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The Cardiovascular System - Coggle Diagram
The Cardiovascular System
L15 Learning Outcomes
1. The Cardiac Cycle:
Explain the pump cycle, atrial and ventricular pressures, aortic pressure, ventricular volume and heart sounds.
Phases of the Cardiac cycle
Definition
Cardiac cycle:
sequence of events in the heart from one heartbeat to the next
Physiological Process:
includes all process linked to blood flow through the heart in a single heartbeat
Blood flow:
describes the complete path of blood as it circulated through heart chambres
Two Main Phases Mechanical
Diastole
- Heart muscle relaxes, allow chambers to fill with blood
Atrial
- atria relax, blood flow passive (vein -> atria)
Ventricular
- ventricle relax, fill with blood passively
Phase 1: Ventricular Filing
Pressure = Atria > Ventricles
AV Valve = Open
Active Phase - atria contract
Passive Phase - fill until atrium contract (no contraction)
Phase 4: Isovolumetric Ventricular Relaxation
Ventricles relax= pressure decrease (until under than atrial pressure)
AV & Semilunar Valves = Closed
No blood flow through ventricles
Systole
- Heart muscles contract, eject blood from chambres, last 0.3s
Atrial
- atria contract, push blood into ventricle
Ventricular
- ventricles contract, close AV valves, force blood out of heart
Phase 2: Isovolumetric Ventricular Contraction
Ventricles contract = pressure increase (until over atrial pressure)
AV & Semilunar Valve = Closed
No blood flow through ventricles
Phase 3: Ventricular Ejection
Pressure = Ventricles > Arteries
Semilunar Valve = Open
Blood flow = ventricle -> aorta
NOTES
Opening of Valves
Open passively, triggered by pressure gradient
AV
- atria pressure > ventricle pressure
Semilunar
- ventricle pressure > arteries pressure (pulmonary artery and aorta)
Atrial and ventricular pressure
Ventricular
Left
Systolic = 90-140 mmHg
Contraction - eject blood to aorta
Diastolic = 3-12 mmHg
Relaxation - filling from the left atrium
Right
Systolic = 15-30 mmHg
Contraction - push blood to pulmonary artery
Diastolic = 0-8 mmHg
Relaxation - filling from the right atrium
Atrial
Left
Pressure = 4-10 mmHg
Right
Pressure = 0-8 mmHg
Aortic pressure
Dicrotic notch
brief dip in waveform
mark aortic valve closure
start of diastole
Aorta and Large Arteries
Function - elastic pressure reservoirs
Energy Storage
Systole
wall expand
store elastic potential energy
Energy Release
Diastole
walls recoil
release kinetic energy
Blood Flow
Continuous
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Ventricular volume
Wigglers Diagram
Heart sounds
S2 "Dub"
Semilunar valve = close simultaneously
Start of diastole
Loud
S1 "Lub"
AV valves = close simultaneously
Start of systole
Soft
End-Diastolic Volume (EDV)
Volume - present in ventricle (130mL)
Stroke Volume (SV)
Volume - blood ejected from ventricle
During each cardiac cycle in one heartbeat
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Ejection Fraction (EF)
Fraction of end-diastolic volume ejected during a heartbeat
EF
= SV / EDV = 70mL/130mL = 0.54 =
54%
46%
remains in ventricle after ejection
End-Systolic Volume (ESV)
Volume - blood remain in ventricle (60mL)
2. Cardiac Output and Its Control:
Explain how each of the following variable affects cardiac output: sympathetic and parasympathetic nervous activity
Factors Affecting Cardiac Output
Autonomic Input to the Heart
Sympathetic
Innervates conduction system & myocardium
NE on β1 receptor
↑ Na+ & Ca2+ Influx
↑ Rate of depolorize
Increase HR
Stimulation
Increase
Rate of sinus nodal discharge
rate of conduction & level of excitability in heart portions
force of contraction of all cardiac musculature (atrial & ventricular)
overall heart activity
Cause opposite effect of vagal stimulation
Maximal
triple heartbeat frequency
increase heart contraction strength 2-fold
Graph
Increase slope of spontaneous depolarization
decrease level of repolarization
AV Nodal Innervation
Increase conduction velocity
Parasympathetic
Innervates only SA & AV node
ACh on M receptor
↑ K+ efflux ↓Ca2+ influx
hyperpolarize cell
↑ Depolarization time (to contract)
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Increase
Vagus Nerve Activity
Stimulation
Slow rate heart pumping to 50%
Strong
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Open state of K channels
Closed state of Ca channels
Decrease
rate of spontaneous depolarization & hyperpolarize cell
HR
Graph
decrease slope of spontaneous depolarization
increase level of repolarization
AV Nodal Innervation
Decrease conduction velocity
Cardiac Output
CO = SV x HR
Rest
AVG CO = 5L/min
AVG Vol = 5L
70mL/beat x 72 beats/min = ~5.0L/min
SV = Stroke Volume
HR = Heart Rate
SA Node Regulation
Intrinsic Firing Rate
100AP/min without external influence
