Ch: 15 & 16 Blood, Heart, Circulation

Front 1

Functions and Components of the

Circulatory System

(quick overview)

Back 1

• Heart
– Dual pump system

• Blood vessels

– Passageways

• Blood
– Transport mechanisms

– Serves many purposes

Front 2

Circulatory System Functions

Back 2

• Transportation

– Respiratory gases, nutrients, and wastes

• Regulation

– Hormonal and temperature

• Protection
– Clotting and immune

Front 3

Circulatory System Components

Back 3

1.• Cardiovascular system

– Heart: four-chambered pump

– Blood vessels: arteries, arterioles, capillaries, venules, and veins

2.• Lymphatic system

– Lymphatic vessels, lymphoid tissues, lymphatic organs (spleen, thymus, tonsils, lymph nodes)

Front 4

Composition of the Blood

Back 4

• 5 Liters of blood

• Liquid, dissolved proteins, cells

• Viscosity: 5-Ames that of water (thickness)

• pH ~ 7.35

• Composition

– Formed elements: 45% (solids)

– Plasma: 55% (liquid portion of blood)

Front 5

Two components of blood

Back 5

1. Plasma: fluid part of blood

– Plasma proteins
– Serum

2. Formed elements

Front 6

Composition of the Blood: Plasma

Back 6

• Nutrients and metabolites

– Glucose, amino acids, fatty acids, etc

• Hormones

– Insulin, glucagon, sex hormones etc.

• Ions
– Na+ (major ion; maintains osmoAc pressure)

– K+, Ca++, Cl-, Mg++ etc

• Bicarbonate; important buffer

• Respiratory gasses

– O2, CO2
• Waste products

– Urea, food additives etc.

Front 7

Plasma: Three types of plasma proteins

Back 7

-extracelluar (dissolved in blood)

• Proteins consAtute 7-9% of plasma

• Three types of plasma proteins: albumins, globulins, & fibrinogen

1.

2.

3.

Front 8

Albumin

Back 8

accounts for 60-80% (Major protein)

• Creates colloid osmotic pressure that draws H20 from interstital fluid into capillaries to maintain blood volume & pressure

Front 9

Globulins

Back 9

• Alpha and beta globulins transport lipid soluble molecules

• Gamma globulins are antibodies (fight infection)

Front 10

Fibrinogen

Back 10

• a soluble protein that functions in clotting

• Converted to fibrin; an insoluble protein polymer
• Serum is fluid len when blood clots (plasma minus fibrinogen)

Front 11

Erythrocytes

Back 11

AKA red blood cells

– 4-6 million mm3

– Biconcave

• Shape is critical to function

– Carry oxygen

– Lack nuclei and mitochondria

– Have a 120-day life span

– Contain hemoglobin(binds oxygen) and transferrin

Front 12

Composition of the Blood: Formed Elements

Back 12

Platelets (thrombocytes)

- Smallest formed element

– Lack nuclei
- Very short-lived (5−9days)

- Clot blood

- Need fibrinogen

Front 13

Hematopoiesis

Back 13

• Is formation of blood cells from stem cells in bone 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

Front 14

Erythropoiesis

Back 14

• 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

Front 15

Antigens:

Back 15

found on the surface of cells to help immune system recognize self cells

Front 16

Antibodies

Back 16

secreted by lymphocytes in response to foreign cells

Front 17

ABO system:

-possibilities

Back 17

antigens on erythrocyte cell surfaces

• Type A = Has the A antigen

• Type B = Has the B antigen
• Type AB= Has both the A and B antigens
• Type O = Has neither the A nor the B antigen

Front 18

Red Blood Cell Antigens and Blood Typing

Back 18

In a transfusion reaction, a person has antibodies against antigens he/she does not have.

Front 19

agglutination

Back 19

fill in

Front 20

erythroblastosis fetalis in

Back 20

Fill in

Front 21

Who are universal donors?

