Lecture 4 anatomy review for fish disease

Fish AnatomyFish Anatomy

Anatomy/PhysiologyAnatomy/Physiology

Definition of terms:Definition of terms:

• Anterior (cranial)Anterior (cranial) toward the headtoward the head• Posterior (caudal)Posterior (caudal) toward the tailtoward the tail• CranialCranial head regionhead region• CaudalCaudal pertaining to the tail regionpertaining to the tail region• DorsalDorsal toward the back (top) of the animaltoward the back (top) of the animal• Ventral Ventral toward the belly of the animaltoward the belly of the animal• MedialMedial toward the median linetoward the median line• DistalDistal away from the center or originaway from the center or origin• ProximalProximal toward the center or origintoward the center or origin

Anatomy/physiologyAnatomy/physiology• External Anatomy of fish External Anatomy of fish

– The body:The body: divided into head, trunk, and tail. divided into head, trunk, and tail.

– The scales: The scales: primary protection, but still a place primary protection, but still a place pathogens could infiltrate.pathogens could infiltrate.

• Even the head is covered by epidermis and Even the head is covered by epidermis and some scales.some scales.


– Lateral line: Lateral line: is present along middle side of is present along middle side of body. body.

– Head:Head:• Nares:Nares: located on dorsal side of the anterior located on dorsal side of the anterior

end of head. end of head. – Each naris is divided into two portions Each naris is divided into two portions

which permits water to circulate through the which permits water to circulate through the olfactory sac.olfactory sac.


– Head:Head:• Eyes:Eyes: located in lateral position at anterior end located in lateral position at anterior end

of head.of head.

• Ears??Ears??

• Operculum: Operculum: Located at the posterior and Located at the posterior and lateral positions of the head.lateral positions of the head.

• Gill arch: Gill arch: Beneath the operculum are located Beneath the operculum are located four pair of gill arches.four pair of gill arches.


– Head:Head:• Gill arch:Gill arch:

– Each arch bears a gill on its outer surface.Each arch bears a gill on its outer surface.– Each gill consists of two rows of filaments.Each gill consists of two rows of filaments.– Each filament consists of numerous Each filament consists of numerous

lamellaelamellae..– Inner margin of arch bears a single row of Inner margin of arch bears a single row of

tooth-like projections the tooth-like projections the gill rakersgill rakers..

Anatomy/physiologyAnatomy/physiology• Sensory perception of the fish:Sensory perception of the fish:

– Sight:Sight:• Sight is the predominant sense of salmon. Sight is the predominant sense of salmon.

– Hearing:Hearing:• Lateral line perceives sounds of low wave Lateral line perceives sounds of low wave

length.length.• Ear perceived sounds of higher wave lengthEar perceived sounds of higher wave length..

– Equilibrium:Equilibrium:• Organs of equilibrium are the lateral line and the Organs of equilibrium are the lateral line and the

ear.ear.

Anatomy/physiologyAnatomy/physiology• Sensory perception of the fish:Sensory perception of the fish:

– Touch:Touch:

– Smell:Smell:• Long range perception of chemicalsLong range perception of chemicals• Preceptors of smell through olfactory sacPreceptors of smell through olfactory sac

– Taste:Taste:• Taste is the perception of chemicals upon Taste is the perception of chemicals upon

contact.contact.• Taste buds:Taste buds:

• Taste buds located on tongue and head.Taste buds located on tongue and head.

Anatomy/physiologyAnatomy/physiology

• Sensory perception of the fish:Sensory perception of the fish:

– Kinesthetic perception? Kinesthetic perception?

– Temperature:Temperature:

• Function of lateral lineFunction of lateral line


• Functions of various sense organs:Functions of various sense organs:– Eye:Eye:

• SightSight– Ear: Inner earEar: Inner ear

• Equilibrium and hearingEquilibrium and hearing– Nares:Nares:

• SmellSmell– Lateral line:Lateral line:

• Hearing, equilibrium, touch, perception, and Hearing, equilibrium, touch, perception, and temperaturetemperature

Anatomy/physiologyAnatomy/physiology• Internal AnatomyInternal Anatomy

– Skeletal system:Skeletal system:• The function of the skeletal system is one of support.The function of the skeletal system is one of support.

– Skeletal tissues:Skeletal tissues: •

– Axial skeleton:Axial skeleton:• Head, trunk, and tail regions.Head, trunk, and tail regions.

