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AN INTRODUCTION TO ANIMAL STRUCTURE AND FUNCTION

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Title: AN INTRODUCTION TO ANIMAL STRUCTURE AND FUNCTION


1
AN INTRODUCTION TO ANIMAL STRUCTURE AND FUNCTION
2
Introduction
  • Anatomy is the study of the structure of an
    organism.
  • Physiology is the study of the functions an
    organism performs.
  • Animals are multicellular organisms with their
    specialized cells grouped into tissues.
  • In most animals, combinations of various tissues
    make up functional units called organs, and
    groups of organs that work together form organ
    systems.
  • For example, the human digestive system consists
    of a stomach, small intestine, large intestine,
    and several other organs, each a composite of
    different tissues

3
Organization
  • Tissues are groups of cell with a common
    structure and function.
  • Different types of tissues have different
    structures that are especially suited to their
    functions.
  • A tissue may be held together by a sticky
    extracellular matrix that coats the cells or
    weaves them together in a fabric of fibers.
  • Tissues are classified into four main categories
    epithelial tissue, connective tissue, nervous
    tissue, and muscle tissue.

4
Epithelial Tissue
  • Sheets of tightly packed cells, epithelial tissue
    covers the outside of the body and lines organs
    and cavities within the body
  • riveted together by tight junctions.
  • functions as a barrier protecting against
    mechanical injury, invasive microorganisms, and
    fluid loss.
  • free surface of the epithelium is exposed to air
    or fluid, and the cells at the base of the
    barrier are attached to a basement membrane, a
    dense mat of extracellular matrix.
  • classified by the number of cell layers and the
    shape of the cells on the free surface

5
Types
simple epithelium has a single layer of cells,
and a stratified epithelium has multiple
layers The shapes may be cuboidal (like dice),
columnar (like bricks on end), or squamous (flat
like floor tiles).
6
Epithelial Examples
  • glandular epithelia lining tubules in the thyroid
    gland secrete a hormone that regulates fuel
    consumption.
  • glandular epithelia that line the lumen of the
    digestive and respiratory tracts form a mucous
    membrane that secretes a slimy solution called
    mucus that lubricates the surface and keeps it
    moist.
  • epithelial surfaces of some mucous membranes have
    beating cilia that move the film of mucus along
    the surface.
  • Ex. Lungs have cilia to sweep away debris and
    invaders

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Connective Tissue
  • Connective tissue functions mainly to bind and
    support other tissues.
  • Connective tissues have a sparse population of
    cells scattered through an extracellular matrix.
  • Matrix consists of a network of fibers embedding
    in a uniform foundation that may be liquid,
    jellylike, or solid.
  • most abundant tissue type
  • 3 kinds of connective tissue fibers, which are
    all proteins collagenous fibers, elastic fibers,
    and reticular fibers.

9
Connective Cont
  • Collagenous fibers are made of collagen.
  • Collagenous fibers are nonelastic and do not tear
    easily when pulled lengthwise.
  • Elastic fibers are long threads of elastin.
  • Elastin fiber provide a rubbery quality.
  • Reticular fibers are very thin and branched
  • major types of connective tissues in vertebrates
    are loose connective tissue, adipose tissue,
    fibrous connective tissue, cartilage, bone, and
    blood.

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Nervous Tissue
  • senses stimuli and transmits signals from one
    part of the animal to another.
  • The functional unit of nervous tissue is the
    neuron, or nerve cell.
  • made of a cell body and two or more extensions,
    called dendrites and axons.
  • Dendrites transmit nerve impulses from their tips
    toward the rest of the neuron.
  • Axons transmit impulses toward another neuron or
    toward an effector, such as a muscle cell.

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Muscle Tissue
  • composed of long cells called muscle fibers that
    are capable of contracting when stimulated by
    nerve impulses.
  • muscle fibers are large numbers of myofibrils
    made of the contractile proteins actin and
    myosin.
  • muscle contraction accounts for most of the
    energy-consuming cellular work in active animals
  • 3 types of muscle tissue in the vertebrate body
    skeletal muscle, cardiac muscle, and smooth
    muscle.