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Autonomic and Hormonal Control
Rest
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Excitement
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Influenced by animal size
Cow = 50L/min at rest
Cow Example
SV = weight x SV Avg
700kg x 35mL/kg = 24 500mL = 24.5L
CO = 24.5L x 70 beats/min
1715L/min
HR = beats per minute
70 beats/min
Regulation
Extrinsic Regulation
Regulation of organ function by originating outside the organ
Hormonal Factors
Neural Factors
Intrinsic Regulation
Self-regulation of organ by factors originating within the organ itself
Autoregulation
Integration of Factors Affecting Cardiac Output
Stroke Volume (SV)
Primary factors it's affected by
Initial stimulus: Venous return
force
Ventricular Contractility
nerve completely empty blood
SR Increase
Increased Sympathetic activity/epinephrine
End-Diastolic Volume (EDV) /Preload
initial stretching of ventricles prior to contraction
degree of stretch in ventricular contraction
Afterload
resistance heart must overcome to pump blood into arteries
resistance the ventricle must overcome to eject blood
Extrinsic
Sympathetic innervation
contractile cells
Cardiac nerves
ventricular muscle fibers
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Hormonal Control
Adrenal Gland
EPI
Potent contraction
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NE
Increase HR
Thyroid Hormones
Insulin
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Glucagon
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Parasympathetic innervation
contractile cells
Not siginificant
Intrinsic
more blood return to heart
EDV increase
stretch ventricular muscle
Increase SV
L16 Learning Outcomes
Describe the
physics of blood
flow through blood vessels
Fluid Flow
Flow Rule
Circulatory System Dynamics
Closed System
blood circulates within a closed network of vessels
Pressure
Blood exerts force on vessel walls, creating pressure
Flow Direction
Blood flows from high to low pressure
larger = more pressure = more blood flow
flow rate (Q) of a fluid through a pipe is directly proportional to the pressure difference (ΔP) between two ends of pipe
inversely proportional to the resistance (R)
Flow = ΔP/R
Explain the
concepts of pressure gradients and resistance
Pressure Gradient (P)
Blood flow
high to low
depends on pressure gradient
higher flow = faster
Systemic Circuit
Left Ventricle (O2)
MAP (O2)
Systemic Organs
CVP (dO2)
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Aortic Pressure
Bulk flow
blood driven by pressure gradient
Heart's Role
create pressure gradient
Systemic Gradient
constant pressure gradient
essential to maintain blood flow
w/o = disease
Circulatory System
pressure gradient = aortic pressure (MAP) - Vena cava pressure (CVP)
Aortic Pressure (MAP) = ~85-90 mmHg
MAP = Mean arterial pressure
Vena Cava Pressure (CVP) = ~ 0 mmHg
CVP = Central venous pressure
MAP - CVP = 85-90 mmHg
longer
Pulmonary Circulation
pressure gradient = pulmonary artery pressure - pulmonary vein pressure
pulmonary artery P = 15 mmHg
pulmonary vein P = 0 mmHg
= 15 mm Hg
shorter
Resistance
Systemic vs. Pulmonary Circuits
Systemic
pressure gradient = higher
Equal flow
Resistance = higher due to distance
longer
Pulmonary
pressure gradient = lower
Resistance = lower due to distance
shorter
Factors Affecting Blood Flow
Vessel Radius (r)
Arterioles & small arteries can adjust radius
Larger
low resist
high flow
Smaller
high resist
low flow
Vessel Length (L)
varies with weight, height & age
Longer - high resist
Short - low resist
Blood Viscosity ( η)
depends on RBC count
High RBC
high viscosity
high resist
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Low RBC
low viscosity
less resist
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More resist = Vasoconstriction
Role on Flow
Poiseuille's Law
r = radius -> impacts flow
-ve = decrease
+ve = increase
Flow (Q) = Cardiac Output (CO)
Pressure Difference (ΔP) = MAP
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CO = MAP/TPR
Arteriole Radius
Vasoconstriction
Vasodilation
Pulmonary Vs. Systemic
Pulmonary
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Systemic
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Increase radius
Decrease resist
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Decrease radius
Increase resist
reduce blood flow
22mm
surrounded by smooth muscle
Describe the
anatomy of the vasculature
, and explain the
basic functional properties of the different types of blood vessels
Vessel Types and Functions
Arteries
Transport blood away from heart (O2)
higher BP
thick smooth muscle
Pressure reservoirs
Characteristics
Rapid Transport
Large diameter
fast blood flow
Low resistance
Structure
Elastic and Fibrous Tissue
provide stiffness and resilience
Elastic Recoil
