?
The circulatory fluid in closed systems includes blood, interstitial fluid, and lymph.
Blood is always contained within vessels and is kept separate from the interstitial fluid surrounding body tissues.
96
What is the composition of the circulatory fluid in open circulatory systems?
The circulatory fluid in open systems is called hemolymph, which flows through open-ended vessels and sometimes into sinuses surrounding organs.
There is no distinction between blood and interstitial fluid.
97
Can you give examples of organisms with an open circulatory system?
Open circulatory systems are found in most mollusks (e.g., snails, clams) and all arthropods (e.g., insects, crabs).
98
Can you give examples of organisms with a closed circulatory system?
Closed circulatory systems are found in vertebrates (e.g., humans, fish) and some invertebrates (e.g., earthworms, squid).
99
What are the major components of the circulatory system?
Circulatory fluid (blood, hemolymph)
Pump (heart)
Vessels (arteries, veins, capillaries)
100
What is the function of arteries?
Arteries carry blood away from the heart.
They transport oxygenated blood (except for the pulmonary artery, which carries deoxygenated blood) to the body.
101
What is the function of veins?
Veins carry blood toward the heart.
They transport deoxygenated blood (except for the pulmonary veins, which carry oxygenated blood) from the body back to the heart.
102
What is the function of capillaries?
Capillaries carry blood between arteries and veins.
They allow for the exchange of gases, nutrients, and waste products between the blood and surrounding tissues.
103
Give examples of animals in the phylum Echinodermata.
Echinodermata includes starfish, sand dollars, and sea urchins.
104
Give examples of animals in the phylum Chordata.
Chordata includes fish, amphibians, reptiles, and mammals.
105
Give examples of animals in the phylum Porifera.
Porifera includes sponges, such as tube sponges, vase sponges, and Scypha.
106
Give examples of animals in the phylum Cnidaria.
Cnidaria includes coral, hydras, jellyfish, and sea anemones.
107
Give examples of animals in the phylum Platyhelminthes.
Platyhelminthes includes flatworms, such as flukes and tapeworms.
108
Give examples of animals in the phylum Mollusca.
Mollusca includes snails, slugs, mussels, clams, oysters, squid, and scallops.
109
Give examples of animals in the phylum Annelida.
Annelida includes earthworms, leeches, and marine polychaetes.
110
Give examples of animals in the phylum Nematoda.
Nematoda includes roundworms.
111
Give examples of animals in the phylum Arthropoda.
Arthropoda includes horseshoe crabs, centipedes, insects, and crustaceans.
112
What is the structure of veins, and how does it differ from arteries?
Veins are thinner-walled and more flaccid than arteries.
Veins have a wider lumen and are further from the heart's pump.
Arteries are thicker-walled and have a smaller lumen to handle high pressure from the heart's pumping.
113
How does the structure of veins influence blood pressure and blood volume?
Veins have very low pressure because they are far from the heart's pumping action.
Veins serve as blood reservoirs, containing a large volume of blood.
114
How does pressure increase in veins to help return blood to the heart?
Smooth muscle contraction: Contraction of smooth muscle in the vein walls helps propel blood forward.
Inhalation: Inhalation creates a pressure gradient, where the chest cavity pressure becomes lower than the abdominal cavity pressure, pulling blood from the abdominal veins toward the chest.
Skeletal muscle contractions: When skeletal muscles contract, they squeeze nearby veins, helping to push blood toward the heart.
115
What are the functions of the lymphatic system?
Returns water and materials that leak out of capillaries back into the blood.
Transports lipids absorbed from the small intestine to the bloodstream.
Carries pathogens and toxins to lymph nodes, where they are filtered and destroyed by immune cells.
116
What is lymph, and how is it formed?
Lymph is the interstitial fluid that is collected and transported by lymph vessels.
It is formed when fluid from the blood capillaries leaks out into surrounding tissues, and some of it is absorbed into the lymphatic system.
