Introduction to Animal Structure

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Chapter 40

• Introduction to Animal Structure Function

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Tissue

• a) epithelial cover exterior lines organs
  cavities (barrier- tightly packed)
• b) connective bind support other tissues
• ex loose, adipose, fibrous, cartilage,
  bone, blood
• c) nervous transmit electrical impulses
• d) muscle long, excitable cells with parallel
  microfilaments most abundant in animals

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Homeostasis

• maintaining internal balance
• negative feedback reaction to shifts in
• variations that reverse mechanisms
• positive feedback triggers mechanisms to
  amplify rather than reverse the change

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Bioenergetics

• -exchange of energy with the environment
• -minimum metabolic rates for endotherms are
  generally higher than for ectotherms
• -rate is inversely related to body size

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Chapter 41

• Animal Nutrition

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Heterotrophic by a variety of methodsStages of
good processing

• ingestion 1st stage act of eating
• digestion enzymatic breakdown of food into
  monomers for absorption
• must occur in specialized compartment where
  hydrolytic enzymes can attack food molecules
  without damaging the animals own cells
• absorption uptake of nutrients by body cells
• elimination passage of undigested materials out
  of the body in feces

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Intracellular digestion
Food particles engulfed digested in vacuoles
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Extracellular digestion
In gastrovascular cavity or alimentary canal
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alimentary canal

• complete with two openings
• mouth pharynx esophagus crop
• gizzard intestine anus

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Mammalian digestive system

• 1-way tract separated by sphincters
• peristalsis moves material through
• accessory glands that add to tract via ducts
• salivary glands
• pancreas
• liver (stores bile in gall bladder)

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• oral cavity site of mechanical digestion start
  of chemical digestion
• gt1L of saliva secreted each day
• Contains mucin (glycoprotein) amylase
• (hydrolytic enzyme)
• bolus ball of food pushed to pharynx to be
  swallowed

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• 2) esophagus carries by peristalsis to
  stomach
• -cardiac sphincter
• stomach stores food grinds secretes gastric
  juice (3L per day)
• small intestine - gt6m in humans most
• digestion almost all absorption
• 1st 25cm duodenum, jejunum, ileum
  absorb great surface area due to villi
  microvilli with blood vessels

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• liver secretes bile to emulsify fats
• pancreas secretes digestive enzymes (zymogens)
  breakdown proteins
• -Ileocecal valve
• large intestine (colon) reabsorbs water
• cecum with appendix
• rectum terminal part of colon
• -2 anal sphincters 1 voluntary 1 involuntary

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Vertebrate digestive system

• dentition dictates diet
• herbivores longer alimentary canals with
  specialized chambers where symbionts digest
  cellulose
• diet carbohydrates stored as glycogen, fats
  (in adipose tissue) are fuel
• vitamins minerals necessary cofactors for
  enzyme action

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Chapter 42

• Circulation Gas Exchange

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• O2, CO2, nutrients metabolic waste exchange
  across fluid bathed membranes
• diffusion is too slow to all cells, so transport
  system is necessary
• Invertebrates gastrovascular cavity
  (Cnidarians,flatworms)
• circulatory system (open or closed)

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• Vertebrates closed system with blood vessels
  2-4 chambered heart
• capillaries connect arterioles venules
• veins carry blood back to heart
• arteries carry blood away from heart
• -1 way flow with valves
• pulmonary circulation to/from lungs
• cardiac through heart
• systemic to/from body

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• heart rate (pulse) determines cardiac output
• volume of blood pumped into systemic circulation
  per minute, which determines pressure
• coordinated by conduction system in sinoatrial
  (SA) node (pacemaker) initiates wave of
  contraction that spreads to both atria,hesitates
  at atrioventricular (AV) node, then to both
  ventricles
• capillary exchange substances traverse
  epithelium by diffusion or are dissolved in
  fluids forced out by blood pressure at atrial
  end

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Blood

• Suspension of cells in plasma (90 water)
• 4-6L of blood on avg.
• pH of 7.4
• RBC (erythrocytes) 25 trillion in blood
• -transport O2 (RBC WBC produced in red bone
  marrow)
• WBC (leukocytes) 5 types
• -phagocytize bacteria debris produce
  antibodies
• platelets fibrinogen allows clotting

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Respiration

• gills aquatic
• tracheae insects
• lungs most terrestrial vertebrates enclosed
  in double walled sac
• nose/mouth inhale air to pharynx
• trachea transports air to lungs branches into
  bronchi bronchioles alveoli
• epiglottis covers opening to trachea (glottis)
• negative pressure breathing in mammals

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Weddell seal
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Chapter 43

• The Bodys Defenses

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Lymphatic system

• Returns fluid to blood aids in body defense
  nodes help fight infection

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Nonspecific defense (general)

• skin/mucus membranes 1st line
• phagocytes (macrophages) 2nd line
• complement (group of 20 proteins)
• Inflammatory response
• prostaglandin increases blood flow
• histamines cause vasodilation

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Specific defense

• Humoral immunity cells (lymphocytes)
• stimulated to secrete antibodies
• B cells proliferate in bone marrow
• T cells mature in the thymus
• both come from stem cells in the bone marrow
  recognize specific pathogens
• antigens foreign molecules that elicit a
  response by lymphocytes are recognized by B T
  cells
• antibodies soluble proteins secreted by B cells
• during an immune response

