An Introduction to Animal Structure and Function

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• An Introduction to Animal Structure and Function

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Animal Needs

• All animals have a few tenants in common
• They must obtain oxygen from the environment
• They must acquire nourishment and
• They must excrete waste
• To study these tenants we look at an animals
• Anatomy the structure of an organism and
• Physiology the functions an organism performs

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Tissue Types

• Basis of anatomy are tissues
• Epithelial (barrier against mechanical injury,
  microbes, and fluid loss)
• Connective (binds and supports other tissues)
• Muscle (movement)
• Nervous (senses stimuli and transmits signals)

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Tissues Epithelial

• Epithelial outside of body and lines organs and
  cavities held together by tight junctions
  (specific proteins that form a seal around the
  cells)
• Types of epithelial tissues
• Simple single layer of cells
• Stratified multiple tiers of cells
• Pseudostratified single layer of cells, but
  appears stratified because the varying cell
  lengths
• Basement membrane dense mat of extracellular
  matrix that form the base of the epithelial layer

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Tissues Epithelial

• Cell shapes
• Cuboidal (like dice)
• Columnar (like bricks on end)
• Squamous (like floor tiles)
• Glandular epithelia (absorb or secrete chemical
  solutions, example mucous membranes)

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Tissues Epithelial
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Tissues Connective

• Connective bind and support other tissues
  scattered cells through the extracellular matrix
  
• Collagenous fibers (collagen protein)
  nonelastic and do not tear easily (keeps flesh
  from tearing away from bone)
• Elastic fibers (elastin protein) has a rubbery
  quality that allows the protein to be stretched
  and then pulled back to original shape
• Reticular fibers (thin branched collagen fibers)
  form a tightly woven fabric that joins
  connective tissue to adjacent tissues

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Tissues Connective

• Loose connective tissue binds epithelia to
  underlying tissue holds organs
• Found in loose connective tissue
• Fibroblasts- cells that secrete extracellular
  proteins
• Macrophages- amoeboid WBCs phagocytosis
• Adipose tissue stores fat in adipose cells
  (pads and insulates body and stores fuel)
• Fibrous connective tissue parallel bundles of
  cells (maximizes nonelastic strength)
• Tendons connects muscle to bone
• Ligaments connects bone to bone (joints)

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Tissues Connective

• Cartilage collagen in a rubbery matrix
  (chondroitin) flexible support (acts as cushion
  between vertebrae or joints)
• Bone mineralized tissue by osteoblasts
  (provides strength and support for body)
• Blood liquid plasma matrix erythrocytes
  (RBCs) carry O2 leukocytes (WBCs) immunity
  platelets for clotting

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Tissues Connective
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Tissues Nervous

• Nervous senses stimuli and transmits signals
  from 1 part of the animal to another
• Neuron functional unit that transmits impulses
• Dendrites receives signals from other neurons
• Axons transmits impulses toward another neuron
  or effector

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Tissues Nervous
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Tissues Muscle

• Muscle composed of muscle fibers that are
  capable of contracting when stimulated by nerve
  impulses myofibrils (contraction unit) are
  composed of the proteins actin and myosin
• Skeletal voluntary movement (striated) attached
  to bones by tendons, can only contract
• Cardiac contractile wall of heart (branched
  striated) although striated, it is still
  involuntary
• Smooth involuntary activities (no striations)
  examples digestion, movement of arteries

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Tissues Muscle
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Organ systems

• Digestive-food processing
• Circulatory-internal distribution
• Respiratory-gas exchange
• Immune/Lymphatic-defense
• Excretory-waste disposal osmoregulation
• Endocrine-coordination of body activities
  (hormones)
• Reproductive-reproduction
• Nervous-detection of stimuli
• Integumentary-protection
• Skeletal-support protection
• Muscular-movement locomotion

• Organ organization of tissues
• Mesentaries suspension of organs (connective
  tissue)
• Thoracic cavity (lungs and heart)
• Abdominal cavity (intestines)
• Diaphragm (respiration) separates the thoracic
  and abdominal cavities

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Microscope Activity

• You will be examining various slides of animal
  tissues
• In your lab notebooks, I want you to draw what
  you see at the 100X and 400X powers and label as
  many parts as you can
• You may use your textbooks for aid (look at the
  diagrams on pp.824-826)

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Metabolism

• Bioenergetics and Thermoregulation

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Bioenergetics

• All organisms require chemical energy for normal
  physiological processes
• The flow of energy through an animal is called
  bioenergetics
• Food is the source of the chemical energy needed
  to survive (remember cellular respiration)
• Creation of ATP

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Metabolic Rate

• To gain a further understanding of energy usage,
  scientists measure energy uses for life processes
  to come up with a metabolic rate (the sum of all
  the energy-requiring biochemical reactions
  occurring over some time interval)
• Energy is measured in calories (cal) or
  kilocalories (kcal)

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Determining Metabolic Rate

• Since nearly all energy that is used in cellular
  respiration eventually appears as heat, we can
  measure rate of heat loss
• Use a calorimeter
• Can also measure the amount of O2 used or CO2
  produced through oxidative phosphorylation
  (remember Krebs cycle and electron transport
  chain)
• Rate of food consumption over long period of time
• Not very accurate because a lot of food can be
  stored as fat

