Chapter 48: Circulatory Systems
What is. the primary function of the circulatory system?
Transport necessary materials to the cells of an animal's body
Transport waste products away from cells so. they can be released into the environment
What are the two main types of circulation?
Open and Closed
What are the three components of circulatory systems
1. Fluid containing cells and solutes
2. System of vessels, hollow tubes through with the fluid travels
3. One or. more muscular structures such as a heart. that pumps fluid through the vessels
In an open circulatory system what happens with the fluid?
Hemolymph (fluid) is pumped bone or more hearts through vessels that open into the animal's body cavity
How are nutrients and wastes exchanged in an open. circulatory system?
By diffusion between hemolymph and body. cells
What is the pro of the open circulatory system? The con?
Pro: Metabolically inexpensive
Con: Cannot divert hemolymph to specific tissues
What are examples of organisms who have an open circulatory system?
Arthropods and come mollusks
In a closed circulatory system what is separated?
Blood and interstitial fluid
- Differ in components and chemical composition
Where is a closed. circulatory. system found?
In earthworms, cephalopods, and all vertebrates
What. are the 7 key features of the closed circulatory system?
- Blood is pumped under pressure to one ormolu contractile, muscular hearts
- Blood remains within vessels for distribution
- Solutes exchanged with environment. and body cells
- Blood contains. disease-fighting. cells and molecules
- Can be. adjusted. to watch the animal's metabolic demands
- Capacity to heal themselves when wounded (clots)
- System grows in size as animal grows
What are the two advantages of the closed circulatory system?
Animal can grow larger with more efficient supply
Blood flow can be selectively controlled
In the fishes single circulation, what is. the purpose of the single atrium?
Collects. blood to form tissues
In the fishes single circulation, what is the purpose of the ventricle?
Pumped blood out of the heart
In the fishes single circulation, what is the purpose of the arteries?
Carry the blood away from the heart to the gulls.
In the fishes single circulation, what. is the purpose. of veins?
Returns partially deoxygenated blood to the heart
What does the blood do In the fishes single circulation
Picks up oxygen, drops of carbon. dioxide and goes on through arteries to other body tissues
(T/F)The heart doesn't generate high pressure?
In the fishes single circulation, what limits the rate of circulation?
The rate at which oxygenated blood can be delivered to body cells
What organisms have a double circulation?
Crocodiles, birds, and mammals
What does "double" circulation mean?
Oxygenated and deoxygenated blood separate into two distinct circuits
What is pulmonary. circulation?
Blood. pumped to lungs, then back to heart
What is systematic circulation?
Blood pumped to the body, deoxygenated blood delivered back to heart
What is the major advantage of double circulation?
2 different blood pressures in two different systems
What system adaptations do closed circulatory systems undergo?
Sleep, activity, and emergencies
What is exercise controlled by?
Vasodilation and. vasoconstriction
What is epinephrine?
A hormone from adrenal gland that increases cardiac output (increasing stroke volume and/or. heart rate)
What are baroreceptors?
Stretch receptors in certain arteries (aorta. and carotid) that communicate with brain to signal when blood pressure is outside the normal. range
What might occur when your blood pressure decreases?
Dehydration or hemorrhage
What. are the four components of blood?
What is plasma composed of?
Water, nutrients, oxygen, waste, and hormones
What is leukocytes composed of?
white blood cells
What is erythrocytes composed of?
Red blood cells
What is the function of plasma?
Functions in buffering, fluid balance, and transport of cells and proteins
What is the function of leukocytes?
Defend body against infection and disease
What is the function of erythrocytes?
Oxygen transport using hemoglobin
What is the function of platelets/thrombocytes?
Formation of blood clots
What do. all vertebrate hearts have?
At least one anterior atrium and one lower ventricle
What separates atria and ventricles when more than one is present?
Where does the blood enter?
From systematic or pulmonary veins into atrium
Blood enters the vertebrate heart through? And goes out through?
In: one-way atrioventricular (AV) valves into ventricles
Out: one-way semilunar valves into aorta (systematic) or pulmonary trunk
How is the myogenetic heart excitable?
