Transcript document

Eldra Solomon
Linda Berg
Diana W. Martin
www.cengage.com/biology/solomon
Chapter 44
(Sections 44.1-44.4)
Internal Transport
Albia Dugger • Miami Dade College
Moving Materials
• Cells require a continuous supply of nutrients and oxygen and
removal of waste products
• In very small animals, materials are exchanged by diffusion,
the net movement of particles from a region of higher
concentration to a region of lower concentration
• Fluid between the cells (interstitial fluid) provides a medium
for diffusion of oxygen, nutrients, and wastes
Circulatory Systems
• Evolution of specialized circulatory systems allowed
animals to increase in size – it transports oxygen, nutrients,
hormones, and other materials to the interstitial fluid
surrounding all the cells and removes metabolic wastes
• The human circulatory system (cardiovascular system)
includes the heart, blood vessels, and blood
• Cardiovascular disease is the leading cause of death in the
United States and throughout the world
44.1 TYPES OF
CIRCULATORY SYSTEMS
LEARNING OBJECTIVE:
• Compare and contrast internal transport in animals with
no circulatory system, those with an open circulatory
system, and those with a closed circulatory system
Animals With No Circulatory System
• No specialized circulatory structures are present in sponges,
cnidarians (hydras, jellyfish), ctenophores (comb jellies),
flatworms, or nematodes (roundworms)
• In cnidarians, the central gastrovascular cavity serves as a
circulatory organ as well as a digestive organ
• The flattened body of the flatworm permits effective gas
exchange by diffusion
• Fluid in the body cavity of nematodes circulates materials
Circulatory Systems
• Larger animals require a circulatory system to efficiently
distribute materials
• A circulatory system typically consist of three parts:
• Blood, a connective tissue consisting of cells and cell
fragments dispersed in fluid, usually called plasma
• A pumping organ, generally a heart
• Blood vessels through which blood circulates
• Two main types of circulatory systems are open and closed
systems
Open Circulatory Systems
• Arthropods and most mollusks have an open circulatory
system, in which the heart pumps blood into vessels that
have open ends
• Blood and interstitial fluid make up hemolymph, which fills
large sinuses (the hemocoel or blood cavity)
• Hemolymph bathes the body cells, then re-enters the
circulatory system through openings in the heart (arthropods)
or through open-ended vessels that lead to gills (mollusks)
Open Circulatory Systems (cont.)
• Most mollusks have a heart with three chambers: two atria
receive hemolymph from gills; a single ventricle pumps
oxygen-rich hemolymph into blood vessels
• In arthropods, a tubular heart pumps hemolymph into arteries
that deliver it to the sinuses of the hemocoel
• Some mollusks and arthropods have a copper-containing
hemolymph pigment (hemocyanin) that transports oxygen
Invertebrates With
Closed Circulatory Systems
• Annelids, cephalopod mollusks, and echinoderms have a
closed circulatory system in which blood flows through a
continuous circuit of blood vessels
• Gases, nutrients, and wastes diffuse between blood in the
vessels and interstitial fluid that bathes the cells through the
thin walls of capillaries
Invertebrates With
Closed Circulatory Systems (cont.)
• Proboscis worms (phylum Nemertea) have a complete
network of blood vessels but no heart
• Annelids (earthworms) have two main blood vessels, five
pairs of contractile blood vessels that act as hearts, and a red
pigment (hemoglobin) that transports oxygen
• Cephalopod mollusks (squids and octopods) have accessory
“hearts” at the base of the gills, which speed passage of blood
through the gills
The Vertebrate Circulatory System
• Vertebrates have a ventral, muscular heart that pumps blood
into a closed system of blood vessels
• Capillaries, the smallest blood vessels, have very thin walls
that permit exchange of materials between blood and
interstitial fluid
• The vertebrate circulatory system consists of heart, blood
vessels, blood, lymph, lymph vessels, and associated organs
such as the thymus, spleen, and liver
Functions of the
Vertebrate Circulatory System
1.
2.
3.
4.
5.
6.
