Download Home Review of Cardiovascular System File

Cardiovascular
Overview for Home Review
The basics
Components of Circulatory System
• Include cardiovascular & lymphatic systems
– Heart pumps blood thru cardiovascular system
– Blood vessels carry blood from heart to cells & back
• Includes arteries, arterioles, capillaries, venules, veins
• Lymphatic system picks up excess fluid filtered
out in capillary beds & returns it to veins
– Its lymph nodes are part of immune system
13-5
Blood
13-6
Composition of Blood
• Consists of formed elements (cells) suspended
& carried in plasma (fluid part)
• Total blood volume is about 5L
• Plasma is straw-colored liquid consisting of H20
& dissolved solutes
– Includes ions, metabolites, hormones, antibodies
13-7
Plasma Proteins
• Constitute 7-9% of plasma
• Three types of plasma proteins: albumins, globulins, &
fibrinogen
– Albumin accounts for 60-80%
• Creates colloid osmotic pressure that draws H20 from interstitial fluid
into capillaries to maintain blood volume & pressure
• Globulins carry lipids
– Gamma globulins are antibodies
• Fibrinogen serves as clotting factor
– Converted to fibrin
– Serum is fluid left when blood clots
13-8
Formed Elements
• Are erythrocytes (RBCs) &
leukocytes (WBCs)
• RBCs are flattened biconcave
discs
Fig 13.3
– Shape provides increased surface
area for diffusion
– Lack nuclei & mitochondria
– Each RBC contains 280 million
hemoglobins
13-9
Leukocytes
• Have nucleus, mitochondria, & amoeboid ability
• Can squeeze through capillary walls (diapedesis)
– Granular leukocytes help detoxify foreign substances &
release heparin
• Include eosinophils, basophils, & neutrophils
Fig 13.3
13-10
Leukocytes continued
• Agranular
leukocytes are
phagocytic &
produce
antibodies
Fig 13.3
• Include
lymphocytes &
monocytes
13-11
Platelets (thrombocytes)
• Are smallest of formed elements, lack
nucleus
• Are fragments of megakaryocytes;
amoeboid
• Constitute most of mass of blood clots
• Release serotonin to vasoconstrict &
reduce blood flow to clot area
• Secrete growth factors to maintain
integrity of blood vessel wall
• Survive 5-9 days
Fig 13.3
13-12
Hematopoiesis
• Is formation of blood cells from stem cells in
marrow (myeloid tissue) & lymphoid tissue
• Erythropoiesis is formation of RBCs
– Stimulated by erythropoietin (EPO) from kidney
• Leukopoiesis is formation of WBCs
– Stimulated by variety of cytokines
• = autocrine regulators secreted by immune system
13-13
Erythropoiesis
• 2.5 million RBCs
are produced/sec
• Lifespan of 120
days
• Old RBCs removed
from blood by
phagocytic cells in
liver, spleen, &
bone marrow
– Iron recycled back
into hemoglobin
production
Fig 13.4
13-14
RBC Antigens & Blood Typing
• Antigens present on RBC surface specify blood type
• Major antigen group is ABO system
–
–
–
–
Type A blood has only A antigens
Type B has only B antigens
Type AB has both A & B antigens
Type O has neither A or B antigens
13-15
Transfusion Reactions
• People with Type A blood
make antibodies to Type B
RBCs, but not to Type A
• Type B blood has antibodies
to Type A RBCs but not to
Type B
• Type AB blood doesn’t have
antibodies to A or B
• Type O has antibodies to
both Type A & B
• If different blood types are
mixed, antibodies will cause
mixture to agglutinate
Fig 13.5
13-16
Transfusion Reactions continued
• If blood types don't match,
recipient’s antibodies
agglutinate donor’s RBCs
• Type O is “universal
donor” because lacks A &
B antigens
• Insert fig. 13.6
– Recipient’s antibodies won’t
agglutinate donor’s Type O
RBCs
• Type AB is “universal
recipient” because doesn’t
make anti-A or anti-B
antibodies
– Won’t agglutinate donor’s
RBCs
Fig 13.6
13-17
Rh Factor
• Is another type of antigen found on RBCs
• Rh+ has Rho(D) antigens; Rh- does not
• Can cause problems when Rh- mother has Rh+
babies
– At birth, mother may be exposed to Rh+ blood of
fetus
– In later pregnancies mom may produce Rh
antibodies
• In Erythroblastosis fetalis, this happens & antibodies
cross placenta causing hemolysis of fetal RBCs
13-18
Hemostasis
• Is cessation of bleeding
• Promoted by reactions initiated by vessel injury:
– Vasoconstriction restricts blood flow to area
– Platelet plug forms
• Plug & surroundings are infiltrated by web of fibrin,
forming clot
13-19
Role of Platelets
• Platelets don't
stick to intact
endothelium
because of
presence of
prostacyclin
(PGI2--a
prostaglandin)
& NO
– Keep clots from
forming & are
vasodilators
Fig 13.7a
13-20
Structure of Heart
• Heart has 4 chambers
– 2 atria receive blood from venous system
– 2 ventricles pump blood to arteries
– 2 sides of heart are 2 pumps separated by muscular septum
Fig 13.10
13-29
Structure of Heart continued
• Between atria & ventricles is layer of dense
connective tissue called fibrous skeleton
– Which structurally & functionally separates the two
• Myocardial cells of atria attach to top of fibrous skeleton
& form 1 unit (or myocardium)
• Cells from ventricles attach to bottom & form another unit
