The relationship between structure and function is an important overarching concept in biology and studying this relationship will help us to understand animals.
Structure (anatomy) and function (physiology) are studied together because function is determined by structure.
Structure and Function
The long bill of the sword-billed hummingbird makes it particularly suited to extracting nectar from flowers with deep hypanthium (nectar chamber).
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The adaptations that different animals have to allow them to perform various functions have all been fashioned by natural selection.
Natural selection has "fitted" structure to function by selecting, over many generations, what works best within a particular population in it's environment.
Structure and Function
What elephant adaptations make it suited for its environment?
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Structure and Function
Ears with large surface area allow efficient heat dissipation.
Tusks are used as tools or for protection.
Trunk is used for breathing, grasping and lifting.
Elephants are suited to their environment:
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tissue organ organ system organism
Structure in living things is organized in a series of
hierarchical levels.
Levels of Organization
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tissue organ organ system organism
A group of cells that
work together
to perform a certain function.
Two or more tissues that
work together to perform a specific
task.
Multiple organs that function together to
perform a vital body function.
All the organ systems
functioning together as
an integrated unit.
Levels of Organization
Cardiac tissueHeart
Circulatory systemHuman
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1 The study of an organism's structure is known as ____, while the study of its function is ____.
A physiology; anatomy
B anatomy; physiology
C physicality; anonymity
D anonymity; physicality
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2 Two or more tissues that work together to perform a specific task is
A a cell.
B an organ.
C an organ system.
D an organism.
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3 The digestive system is an organ system that is composed of several organs, including the stomach, small intestine and liver. Each of these organs are composed of
Epithelial TissueEpithelial Tissue consists of many cells tightly packed together with very little extracellular matrix. It covers body surfaces and lines internal organs and body cavities.
One side of the tissue is anchored to the underlying tissues by a basement membrane (a dense layer of extracellular matrix consisting of fibrous proteins and polysaccharides.) The other side is the free surface and it faces the outside of an organ or the inside of a tube or passageway.
Source: Davidson College Biology Department
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Epithelial tissues are named according to the number of cell layers they have and to the shape of the cells on the free surface: Simple: A single layer of cells.
The structure of each type of epithelial tissue fits its function.
Simple squamous epithelium is very thin and is suitable for exchange of materials via diffusion. It makes up capillaries and alveoli (air sacs in the lungs).
Stratified squamous epithelium can be found in areas subject to abrasion, such as the esophagus or our skin.
Epithelial Tissue
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4 A dense layer of extracellular matrix that anchors epithelial tissue to underlying tissues is called the
A apical surface.
B epithelia.
C basement membrane.
D lymph.
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5 How would you classify an epithelial tissue that has many layers of cube shaped cells?
A simple cuboidal
B simple squamous
C stratified cuboidal
D stratified columnar
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Connective Tissue
Connective tissue is opposite of epithelial tissue in that it contains few cells and a lot of extracellular matrix. The extracellular matrix includes certain fibers and other chemicals that are secreted by the cells.
There are six major types of connective tissue:
cartilage, bone, adipose (fat), blood, loose
connective and fibrous connective.
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Connective Tissue
Type Description Location
Loose connective
Binds epithelia to underlying tissues and holds organs in
place.
In the skin and throughout body.
Fibrous connective
Attaches muscles to bones and connects bones at joints.
Tendons and ligaments
Bone Hard mineralized tissue that gives structure. Skeleton
BloodLiquid extracellular matrix.
Functions: defense, carry O2 and clotting.
Blood vessels
Cartilage Strong but flexible support.
Various locations: nose, ears,
between vertebrae.
Adipose Stores fat for fuel and insulation. Various locations.
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6 The Achille's tendon attaches the calf muscle to the heel bone. Of what type of tissue is this composed?
A fibrous connective
B cartilage
C loose connective
D adipose
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7 This is the only liquid tissue.
A loose connective
B cartilage
C bone
D blood
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Muscle Tissue
Muscle tissue consists of bundles of long cells called muscle fibers.
There are many contractile proteins arranged a certain way within the cytoplasm of the muscle cells.