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Bioenergetic Strategy

• Many organisms have different life strategies
  that utilize energy differently
• Endothermic warm-blooded their bodies are
  warmed by metabolism and temperature is
  maintained in a narrow range (98.6 F in humans)
• Mostly in birds and mammals
• Ectothermic cold-blooded their bodies are
  warmed by external sources
• Lower energy cost for animal
• Mostly in fish, amphibians, reptiles and
  invertebrates

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Influence on Metabolic Rate

• Many factors also contribute to the metabolic
  rate of animals
• Size in general, the smaller the animal, the
  higher the metabolic rate (mice and other rodents
  use about 20 times more energy/gram than an
  elephant)
• Activity basal metabolic rate (BMR) the basic
  amount of energy needed to sustain basic life
  functions
• Average human male 1600-1800 kcal
• Average human female 1300-1500 kcal
• In general, the more fit an individual, the
  higher the BMR (swimmers, runners, etc)

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Metabolic Activity in Ectotherms

• In ectotherms, the amount of energy needed to
  sustain life functions is determined by the
  environment (this is where they get their energy
  to regulate their temperature)
• In ectotherms, we use a standard metabolic rate
  (SMR) which is based on a specific temperature
  range

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Internal Environments

• How organisms regulate their internal anatomy

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Homeostasis

• Organisms have many strategies to maintain their
  internal environment
• interstitial fluids (fills the spaces between
  cells) are responsible for exchanging waste and
  nutrients
• The goal of metabolism is to maintain a balanced
  steady-state condition where all materials and
  temperatures within the body are in homeostasis
• a narrow range of optimal conditions that allow
  an organism to resist change

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Homeostatis Strategies

• Regulator uses internal mechanisms to moderate
  fluctuations in the environment
• Example Shivering is your bodies response to
  cold (kinetic energy produces heat to warm you
  up)
• Conformer organism is able to alter their
  physiological state to suit their environment
• Example Ectotherms alter their body temperature
  and metabolism based on temperture
• Most organisms are not JUST regulators or
  conformers, but have a wide variety of strategies
  to deal with their environment

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Mechanism of homeostasis

• To enact regulation, any control system has 3
  parts 1) receptor (to sense the changing
  condition) 2) control center (to process the
  condition) and 3) effector (the appropriate
  response)
• There are two ways in which to enact this
  regulation
• Negative feedback change in a physiological
  variable that is being monitored triggers a
  response that counteracts the initial
  fluctuation i.e., body temperature
• Positive feedback physiological control
  mechanism in which a change in some variable
  triggers mechanisms that amplify the change
  i.e., uterine contractions at childbirth

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Thermoregulation negative feedback

• Example Thermoregulation (maintaining a
  specific range of temperature)
• Body senses temperature change (nerves in skin)
• The impulses are sent to the brain to process
• Appropriate response

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Other Strategies of Thermoregulation

• There are 4 basic strategies of heat transfer
• Conduction direct transfer of heat from objects
  touching (lizard on a warm rock)
• Convection transfer of heat by the movement of
  air or liquid (a breeze cooling you down)
• Radiation transfer of heat through space by
  some form of electromagnetic waves (warming up in
  the sunlight)
• Evaporation removal of heat from a surface by
  converting a liquid to a gas (sweating)

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Heat Loss vs. Heat Gain

• Organisms need to use different heat transfer
  strategies to balance heat loss with heat gain
  (maintain temperature homeostasis)
• Insulation many organisms have different
  strategies to limit heat loss or gain through
  insulation (skin, hair, feathers, fat)
• Most of the insulation is provided by the air
  trapped by the hair or fur, or
• The layers of fat in the adipose tissue in the
  hypodermis (lowest layer of skin)

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Heat Loss vs. Heat Gain

• Control of blood flow
• In endotherms, vasodilation (blood vessels
  expand) increases blood flow to the skin and
  warms the skin (blood is from your core)
• To cool the skin, vasoconstriction (blood vessels
  contract) reduce blood flow to skin

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Marine Animals

• An important strategy for many marine mammals and
  birds is countercurrent heat exchange
• Blood vessels are arranged so that warmer,
  internal blood vessels, are near blood vessels
  that are sending blood to extremities
• The warmer blood increases the temperature of the
  cooler blood

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Heat Loss vs. Heat Gain

• Cooling with evaporation
• Can lose heat by evaporation through the skin
  (sweat) or when they breathe (water vapor)
• Dogs panting
• Birds have a pouch of blood vessels in the floor
  of their mouth (panting releases the heat from
  the blood)
• Sweat glands in skin
• Spreading saliva on body

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Energy and Temperature Regulation

• Behavioral responses can help with
  thermoregulation and energy savings during
  stressful environmental conditions
• Reptiles and amphibians basking in the sun or
  finding shade when hot out
• Migration during winter
• Organisms huddle together when cold
• Some organisms are only active when it is warm
  enough

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Energy and Temperature Regulation

• Temperature can induce the body to make brown
  fat, causes the cells to produce heat instead of
  ATP
• Hibernation during the cold (torpor, reduced
  physiological state to save energy lowered body
  temperature and lowered pulse)
• Estivation during hot periods (a state of torpor
  during extreme heat)
• Daily torpor (reduced metabolic activity during
  certain times of the day)

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Adjusting to Temperature

• Animals can also acclimatize to different
  environment temperature
• Mammals and birds adjust the amount of insulation
  (thicker coat of fur or blubber or shedding fur)
• In ectotherms, changes are often made at the
  cellular level
• Produce different enzymes that work at different
  temperatures, produce biological antifreeze