Transports nutrients from digestive system or storage to cells
Transports oxygen from respiratory structures to cells
Transports metabolic wastes from cells to excretory organs
Transports hormones from endocrine glands to target tissues
Helps maintain fluid balance
Helps distribute metabolic heat and maintain body
temperature
7. Helps maintain appropriate pH
8. Defends the body against invading microorganisms
KEY CONCEPTS 44.1
• Arthropods and most mollusks have an open circulatory
system in which blood bathes the tissues directly
• Some invertebrates and all vertebrates have a closed
circulatory system in which a heart pumps blood that flows
through a continuous circuit of blood vessels
44.2 VERTEBRATE BLOOD
LEARNING OBJECTIVES:
• Compare the structure and function of plasma, red blood
cells, white blood cells, and platelets
• Summarize the sequence of events involved in blood
clotting
Blood
• In vertebrates, blood consists of a fluid plasma in which red
blood cells, white blood cells, and platelets are suspended
• In humans, blood volume is approximately 5 L (5.3 qt) in an
adult female and about 5.5 L (5.8 qt) in an adult male
• About 55% of the blood volume is plasma and 45% is blood
cells and platelets
Plasma
• Plasma consists of water (about 92%), proteins (about 7%),
salts, and transported materials such as dissolved gases,
nutrients, wastes, and hormones
• Plasma contains several kinds of plasma proteins:
• Fibrinogen is involved in clotting
• Globulins: Alpha globulins (hormones and proteins that
transport hormones); beta globulins (transport fats,
cholesterol, vitamins and minerals); gamma globulin
(contains many types of antibodies)
• Albumins help control blood’s osmotic pressure
Red Blood Cells
• Erythrocytes or red blood cells (RBCs), are highly
specialized for transporting oxygen
• In mammals, the RBC nucleus is ejected – each RBC is a
flexible, biconcave disc with an elastic internal framework
• Erythrocytes are produced in red bone marrow of vertebrae,
ribs, breastbone, skull bones, and long bones
• As an RBC develops, it produces large quantities of the
oxygen-transporting pigment hemoglobin
Red Blood Cells (cont.)
• A human RBC lives about 120 days; old RBCs are removed
from circulation by phagocytic cells in the liver and spleen
• New RBCs are produced in bone marrow, regulated by a
hormone released by the kidneys (erythropoietin)
• Anemia, a deficiency in hemoglobin, may be caused by:
• Loss of blood from hemorrhage or internal bleeding
• Decreased production of hemoglobin or red blood cells
(iron-deficiency anemia or pernicious anemia)
• Increased rate of RBC destruction (hemolytic anemias)
White Blood Cells
• Leukocytes or white blood cells (WBCs) defend the body
against harmful bacteria and other microorganisms
• Leukocytes are amoeba-like cells capable of independent
movement – some slip through the walls of blood vessels and
enter the tissues
• Human blood contains three kinds of granular leukocytes and
two types of agranular leukocytes – all manufactured in the
red bone marrow
Granular Leukocytes
• Granular leukocytes have large, lobed nuclei and distinctive
granules in their cytoplasm
• Neutrophils are phagocytic cells that ingest bacteria and
dead cells – granules contain digestive enzymes
• Eosinophils contain lysosomes with enzymes that degrade
cell membranes of parasitic worms and protozoa
• Basophils release histamine in injured tissues and in allergic
responses; and heparin, an anticoagulant
Agranular Leukocytes
• Agranular leukocytes lack granules; their nuclei are rounded
or kidney-shaped
• Lymphocytes fight infections; some produce antibodies,
others directly attack invaders such as bacteria or viruses
• Monocytes are phagocytes that migrate from blood into
tissues during an infection; they differentiate into:
• Macrophages that engulf bacteria, dead cells, and debris
• Dendritic cells, important in the immune system
Leukemia
• Leukemia is a form of cancer in which WBCs multiply rapidly
within the bone marrow, crowding out developing RBCs and
platelets, leading to anemia and impaired clotting
• Death is often caused by internal hemorrhaging, especially in
the brain; or infection
• Leukemia is treated with chemotherapy, and sometimes with
radiation therapy or bone marrow transplant
Platelets
• Most vertebrates other than mammals have small, oval,
nucleated cells (thrombocytes) that function in blood clotting
• Mammals have platelets, tiny spherical or disc-shaped
fragments of cytoplasm pinched off from large cells in the
bone marrow (lacking nuclei)
• When a blood vessel is cut, platelets stick to the rough, cut
edges and release substances that attract other platelets
Blood Clotting
• Platelets become sticky and adhere to collagen fibers in the
blood vessel wall, forming a platelet plug or temporary clot
• Using clotting factors, calcium ions, and compounds released
from platelets, prothrombin is converted to thrombin
• Thrombin catalyzes conversion of the soluble plasma protein
fibrinogen to an insoluble protein, fibrin
• Fibrin polymerizes, producing long threads that form the
webbing of the clot, trapping more blood cells and platelets
KEY CONCEPTS 44.2
• Vertebrate blood consists of plasma, which transports
nutrients, wastes, gases, and hormones; red blood cells,
which are specialized to transport oxygen; white blood cells,
which defend the body against disease; and platelets, which
function in blood clotting
44.3 VERTEBRATE BLOOD VESSELS
LEARNING OBJECTIVE:
• Compare the structure and function of different types of
blood vessels, including arteries, arterioles, capillaries,
and veins
Blood Vessels
• Vertebrates have three main types of blood vessels
• Arteries carry blood away from the heart; they divide into
many smaller branches (arterioles) which lead to capillaries
• Capillaries are microscopic vessels that form networks which
exchange materials between blood and tissues
• Veins carry blood back toward the heart
Blood Vessels (cont.)