What muscle is the signaling mechanism that initiates contractions?
What kind of hearts require regular electrical impulses from the nervous system?
What kind of hearts do all vertebrates have?
What are cardiac muscle cells called?
When a bunch of myocytes forms an interlocking network, what is created?
Rapid spread of electric current
What can increase or decrease rate?
How can a myogenic heart beat on its own if dissected out of an animal?
If it is placed in a nutrient bath
What are the two phases of the excitation of the vertebrate heart?
1. Atrial phase
2. Ventricular Phase
What. happens in the atrial phase?
Electrical signals generated at sinoatrial node (SA node)
- Action potentials spread quickly through gap junctions
- Both atria contract together forcing blood through AV valves into ventricles
What happens in the Ventricular Phase?
Electrical impulses reach atrioventricular (AV node)
- Conducts impulse from stria to ventricles
- Both ventricles contract together through Purkinje fibers
What cycle produced a single heartbeat?
What are the two phases of the cardiac cycle?
Diastole and Systole
What is the diastole?
Ventricles are relaxes and fill with blood coming from the atria
What is the systole?
Ventricles contract and. blood is ejected through semilunar valves
When blood pressure is the lowest what phase is the cardiac cycle in?
When blood pressure is the highest what phase is the cardiac cycle in?
Heart valved open and shut in response too?
What are arteries? What do they do?
Layers of smooth muscle and connective tissue around smooth endothelium
Conduct blood away from the heart
Wall of the largest arteries are made of what?
What are arterioles? What do they. do?
Formed as arteries branch repeatedly and become narrower
Can dilate or constrict to control blood distribution to tissues
What are capillaries?
Site of gas and nutrient/waste exchange
What are continuous capillaries?
Smooth walls and small number of tiny openings
What are fenestrated capillaries?
Numerous larger holes
What are the narrowest vessels in the body?
How does blood enter a capillary?
- Pressure forces some water out through openings in capillary walls. and into interstitial fluid (but not red blood cells or large proteins)
Most of the fluid that leaves is __________ at the end of the capillary?
- Pressure decreases along the capillary
- Proteins in the blood create an osmotic force that draws fluid back into blood
What is the purpose of the lymphatic system?
Collects fluid is not captured and will return it to the blood
What are venules?
Small, thin extensions of capillaries
What are veins and what do they do?
Thinner and less muscular than arteries that conduct blood back to the heart
Why are veins needed?
Returning of blood to the heart because residual blood pressure is very low
- Smooth muscle contractions help propel blood
- Veins squeezed by skeletal muscles
What is responsible for blood flow?
Why is blood pressure and blood flow not equal in all regions of an animal's body?
Because of resistance
What is Resistance (R)?
Tendency of blood vessels to slow down the flow of blood
Is blood pressure higher in arteries or in veins?
What is resistance a function of?
Vessel radius, length, and blood viscosity
What is a major mechanism controlling blood flow to a region?
Change in arteriolar resistance
What. is vasodilation?
Increase in radius
What is vasoconstriction?
Decrease in radius
What is resistance to flow controlled by?
Locally produced substances, hormones, and nervous system input
What is Cardiac output (OC)?
Amount of blood the heart pumped in liters/minute
What does Cardiac output depend on?
Size of the heart, how often it beats each. minute, and how much blood it ejects
What is stroke volume?
Amount of blood a heart ejects at each beat
What isCardiovascular disease?
Disease of the heart and blood vessels accounts for more deaths each year in the US than any other cause
What is Hypertension?
High blood pressure
What is a normal resting blood pressure?
Above 140/90 mmHg
What are causes of hypertension?
Obesity, smoking, aging, etc.
How can hypertension be treated?
With. diet, exercise, and drugs
What can hypertension damage in the future?
Formation of plaques and atherosclerosis
What is Myocardial infraction (MI) - heart attack usually caused by?
Blockage of one of the coronary arteries
What can serious. heart attacks lead. to?
Significant. damage or death to the heart
Does dead cardiac muscle regenerate?
What is the. purpose of coronary artery bypasses?
Usage of a healthy blood vessel to replace a blocked coronary artery