Circulatory Systems in Animals

Questions and Answers

What is a gastrovascular cavity? In what organisms are these typically found?

A gastrovascular cavity is a central cavity with a single opening in the body of certain animals, including cnidarians and flatworms, that functions in both digestion and distribution of nutrients. They are typically found in hydras, jellies, and other cnidarians.

What are the main components of a circulatory system?

A circulatory fluid, a set of interconnecting vessels, and a muscular pump.

Compare and contrast an open circulatory system and a closed circulatory system.

What is the basic organization of a circulatory system?

The circulatory system comprises the cardiovascular and lymphatic systems. The cardiovascular system includes the heart and its vessels: arteries, capillaries, and veins. Signup and view all the answers

What type of animals have single circulation? Describe this type of circulation.

Sharks, rays, and bony fishes have single circulation, which consists of a single pump and circuit where blood passes from sites of gas exchange to the rest of the body before returning to the heart. Signup and view all the answers

What type of animals have double circulation? Describe this type of circulation in mammals.

Mammals have double circulation, consisting of pulmonary and systemic circuits, where blood passes through the heart after completing each circuit. Signup and view all the answers

Describe double circulation in amphibians.

Frogs and other amphibians have a three-chambered heart, with two atria and one ventricle. Blood is pumped into a forked artery that splits output into pulmocutaneous and systemic circuits. Signup and view all the answers

Describe the coordinated cycles of heart contraction in mammals.

The right ventricle pumps blood to the lungs via pulmonary arteries, where it loads O2 and unloads CO2. Oxygen-rich blood returns to the left atrium, flows into the left ventricle, and is pumped out to body tissues through the systemic circuit. Signup and view all the answers

Describe the cardiac cycle and cardiac output.

The cardiac cycle is the alternating contractions and relaxations of the heart. Cardiac output is the volume of blood pumped per minute by each ventricle. Signup and view all the answers

How is heart rhythm controlled? How does this look in an EKG/ECG?

Cardiac muscle cells are self-excitable, contracting without nervous system signals. The sinoatrial (SA) node sets the rate and timing of contractions, which can be recorded as an electrocardiogram (ECG or EKG). Signup and view all the answers

Describe the pacemaker of the heart. How is it regulated by hormones?

The pacemaker is controlled by the sympathetic and parasympathetic nervous systems. The sympathetic speeds it up, while the parasympathetic slows it down. Hormones, like epinephrine, also regulate it. Signup and view all the answers

Compare and contrast the structure of an artery and a vein.

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What are the changes in blood pressure that occur during the cardiac cycle?

Arterial blood pressure is highest during ventricular systole (systolic pressure) and lower during diastole (diastolic pressure). Signup and view all the answers

How is blood pressure regulated?

Blood pressure is regulated by altering arteriole diameter through vasoconstriction and vasodilation. Signup and view all the answers

What mechanisms help blood flow combat gravity?

Valves in veins prevent backflow, and the contraction of skeletal muscles during exercise aids in blood return to the heart. Signup and view all the answers

What are the functions of capillaries?

Capillaries are the links between arterial and venous systems where gas, nutrient, waste, and hormone exchanges occur. Signup and view all the answers

What is the goal of the lymphatic system? How does it accomplish this?

The goal is to return fluids, proteins, and cells to the blood through lymph circulation, which involves valves and smooth muscle contractions. Signup and view all the answers

What is the role of plasma in blood? What percentage of blood does it comprise?

Plasma suspends blood cells and comprises 45% of blood. Signup and view all the answers

What are the major cellular elements of blood? What percentage of blood do they comprise?

The major elements include erythrocytes, leukocytes, and platelets, comprising about 55% of blood. Signup and view all the answers

Describe sickle-cell disease and how it impairs the function of the circulatory system.

Sickle-cell disease is a genetic disorder affecting hemoglobin, leading to misshapen red blood cells that obstruct blood flow, causing pain and reducing oxygen delivery. Signup and view all the answers

What are the respiratory adaptations of diving mammals?

Diving mammals have adaptations for storing large amounts of O2, conserve O2 during dives, and have genetic traits that improve diving ability. Signup and view all the answers

If carbon dioxide is a product of respiration, how does the body get rid of it? Describe the Bohr shift.

CO2 diffuses into erythrocytes, forming H2CO3, which dissociates. The Bohr shift lowers hemoglobin's affinity for O2, facilitating oxygen release near active tissues. Signup and view all the answers

Describe how blood clots.

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In order to understand cardiovascular disease, describe the role of cholesterol and LDL/HDL in disease progression.

LDL delivers cholesterol, while HDL scavenges excess cholesterol. A high LDL/HDL ratio increases atherosclerosis risk. Signup and view all the answers

What are some of the results of cardiovascular disease?

Cardiovascular disease can lead to atherosclerosis, heart attacks, and strokes. Signup and view all the answers

What are some different respiratory surfaces in organisms?

Gills, tracheae, and lungs. Signup and view all the answers

How are lungs adapted for gas exchange?

Lungs in most reptiles and mammals are specialized for gas exchange, while amphibians rely on diffusion across skin. Signup and view all the answers

How do mammals breathe and ventilate the lungs?