– Head:Head: – Trunk skeleton:Trunk skeleton: modified portion of the modified portion of the

vertebral column.vertebral column.– Tail skeleton:Tail skeleton: remainder of the vertebral column remainder of the vertebral column

Anatomy/physiologyAnatomy/physiology• Supporting tissues:Supporting tissues:

– Connective tissue:Connective tissue: ligaments, tendons, septa, fascia, ligaments, tendons, septa, fascia, and mesenteriesand mesenteries..

• Ligaments:Ligaments: tough bands of tissue between bones. tough bands of tissue between bones.• Tendons:Tendons: thick narrow bands by which muscles are thick narrow bands by which muscles are

attached to the skeleton.attached to the skeleton.• Septa: Septa: are heavy tissues which separate various are heavy tissues which separate various

portions of the body.portions of the body.• Fascia:Fascia: are the thin sheets of connective tissue are the thin sheets of connective tissue

which surround muscles.which surround muscles.• Mesenteries: Mesenteries: are delicate tissues which support the are delicate tissues which support the

organs of the body cavityorgans of the body cavity..

Anatomy/physiologyAnatomy/physiology• Muscular system:Muscular system:

– Three types of muscle tissue: smooth, striated, and Three types of muscle tissue: smooth, striated, and cardiac.cardiac.

– Smooth and cardiac:Smooth and cardiac: muscles are involuntary. muscles are involuntary.– StriatedStriated muscle is voluntary. muscle is voluntary.– Smooth or involuntary muscles:Smooth or involuntary muscles:

• Found in various organs Found in various organs – –

– Cardiac muscle:Cardiac muscle: is striated but involuntary. is striated but involuntary.– Primary function of muscles is motion and locomotion.Primary function of muscles is motion and locomotion.

Anatomy/physiologyAnatomy/physiology• Digestive system:Digestive system:

– Mouth, pharynx, esophagus, stomach, small Mouth, pharynx, esophagus, stomach, small intestine, pyloric cecae, liver and pancreas.intestine, pyloric cecae, liver and pancreas.

– Mouth:Mouth: grasping organ; teeth function to grasping organ; teeth function to retain prey.retain prey.

– Pharynx:Pharynx: leads to the esophagus: leads to the esophagus:

– Esophagus: Esophagus: muscular tube leading from the muscular tube leading from the

pharynx to the stomach.pharynx to the stomach.


• Digestive system:Digestive system:– Stomach: Stomach: consists of two parts: consists of two parts:

• Cardiac:Cardiac: • Pyloric: Pyloric:

–At end of pyloric section: heavy muscleAt end of pyloric section: heavy muscle»Pyloric sphincter:Pyloric sphincter:»

Anatomy/physiologyAnatomy/physiology• Digestive system:Digestive system:

– Intestine:Intestine: duodenum, and small and large duodenum, and small and large intestines.intestines.

– Duodenum:Duodenum: short portion of the intestine short portion of the intestine » pyloric caeca are attached and which pyloric caeca are attached and which

receives the bile duct and the pancreatic ductreceives the bile duct and the pancreatic duct»

– Small intestine:Small intestine: predominant portion of predominant portion of intestinal tract.intestinal tract.

– Large intestine:Large intestine: extremely short and located extremely short and located just anterior to the anus.just anterior to the anus.

Anatomy/physiologyAnatomy/physiology• Digestive glands in the salmon and trout Digestive glands in the salmon and trout

include the gastric and intestinal glands, the include the gastric and intestinal glands, the liver, and the pancreas. liver, and the pancreas. – Gastric glands:Gastric glands:

– Intestinal glands: Intestinal glands:

– Liver:Liver: a bilobed organ located in the anterior and a bilobed organ located in the anterior and left lateral portion of the body cavityleft lateral portion of the body cavity• Gall bladder:Gall bladder: a thin-walled sac embedded in the a thin-walled sac embedded in the

liver,liver,

• Bile duct:Bile duct:


• Pancreas:Pancreas: diffuse gland located on the diffuse gland located on the pyloric caecapyloric caeca

– Pancreatic duct: Pancreatic duct: discharge enzymes into the discharge enzymes into the intestineintestine• Pancreatic juices contain 3 enzymes that act on Pancreatic juices contain 3 enzymes that act on

proteins, carbohydrates, and fatsproteins, carbohydrates, and fats


• Respiratory system:Respiratory system:– Gills: Gills: Function to exchange gasesFunction to exchange gases

• Oxygen absorbed through gills into bloodOxygen absorbed through gills into blood• • Gas exchange:Gas exchange:

– Flow from dense to less denseFlow from dense to less dense

– Air bladder: Air bladder: doesn’t function as respiratory doesn’t function as respiratory organ in salmonidsorgan in salmonids• • Fry and fingerling stages: Fry and fingerling stages: air bladder connected air bladder connected

by duct to the esophagus (surface feeding?)by duct to the esophagus (surface feeding?)