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Specific defense

• B or T cell activation occurs when an antigen
  binds to a B or T cell
• The lymphocyte forms 2 clones of cells in a
  process called clonal selection,resulting in
• thousands of cells, all specific to this
  antigen.
• effector cells combat the antigen
• memory cells (long-lived) bear receptors for
• the same antigen allowing them to quickly
• mount an immune response in subsequent
• infections

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Specific defense

• T-cell receptors bind antigens that are displayed
  by antigen-presenting cells (APCs) on their MHCs
  (major histocompatibility complex)-
• proteins that are the product of a group of
  genes
• Specificity of B T cells is a result of
  shuffling
• recombination of several gene segments results
  in gt1million different B cells 10 million
• different T cells, ea. responding to only 1
  antigen

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Specific defense

• Cytotoxic T cells destroy body cells that are
  infected by a pathogen or cancer cells
• Helper T cells activate both B and T cells

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Chapter 44

• Regulating the Internal Environment

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Adaptations

• body insulation
• vasodilation/vasoconstriction
• countercurrent heat exchangers
• panting, sweating, bathing
• 5) liver has multiple functions in homeostasis

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Torpor

• Physiological state characterized by decrease in
  metabolism, heart, respiratory rates enables
  temperatures withstanding varying unbearable
  temperatures or absences of food/water
• ex aestivation (summer torpor) hibernation

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Osmoregulatory mechanisms

• transport epithelia single sheet of cells
  facing
• ext. env. or some channel that leads to
  exterior
• through an opening on bodys surface
  transports
• salt followed by osmotic flow of water

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Osmoregulation

• Balance is essential
• Requires mechanisms of osmoregulation
• 2 basic
• 1) osmoconformers (most marine inverts.)
• marine animals that are isotonic with
  their
• SW environments do no actively adjust
• 2) osmoregulators (most marine verts.)
• animals whose body fluids are not isotonic
  with ext.
• env. either discharge or take in water in
  hypertonic
• env.

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Adaptations

• FW organisms
• -take in H2O from hypotonic env. by contractile
  vacuoles (in Protozoa) excrete lots of
  dilute urine
• Terrestrial animals
• -protect against desiccation by drinking
  eating high content water foods by hormonal
  nervous control of thirst, behavioral
  adaptations excretory organs that conserve
  water

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Osmoregulatory mechanisms

• tubular systems
• a) protonephridia (in flatworms) - network of
• closed tubes lacking internal openings
• capped by flame bulbs excrete dilute fluid
• b) metanephridia internal openings that collect
  
• body fluids (in most annelids) pump out
  salt for
• reabsorption dilute urine is excreted
• c) Malpighian tubules remove nitrogenous
• waste from hemolymph produce dry waste
  matter

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Kidney

• compact organ with many excretory tubules
• consisting of nephrons collecting ducts
  associated blood vessels

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Nephron

• Bowmans capsule surrounds ball of capillaries
• called glomerulus
• Proximal tubule
• Loop of Henle
• Distal tubule
• collecting duct gets fluid from several nephrons
  
• passes urine to kidneys central receptacle
  (renal
• pelvis) urine carried by ureter to urinary
  bladder

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• Kidneys transport epithelia regulate blood
  composition
• Nephrons control is through
• a) filtration - blood pressure nonselectively
  filters water small solutes from glomerulus
  into lumen of nephron tubule
• b) secretion additional substances destined
  for excretion are directly secreted from
  interstitial fluid into tubule by active
  passive transport
• c) reabsorption filtered substances that must
  be returned to blood, such as vital nutrients
  water are reabsorbed from filtrate at various
  points along nephron
• Most salt water filtered from blood is
  reabsorbed by proximal tubule NH3, drugs, H are
  selectively secreted into filtrate glucose
  AAs actively transported out of filtrate K
  reabsorbed

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Mammalian kidney

• terrestrial adaptation
• water-conserving
• collecting duct carries filtrate through medulla
  water exits by osmosis
• urea diffuses out of tubule, joining salt in
  forming osmotic gradient enabling kidney to
  produce urine hypertonic to blood
• regulation varies as it moves through nephron
• produces 2 solute gradients making hypertonic
  urine
• bodys hydration needs determine osmoregularity
  of urine

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• ADH (antidiuretic hormone) released in response
  to rise in blood osmolarity signaled by
  osmoreceptor cells in hypothalamus, triggering
  increased water reabsorption by tubule
• JGA (juxtaglomerular apparatus) responds to
  decreased blood pressure or blood volume by
  releasing renin triggering formation of
  angiotensin II (peptide) causes vasoconstriction
  releases aldosterone stimulating reabsorption
  of Na passive flow of H2O from filtrate

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Adaptations

• Excretion of N wastes are secondary function of
  kidney through evolution
• NH3 excreted as
• 1) NH3 in most aquatic animals through gills
  or
• ext. surfaces
• 2) urea (less toxic) converted by liver in
  mammals
• amphibians, excreted in conc. forms
  with
• minimal water loss
• 3) uric acid insoluble precipitate,
  excreted in paste-
• like urine of land snails, insects,
  birds, reptiles
• reproductive mode of terr. animals is
  related to N- waste form