Stiffness
require lots of energy to stretch walls
Fibers
store energy and release through recoil
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High pressure
walls withstand and manage high arterial pressure
Thick Elastic Walls
Diameter = 1-5 mm
Thick smooth muscle with elastin
Function
Muscle (involuntary) allow control over vessel diameter
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Systole
Expands
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Aortic Pressure
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Diastole
Recoil
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Min P, maintain by elastic recoil of aortic walls
Microcirculation
Includes vessels visible only under microscope
Arterioles
Small branches of arteries, regulate blood flow into capillaries
site of vasoconstriction & vasodilation
Capillaries
Primary exchange site for gases, nutrients, and wastes
smallest vessel
Permeability
Pericytes
cells surrounding capillaries
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Blood Brain Barrier (BBB)
Cerebral capillaries
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Venules
Collect blood from capillaries, lead to veins
no exchange
Veins
Return blood to heart (dO2)
lower BP
thin smooth muscle
has valves
volume reservoir
flexible, accommodate blood if blood loss occurs
Structure
Walls
Endothelial cells
line inner layer, create smooth surface
Additional
Smooth Muscle
Regulate vessel diameter
Fibrous Connective Tissue
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Explain the
role of arterioles
in
varying resistance
Arterioles
Primary Resistance Vessels
High resist
small diameter
great resist blood flow
Pressure drop
largest in circulation
90 mmHg to 40 mmHg
arterioles to capillary
Regulation
Contrict
response to sympathetic stimulation
Dilate
response to low O2
Muscular Walls
Smooth muscle
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Arteriolar
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link arteries to capillaries
Smooth muscle rings
regulation of vessel radius
control resistance and blood flow
Major Functions
Control Blood Flow
Direct to specific capillary beds
Regulate MAP
Adjust resist to maintain overall BP
Microcirculation
Blood Flow
Precapillary Sphincters
Relaxed
metarterioles to capillary beds
exchange
Constricted
bypass capillaries
flow directly to venous circulation
Explain the role of
extrinsic control of the arteriole radius
in determining the
mean arterial pressure
Arteriole Radius
Intristic
Blood Flow Regulation
Adjusted by need
Controlled by altering vascular resistance
Formula
= MAP/Organ Resistance
Blood Flow
Pressure Gradient
Organ blood flow driving force = Arterial pressure (AP) - Venous pressure (VP)
Varies due to diff in resistant
change when resistance change
Extrinsic
MAP = CO x TPR
MAP depends on TPR
TPR depends on arterioles
vascular resistance of individual organs
change in CO% supplied to each organ
Purpose
regulate radius
maintain MAP
Mechanisms
SNS
Adjust vessel tone
Hormone
Influence vascular resist
Control
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smooth muscle
Release NE
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L17 Learning Outcomes
Describe the
three types of capillaries
and
blood flow
through
capillary beds
Capillaries
NOTES
10-40 billion per body
Endothelial pores
allow protein-free plasma flow
primary site of exchange
diameter = 5-10µm
enable small diffusion distance
walls
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Total SA = 600m2
Types
Continuous
most common
small gaps
between endothelial cells
least "leaky"
Permit Movement
small water-soluble molecules
lipid-soluble
location
skin
most nervous & connective tissue
muscle tissue
Fenestrated
large gaps or pores
between endothelial cells
moderately "leaky"
allow proteins & blood cells to pass through
location
kidneys
endocrine glands
small intestine
Sinusoidal
very large pores
discontinuous endothelial layer
permit large molecules & cells to cross walls
"leakiest"
allow release of proteins
albumin
clotting factors
stop bleeding
in liver
enable movement of blood cells through walls
in bone marrow & spleen
location
liver
lymphoid organs
bone marrow
spleen
Local Control of Smooth Muscle in Microcirculation
Metarterioles
Capillary flow regulators
Link arterioles directly to venules
bypass capillaries
Smooth muscle rings
control blood flow
Contract
reduce capillary blood flow
Relax
increase capillary blood flow
Precapillary Sphincters
Open
low pH & high CO2
surrounding environment
Vasodilation
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Closed
High O2
Vasalconstrict
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Capillary Walls Exchange Mechanisms
capillary -> ECF
Primary Mechanism
Diffusion
high conc. -> low conc.