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Next Level of Organization
  • In all but the simplest animals (sponges and some
    cnidarians) different tissues are organized into
    organs.
  • vertebrate organs are suspended by sheets of
    connective tissues called mesenteries in body
    cavities moistened or filled with fluid.
  • some organs the tissues are arranged in layers.
  • For example, the vertebrate stomach has four
    major tissues layers.

16
Organ Systems and Functions
17
Overview How it all Works
18
Digestive System
  • Feeding Types Herbivores, such as gorillas,
    cows, hares, and many snails, eat mainly
    autotrophs (plants, algae).
  • Carnivores, such as sharks, hawks, spiders, and
    snakes, eat other animals.
  • Omnivores, such as cockroaches, bears, raccoons,
    and humans, consume animal and plant or algal
    matter.
  • most animals are opportunistic, eating foods that
    are outside their main dietary category when
    these foods are available.
  • For example, cattle and deer, which are
    herbivores, may occasionally eat small animals or
    birds eggs.

19
Ways of Eating
  • suspension-feeders that sift small food particles
    from the water.
  • Deposit-feeders, like earthworms, eat their way
    through dirt or sediments and extract partially
    decayed organic material consumed along with the
    soil or sediments.
  • Substrate-feeders live in or on their food
    source, eating their way through the food.
  • Ex, maggots burrow into animal carcasses and leaf
    miners tunnel through the interior of leaves.

20
Cont..
  • Fluid-feeders make their living sucking
    nutrient-rich fluids from a living host and are
    considered parasites.
  • Mosquitoes and leaches suck blood from animals.
  • Aphids tap the phloem sap of plants.
  • Most animals are bulk-feeders that eat relatively
    large pieces of food.
  • Their adaptations include such diverse utensils
    as tentacles, pincers, claws, poisonous fangs,
    and jaws and teeth that kill their prey or tear
    off pieces of meat or vegetation.

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22
Digesting What Ya Ate
  • The main purpose of the digestive system is to
    breakdown food for fuel, carbon skeletons, and
    essential nutrients
  • four main stages of food processing are
    ingestion, digestion, absorption, and elimination
  • To avoid digesting their own cells and tissues,
    most organisms conduct digestion in specialized
    compartments.
  • Done many different ways in the animal
    kingdom!!!!!!! We will focus on mammals

23
Digestive System
  • mammalian digestive system consists of the
    alimentary canal and various accessory glands
    that secrete digestive juices into the canal
    through ducts
  • Peristalsis, rhythmic waves of contraction by
    smooth muscles in the walls of the canal, push
    food along.
  • Sphincters, muscular ringlike valves, regulate
    the passage of material between specialized
    chambers of the canal.
  • The accessory glands include the salivary glands,
    the pancreas, the liver, and the gallbladder

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From Start to Finish
  • physical and chemical digestion of food begins in
    the mouth.
  • teeth of various shapes cut, smash, and grind
    food, making it easier to swallow
  • Salivary glands secrete saliva that contains
    salivary amylase, an enzyme that starts the
    breakdown of sugar.
  • tongue tastes food, manipulates it during
    chewing, and helps shape the food into a ball
    called a bolus.
  • pharynx, also called the throat, is a junction
    that opens to both the esophagus and the trachea

26
Cont
  • When we swallow, the top of the windpipe moves up
    so that its opening, the glottis, is blocked by a
    cartilaginous flap, the epiglottis.
  • This mechanism normally ensures that a bolus will
    be guided into the entrance of the esophagus and
    not directed down the windpipe.
  • esophagus conducts food from the pharynx down to
    the stomach by peristalsis.
  • stomach stores food and performs preliminary
    digestion
  • stomach is located in the upper abdominal cavity,
    just below the diaphragm. Hold 2L of Food
  • The stomach also secretes a digestive fluid
    called gastric juice and mixes this secretion
    with the food by the churning action of the
    smooth muscles in the stomach wall.

