Chapter 29: Circulatory System Flashcards
Blood
Fluid that the circulatory system transports throughout the body. Carries many substances including glucose and oxygen gas (O2) required in aerobic cellular respiration. Also carries off waste like CO2.
Heart
Central pump that keeps the blood moving through the vessels
Open circulatory system
Heart pumps fluid through short, open-ended vessels. Vessels lead to open spaces in the body cavity, where the fluid can exchange materials with the body’s cells. Fluid enters other vessels leading back to the heart.
Mollusks and arthropods.
Requires fewer vessels, moves under low pressure.
Closed circulatory system
Blood remains within vessels that exchange materials with the fluid surrounding the body’s tissues.
Vertebrates, annelids and cephalopod mollusk.
Blood moves at a higher pressure so nutrient delivery and waste removal occur more rapidly. Can direct blood flow toward and away from specific areas. More efficient.
Fish heart
Has two chambers: atrium and ventricle.
Atrium
Where blood enters
Ventricle
Where blood exits
Circulatory system is divided into two interrelated circuits
Pulmonary circulation and systematic circulation
Pulmonary circulation
Blood exchanges gases at the lungs and returns to the heart.
Systemic circulation
Blood circulates throughout the rest of the body and back to the heart.
Frog heart
Has three chambers: one undivided ventricle and two atrias.
Left atrium vs right atrium
Left receives oxygen rich blood from the lungs
Right receives oxygen depleted blood from the rest of the body
Blood from both atria mixes in the ventricles which pumps the blood throughout the body.
Plasma
The liquid matrix of blood. Makes up more than half of blood’s volume is 90% to 92% water.
More than 70 types of dissolved proteins make up the largest component of plasma.
Components of blood: a summary
Plasma: exchanges water and many dissolved substances with interstitial fluid
Red blood cells: Carry O2
White blood cells: destroy foreign substances, initiate inflammation
Platelets: initiate clotting
Functions of blood: a summary
Gas exchange: carries O2 from lungs to tissues; carries CO2 to the lungs to be exhaled
Nutrient transport: carries nutrients absorbed by the digestive system throughout the body
Waste transport: carries urea to the kidneys for excretion in urine
Hormone transport: carries hormones secreted by endocrine glands
Creation of interstitial fluid: Interstitial fluid that surrounds cells originates as blood plasma
Maintain homeostasis: regulates blood pH, regulates cells water content, creates pressure gradient
Protection: blood clots plug damages vessels, white blood cells destroy foreign particles
Blood composition
Plasma: 55%= 1% salts, hormones, metabolic wastes, CO2, nutrients and vitamins and 7% proteins
Cells and cell fragments: 45% = red blood cells 95.1%, 4.8% platelets and 0.1% white blood cells
Red blood cells (erythocytes)
Saucer-shaped disks packed with the pigment hemoglobin. Originate from stem cells in red bone marrow.
Fill with hemoglobin, but loses nuclei, ribosomes, and mitochondria. Mature cells cannot divide or repair damage.
Hemoglobin
Protein that carries O2. Carries 4 iron atoms, each of which can combine with one O2 molecule picked up in the lungs.
Blood type
Derives from various carbs and other molecules embedded in the outer membranes of red blood cells. The genes dictating the structures of these molecules may have multiple alleles. each corresponding to a different blood type.
Agglutination
A reaction in which the cells clump together. Caused when antibodies are produced against incompatible blood types.
White blood cells (leukocytes)
Five types. Immune system cells are larger than red blood cells, retain their nuclei, and lack hemoglobin.
Originates from stem cells in red bone marrow. Most wander in body tissues or settle in the lymphatic system.
Leukemias are cancers in which the bone marrow overproduces white blood cells.
Platelets
Small, colorless cell fragments that initiate blood clotting. Travels freely within the vessels.
When a wound nicks a blood vessel, platelets then “catch” on the obstacle and shatter, releasing biochemicals that combine with plasma proteins.
Blood clot
A plug of solidified blood. Deficiencies of vitamins C or K can slow clotting and wound health.
Cardiovascular system
Plasma, cells, platelets that make up blood circulate throughout the body in an elaborate system of blood vessels, thanks to the relentless pumping of the heart.
Cardio= heart; vascular=vessels
Arteries
Large vessels that conduct blood away from the heart
Major arteries
see page 607
Arterioles
Branched from arteries. Smaller vessels than then diverge into a network of capillaries.
Capillaries
Branched from arterioles. The body’s tiniest blood vessels. Empties into venules.
Interstitial fluid
Liquid that bathes the body’s cells. Exchanges materials with the tissue cells.
Venules
Branched from capillaries. Slightly larger vessels which unite to form the veins.
Veins
Formed by venules. Carries blood back to the heart.
How many volumes of blood does the heart pump throughout the body?
7000 liters. Contract more than 2.5 billion times in a lifetime.
