Cardiovascular SystemChapter 17&18
Blood
• Connective tissue composed of fluid, cells, and fragments of cells
1. Plasma:
• fluid part of blood
• straw-colored
• 55% of blood volume
Blood
2. Red blood cells: (erythrocytes)• round, disk-shaped cells• carry oxygen to cells and carbon dioxide away
attached to hemoglobin• 44% of blood volume• produced in red bone marrow of long bones• lack a nucleus once enter blood stream• only live about 120 days
Blood
3. White blood cells: (leukocytes)• 1% of blood volume• protect body from pathogens• large and many different types• contain a nucleus
neutrophils lymphocytes
eosinophils monocytes
basophils
Blood
4. Platelets:
• cell fragments
• produced in bone marrow
• remain in blood for about 7 days
• clotting with fibrin (becomes scab)
Blood Types
• Types: Red blood cells: Plasma:– IA i or IA IA A: A antigen B antibodies– IB i or IB IB B: B antigen A antibodies– IA IB AB: A and B antigens NO antibodies– i i O: NO antigens A and B antibodiesUniversal donor: Type O-negative (no antigens) is
compatible with all blood types because it has no antigens for other blood types to recognize with their antibodies
Universal Recipient: Type AB-positive has no antibodies in its plasma so it can accept any type without destroying those foreign cells
Rh factor
• Rh factor is an additional antigen found on the red blood cells and it is a separate gene from the ABO gene.
• If a person has two (+) genes for Rh or one (+) and one (-) they will test (+).
• A person will be (-) ONLY if they have two (-) because Rh(+) is dominant.
• Positive means you have the Rh antigen, negative means you don’t.
• Other minor antigens include Kell, Lewis A, Lewis B, rho, P etc. and doctors also attempt to match as many of those minor antigens as possible when selecting blood for transfusions.
Exchange of materials• Animal cells exchange material across
their cell membrane– Diffusion – Osmosis– Passive Transport– Active Transport
• If you are a 1-cell organism that’s easy!
• If you are many-celled that’s harder
In circulation…• What needs to be transported
– Nutrients• from digestive system
– Gases• O2 & CO2 from & to gas exchange systems: lungs, gills
– Wastes• waste products from cells
– water, salts, nitrogenous wastes (urea)
– Protective• immune defenses
– Antibodies and white blood cells
• blood clotting agents
– Stimulants• hormones
Closed circulatory system• Taxonomy
– Some Invertebrates• earthworms, squid,
octopuses
– Vertebrates
• Structure– blood confined to vessels
& separate from interstitial fluid
• 1 or more hearts• large vessels to smaller
vessels
• More effective at transporting fluids
closed system = higher pressures
Vertebrate cardiovascular system
• Chambered heart– Atria = receive blood– Ventricles = pump blood out
• Blood vessels– Arteries = carry blood away from heart
• arterioles
– Veins = return blood to heart• venules
– Capillaries = thin wall, exchange / diffusion • capillary beds = networks of capillaries
Blood vesselsArteries
arterioles
Capillaries
venules
Veins
artery
arteriolesvenules
veins
Arteries: Built for high pressure pump• Thick wall
• provide strength for high pressure pumping of blood
Connective tissue
Smooth Muscle• elastic recoil helps
maintain blood pressure even when heart relaxes
Veins: Built for low pressure flow
• Veins– Thinner Connective tissue– Thinner Smooth Muscle
• blood travels back to heart at low velocity & pressure
• lower pressure– distant from heart– blood must flow by skeletal muscle contractions
when we move » squeeze blood through veins
– Contains valves• in larger veins one-way valves
allow blood to flow only toward heart
Open valve
Blood flowstoward heart
Closed valve
Capillaries: Built for exchange• Small diameter
– No connective tissue or smooth muscle
• lack 2 outer wall layers • only endothelium
– enhances exchange across capillary
– This allows• exchange between blood
& cells
Controlling blood flow to tissues• Blood flow in capillaries controlled by
pre-capillary Spincters• supply varies as blood is needed• after a meal, blood supply to digestive tract increases• during strenuous exercise, blood is diverted from digestive
tract to skeletal muscles
– capillaries in brain, heart, kidneys & liver usually filled to capacity
sphincters open sphincters closed
Lymphatic system• Parallel circulatory system
– Part of Immune system• defending against infection
– collects interstitial fluid & returns to blood• maintains volume & protein
concentration of blood• drains into circulatory
system near junction of vena cava & right atrium
Lymph systemProduction & transport of WBCs
Traps foreign invaders
lymph node
lymph vessels(intertwined amongst blood vessels)
Mammaliancirculation
What do blue vs. red areas represent?What do blue vs. red areas represent?
pulmonary
systemic
systemic
Mammalian heart
Coronary arteries
to neck & head& arms
Coronary arteries
bypass surgery
AV
SL
AV
Heart valves• 4 valves in the heart
– flaps of connective tissue– prevent backflow
• AV valves – between atrium & ventricle– keeps blood from flowing back
into atria when ventricles contract• “lub”
• SL valves– between ventricle & arteries– prevent backflow from arteries into
ventricles while they are relaxing• “dub”
AV
SL
AV
Lub-dub, lub-dub• Heart sounds
– closing of valves– “Lub”
• recoil of blood against closed AV valves
– “Dub”• recoil of blood against
semilunar valves
• Heart murmur– defect in valves causes hissing sound when stream
of blood squirts backward through valve
Cardiac cycle
systolic________diastolic
pump (peak pressure)_________________fill (minimum pressure)
• 1 complete sequence of pumping– heart contracts & pumps– heart relaxes & chambers fill – contraction phase
• Systolic• ventricles pumps blood out
– relaxation phase• Diastolic• atria refill with blood
120
____
80