Mammals ventilate their lungs through negative pressure breathing, which pulls air into the lungs as rib muscles and the diaphragm contract. Signup and view all the answers

Define tidal volume, vital capacity, and residual volume.

Tidal volume is the air volume per breath, vital capacity is the maximum air volume exchanged, and residual volume is air remaining after exhalation. Signup and view all the answers

Describe the control of breathing in humans.

Breathing is regulated by neurons in the medulla oblongata, which establish a rhythm and rely on feedback and sensors to prevent overexpansion. Signup and view all the answers

Study Notes

Gastrovascular Cavity

Central cavity with a single opening for digestion and nutrient distribution found in cnidarians and flatworms.
Commonly seen in hydras and jellies.

Components of Circulatory System

Composed of a circulatory fluid, interconnected vessels, and a muscular pump.

Open vs Closed Circulatory System

Open circulatory systems have fluid (hemolymph) freely circulating through body cavities; closed systems have blood confined to vessels.
Closed systems are generally more efficient for nutrient and gas transport.

Organization of Circulatory System

Includes the cardiovascular and lymphatic systems; the cardiovascular system comprises the heart, arteries, capillaries, and veins.
The heart propels blood throughout the body tissues.

Single Circulation in Animals

Present in sharks, rays, and bony fishes; consists of a single pump and circuit.
Blood moves from gas exchange sites to body tissues before returning to the heart.

Double Circulation in Mammals

Involves pulmonary (lungs) and systemic (body) circuits; blood passes through the heart twice in each complete circuit.

Double Circulation in Amphibians

Frogs have a three-chambered heart (two atria, one ventricle) facilitating a forked path for two circuits.
Blood flow to lungs is restricted when underwater.

Heart Contraction in Mammals

Right ventricle pumps blood to lungs; oxygen-rich blood returns to the left atrium.
Left ventricle pumps oxygenated blood to body tissues via the aorta.

Cardiac Cycle and Output

Alternating contraction and relaxation of the heart; cardiac output is the blood volume pumped per minute by each ventricle.

Heart Rhythm Control

Certain cardiac muscle cells are self-excitable; the sinoatrial (SA) node regulates cardiac contractions.
Electrocardiogram (ECG) records electrical impulses during the cardiac cycle.

Pacemaker Regulation

Regulated by the sympathetic (accelerates) and parasympathetic (slows) nervous systems.
Hormones like epinephrine also influence pacemaker activity.

Arteries vs Veins Structure

Arteries have thicker, elastic walls to withstand high pressure; veins contain valves to prevent backflow.

Changes in Blood Pressure

Systolic pressure is highest during heart contraction; diastolic pressure is the lower pressure during relaxation.
Arteries remain pressurized, allowing continuous blood flow.

Blood Pressure Regulation

Controlled by altering arteriole diameter; vasoconstriction increases pressure, vasodilation decreases it.

Mechanisms Against Gravity in Blood Flow

Fainting response assists blood return to the heart; vein valves prevent backflow.
Skeletal muscle contraction enhances venous return.

Capillary Functions

Capillaries facilitate gas, nutrient, and waste exchange between blood and interstitial fluid.

Lymphatic System Goals

Returns fluids, proteins, and cells to the blood; lymph is circulated via valves and vessel contractions.

Plasma and Blood Composition

Plasma suspends blood cells, constituting 45% of blood volume.

Major Cellular Elements of Blood

Erythrocytes (red blood cells), leukocytes (white blood cells), and platelets; they play roles in oxygen transport, immune response, and clotting.

Sickle-Cell Disease Impact

Genetic disorder altering hemoglobin, leading to blocked blood flow and pain; sickled cells rupture quickly.

Diving Mammals' Respiratory Adaptations

High oxygen storage capacity, reduced heart rate during dives, and prioritized blood flow to vital organs.

Carbon Dioxide Removal and Bohr Shift

CO2 diffuses into erythrocytes, forming bicarbonate; the Bohr shift decreases hemoglobin's oxygen affinity in active tissues.

Blood Clotting Mechanism

Platelets aggregate and form a clot in response to vessel injury.

Role of Cholesterol in Cardiovascular Disease

LDL delivers cholesterol to cells; HDL removes excess cholesterol. High LDL to HDL ratio increases atherosclerosis risk.

Consequences of Cardiovascular Disease

Can result in conditions like atherosclerosis, heart attacks, and strokes.

Respiratory Surfaces in Organisms

Gills, tracheae, and lungs serve as sites for gas exchange.

Lung Adaptations for Gas Exchange

Varying reliance on lungs among vertebrates; amphibians may utilize skin diffusion.

Mammalian Breathing and Lung Ventilation

Negative pressure breathing mechanism facilitates air intake; rib muscles and diaphragm contraction increase lung volume.

Definitions of Lung Volumes

Tidal volume: air exchanged per breath; vital capacity: maximum air exchange; residual volume: air remaining after exhalation.

Control of Breathing in Humans

Medulla oblongata regulates breathing rhythm and prevents lung overexpansion via negative feedback mechanisms.

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Description

Explore the various types of circulatory systems present in animals, including open and closed systems. This quiz covers key concepts such as the organization of the circulatory system and the unique characteristics of single and double circulation found in different species.