Soft Anatomy Chapter 4

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Soft Anatomy Chapter 4
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Fish Muscle
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Muscle types

• Fish have the same three basic types of muscles
  as other vertebrates skeletal, smooth, and
  cardiac.
• Skeletal Voluntary, used for locomotion,
  comprises the majority of the fishs muscle mass.
• Smooth Involuntary such as intestine, many
  organs, and the circulatory system.
• Cardiac Heart

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Skeletal Fish Muscle

• Essentially three types of fish muscle red,
  white, pink.
• Red muscle (oxidative) Highly vascularized,
  myoglobin containing tissue used during sustained
  swimming. Small diameter and high blood volume
  rich O2 supply! Presence leads to strong flavor
  in some fishes (tuna).
• White muscle (glycolytic) Little
  vascularization. Used during burst swimming.
  Large diameter fibers.
• Pink muscle This one is sort of in between red
  and white. Serves in sustained swimming, but not
  to the extent that red muscle is used.

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Red vs. White Muscle Fibers Red White
Capilary beds Extensive Sparse Muscle fiber
density Low High Myoglobin content High Low Gly
cogen content Low High Muscle mass Low High
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Alimentary Canal

• Essentially the gastrointestinal tract (GI).
• Two parts (Antierior) mouth, buccal cavity,
  pharynx
• (Posterior) esophagus, stomach, intestine,
  rectum.
• Mouth to esophagus rectum is comprised of
  voluntary muscle while the stomach to posterior
  is involuntary.
• GI tract varying considerably from spp. to spp.
  group.
• Nutrient absorption increased by folding and
  increase of surface area (typhlosole, sprial
  valve).

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Alimentary Canal Oddities...

• Esophagus (Peristalsis)
• -one-way trip for food!
• Stomach (Killer pH!)
• -Some tilipia lt2! Can actually break down plant
  cell walls in absence of appropriate gastric
  enzymes.

• No stomach (lungfish)! If no stomach, then no
  HCl no shell or
• bone digestion.

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Alimentary Canal Oddities...

• Intestine
• -Pyloric caeca are fingerlike pouches that may
  aid in nutrient uptake.

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GI (cont.)

• Liver-fat storage, detox., oil source.
• Sharkshuge liver 50 of gut space, but they
  dont get cancer??
• Gallbladdersource of bile (fat emulsification).
• Pancreassource of digestive enzymes
• part of liver in some fish and crustaceans
  (hepatopancreas)

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Buoyancy

• Fish regulate buoyancy several ways
• (1) Low density tissue (liver in
  sharks)increase fat
• (2) Lift from fin movement or hydrodynamics
• (3) Reduced heavy tissue (bones and muscle)
• (4) Gas (swim) bladder

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Gas Bladder

• Used for buoyancy control.
• Physostomas-gas bladder is connected to the
  stomach.
• Buoyancy achieved by gulping air.
• Physoclistous-not connected to stomach. Fish
  has
• developed rete mirable and gas gland which serve
• to promote gas exhange.