Vertebrates have three types of muscle tissue: skeletal, smooth, and cardiac.
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It is attached to bones by tendons and is responsible for voluntary movement. Under the microscope, cells appear striped or striated due to the arrangement of the contractile units; therefore, it is also called striated muscle .
Skeletal Muscle Tissue
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Found in hollow organs and blood vessels. It is "smooth" due to the lack of striations.
It is an involuntary muscle, meaning you do not have to think about your stomach digesting food.
Smooth Muscle Tissue
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intercalated discs nuclei
It forms the contractile tissue of the heart. It is striated, but the cells are branched, not straight as in skeletal muscle.
It has specialized junctions, known as intercalated discs, between cells that rapidly conduct the signal to contract from cell to cell.
Cardiac Muscle Tissue
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8 The iris of the eye is composed of involuntary muscle. What type of tissue is this?
A Cardiac
B Skeletal
C Smooth
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9 Striated muscle is also known as
A cardiac muscle.
B skeletal muscle.
C smooth muscle.
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Nervous Tissue
Nervous tissue is specialized to sense and respond to stimuli, both internal and external by conducting electrical impulses.
The structural and functional unit of nervous tissue is the cell called a neuron.
Nervous Tissue
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Dendrites
Cell body
Axon
Nervous TissueNeurons receive information in the dendrites and transmit that
information via the axon.
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10 The structural and functional unit of the nervous system is the
A neuron.
B dendrite.
C axon.
D glial cell.
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11 Information is received and transmitted in a neuron in which direction?
A axon to dendrite
B dendrite to axon
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Test your knowledge:Tissues
Type Composition Function
EpithelialMany cells tightly packed
together with very little extracellular matrix
Covers body surfaces and lines internal organs and body
cavities
Connective Few cells and a lot of extracellular matrix
Holds tissues and organs in place
Muscle Cells with filaments of protein
Enables body movement
Nervous Nerve cells (neurons) Recieve, process and transmit information
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Organ Systems
Return to Table of Contents
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Organs
In most animals, tissues are arranged into organs that perform specific functions.
Organs are at a higher level of structure than any of the tissues composing them and they perform functions that none of their tissues can do on their own.
An example of an organ that consists of different tissues is the heart, which consists mainly of cardiac muscle but also contains epithelial, connective, and nervous tissue.
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Organ Systems
It takes the integration of several organs into organ systems to carry out the major body functions.
Integumentary SystemIncludes the skin and hair, nails/claws, sweat glands, and oil glands.
Functions of the integumentary system are:· Protection of internal body
structures· Body temperature regulation· Sensation· Vitamin D production· Excretion of a limited amount
of nitrogenous wastes through sweat
· Reservoir for blood
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Consists of three major regions:
Epidermis - outermost regionDermis - middle regionHypodermis - deepest region
Note: Soles of the feet and palms of the hands have an extra layer not found anywhere else in the body
(hypodermis)
Integumentary System
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Skeletal System
The skeleton of animals functions as: · support· movement· protection of organs
There are three main types of skeletons: · hydrostatic skeletons· exoskeletons· endoskeletons
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Hydroskeletons consist of fluid-filled cavities surrounded my muscles. They give the body shape and help protect internal organs.
Hydroskeletons
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Many animals, such as insects and arthropods, have a rigid external skeleton called an exoskeleton.
In some animals (e.g. arthropods) the exoskeleton must be shed as the animal grows. This is a process called molting and it is replaced by a larger exoskeleton as the animal grows.
Exoskeletons
discarded dragonfly nymph exoskeleton
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Endoskeletons consist of hard or leathery metabolically active support structures surrounding the soft tissues and organs of certain animals.
Different types of endoskeletons range from a framework of protein fibers in a sponge up to a complete skeleton made up of bones and cartilage in vertebrates.
Endoskeletons
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Human Skeleton
Our skeleton consists of 206 individual bones and is divided into two regions.
Axial skeleton: skull, vertebral column, and thorax.
Appendicular skeleton: upper and lower limbs and their respective girdles which attach to the axial skeleton
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The muscular system is composed of skeletal, smooth, and cardiac muscle.