Back 21

fill in

Front 22

Blood Clotting:

Hemostasis

Back 22

Hemostasis: cessation of bleeding when a blood vessel is damaged

• Process turns liquid blood into solid (gel) by converting soluble protein (fibrinogen) into insoluble protein (fibrin)

• Damage exposes collagen fibers to blood,

producing:

1. Vasoconstriction
2. Formation of platelet plug
3. Formation of fibrin protein web

Front 23

Blood Clotting: Platelets

Back 23

• Platelets don't stick to intact endothelium because of presence of prostacyclin (PGI2--a prostaglandin) & nitric oxide (NO)

– Keep clots from forming & are vasodilators (dilated)

• Also the removal of ADP by CD39 (taking ADP & converting it to AMP) (which keeps from blood clotting)

Front 24

Blood Clotting: Platelets continued

what if we have an injury>

Back 24

• Damage to endothelium allows platelets to bind to exposed collagen

– releases von Willebrand factor; increases bond by binding to both collagen & platelets

– Platelets stick to collagen & release ADP, serotonin, & thromboxane A2

• = platelet release reaction

Front 25

Blood Clotting: Platelet aggregation

Back 25

• Some chemicals (serotonin & thromboxane A2) stimulate vasoconstriction, reducing blood flow to wound

• Other chemicals (ADP& thromboxane A2) cause other platelets to become sticky & attach & undergo platelet release reaction

– This aggregation continues until platelet plug is formed

Front 26

Blood Clotting: Fibrin

Back 26

• Fibrinogen turns to fibrin and forms meshwork around platelets

• Calcium and phospholipids (from the platelets) convert prothrombin to the active enzyme thrombin, which converts fibrinogen to fibrin.

• Conversion of prothrombin(inactive) to thrombin(active) done by Factor X

• How Factor X is controlled depends on the nature of the clotting reaction

– Intrinsic pathway

– Extrinsic pathway

Front 27

Blood Clotting: Fibrin (Intrinsic pathway)

Back 27

Fibrinogen is converted to fibrin via one of two pathways:

1. Intrinsic pathway: Activated by exposure to a negatively charges surface

1. collagen (or glass)
2. Activation of cascade reaction of other blood

factors.
3. Ultimately Factor X is activated

Front 28

Blood Clotting: Fibrin (Extrinsic pathway)

Back 28

Fibrinogen is converted to fibrin via one of two pathways:

2. Extrinsic pathway: shorter/faster pathway

1. Initiated by thromboplastin, only present in tissue

2. Clomng of blood that enters tissues due to injury

3. Thromboplastin directly activates factor X

Front 29

Role of Fibrin

Back 29

• Once fibrin network is established clot now contains platelets, fibrin, trapped RBCs

• Platelet plug undergoes plug contraction to form more compact structure

– Physical restructuring of platlets

– Actin contraction • Analogous to smooth muscle contraction

Front 30

Anticoagulants

Back 30

• Clotting can be prevented with certain drugs:

– Calcium chelators (sodium citrate or EDTA)

– Heparin: blocks thrombin
– Coumarin: inhibits vitamin K

Front 31

Dissolution of Clots

Back 31

When damage is repaired, activated factor XII(12) causes activation of kallikrein

– Kallikrein converts plasminogen to plasmin

• Plasmin digests fibrin, dissolving clot

Front 32

HEP

Back 32

intrinsic and extrinxic pathways of clotting. How are they different, how are they similar?

Front 33

Structure of the Heart: 4 chambers

Back 33

1. Right atrium: receives deoxygenated blood from the body

2. Left atrium: receives oxygenated blood from the lungs

3. Right ventricle: pumps deoxygenated blood to the lungs

4. Left ventricle: pumps oxygenated blood to the body

• Chambers separated by fibrous skeleton

Front 34

Structure of the Heart

Back 34

• Fibrous skeleton:

– Dense collection of connective tissue

– Separates atria from ventricles. The atria therefore work as one unit, while the ventricles work as a separate unit.

– Forms the annuli fibrosi which hold in heart valves

Front 35

The heart is responsible for the continuous pumping of blood through 2 independent systems

Back 35

-Oxygen-rich, CO2-poor blood

-Oxygen-poor, CO2-rich blood

Front 36

Pulmonary Circulations

Back 36

Pulmonary: between heart and lungs

– Blood pumps to lungs via pulmonary arteries.

– Blood returns to heart via pulmonary veins.

Front 37

Systemic Circulations

Back 37

Systemic: between heart and body tissues

– Blood pumps to body tissues via aorta.

– Blood returns to heart via superior and inferior venae cavae.

Front 38

Circulatory Sequence

Back 38

-Arteries run in parallel

-All tissues have access to fully oxygenated blood

-fill in from lecture!