Lipophilic
lipid-soluble cross
membrane
Lipophobic
water-soluble pass through
pores
Transcytosis
exchangeable proteins
Mediated transport
specific to brain
Capillary Walls Fluid Movement
Bulk flow
move fluid and solutes from high to low pressure in capillaries
based on pressure gradient
in and out
Filtration
movement from capillary to interstitial fluid (ECF)
Absorption
movement from interstitial fluid (ECF) to capillary
Purpose
distributes ECF
Get acquainted with
Starling forces
that influence
movement of fluids in capillaries
Capillaries
Starling Forces
Forces Driving Bulk Flow
Hydrostatic Pressure
exerted by stationary fluid within blood vessels
push plasma out of capillaries
filtration
Pressure Gradient
Capillary Hydrostatic Pressure (P.CAP) - Capillary BP
Arteriole End
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Venous End
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Effect
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Interstitial Hydrostatic Pressure (P.IF)
Value
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Effect
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For exchange of materials (nutrients/wastes)
Net Filtration Pressure (NFP)
= (+ve) Filtration Pressure - (-ve)Absorption Pressure
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Osmotic Pressure
due to non-permeable solutes
albumin
main blood determinant
pulls water back to capillaries
absorption
osmotic force of protein = oncotic pressure
Pressure Gradient
Capillary Oncotic (Osmotic) Pressure
Value
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Effect
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Interstitial Fluid Oncotic (Osmotic) Pressure
Range
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Effect
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Forces Driving Fluid Movement
Capillary Hydrostatic Pressure (P.CAP)
pressure fluid inside capillary
Interstitial Fluid Hydrostatic Pressure (P.IF)
pressure fluid outside capillary
Capillary Osmotic Pressure (πCAP)
Due to non-permeable solutes inside capillary
Interstitial Fluid Osmotic Pressure
Due to non-permeable solutes outside capillary
Explain the role of
lymphatic system
Venule
Structure
smaller diameter than arterioles
connect capillaries to veins
Composition
Minimal smooth muscle
Single endothelial layer
porous walls
Function
Allows limited exchange between blood and interstitial fluid
allow immune cells out
Lymphatic Capillaries
Structure
Network of vessels, nodes, & organs
Lymphatic capillaries & veins have valves
Function
Return excess filtrate to circulation
initiate at blinded lymphatic capillaries
Role
Integral part of immune system
lymph nodes
System
Pathway
Lymph flows from capillaries to lymphatic veins
Lymph enters veins near jugular veins
to right atrium
Lymph passes through lymph nodes
Drainage
Lymphatic veins empty to thoracic duct
enter blood stream near jugular veins
to right atrium
Movement
Lymph Movement Mechanisms
Driven by:
skeletal muscle pump
Respiratory pump
Smooth muscle contraction
vessel wall
moves similarly to blood in veins
aided by valves & muscle contractions
Primary Functions
Fluid Balance
return excess interstitial fluid & proteins to venous blood
Nutrient Absorption
intestinal villi
lymphatic vessels
Absorb fats & fat-soluble vitamins
Immune Defence
Filters lymph to remove microorganisms & foreign particles
lack central pump
there is no lymph in bone marrow, cns & epidermis
Lymph Nodes
Cell Types
B-cells
dendritic cells
macrophages
T-cells
Function
Filters lymph to remove bacteria & foreign particles
Why
veins
are known as
volume reservoirs
Veins
Structure
large diameter
thin walls
0.5mm
5 mm
Valves
peripheral veins
present
ensure bidirectional flow
outside thoracic cavity
central veins
within thoracic cavity
absent
Comparative Size
vena cavae
30 mm
aorta
12.5 mm
Volume Reservoir
Highly Compliant Vessels
expand easily w/ minimal pressure
act as blood reservoir
Compliant = property of veins where small increase in internal pressure -> significan expand in volume
Blood Volume
systemic veins