• Walls of arteries or veins have three layers:
• Inner lining: endothelium
• Middle layer: connective tissue and smooth muscle cells
• Outer layer: connective tissue rich in elastic and collagen
fibers
• Materials are exchanged between blood and interstitial fluid
through capillary walls, which are only one cell thick
Blood Vessels (cont.)
• Smooth muscle in arteriole walls can constrict
(vasoconstriction) or relax (vasodilation), changing the
radius of the arteriole
• Regulated by the nervous system, arterioles help maintain
appropriate blood pressure and control the volume of blood
passing to a particular tissue
• Small vessels (metarterioles) directly link arterioles with
venules (small veins)
Blood Vessels (cont.)
• Capillaries branch off from metarterioles and rejoin them, and
also interconnect with one another
• Where a capillary branches from a metarteriole, a smooth
muscle cell serves as a precapillary sphincter that directs
blood first to one and then to another section of tissue
• Precapillary sphincters (along with the smooth muscle in the
walls of arteries and arterioles) regulate the blood supply to
each organ and its subdivisions
KEY CONCEPTS 44.3
• Three main types of vertebrate blood vessels are arteries,
which carry blood away from the heart; capillaries, which are
exchange vessels; and veins, which carry blood back toward
the heart
44.4 EVOLUTION OF THE
CARDIOVASCULAR SYSTEM
LEARNING OBJECTIVE:
• Trace the evolution of the vertebrate cardiovascular
system from fish to mammal
Evolution of the Vertebrate Cardiovascular
System
• The vertebrate cardiovascular system became modified as
the site of gas exchange shifted from gills to lungs, and as
metabolic rates increased
• The vertebrate heart has one or two chambers (atria) that
receive blood returning from the tissues and one or two
ventricles that pump blood into arteries
• The fish heart has one atrium and one ventricle; there is a
single circuit of blood vessels; blood is oxygenated at
capillaries in the gills
Evolution of the Vertebrate Cardiovascular
System (cont.)
• Amphibians have a double circuit of blood vessels:
pulmonary circulation and systemic circulation
• The heart has two atria and one ventricle – a sinus venosus
collects oxygen-poor blood returning from the veins and
pumps it into the right atrium; blood is oxygenated in lungs
and passes directly into the left atrium
• Oxygen-poor blood is pumped out of the ventricle before
oxygen-rich blood enters; the conus arteriosus helps separate
the two
Evolution of the Vertebrate Cardiovascular
System (cont.)
• Most nonavian reptiles have a double circuit of blood flow – a
wall partly divides the ventricles
• In crocodilians, the wall between the ventricles is complete –
the heart consists of two atria and two separate ventricles
• Nonavian reptiles (and amphibians) do not ventilate their
lungs constantly – shunts between the two sides of the heart
allow blood to be distributed to the lungs as needed
Evolution of the Vertebrate Cardiovascular
System (cont.)
• In birds, mammals, and crocodilians, the septum (wall)
between the ventricles is complete
• Biologists hypothesize that the completely divided heart
evolved twice during the course of vertebrate evolution; first in
the crocodilian-bird clade, then independently in mammals
• The conus arteriosus split and became the base of the aorta
and the pulmonary artery; a vestige of the sinus venosus
remains as the sinoatrial node (pacemaker)
Evolution of the Vertebrate Cardiovascular
System (cont.)
• A complete double circuit allows birds and mammals to
maintain relatively high blood pressures in the systemic
circulation and lower pressures in the pulmonary circulation
• The pattern of blood circulation in birds and mammals can be
summarized as follows:
veins (from organs) → right atrium → right ventricle →
pulmonary arteries → capillaries in the lungs →
pulmonary veins → left atrium → left ventricle → aorta →
arteries (to organs) → arterioles → capillaries → veins
KEY CONCEPTS 44.4
• During the evolution of terrestrial vertebrates, adaptations in
circulatory system structures separated oxygen-rich from
oxygen-poor blood
• The four-chambered hearts and double circuits of
endothermic birds and mammals completely separate
oxygen-rich blood from oxygen-poor blood