Functions of the muscular system include · body movement· maintaining posture · circulating blood
Muscular System
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Movement of the Human Skeleton
The skeletal system and the muscular system work together as the musculoskeletal system to move the human skeleton.
Much of the versatility in movement of our skeleton comes from the various types of articulations (joints) between two or more bones.
Bones serve as attachment points for muscles, via their tendons. Bones of moveable joints are held together by ligaments.
Muscles and bones interact in movement.
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12 In humans, the visible portion of the skin would be part of which layer?
A Dermis
B Epidermis
C Hypodermis
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13 Which is not a function of the integumentary system?
A protection of internal organs
B vitamin B synthesis
C excretion of nitrogenous wastes
D sensation
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14 The nautilus is a mollusk that lives inside of a shell. What type of skeleton does the nautilus have?
A Hydroskeleton
B Endoskeleton
C Exoskeleton
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15 In vertebrates, the bones of moveable joints are held together by
A muscles
B tendons
C ligaments
D dermis
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16 Which type(s) of muscle are involuntary?
A skeletal
B smooth
C cardiac
D B & C
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17 What type of muscle tissue would you find in the walls of a blood vessel?
A striated
B smooth
C cardiac
D skeletal
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There are three main functions of the nervous system:
Sensory input: Recieve signals from sensory receptors. Integration: Interpret the sensory signals and form the appropriate responses.
Motor output: Conduct signals from the integration center to effector organs (muscles or glands) to carry out the response.
Nervous System
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Discuss the scenario below in respect to the functions of the nervous system
Sensory input? Integration?
Motor output?
Nervous System
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Nervous System DivisionsMost animals have a nervous system that is divided into two divisions:
· Central Nervous System (CNS) - brain and spinal cord which act as the main processing centers
· Peripheral Nervous System (PNS) - all other nerves which act as cables that carry information to and away from the CNS.
In this depiction of the nervous system, the CNS is colored red and the PNS is colored blue.
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The organization of the nervous system varies throughout the animal kingdom. Some animals, sponges for example, lack a nervous system altogether
Hydras have a simple type of nervous system called a nerve net which is a weblike system of neurons extending throughout the body. There is no brain and there are no CNS and PNS divisions.
Cephalization refers to the concentration of nerve tissue at the head end of an animal. This is the pattern seen in animals that display bilateral symmetry (having a head end and a tail end)
Nervous System Organization
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Endocrine SystemThe endocrine system is a hormone regulating system. Hormones act as messengers and regulate different body functions. They are produced by a gland in one part of the body, secreted into the blood and carried to another part of the body.
Hormones have a wide range of targets. Some, like the sex hormones, affect most tissues of the body whereas others, like glucagon, only act on specific cells.
Endocrine glands and hormones of the digestive system.
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The hypothalamus, which is part of the brain, has a close association with the endocrine system. It secretes many hormones that regulate the function of other endocrine glands. In fact, the hypothalamus is sometimes referred to as the "master gland" of the body because of its many functions.
Endocrine System
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18 Which structure(s) make up the PNS?
A brain
B spinal cord
C nerves of the arms and legs
D A & B
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19 The concentration of nerve tissue in the head of an animal is called
A internalization
B integration
C centralization
D cephalization
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20 A gland that secretes its products directly into the blood is a(n) ___ gland.
A exocrine
B circulatory
C endocrine
D holocrine
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21 Which gland is sometims referred to as the "master gland" of the body?
A pancreas
B hypothalamus
C pituitary gland
D pineal gland
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The functions of the lymphatic system are:· return interstitial (tissue) fluid to the circulatory
system· fight infection
The components of the lymphatic system include lymphatic vessels, lymph nodes, tonsils and adenoids, appendix, spleen, bone marrow, and the thymus gland.
The bone marrow and thymus is where white blood cells are made.
Lymphatic/Immune System
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Innate immunity functions via phagocytosis. In this picture, the phagocyte (yellow) in engulfing a bacterial cell (orange). After ingesting a pathogen, digestive enzymes will destroy them.
