Flashcards in chapter 32 pp Deck (68)
Small aquatic animals with no circulatory system
Each cell is exposed to water and can independently exchange gases and eliminate wastes.
Use the coelomic fluid of their body cavity as a means of transporting substances
: double lined gut cavity
Also rely on movement of coelomic fluid within a body cavity as a circulatory system
May still rely on body fluids for the purpose of locomotion
Two types of circulatory fluids
Blood – contained within blood vessels
Hemolymph – mixture of blood and tissue fluid that fills the body cavity and surrounds internal organs
Open Circulatory System
They were first to evolve.
The heart pumps hemolymph via vessels.
Vessels empty into tissue spaces.
Hemolymph drains back into heart
Closed Circulatory System
Most cells in the body aren’t far from a capillary.
Heart pumps blood to capillaries.
Gases and materials diffuse to and from nearby cells.
Vessels return blood to the heart without contact between blood and tissues.
All vertebrates have a closed circulatory system
Atria of the heart receives blood from general circulation
Ventricles of the heart pump blood out through blood vessels
arteries, arterioles, capillaries, venules, veins
Carry blood away from heart
Small arteries which lead to capillaries
Diameters are regulated by nervous and endocrine systems (ex. Temp. control).
Exchange materials with tissue fluid (interstitial)
Join to form a vein
Return blood to heart
Both venules and veins collect blood from capillary beds
Blood flows in single loop
Single atrium and single ventricle
Blood flows in double loop
Systemic circuit and pulmonary circuit
Two atria with a single ventricle
A septum partially divides the ventricle
Mixing of oxygen-rich and oxygen-poor blood is kept to a minimum.
In crocodilians, septum completely separates the ventricle.
Birds and mammals
Blood flows in a double loop (two circuits)
Birds and mammals types of circuits in circulatory system
The heart is also divided by septum into separate sides.
Right ventricle pumps blood to lungs; left ventricle pumps blood to rest of body.
Blood pressure is adequate for both pulmonary and systemic circuits.
The Human Heart
Located between lungs directly behind sternum (breastbone)
Muscular organ (cardiac fibers)
Lies within a membranous sac (the pericardium)
separates the heart into left and right sides.
Each side has two chambers.
atria in the human heart
Upper two chambers are the atria
Receive blood from circulation
ventricles in the human heart
Lower two chambers are the ventricles
Pump blood away from heart
Types of valves
open and close to control blood flow through the heart.
1. Atrioventricular valves
2. Semilunar valves
Tricuspid valve between right atrium and ventricle
Bicuspid valve between left atrium and ventricle
Pulmonary semilunar valve between right ventricle and pulmonary trunk
Aortic semilunar valve between left ventricle and aorta
Contraction of heart chambers
Relaxation of heart chambers