Circulatory System

Phyla with No circulatory System

No circulatory system:

• Porifera

• Cnidaria

• Platyhelminthes

• Rotifera

• Nematoda

Phyla with Circulatory system

Major groups with circulatory systems

• Mollusca

• Annelida

• Arthropoda

• Echinodermata

• Vertebrata

Open Vs Closed Circulatory Systems

Open Circulatory system

• Arhropoda : Crabs, Shrimp

• Mollusca : Soft bodies

Closed Circulatory System

• Annelida : worms

• Vertebrata : fish

Heart Pump Control : Neurogenic vs Myogenic

Neurogenic Heart : Nerves control the heart

meaning : The heartbeat is started and controlled by the nervous system

• Arthropoda :

The nervous system tells the heart when to beat

Example : Insects, crabs, lobster

Myogenic Heart : Muscle makes the beat

Meaning: The heart msucle itself creates the heartbeat without needing a nerve singal to start it

• Annelida

• Vertebrata

The heart has its own natural rhythm

The nervous system can adjust the rate

Respiratory Pigments by phyla

Hemoglobin : ( Red blood pigment )

• Annelida : arthworms

• Vertebrata : Fish , reptiles, birds, mammals

Hemocyanin (Blue blood pigment)

• Arthropoda: Crabs , insects, spiders

No respiratory Pigment

• Profiera

• Cnidaria

• Platyhelminthes

• Rotifera

• Nematoda

• Echindermata

Vertebrate Heart Chambers

Fish : 2 Chambers :

• 1 atrium

• 1 ventricle

Amphibians: 3 chambers :

• 2 atria

• 1 ventricle

Most reptiles

Birds: 4 Chambers :

• 2 atria

• 2 ventricles

mammals

• fish: 2

• Amphibians + Reptiles : 4

• Birds + mammals : 4

Circulation: Key concepts

Purpose

• Move nutrients around body

• Removes waste

• Transport 02

Difussion

• Some animals move materials by passive diffusion

• Other animals need a circulatory system

Circulatory System : Fluid + pump

• Fluid: Blood hemolymph

• Pump: heart

• Respiratory pigments → These help transport 02

Respiratory Pigments

• Help trnasport 02

• Hemocyanin: Copper based oxygen carrying pigment found in arhtropods and mollusks

Open vs closed Circulation

• Open: Hemolymph bathes organs

• Closed: blood stays inside vessels

• Vessels → Arteries, veins, capillaries

Blood vessels

Arteries : carry blood away from the heart

Veins: Carry blood back to the heart

Capillaries: Tiny vessels where oxygen and nutrients are exchanged with tissues

Circuits

• Single : Blood goes through the heart once

• Double: Blood goes through the heart twice

• Chambers: Hearts can have different numbers of chambers

Heartbeat :

• Neurogenic: The nervous system controls the heartbeat

• Myogenic: Heart muscle controls the heartbeat

• Myogenic: Positive ions move through the cells, causing the heart muscle to contract

Circulatory system

• Fluid: bloord or hemolymph

• Pump: heart

Respiratory Pigments

• Help transport 02

• Hemocyanin: Cooper based oxygen carrying pigment found in arthropods and mollusks

Open

• Fluid: Hemolymph

• Hemolymph bathes the organs

• Not completely contained in vessels

Closed

• fluid = Blood

• Blood stays inside vessels

• Vessels= Arteries, veins, capillaries

Blood Vessels

• Arteries : Carry blood away from the heart

• Veins: Carry blood toward the heart

• Capillaries: Tiny vessels where 02 , nutrients and waste are exchanged with tissues

Circuits

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Single circuit

Blood passes through the heart once

Double circuit

Blood passes through the heart twice

Pulmonary circuit

Heat ← → lungs

Systemic circuit

Heart ← → body

HeartBeat

—

Neurogenic

nervous system controls the heartbeat

Myogenic

Heart muscle controls the heartbeat

Myogenic : 2

Positive ions move through the cells, causing the heart muscle to contract