Animals have two types of immunity:· Innate immunity - nonspecific immunity against pathogens· Acquired immunity - specific immunity against pathogens; only
present in vertebrates
Lymphatic/Immune System
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Acquired immunity targets pathogens to which an organism has previously been exposed. When a pathogen is recognized by the immune system, specific lymphocytes are triggered that can react to and destroy the pathogen.
Describe how vaccines and acquired immunity are related?
Lymphatic/Immune System
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Respiratory System
The function of the respiratory system is to exchange oxygen and carbon dioxide in the body. The part of an animal where gases are exchanged with the environment is called the respiratory surface.
Respiratory surfaces must be moist in order to function properlybecause gases are dissolved in water before diffusing across these surfaces.
Gas exchange in this newt occur in the feathery gills behind the head.
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Other animals have body parts that are adapted for respiration because their skin surfaces are not extensive enough to provide gas exchange for the entire body. Examples of these include gills in fish, and lungs in mammals.
Some animals, such as earthworms, use their entire outer skin as a respiratory organ. Gases are exchanged via diffusion.
Respiratory System
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Respiratory System
In humans the flow of oxygen is: mouth/nasal cavity, larynx, trachea, bronchial tubes, alveoli.
Gas exchange occurs across the mucus membranes of the aveoli into the capillaries that surround them.
Source: National Heart, Lung, and Blood Institute
CO2 exits the body by moving from the capillaries into the aveoli and out through the mouth.
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Urinary System
The urinary system excretes urine and regulates the amount of water and ions in body fluids.
In order to survive in any environment, an animal needs to balance its need for water with the disposal of waste.
In humans, the main organs of the urinary system are the kidneys.
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Each day, our kidneys filter out about 180 L of fluid as blood filters through them. This is referred to as filtrate and consists of water, urea and many other solutes. Of this, only about 1.5L of concentrated waste is excreted from the body.
What do you think would happen if we excreted ALL of this filtrate every day?
Urinary System
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Filtration: Water and mostly any other molecule small enough to pass through the capillary wall enters the kidney.
Reabsorption: Water and valuable solutes are returned to the blood from the filtrate.
Secretion: Substances in the blood are transported into the filtrate. This eliminates certain drugs and other toxins.
Excretion: The product of the first three processes is urine. This passes from the kidneys into the ureters which lead to the urinary bladder. From the bladder, the urine passes to the outside via the urethra.
Urinary System Processes
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22 A main tool of innate immunity is
A exocytosis.
B recognition.
C phagocytosis.
D memory.
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23 A toddler contracts chickenpox at the age of 3. As an adult, she is exposed to the disease when she works at a daycare. What type of immunity protects her from getting sick a second time?
A acquired
B innate
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24 There are a variety of respiratory surfaces in animals. What is true of all of them?
A They must have access to capillaries.
B They must have moist surfaces.
C They must have a mouth or nasal cavity.
D They must be located inside the body.
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25 In humans, oxygen travels into the capillaries from what structure?
A trachea
B pharynx
C arteries
D aveoli
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26 The main organ of the urinary system is the
A ureter
B kidney
C bladder
D liver
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27 During which process are certain drugs and other toxins transported from the blood into the filtrate in the kidneys?
A Filtration
B Reabsorption
C Secretion
D Excretion
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Digestive System
The functions of the digestive system are:
· Ingestion: the act of eating· Digestion: the process of breaking
food down into molecules small enough to absorb
· Absorption: the uptake of nutrients by body cells
· Elimination: the passage of undigested material out of the digestive compartment
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Most other animals have a digestive tube with two openings, a mouth and an anus. The tube is called the alimentary canal.
Simple vs. Complex Digestive Systems
Simple animals, such as cnidarians and flatworms, have a digestive compartment called the gastrovascular cavity with a single opening called the mouth.
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In the alimentary canal, food moves in one direction and specialized regions of the tube carry out digestion and absorption in sequence. Food is pushed along the canal by peristalsis, rhythmic contractions of smooth muscles in the wall of the canal.
