Animal Circulatory Systems Flashcards
Circulatory System Basics
- a CIRCULATORY FLUID to facilitate nutrient and/or gas exchange
- TUBES/VESSLES (arteries, capillaries, veins) that transport the fluid
- MUSCULAR PUMP (heart) to move the fluid
Gastrovascular Cavity
not a “true” CS since it lacks a heart and blood vessels; serves the role of a CS since it is integral to the process of distributing digested nutrients
- common in diploblastic animals with radial symmetry
- exchange of fluids is assisted by the pulsing of the animal’s body
Open Circulatory Sysem
the CS with circulatory fluid, vessels, and a muscular pump
- HEMOLYMPH
- the interstitial fluid is also the circulatory fluid
- as the heart beats and the animal moves, the hemolymph circulates around the organs within the body cavity and reenters the heart
- lower pressure required = less energy cost
Hemolymph
circulatory fluid in OCS, is pumped by the heart through vessels but then exits the vessels into a body cavity where it bathes the organs for nutrient and/or gas exchange
- alternative to blood in invertebrates, has alternatives to hemoglobin to bind and transport O2: Hemocyanin, Chlorocruorin, Hemerythrin
Closed Circulatory System
a TRUE CS where the circulatory fluid is pumped by a muscular heart + remains confined to vessels
- circulatory fluid is distinct from interstitial fluid
- CCS are UNIVERSAL among vertebrates + common in some invertebrates
- under high pressure = more energy cost = greater physical pressure and strain
Fish Heart
TWO CHAMBERS AND ONE CIRCUIT; has a single atrium and a single ventricle
- atrium collects blood that has returned from the body
- ventricle pumps the blood to the gills where gas exchange occurs + blood is re-oxygenated (GILL CIRCULATION)
- blood runs continuous throughout the body before arriving back at the atrium (SYSTEMIC (BODY) CIRCULATION
Amphibian Heart
THREE CHAMBERS AND TWO CIRCUITS
- 2 atria receive blood from different circuits
- blood moves into a single ventricle where some mixing occurs, but a ridge helps divert oxygen-rich blood to the systemic circuit and deoxygenated blood to the pulmonary circuit
- perform gas exchange through the lungs and skin
- 3 chambered heart has the oxygenated blood return to the heart for a second pump, improving circulation
Amphibian Heart: Pulmonary Circuit
circuit that goes through the lungs and back to the heart
- atria receives oxygenated blood from lungs/skin
Amphibian Heart: Systemic Circuit
circuit that goes through the rest of the body and organs
- atria receives deoxygenated blood from the body
Reptile Heart
3 CHAMBERS, 2 CIRCUITS, & A PARTIAL SEPTUM
- partial septum results in less mixing of oxygenated and deoxygenated blood
- some aquatic reptiles have a mechanism where the heart shunts blood from the lungs to the stomach and other organs during submergence
- allows for blood to bypass the pulmonary circuit when no gas exchange can occur underwater
- reduces energy requirement for circulating blood throughout the entire body
Bird + Mammal Heart
4 CHAMBERS AND 2 CIRCUITS: 2 atria and 2 ventricles
- oxygenated blood is FULLY separated from deoxygenated blood
- more efficient
- supports the warm-blooded lifestyle
- evolved independent from the 3 Chamber Heart (Convergent Evolution)
Atria/Atrium
upper chambers that receive blood from the veins and pump it into the ventricles
Ventricle
lower chambers that receive blood from the atria and pump it out to the lungs and body
Arteries
take blood AWAY from the heart under high pressure; defined by the fact that they take blood away from their heart, not their oxygenation status
- not all arteries carry oxygenated blood
- lined with thick connective tissue + muscle tissue to support the wall and regulate the pressure sustained
- arteries -> smaller arteries -> arterioles -> capillaries
- this succession helps reach more deeply into muscles and organs
Capillaries
sites for the exchange of nutrients, waste, and oxygen with tissues at the cellular level; occurs in the lungs (capillaries acquire O2 + release CO2) and tissues (opposite process)
- narrow, allowing one single red blood cell to pass at a time
- thin, allowing for exchange
- fluid that leaks out can return and be brought back to the heart via the lymphatic system
- converge again into VENULES (small veins)
EXCHANGE OF GASSES, NUTRIENTS, AND FLUID OCCUR ONLY AT THESE
Veins
RETURN blood to the heart; minor veins connect to major veins to take blood high in CO2 to the heart; veins are blood vessels that work under low pressure
- not all veins carry deoxygenated blood
- lined with connective and muscle tissues
- thinner than arteries
- use valves to prevent blood backflow
- contraction of skeletal muscle assists with the flow of blood back to the heart against gravity
Blood Pressure + Velocity Variation
- blood exits the heart under high pressure and high velocity in the arteries
- pressure and velocity drop rapidly as blood enters the capillaries
- slowest when passing through the capillary system
- velocity increases in veins, but pressure continues to drop
BP + V Variation Regulation
regulated within the capillaries by muscles lining the arterioles and venules on either side of the capillaries
- Vasoconstriction
- Vasodilation
Vasoconstriction
narrowing of the blood vessels that increases blood pressure
- when contracted, blood bypasses the capillary bed + moves directly to the venule
Vasodilation
widening of the blood vessels to reduce blood pressure
- when relaxed, blood flows from the arteriole into capillary branches
VASOOOO
- controlled by small muscles at the start of the capillary bed to regulate blood flow
- ~5-10% of capillary beds receive blood flow at any given time, allowing precise regulation of circulation
Capillary System
- material exchange is facilitated by the slow rate that blood travels through the capillaries + thin diffusion distance
- PLASMA also leaves the capillaries and contributes to the interstitial fluid
- most plasma-derived interstitial fluid returns to the capillaries before they converge to venules because of an OSMOTIC + PRESSURE GRADIENT across the capillary length
Plasma
watery connective tissue in blood; liquid portion of blood containing water, proteins, salts, lipids, and glucose
Interstitial Fluid
extracellular fluid surrounding body tissues