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Cont..
  • high concentration of hydrochloric acid, the pH
    of the gastric juice is about 2 - acidic enough
    to digest iron nails.
  • pepsin, an enzyme in the stomach begins the
    breakdown of proteins.
  • coating of mucus, secreted by epithelial cells,
    that protects the stomach lining
  • epithelium is continually eroded, and the
    epithelium is completely replaced by mitosis
    every three days.
  • Side Note Gastric ulcers, lesions in the
    stomach lining, are caused by the acid-tolerant
    bacterium Heliobacter pylori.
  • Ulcers are often treated with antibiotics
  • it takes about 2 to 6 hours after a meal for the
    stomach to empty

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Cont..
  • small intestine is the major organ of digestion
    and absorption
  • length of over 6 m in humans, the small intestine
    is the longest section of the alimentary canal.
  • In the first 25 cm or so of the small intestine,
    the duodenum, acid chyme from the stomach mixes
    with digestive juices from the pancreas, liver,
    gall bladder, and gland cells of the intestinal
    wall
  • pancreatic amylase splits glycogen into
    disaccharides
  • pancreatic lipase breaks down triglycerides
  • trypsin, chymotrypsin, and carboxypeptidase
    digest proteins
  • nucleases digest nucleic acids
  • bicarbonate ions make pancreatic juice
    alkaline pH now 8

31
Working Together
32
Cont
  • Most digestion occurs in the duodenum.
  • The other two sections of the small intestine,
    the jejunum and ileum, function mainly in the
    absorption of nutrients and water.
  • small intestine has a huge surface area - 300 m2,
    roughly the size of a tennis court. Increase
    surface area increase reaction rate
  • transport of nutrients across the epithelial
    cells is passive, in some cases, as molecules
    move down their concentration gradients from the
    lumen of the intestine into the epithelial cells,
    and then into capillaries

33
Cont
  • Other nutrients, including amino acids, small
    peptides, vitamins, and glucose, are pumped
    against concentration gradients by epithelial
    membranes.
  • This active transport allows the intestine to
    absorb a much higher proportion of the nutrients
    in the intestine than would be possible with
    passive diffusion
  • We absorb 80 to 90 percent of the organic
    material in their food.
  • The active mechanisms of digestion, including
    peristalsis, enzyme secretion, and active
    transport, may require that an animal expend an
    amount of energy equal to between 3 and 30 of
    the chemical energy contained in the meal.

34
Cont
  • Reclaiming water is a major function of the large
    intestine
  • large intestine, or colon, is connected to the
    small intestine at a T-shaped junction where a
    sphincter controls the movement of materials.
  • One arm of the T is a pouch called the cecum. the
    appendix, fingerlike projection of cecum, makes a
    minor contribution to body defense
  • Over 90 of the water is reabsorbed, most in the
    the small intestine, the rest in the colon.
  • Digestive wastes, the feces, become more solid as
    they are moved along the colon by peristalsis.
  • Movement in the colon is sluggish, requiring 12
    to 24 hours for material to travel the length of
    the organ.
  • Diarrhea results if insufficient water is
    absorbed and constipation if too much water is
    absorbed

35
Bacterial Help
  • Living in the large intestine is a rich flora of
    mostly harmless bacteria.
  • One of the most common inhabitants of the human
    colon is Escherichia coli, a favorite research
    organism.
  • As a byproduct of their metabolism, many colon
    bacteria generate gases, including methane and
    hydrogen sulfide.
  • Some bacteria produce vitamins, including biotin,
    folic acid, vitamin K, and several B vitamins,
    which supplement our dietary intake of vitamins.

36
End of the Road
  • The terminal portion of the colon is called the
    rectum, where feces are stored until they can be
    eliminated.
  • Between the rectum and the anus are two
    sphincters, one involuntary and one voluntary
  • Finally evolution has provided many ways for
    animals to get and digest their food. Compare
    carnivore to herbivore, different ways of getting
    food like snakes jaws, and different symbiotic
    bacteria used by different organisms, and

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Differences but same Goal!!
39
Overview
40
References
  • Jack Brown M.S. Biology
  • Shier,David, Jackie Butler, Ricki Lewis Holes
    Human Anatomy and Physiology 10th edition 2004
    McGraw-Hill
  • Marieb, Elaine Essentials of Human Anatomy and
    Physiology 7th edition. 2003 Pearson Education
    Inc Benjamin Cummings pub.
  • Microsoft Encarta Encyclopedia 2004
  • Starr and Taggart The Unity and Diversity of
    Life 10th edition 2004 Thomson Brookes/Cole
  • Campbell and Reece Biology 6th edition 2002
    Benjamin Cummings.
  • Raven and Johnson Holt Biology 2004 Holt,
    Rinehart and Winston.
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