Transcript Circulatory System

Circulation and Defense
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Circulatory System
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Background
Closed system vs. open systems
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Blood Vessels
Arteries
Veins
Capillaries
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Blood Vessels
Arteries - away from heart
-Thick elastic walls – why?
- withstand pressure
- Branch into arterioles
- smaller arteries
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Specific Arteries
Aorta
- largest artery – 2.5cm in diameter
- extends from left ventricle of heart
Carotid
- from aorta to head
- internal to brain, external to face
- have chemoreceptors to detect pH
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Specific Arteries cont’d
Coronary - branch off aorta & lead back to
heart muscle
Brachial - extends from aorta to arms
Hepatic - from aorta to liver
Femoral - from aorta to legs
Renal - from aorta to kidneys
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Veins
To heart
Thinner walls w/ some elastic
Valves to prevent backflow
Venules branch from capillaries to veins
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Specific Veins
Inferior Vena Cava
- from lower body to right atrium
- all veins from lower body lead here
- 3cm in diameter
Superior Vena Cava
- from head to rt. atrium
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Specific veins cont’d
Jugular veins
- from brain & face to superior vena cava
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Capillaries
One cell thick
Site of gas exchange b/w cells & blood
Fluids from tissues re-enters blood due to
hypertonicity (increased plasma protein
concentration)
Edema – swelling of tissue – water retention
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The Heart
2 pathways of circulation
- pulmonary circulation - b/w heart & lungs
blood becomes oxygenated at lungs
- systemic circulation
b/w heart & all body parts
blood drops off O2, picks up CO2
Path of blood through heart – see diagram
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Features of the Heart
Made of cardiac muscle (cross striated)
Heartbeat has 2 parts
1. Systole
- contracting of muscle
- ventricles push blood out
2. Diastole
- relaxed
- atria filling up
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Heart action
Both atria fill simultaneously
- A-V valves closed
- semilunars closed
A-V valves open as atria contract
Ventricles fill and A-V valves forced shut
Semilunars open as ventricles contract
Blood pushed into arteries
semilunars forced to close
Lub-dupp sound is closing of valves
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Regulation of Heartbeat
Heart beats w/o control from CNS
Contractions coordinated by sinoatrial
node(S-A node) AKA pacemaker
- located in rt. atrium
- made of cells that spontaneously initiate
electrical impulses
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Steps of heart beat
- Pacemaker initiates impulse
- Electric current spreads across both atria
causing them to contract
- A-V node in rt. Atrium hit by impulse
- A-V node stimulates ventricles to contract
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Regulation of Pacemaker
Medulla sends messages (hormones) to
change heart rate
- epinephrine aka adrenaline causes  heart
rate
- temperature causes  heart rate
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Regulation of blood flow
Flow is not even to all parts
Smooth muscles in arterioles constrict &
relax thus changing blood flow
Vasodilation - muscles relax & dilate thus
 blood flow
Vasoconstriction – muscles contract &
constrict the arteriole thus  blood flow
i.e. - after eating
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Blood Pressure
Greater the pressure the greater the flow
Negative feedback regulates pressure
Stretch receptors in aorta & carotids
If pressure  the heart rate should  &
blood vessels should dilate
If pressure  the heart rate should  &
vessels should constrict
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Blood Pressure cont’d
Hypertension – high blood pressure
- dilation doesn’t occur
- medication helps dilate vessels
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Functions of Blood
Transport
- O2
- CO2 and other wastes
- nutrients, hormones, electrolytes
Regulates pH
Regulates temperature
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Components of Blood
2 parts of whole blood
1. Plasma – liquid 55%
2. Cellular part – solid 45%
4-6 L in ave. person
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Plasma
90% water
10%
- substances moving from place to place
ie, nutrients, hormones
- electrolytes – dissolved ions
osmotic balance & pH balance (7.4)
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Plasma cont’d
Plasma proteins
- enzymes
- immunoglobulins – antibodies
- fibrinogens – clotting
- when these proteins are gone the plasma is
called serum
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Red Blood Cells
Aka erythrocytes
Most numerous
Made in bone marrow
Carries O2 - hemoglobin binds w/iron
No nucleus when mature
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White Blood Cells
1 WBC for every 1,000 RBC
Larger than RBC’s
Defends against foreign particles
Made in bone marrow
Mature in spleen, thymus, tonsils, adenoids
& lymph nodes
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WBC’s cont’d
Different types of WBC’s
- macrophages – eating phagocytes
- T lymphocytes
- B lymphocytes
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Platelets
Chips of cells, no nucleus
Smaller than RBC’s
Blood clotting
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The Lymphatic System
Some fluid (plasma) leaks out at capillaries