Alimentary Canal
Mouth
Pharynx
Esophagus
Intestine
Anus
The alimentary canal is divided into the following regions:
· Mouth: Where food enters· Pharynx: The throat region· Esophagus: Channels food to a
compartment (such as the stomach)· Intestine: Main site of chemical
digestion and nutrient absorption· Anus: Undigested material is expelled
through this region
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In addition to the alimentary canal, the digestive system contains accessory glands that secrete digestive juices through ducts.
Accessory Glands
Accessory glands include the:· salivary glands - secretes amylase, an
enzyme that breaks down starch· pancreas - secretes digestive enzymes into
the small intestine to break down food· liver - produces bile that aids in the digestion
of fats· gallbladder - stores bile
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The structure of the digestive system varies based on the functions necessary in various animals.
Dentition, an animal’s assortment of teeth, varies based on diet.
Herbivores generally have longer alimentary canals than carnivores, reflecting the longer time needed to digest vegetation.
Many herbivores have fermentation chambers, where symbiotic microorganisms digest cellulose.
Structural Variations
Sheep skullDog skull
Explain differences in
sheep and dog dentition.
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28 Which stage of food processing is occurring when nutrients diffuse into capillaries in the small intestine?
A ingestion
B digestion
C absorption
D elimination
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29 Cnidarians have a simple digestive system with one opening. This is called a(n)
A alimentary canal.
B pharynx.
C gastrovascular cavity.
D anus.
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30 In which part of the alimentary canal does most digestion and absorption take place?
A oral cavity
B intestine
C stomach
D liver
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31 Rhythmic contractions of the muscles of the walls of the alimentary canal are called
A peristalsis.
B spasms.
C voluntary contractions.
D reflux.
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32 Which of the following is not an accessory organ for digestion?
A salivary glands
B liver
C pancreas
D spleen
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33 Why do herbivores have longer alimentary canals than carnivores?
A Ingestion takes longer in herbivores.
B Digestion takes longer in herbivores.
C Elimination takes longer in carnivores.
D Carnivore dentition allows faster digestion.
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Circulatory SystemEvery organism must exchange materials with its environment. This exchange ultimately occurs at the cellular level.
Small, simple animals exchange materials directly with the environment via diffusion. For large, more complex animals, diffusion is not a sufficient method of exchange. These animals have a circulatory system.
These flatworms exchange materials via diffusion.
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Circulatory System
Both open and closed circulatory systems have three components:1. Circulatory fluid (blood or hemolymph)2. Tubes (blood vessels)3. Muscular pump (heart)
There are two types of circulatory systems: open or closed.
Closed Circulatory System
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Blood Components
Blood consists of several kinds of cells and cell products suspended in a liquid matrix called plasma:· Erythrocytes (red blood cells): transport oxygen· Leukocytes (white blood cells): defense/immunity· Platelets: involved in blood clotting
erythrocyte
leukocyte
platelet
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Open Circulatory System
This system is called "open" because blood is pumped through open-ended vessels and flows out among cells.
There is no distinction between blood and interstitial fluid, and this general body fluid is more correctly called hemolymph.
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Closed Circulatory System
In a closed circulatory system, blood is confined to vessels and is distinct from the interstitial fluid.
Closed systems are more efficient at transporting circulatory fluids to tissues and cells.
As a result, this type of system is more commonly referred to in vertebrates as the cardiovascular system.
Closed Circulatory System
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There are three types of blood vessels in a closed circulatory system:· Arteries: Carry blood away from the heart to the body· Veins: Return blood towards the heart from the body· Capillaries: Microscopic blood vessels that carry blood
between arteries and veins
NOTE: Arteries and veins are distinguished by the direction in which they carry blood.
Blood Vessels
Red blood cells pass single file through a capillary.
This ensures that each red blood cell comes in close contact with the surrounding tissue to maximize the exchange of materials.
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Circulatory System
In addition to transporting O2 and nutrients, the circulatory system conveys metabolic waste products to the appropriate organs for disposal:
CO2 is taken to the lungs and is expelled when you exhale.
Nitrogenous waste products are taken to the kidneys where they are expelled in the urine.
The circulatory system also functions in immunity via the leukocytes.
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Vertebrate cardiovascular systems range from 2-4 chambers.