Front 39

Pulmonary & Systemic Circulations

Back 39

• 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))

-much easier to pump blood to lungs, hard to blood blood to the entire body (which is why the left ventricle works much harder )

Front 40

Valves of the Heart: Atrioventricular valves (AV):

Back 40

Atrioventricular valves (AV): located between the atria and the ventricles

– Tricuspid: between right atrium and ventricle

– Bicuspid (mitral): between left atrium and ventricle

Valves: monitors flow (makes sure only flows in one direction)

Front 41

Valves of the Heart: Semilunar valves

Back 41

Semilunar valves: located between the ventricles and arteries leaving the heart

– Pulmonary: between right ventricle and pulmonary trunk

– Aortic: between left ventricle and aorta

Front 42

Valves of the Heart

Back 42

Opening & closing of valves results from pressure differences

– High pressure of ventricular contraction is prevented from inverting AV valves by contraction of papillary muscles which are connected to AVs by chorda tendinea

Front 43

Three Types of Muscle

Back 43

• Skeletal Muscle

– Voluntary

– Striated
– Not interconnected
– Long and not branched

• Cardiac Muscle

– Involuntary

– Striated

– Interconnected via intercalated discs (Gap junctions)

– Functional syncytium

• Smooth Muscle

– Involuntary

– Non-striated

Front 44

Structure of Heart Wall

Back 44

• 3 cell layers
– Endocardium: epithelial tissue

– Myocardium: cardiac muscle

– Epicardium: thin covering of outer surface

• Pericardial Sac:

– Anchors the heart

– Double layer

– Secretes pericardial fluid •-> reduces friction

Front 45

Dividing the heart

Back 45

Left & right (Pulmonary & systemic)

Top & bottom (atria & ventricle)

-cant both contract at same time)

Front 46

Myocardium

Back 46

-a mass of cardiac muscle cells connected to each other via gap junctions.

-Action potentials that occur at any cell in a myocardium can stimulate all the cells in the myocardium

-behaves as a single functional unit (different from skeletal muscle)

-the atria of the heart compose one myocardium & the ventricles of the heart compose another myocardium

Front 47

Electrical Activity of the Heart

Back 47

Autorhythmicity: Rhythmic beat of heart produced by producing its own action potentials

Autorhythmic cells: Special cardiomyocytes that initiate and conduct action potentials

-doesn't need any help from CNS, heart can beet on its own

Front 48

Electrical Activity of the Heart

Back 48

Sinoatrial (SA) node: "pacemaker"; located in right atrium

– Pacemaker potential: slow, spontaneous depolarization

-where the typical heartbeat starts, they initiate their own AP, & if will travel through the rest of the myocardium

-No need from external stimulus,

-continuously creating own AP, polarizes & depolarizes

Front 49

Brain's role in Electrical Activity of the Heart

Back 49

Pacemaker cells in the sinoatrial node depolarize spontaneously, but the rate at which they do so can be modulated:

-PNS slows heart rate (Vagus nerve)

-SNS (epinephrine & norepinephrine) increase the heart rate

-higher level of regulation in medulla

Front 50

Myocardial action potentials

Back 50

– Cardiac muscle cells have a resting potential of −90mV.

– They are depolarized to threshold by action potentials from the SA node.

Ap: cardiac AP is about 100 slower than skeletal AP

Front 51

Calcium Channels in Cardiac Muscle

Back 51

fill in

Front 52

Process of Electrical Activity of the Heart

Back 52

– Action potentials spread via intercalated discs (gap junctions).

• Within a mycocardium – (Atria, ventricle)

– AV node at base of right atrium and bundle of His conduct stimulation to ventricles.

– In the interventricular septum, the bundle of His divides into bundle branches.

– Branch bundles become Purkinje fibers, which stimulate ventricular contraction.

Front 53

Timing of Electrical Activity of the Heart

Back 53

– Action potentials from the SA node spread rapidly.

• 0.8–1.0 meters/second

– At the AV node, APs slow

down.

• 0.03−0.05 m/sec

• This accounts for half of the time delay between atrial and ventricular contraction.

– The speed picks up in the bundle of His, reaching 5 m/ sec in the Purkinje fibers.

– Ventricles contract 0.1–0.2 seconds after atria.

Front 54

Refractory Periods

Back 54

• Because the atria and ventricles contract as single units, they cannot sustain a contraction.

• Because the action potential of cardiac cells is long, they also have long refractory periods before they can contract again.

• Avoidance of “typical” muscle issues like tetanus

Front 55

Electrocardiogram

Back 55

This instrument records the electrical activity of the heart by picking up the movement of ions in body tissues in response to this activity.

Front 56

Electrocardiogram waves

Back 56

• P wave: atrial depolarization

• QRS wave: ventricular depolarization

• S-T segment: plateau phase

• T wave: ventricular repolarization

Front 57

HEP: understand the correlation between ECG, heart sounds, action potentials, contraction

Back 57

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