Anatomy/physiologyAnatomy/physiology• Circulatory system: Circulatory system: Blood and lymph Blood and lymph

systemssystems– Blood: Blood: Fluid tissue – liquid plasma and cellular Fluid tissue – liquid plasma and cellular

componentscomponents• Plasma: 80% waterPlasma: 80% water

– Proteins and carbohydratesProteins and carbohydrates– Waste materials Waste materials (urea and uric acid)(urea and uric acid)– Mineral saltsMineral salts– Enzyme secretions from glandsEnzyme secretions from glands– AntibodiesAntibodies

Anatomy/physiologyAnatomy/physiology• Blood cellsBlood cells

– Red cells (erythrocytes)Red cells (erythrocytes)• Flattened, nucleated cells with hemoglobinFlattened, nucleated cells with hemoglobin

– White cells (leukocytes)White cells (leukocytes)•

– Thrombocytes: Thrombocytes: Present in blood and aid in formation Present in blood and aid in formation of blood clotsof blood clots

• Blood vessels: Blood vessels: Closed system which blood circulates Closed system which blood circulates – heart, arteries, veins, and capillaries– heart, arteries, veins, and capillaries– Heart: Heart: Consists of 2 chambers - auricle(atrium) and Consists of 2 chambers - auricle(atrium) and

ventricleventricle

Anatomy/physiologyAnatomy/physiology• Lymph system: Lymph system: consists of plasma and consists of plasma and

leukocytes leukocytes – Starts in the intercellular spaces and eventually empty Starts in the intercellular spaces and eventually empty

into veinsinto veins– – Spleen is associated with lymphatic systemSpleen is associated with lymphatic system– GALT and MALTGALT and MALT

• Blood producing organs:Blood producing organs:–

• Functions is same as bone marrow in mammalsFunctions is same as bone marrow in mammals

– Spleen, lymph nodes, and thymusSpleen, lymph nodes, and thymus: :


• Primary functions of major organs:Primary functions of major organs:• Pancreas:Pancreas:

• Spleen: Spleen: produces leukocytes, serves as a produces leukocytes, serves as a storage space for RBCs, and destroys worn storage space for RBCs, and destroys worn out red blood cellsout red blood cells

• Kidney: Kidney: divided into 2 partsdivided into 2 parts– Anterior: Anterior: produces red and white blood cells produces red and white blood cells – Posterior: Posterior:

• Swim bladder: Swim bladder: hydrostatic organhydrostatic organ


• Heart: Heart: serves to move blood through circulatory serves to move blood through circulatory system – consists of atrium, ventricle, and bulbous system – consists of atrium, ventricle, and bulbous arteriosis (smoothes out pressure to steady flow)arteriosis (smoothes out pressure to steady flow)

• Liver:Liver:– Detoxification, digestion, excretion, and Detoxification, digestion, excretion, and

hematopoiesishematopoiesis• Digestion: Digestion: secretion of bile saltssecretion of bile salts• Excretion: Excretion: destruction of worn out RBCs, destruction of worn out RBCs,

conversion of hemoglobin into bile salts and conversion of hemoglobin into bile salts and ammonium salts into ureaammonium salts into urea

• The liver also serves for storage of glycogen The liver also serves for storage of glycogen (animal starch)(animal starch)

Anatomy/physiologyAnatomy/physiology• Gastro-intestinal tract:Gastro-intestinal tract:

– Cardiac and pyloric stomach:Cardiac and pyloric stomach:•

– Pyloric caeca: Pyloric caeca:

– Small intestine: Small intestine: digestion and absorption of fooddigestion and absorption of food• Enzymes secreted by glands – break down proteins Enzymes secreted by glands – break down proteins

and carbohydratesand carbohydrates• Carbs. and proteins absorbed directly in to Carbs. and proteins absorbed directly in to

bloodstreambloodstream– Large intestine: Large intestine: serves as storage space for serves as storage space for

accumulation of waste before excretionaccumulation of waste before excretion

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Lecture 4 anatomy review for fish disease