Fish: two main chambers: one ventricle and one atrium.
Amphibians: three-chambered heart: two atria and one ventricle.
Turtles, snakes, and lizards : a three-chambered heart in which the ventricle is partially divided.
Crocodilians: a three-chambered heart with a completely divided ventricle
Mammals and birds : a four chambered heart (two atria and two ventricles). The left side of the heart pumps and receives only oxygen-rich blood, while the right side receives and pumps only oxygen- poor blood.
Chambered Hearts
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Evolution of the Heart
In what animal does mixing of oxygenated and deoxygenated blood occur?
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34 Which of the following exeriences mixing of blood and interstitial fluid?
A three chambered heart of a frog
B two chambered heart of a fish
C open circuatory system of a grasshopper
D three chambered heart of a crocodile
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35 Which type of blood vessels carry blood away from the heart?
A arteries
B capillaries
C veins
D venules
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36 Red blood cells, whose main function is to transport oxygen, are more properly known as
A leukocytes.
B thrombocytes.
C platelets.
D erythrocytes.
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37 Which of the following is not a function of the circulatory system?
A Remove metabolic waste
B Transmit nerve responses
C Transport oxygen and nutrients
D Aid in immunity
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Integration of Organ SystemsAlthough organ systems each have specific functions, they usually work together to carry out those functions.
Think about the following processes and determine which organ systems are involved in each:
Many animals maintain relatively constant conditions in their internal environment through a process known as homeostasis.
Even as external conditions fluctuate widely, homeostatic mechanisms regulate internal conditions to keep systems functioning at their optimum.
There are two types of feedback systems that regulate homeostasis:· Negative feedback · Positive feedback
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Most of the control mechanisms of homeostasis are based on negative feedback . Negative feedback is when a change in a variable triggers mechanisms that reverse that change.
Negative Feedback System
The thermostat in your house works this way. When it registers that it has gotten too cold, the thermostat sends a signal to the furnace to turn on and raise the temperature in the house. The change (cold temperature) triggers mechanisms to reverse it (make it warm).
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Histamines released.
Blood vessels dilate.
Redness and swelling.
Positive Feedback System
A positive feedback system is one in which homeostasis is regulated by magnifying a change instead of reversing it.
The inflammatory response is an example of positive feedback. When injury/infection occurs, histamines are released at the site of damage. Histamines cause local blood vessels to dilate. Blood flow is increased, which causes redness and swelling. The redness and swelling, in turn, cause more histamines to be released. The cycle restarts and is continually amplified until any pathogens are destroyed and homeostasis is restored.
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Thermoregulation
Animals must regulate how they exchange heat with their environment
Different types of animals have different ways of regulating body heat
Animals fit into one of two categories: · ectotherms · endotherms
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Ectotherms
Ectotherms are "cold blooded" animals.
Most of their heat energy escapes into the environment so their body temperature is close to that of their surroundings. Activity of these animals is drastically affected by temperature changes in their environment. When outside temperatures rise, they become more active. When outside temperatures drop, they become more sluggishin their activity.
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Endotherms are the "warm blooded" animals, such as mammals and birds. These animals have evolved homeostatic mechanisms that allow them to use the heat they generate.
Endotherms
They have adaptations such as hair, fur, feathers, and fat that help prevent heat loss. They maintain constant body temperatures that are higher than their environment.
What are some pros and cons for being endothermic and ectothermic?
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38 Which of the following best illustrates homeostasis?
A Most adult humans are between 5 and 6 feet.
B The lungs and intestines have large surface areas.
C When blood salt concentration rises, the kidney expels more salt.
D All the cells of the body are about the same size.
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39 During childbirth, contractions stimulate the release of oxytocin, which in turn cause more contractions. The cycle continues until the baby is born. What type of process is this?
A Negative feedback
B Positive feedback
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40 When blood sugar levels lower below a set point, glucagon prompts the liver to hydrolyze more glycogen which releases glucose into the blood. What type of process is this?
A Negative feedback
B Positive feedback
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41 A crocodile's activity increases when the outside temperature rises. How would you classify this animal?