– Fibrous skeleton also forms rings, the annuli fibrosi,
to hold heart valves
13-30
Pulmonary & Systemic Circulations
• Blood coming from
tissues enters
superior & inferior
vena cavae which
empties into right
atrium, then goes to
right ventricle which
pumps it through
pulmonary arteries
to lungs
Fig 13.10
13-31
Pulmonary & Systemic Circulations
continued
• Oygenated blood
from lungs
passes thru
pulmonary veins
to left atrium,
then to left
ventricle which
pumps it through
aorta to body
Fig 13.10
13-32
Pulmonary & Systemic Circulations
continued
• Pulmonary circulation is
path of blood from right
ventricle through lungs
& back to heart
• Systemic circulation is
path of blood from left
ventricle to body & back
to heart
• Rate of flow through
systemic circulation =
flow rate thru pulmonary
circuit
Fig 13.10
13-33
Pulmonary & Systemic Circulations
continued
• Resistance in systemic circuit > pulmonary
– Amount of work done by left ventricle pumping to systemic is
5-7X greater
• Causing left ventricle to be more muscular (3-4X thicker)
Fig 13.11
13-34
Heart Valves
13-35
Atrioventricular Valves
• Blood flows from
atria into ventricles
thru 1-way
atrioventricular (AV)
valves
– Between right atrium
& ventricular is
tricuspid valve
– Between left atrium &
ventricular is bicuspid
or mitral valve
Fig 13.11
13-36
Atrioventricular Valves continued
• Opening & closing of valves results from
pressure differences
– High pressure of ventricular contraction is
prevented from everting AV valves by contraction of
papillary muscles which are connected to AVs by
chorda tendinea
13-37
Semilunar Valves
• During
ventricular
contraction
blood is
pumped
through aortic
& pulmonary
semilunar
valves
– Close during
relaxation
Fig 13.11
13-38
Structure of Blood Vessels
13-65
Structure of Blood Vessels
• Innermost layer of all vessels is the
endothelium
• Capillaries are made of only endothelial cells
• Arteries & veins have 3 layers called tunica
externa, media, & interna
– Externa is connective tissue
– Media is mostly smooth muscle
– Interna is made of endothelium, basement
membrane, & elastin
• Although have same basic elements, arteries &
veins are quite different
13-66
Arteries
• Large arteries are muscular & elastic
– Contain lots of elastin
– Expand during systole & recoil during diastole
• Helps maintain smooth blood flow during diastole
13-67
Arteries
• Small arteries & arterioles are muscular
– Provide most resistance in circulatory system
– Arterioles cause greatest pressure drop
– Mostly connect to capillary beds
• Some connect directly to veins to form arteriovenous anastomoses
Fig 13.27
13-68
Capillaries
• Provide extensive surface area for exchange
• Blood flow through a capillary bed is determined by state of
precapillary spincters of arteriole supplying it
Fig 13.27
13-69
Types of Capillaries
• In continuous capillaries, endothelial cells are tightly
joined together
– Have narrow intercellular channels that permit exchange of
molecules smaller than proteins
– Present in muscle, lungs, adipose tissue
• Fenestrated capillaries have wide intercellular pores
– Very permeable
– Present in kidneys, endocrine glands, intestines.
• Discontinuous capillaries have large gaps in
endothelium
• Are large & leaky
• Present in liver, spleen, bone marrow.
13-70
Veins
• Contain majority of blood in circulatory system
• Very compliant (expand readily)
• Contain very low pressure (about 2mm Hg)
– Insufficient to return blood to heart
13-71
Veins
Fig 13.30
• Blood is moved
toward heart by
contraction of
surrounding
skeletal muscles
(skeletal muscle
pump)
– & pressure drops
in chest during
breathing
– 1-way venous
valves ensure
blood moves only
toward heart
13-72
Heart Disease
13-73
Atherosclerosis
• Is most common
form of
arteriosclerosis
(hardening of
arteries)
Fig 13.32
– Accounts for 50% of
deaths in US
• Localized plaques
(atheromas) reduce
flow in an artery
– & act as sites for
thrombus (blood
clots)
13-74
Atherosclerosis
• Plaques begin at
sites of damage
to endothelium
– E.g. from
hypertension,
smoking, high
cholesterol, or
diabetes
Fig 13.32b
13-75
Lymphatic System
13-86
Lymphatic System
• Has 3 basic functions:
– Transports interstitial fluid (lymph) back to blood
– Transports absorbed fat from small intestine to
blood
– Helps provide immunological defenses against
pathogens
13-87
Lymphatic System continued
• Lymphatic
capillaries are
closed-end tubes
that form vast
networks in
intercellular spaces
– Very porous, absorb
proteins,
microorganisms, fat
Fig 13.37
13-88
Lymphatic System continued
• Lymph is
carried from
lymph
capillaries to
lymph ducts to
lymph nodes
Fig 13.38
13-89
Lymphatic System continued
• Lymph nodes filter
lymph before
returning it to veins
via thoracic duct or
right lymphatic duct
• Nodes make
lymphocytes &
contain phagocytic
cells that remove
pathogens
• Lymphocytes also
made in tonsils,
spleen, thymus
Fig 13.39
13-90
Mucosal Associated Lymphoid
Tissues
•
•
•
•
Tonsils
Peyers patches
Appendix w/ GALT
Others!