chapter 32 pp Flashcards
Small aquatic animals with no circulatory system
Each cell is exposed to water and can independently exchange gases and eliminate wastes.
Pseudocoelomates
“false cavity”
Use the coelomic fluid of their body cavity as a means of transporting substances
Coelomate echinoderms
: 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.
cardiovascular system.
All vertebrates have a closed circulatory system
Vertebrate heart
Atria of the heart receives blood from general circulation
Ventricles of the heart pump blood out through blood vessels
Vertebrate vessels
arteries, arterioles, capillaries, venules, veins
Arteries
Carry blood away from heart
Arterioles
Small arteries which lead to capillaries
Diameters are regulated by nervous and endocrine systems (ex. Temp. control).
Capillaries
Exchange materials with tissue fluid (interstitial)
Venules
Join to form a vein
Veins
Return blood to heart
Both venules and veins collect blood from capillary beds
fish
Blood flows in single loop
Single atrium and single ventricle
Amphibians
Blood flows in double loop
Systemic circuit and pulmonary circuit
Two atria with a single ventricle
Most reptiles
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
Fist-sized
Located between lungs directly behind sternum (breastbone)
Muscular organ (cardiac fibers)
Lies within a membranous sac (the pericardium)
vessels
c
The septum
separates the heart into left and right sides.
Each side has two chambers.
atria in the human heart
Upper two chambers are the atria
Thin-walled
Receive blood from circulation
ventricles in the human heart
Lower two chambers are the ventricles
Thick-walled
Pump blood away from heart
Valves
Types of valves
open and close to control blood flow through the heart.
- Atrioventricular valves
- Semilunar valves
Atrioventricular valves
Tricuspid valve between right atrium and ventricle
Bicuspid valve between left atrium and ventricle
Semilunar valves
Pulmonary semilunar valve between right ventricle and pulmonary trunk
Aortic semilunar valve between left ventricle and aorta
Systole
Contraction of heart chambers
Diastole
Relaxation of heart chambers
Cardiac cycle
Two-part pumping action that takes about a second
Electrocardiogram (ECG)
A recording of electrical changes that occurs in the myocardium during cardiac cycle
The human cardiovascular system includes two major circular pathways:
Pulmonary Circuit
Systemic Circuit
Systemic Circuit
Takes O2-rich blood from the heart to tissues throughout the body, returning O2-poor blood to the heart through the venae cavae
Pulmonary Circuit
Takes O2-poor blood to the lungs, returning O2-rich blood to the heart
portal system
blood from capillaries goes through veins to another set of capillaries without traveling first through the heart.
Example: hepatic portal system takes blood from intestines directly to the liver
Blood Pressure
Contraction of the heart supplies pressure that keeps blood moving in the arteries.
Normally measured with a sphygmomanometer on the brachial artery, an artery on the upper arm.
Example: 120/80, represents systolic and diastolic pressures
Systolic pressure
results from blood forced into the arteries during ventricular systole.
Diastolic pressure
is the pressure in the arteries during ventricular diastole.
how is blood pressure measured
Blood pressure Is measured in millimeters (mm) of mercury.
Cardiovascular Disease (CVD)
Leading cause of death in most Western countries
Hypertension
High blood pressure
30% of Americans are sufferers
Caused by narrowing of arteries due to atherosclerosis
Atherosclerosis
Accumulation of fatty materials between the inner linings of arteries
Deposits are called plaque
A clot, called a thrombus, may form on an arterial wall
Stroke
A disruption of blood supply to the brain
Results when a cranial arteriole bursts or is blocked by an embolus
Angina pectoris
Painful squeezing sensation from myocardial oxygen insufficiency due to partial blockage of a coronary artery
Heart attack (myocardial infarction)
Coronary artery becomes completely blocked
Stents, or self-expanding wire mesh tubes, can be inserted into blocked artery to keep it open.
If stents are unsuccessful, a coronary bypass may be required in which a surgeon replaces artery with a healthy artery from elsewhere in the body
blood
Transports gases, nutrients, waste products, antibodies, and hormones throughout the body
Helps combat pathogenic microorganisms
Helps maintain water balance and pH
Regulates body temperature
Carries platelets and factors that ensure clotting to prevent blood loss
Red Blood Cells (RBCs)
Small, biconcave disks
Lack a nucleus and contain hemoglobin
Hemoglobin contains
Four globin protein chains
Each associated with heme, an iron-containing group
Manufactured continuously in bone marrow of skull, ribs, vertebrae, and ends of long bones
If the number of RBC is insufficient or if cells don’t have enough hemoglobin, the individual has
anemia.
The hormone, erythropoetin, stimulates RBC production.
Blood Types
Blood type is determined by the presence or absence of a surface antigen.
ABO System
Rh System
Antibodies in the plasma can cause
agglutination. “stickiness”
Cross-reactions occur when antigens meet antibodies.
Organ damage can result.
O is considered
the universal donor
White Blood Cells (WBCs)
Contain a nucleus and lack hemoglobin
Important in inflammatory response
Five main types can be identified.
Divided into two categories based on presence or absence of cytoplasmic granules:
Granular Leukocytes (WBCs)
Contain granules composed of proteins and enzymes used to help defend the body against invading organisms
Neutrophils (WBCs)
phagocytize and digest bacteria
Basophil (WBCs)
contain histamine
Eosinophils (WBCs)
involved in fighting parasitic worms, among other activities
Agranular Leukocytes
Lack granules
Monocytes
migrate into tissues in response to chronic, ongoing infections
Differentiate into macrophages
Fight infection, release growth factors that increase the production of WBCs by the bone marrow
Lymphocytes
T cells and B cells involved in the immune response and antibody production
Platelets
Non-cellular, formed elements
150,000–300,000 per cubic millimeter of blood
Involved in blood clotting
clotting
(coagulation) A blood clot consists of: Platelets Red blood cells Fibrin threads
enzymes that are blood clotts
- Thrombin is an enzyme that, when activated by prothrombin activator, converts fibrinogen to fibrin.
- Fibrin threads wind around the platelet plug to provide a framework for a clot.
- Plasmin destroys the fibrin network
Capillary Exchange
Capillaries are very narrow and tiny RBCs must go through single file.
The movement of fluid through a capillary wall is controlled by osmotic pressure and blood pressure.
Walls of capillaries are very thin to facilitate diffusion of nutrients, gases, and wastes
Solutes diffuse into and out of a capillary according to
their concentration gradient.
Oxygen and nutrients diffuse out of capillaries.
Carbon dioxide and wastes diffuse into the capillary.
Substances leaving capillaries contribute to
interstitial fluid
lymph
Excess interstitial fluid is collected by lymphatic capillaries
Lymph is returned to systemic venous blood when
the major lymphatic vessels enter the subclavian veins in the shoulder region.