Pericardium
Means “around the heart.” Tough connective tissue that surrounds the heart and anchors it to surrounding tissues.
Myocardium
A thick layer of muscle that consists the wall of the heart.
Cardiac muscle
Makes up the myocardium. Contraction provides the force that propels the blood.
Endothelium
One-cell thick layer of simple squamous epithelium. The innermost lining of the heart and of all blood vessels.
How many chambers does the heart have?
Four. Two upper atria and two lower ventricles.
Atrioventricular valves (AV valves)
Thin flaps of tissue that prevent blood from moving back into the atrium when the ventricle contracts.
Semilunar valves
Prevent backflow into the ventricles from the arteries leaving the heart.
What are the two largest veins in the body?
Superior vena cava and the inferior vena cava. They deliver blood from the systematic circulation to the right atrium. Passes into the right ventricle and through the pulmonary arteries.
Pulmonary arteries
Where blood picks up O2 and unloads CO2.
Pulmonary veins
Carry oxygen-rich blood from the lungs to the left atrium of the heart, completing the pulmonary circuit.
Aorta
Largest artery in the body.
Pulmonary circuit
Superior and inferior vena cava deliver blood from the systemic circulation to the right atrium. Blood then passes into the right ventricle and through the pulmonary arteries to the lungs where blood picks up O2 and unloads CO2. The pulmonary veins carry oxygen-rich blood from the lungs to the left atrium of the heart.
Systemic circuit
See pulmonary circuit. Blood flows from the left atrium into the left ventricle. Contraction sense blood into the aorta. Circulates throughout the body before returning to the veins that deliver blood to the right side of the heart.
Portal system
Blood passes from capillaries into a vein that drains into a second set of capillaries before returning to the heart.
Coronary arteries
Supply blood to the heart muscle
Cardiac cycle
Single beat of the heart. Occurs with each contraction and relaxation of the heart muscle.
Cardiac muscle contraction
- Starts at the Sinoatrial (SA) node
- SA node cells fire stimulating the cardiac cells of the atria to contract.
- Electrical impulses race across the atrial wall to the AV node
- The ventricles have time to fill, the AV node conducts electrical stimulation throughout the ventricle walls. The cardiac cells of the ventricles contract in unison.
Lup dup sound comes from the two sets of valves closing, preventing backflow of blood.
Sinoatrial (SA) node
Region of specialized cardiac muscle cells in the upper wall of the right atrium. Pacemaker. When cells fire, they stimulate the cardiac cells of the atria to contract.
Atrioventricular (AV) node
Located in the wall of the lower right atrium.
Cardiac output
A measure of the volume of blood that the heart pumps each minute. Function of the heart rate and the volume of blood pumped her stroke.
EKG reading
P: depolarization of the atria
QRS: depolarization of the ventricles
T: repolorization of the ventricles.
Lub dup sound
Lub: closing of the AV valve
Dup: closing of the semilunar valves during ventricle relaxation
Arteries vs veins
Arteries: carry blood away from the heart
Veins: return blood to the heart
Similarities:
Outermost layer is a sheath of connective tissue
The middle layer is made mostly of smooth muscle
Endothelium forms the innermost layer
Differences:
Arteries is the thick layer of smooth muscle
Capillary beds
Networks of tiny blood vessels that connect an arteriole and a venule
Provides extensive surface area where materials are exchanged with the interstitial fluid. Walls consist of a single layer of endothelial cells, so nutrients and gases diffuse into and out of capillaries.
If pressure in the veins is so low, what propels blood back to the heart against the force of gravity?
Venous valves, flaps that keep blood flowing in one direction.
Blood pressure
Force that blood exerts on artery walls.
A sphygmomanometer measure the changes in blood pressure.
Blood in the arteries have the highest pressure, then capillaries and then veins. Blood velocity is lowest in the capillaries.
Reflects:
Blood vessel diameter, heart rate, and blood volume.
Systolic pressure
Reflects the contraction of the ventricles. The upper number in a blood pressure reading.
Diastolic pressure
Low point. Occurs when the ventricles relax.
Vasoconstriction
Narrowing of blood vessels that results from the contraction of smooth muscle in arteriole walls. When arteriole diameter decreases, blood pressure rises.
Vasodilation
The widening of blood vessels that occurs when the same muscles relax
Lymphatic system
Collects the fluid, removes bacteria, debris, and cancer cells and returns the liquid that leaks out of blood vessels to the blood.
Lymph
Colorless fluid of the lymphatic system. Originates in the lymph capillaries
Lymph capillaries
Tiny, dead-end vessels that absorb fluid from the spaces between cells. Similar to blood plasma, but the proteins are too large to leave blood capillaries.
Lymph nodes
Lymph passes through here. Kidney shaped organs that contain millions of white blood cells. Infection fighting cells intercept and destroy cellular debris, cancer cells and bacteria in the lymph flow.