& doesn’t return
Lymph system returns this fluid (now called
lymph) to the circulatory system
Lymph nodes filter lymph and attack
viruses & bacteria
System also functions in fat absorption
See diagram pg. 934
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The Body’s Defense
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Two Mechanisms
Nonspecific
Specific
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Nonspecific
1st line
skin
mucous membranes
secretions like lysosyme
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Nonspecific cont’d
- 2nd line
a. phagocytic WBC’s (eat & use digestive
enzymes) - 3 kinds
1. Neutrophils
- attracted by chemicals (chemotaxis)
- amoeboid movements
- short life b/c self destruct
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Phagocytic WBC’s cont’d
2. Monocytes which become macrophages
have long pseudopods & long life
3. Eosinophils – defend against lg. parasites
like fluke
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2nd line cont’d
b. Natural Killer Cells
- destroy bodies own cells that are infected
by virus or may cause tumors
- not phagocytic but cause lyseing
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2nd line cont’d
c. Inflammatory response pg. 935
- wounded cells release histamine
- local vasodilation (capillaries dilate) causing
more leaks
- signals phagocytic WBC’s
- more WBC’s to area (pus is dead phagocytes &
fluids)
- local temperature 
- fever
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2nd line cont’d
d. Antimicrobial proteins
* Interferon
- emitted from virus infected cell
- warns neighbors
- neighbors block entry by changing cell
proteins
- prevents cell proliferation
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2nd line cont’d
* Complement system
- 20 proteins interact in steps resulting in
lysis of invader
- some work w/chemotaxins
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Specific Defense – 3rd line
Also known as the immune system
Utilizes lymphocytes & antibodies
Four features of immune system
1. Specificity
2. Diversity
3. Self/nonself recognition
4. Memory
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Specificity
Recognizes & eliminates antigens
Antigens are any foreign invader that
trigger an immune response
- antibody generating
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Diversity
Responds to millions of types of invaders
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Self/Nonself Recognition
Is a problem for transplants
A breakdown here is an Autoimmune
Disorder & results in attacking self cells
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Memory
Remembers antigens previously
encountered
Responds quicker & more effectively on 2nd
or 3rd exposure
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Acquired Immunity
Active Immunity
Body builds its own antibodies to fight
invader
2 types
1. Natural as in chickenpox
2. Stimulated by a vaccine
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Acquired Immunity
Passive
Antibodies given from one organism to
another
2types
1. Take antibiotics
2. From mother to child
Immunity persists only as long as the
antibodies are present
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How specific immunity arises
Lymphocytes provide the specificity &
diversity
1. originate from stem cells in marrow –
mature elsewhere
ie. T-cells in thymus
B-cells in bone marrow
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2. Travel through lymph vessels &
concentrate in nodes & spleen
3. Antigen receptors on cell membrane
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Antigens interact w/lymphocytes inducing
immune response & memory (clonal
selection)
Fig. 43.14 pg. 934
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Immune Responses – 2 types
1. Humoral Immunity
- works on free bacteria, viruses & toxins
- produces antibodies
- uses B-cells
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Immune responses cont’d
2. Cell – Mediated Immunity
- works on bacteria, viruses inside of cells
- also on Protists, parasites, worms,
transplants, cancer cells (nonself cells)
- uses direct action of lymphocytes
- uses T-cells
Diagram pg 942
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Role of Helper T Cells
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Antigen/Antibody
Antigen – macromolecule that causes
immune response
Antibody - Y-shaped quaternary protein
1. Called immunoglobulins
2. Antigen binding sites at tips – pg. 937
3. Types – IgM, IgA, IgG, IgB, IgE
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Rh Factor
Protein on RBC’s
Rh+ means you have this protein
Rh-means you don’t have it
Important during pregnancy – Why?
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Disorders of Immune System
Autoimmune disease
- fails to recognize self
- lupus
- rheumatic fever
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Disorders cont’d
Allergies
- hypersensitivity of defense
- similar to defense against some parasitic
worms
- hayfever – IgE recognizes pollen as
invader
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Disorders cont’d
Immunodeficiency
- Depressed humoral or cell-mediated response
- Causes
a. cancer – Hodgkin's
b. genetic – need bone marrow transplant
c. AIDS Acquired Immunodeficiency Syndrome
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Disorders cont’d
- AIDS
a. infects cells with CD4 receptors
- T-cells (including helper T’s)
- some B-cells
- some macrophages
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AIDS cont’d
b. Immune system responds ok at first then as
more HIV’s accumulate imm. sys. can’t
keep up
c. See graph pg 951
 HIV
T-cells
d. Eventually imm. sys. can’t fight off
invaders
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