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Smooth Cardiac MusclesCirculation and the
Heart
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Circulatory System
Mammals double circuit 1- heart to lungs 2-
heart to body Fish single circuit heart gills
body heart
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Special conditions for fish circulation
Environment is oxygen poor Heart is simplest
of vertebrates Fish have less blood volume
than other vertebrates Adaptations by fish
Composition of blood Morphology of circulatory
apparatus Behavioral responses to oxygen
availability
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Functions of the Circulatory System
Delivers oxygen Delivers nutrients
Removes metabolic waste Fights pathogens
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Components of the Circulatory System to Study
Blood Erythrocytes Leukocytes
Structure of Hemoglobin Vascular system
Heart Vessels
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Blood Oxygen Affinity
pH Decreasing pH decreases affinity
Often associated with carbon dioxide Carbon
dioxide Increase in CO2 drives off O2 (Bohr
effect) Decrease in blood pH magnifies Bohr
effect
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Blood Oxygen Affinity
Temperature Increase in temperature
depresses oxygen affinity and capacity
Results in fish having narrow temperature
tolerances Organic phosphate ATP
depresses O2 affinity Urea increases O2
affinity
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Fish Circulatory System
Primary circulation Closed system
Heart Arteries Capillaries Veins
Secondary circulation Collects blood that is
outside the primary Originally thought to be
lymphatic No lymph or lymph nodes
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Divisions of Primary Circulation
Branchial circulation Blood from heart
through gills Systemic circulation Blood
from gills to body to heart Blood flow is
continuous from heart, to lungs, to body, back
to heart
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Proximity of Heart Gills
Exceptions to Normal Circulation Hagfish
have accessory inline hearts Lungfish have
pulmonary circulation There are also many
small adaptations in some species
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(Vascular circulation in lungfish.)
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Structure of the Fish Heart
Four chambered heart All four chambers are
in line The heart pumps only venous blood
Except for a few air breathing fish, all blood
is pumped to the gills
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Chambers of the Fish Heart
(1) Sinus venous Collects blood from venous
ducts (2) Atrium Accelerates blood flow
(3) Ventricle Large muscled chamber
Provides propulsive flow for circulation (4)
Bulbus arteriosus (bony)         Conus
arteriosus Changes blood from a pulse to
continuous flow
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Conus Arteriosus vs. Bulbus Arteriosus
Conus Arteriosus Contractile Cardiac
muscle More than one valve Bulbus
Arteriosus Elastic Mostly connective
tissue One valve dividing it from ventricle
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Regulation of the Fish Heart
Self-regulating Timing can be modified by
brain (influence on the autonomic nervous
system) Pace is set by pacemaker cells
Many areas show pacemaker activity
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The Hagfish Heart
Most primitive Sinus venous well developed
Divided into two parts to receive different
veins Bulbus arteriosus Have 3
additional hearts Cardinal heart in head
Caudal heart near end of tail Portal heart
pumps blood through liver
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Lamprey Heart
Largest of fish hearts Atrium overlies
ventricle Bulbus arteriosus
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Elasmobranch Heart
Conus arteriosus Sinus venosus with almost
no cardiac muscle Ventricle has two muscle
layers Compacta compact outer layer
Spongiosa inner layer
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Teleost Heart
Variation exists across the group Sinus
venosus is thick-walled Most have bulbus
arteriosus Some have conus arteriosus
(usually more primitive)
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Lungfish Heart
Atrium is divided into two parts by an
incomplete septum Functional 3 chamber heart
Like amphibians Right atrium larger than
left Right deoxygenated from sinus venosus
Left oxygenated from pulmonary vein
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Blood and Freezing Temp.

• Osmolality
• ?fp delta freezing point
• -0.06 FW
• -0.75 SW
• Ice fishes Nototheniidae
• glycoproteins
• Winter Flounder -- Pleuronectes

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Circulatory Systems of Fishes Functions

• Delivery of needed substances for metalolism to
  tissues where needed
• oxygen
• nutrients (sugars, lipids, proteins)
• minerals
• hormones

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Functions of Circulatory System

• Delivery of waste products away from tissues
• carbon dioxide
• nitrogenous wastes (NH3, NH4, urea)
• excess minerals
• invading organisms (pathogens)

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Functions of Circulatory System

• Maintenance of stable pH via buffer system
• H20 CO2 H2CO3 HCO3- H 2H CO3
• Last step only at pH gt 10, so not in fish blood

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Components of Fish Circulatory Systems

• Blood
• aqueous solution
• solutes (proteins, sugars, minerals)
• blood cells
• erythrocytes (red blood cells)
• leucocytes (white blood cells)
• lymphocytes
• thrombocytes
• monocytes
• granulocytes

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Components of Fish Circulatory Systems

• Plumbing
• heart
• sinus venosus
• atrium
• ventricle
• bulbus (conus) arteriosus
• Blood vessels
• arteries
• veins
• capillaries

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Nervous Systems of Fishes

• Sensory, Motor and Integrative Functions

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Organization of the brain(anterior to posterior)

• Telencephalon (forebrain)
• olfactory sensation
• coordination of smell-driven activities
• receives visual and mechanical information, too
• Diencephalon
• homeostasis
• pineal organ (gland)
• light sensitive
• endocrine functions (hypothalamus)

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Brain Organization (anterior to posterior)

• Mesencephalon (mid-brain)
• Optic tectum (dorsal portion of mesencephalon)
• receives visual input (optic nerve)
• central processing center
• coordinates visual input with other sensory
  inputs
• sends out motor signals to musculature, e.g.
  escape response from sight of predator

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Brain (cont.)

• Metencephalon (cerebellum)
• coordinates
• swimming activity
• coordinates
• balance input with motor response
• electrical sense input with motor response

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Organization of the brain(anterior to posterior)

• Myelencephalon (medulla obongata)
• relay system for the senses
• receives sensory input from cranial nerves 3 -
  12
• acoustic
• tactile
• taste
• lateral line
• electrical (some)