hold ~60% of total blood volume
at rest
Function
provide ready available blood
can shift to arterial circulation when needed
Describe
factors
that are
involved
in
central venous pressure and venous return
Venous Pressure and MAP
venous pressure significantly influence MAP
determine blood flow to systemic organs
Driving Force for Venous Return
created by pressure gradient
between peripheral veins and right atrium
Key factors affecting Venous Pressure
Skeletal Muscle Pump
Contraction
Compress veins
raise venous pressure
distal valves
close
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Proximal valves
open
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One-way Valves
prevent backflow
direct blood to heart
Blood Flow Direction
compressed veins --> heart
aid venous return
Relaxation
reduce pressure in vein
Distal Valves
lower pressure
open valve
Blood Flow Direction
forward
vein --> heart
Valve funtion
prevent backflow
unidirectional
Respiratory pump
Inspiration
Thoracic Cavity
Expands
decrease pressure
Abdominal Cavity
increase pressure
Pressure gradient
difference encourage blood flow
abdominal veins -> thoracic cavity
Venous Return
increase central venous pressure
enhance venous return to heart
support circulation
Expiration
Thoracic Cavity
increase pressure
Abdominal Cavity
decrease pressure
Blood Flow
favour blood movement --> abdominal vein
Valve Function
close abdominal valve
prevent back flow
blood --> heart
Venous return
blood pushed forward to heart
support venous return
Venomotor Tone
Increase
constrict smooth muscle in veins
↑ venous pressure
blood -> heart
Decrease
relax smooth muscle
dilate vein
reduce venous return
Blood Volume
Increase
↑ venous pressure
boost venous return to heart
Decrease
↓ venous pressure
reduce venous return
L18 Learning Outcomes
Describe the
life cycle of RBC
Life Cycle of Erythrocyte
No RNA, DNA or organelles (mitochondria)
Don't divide or multiply
Short life span (120 days)
Replace 2-3 million/sec
200 billion/day
Synthesized in bone marrow
Erythropoeisis
Old RBC filtered by spleen (& liver)
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Production
develop in bone marrow
same stem cell (mother) as leukocytes
synthesis stimulated by erythropoietin
hormone produced in kidney
released during low lvls of O2 in blood flowing to kidney
Steps
Stem cell
Hemocytoblast
Committed cell
Proerythroblast
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Requirement
Iron
main nutrient component
component of Hb
12-18 gram/ dL
Folic acid (Vit B9)
need for DNA replication & maturation
cell proliferation
Vit B12
donate methyl (CH3)
Differentiation
triggered by erythropoietin
development
developing lose nuclei & organelles
developing produce hemoglobin
Destruction
Spleen
filter & remove old erythrocytes
'RBC Graveyard'
phagocytosis
macrophages filter blood
Hb catabolized
removal of iron
heme -> bilirubin
release to blood stream
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Fate of Iron
recycled for synthesis of new Hb
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Liver
metabolize byproducts from erythrocyte breakdown
Identify different
classes of leukocytes
and their
functions
WBC Classification
Granulocytes
Neutrophils
Neutral
stain red & blue
H&E dye
phagocyte bacteria & debris
circulate blood in 7-10 hrs
migrate to tissues for few days
increase during infections
50-80%
Contain cytoplasmic granules (vesicles)
visible under microscope
Eosinophils
Acidic
stain red
eosin dye
fight parasitic infections
modulate allergic responses
phagocytes but not main mechanism
granules contain toxic molecule that attack parasites
1-4%
Basophils
Basic
stain blue
hematoxylin dye
release histamine
mediate inflammatory responses
Nonphagocytic
defend against large parasites by toxic substance release
contribute to allergic reaction & wound infection
Histamin
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Heparine
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<1%
Agranulocytes
Lack visible cytoplasmic granules
Monocytes
largest WBC
macrophage precursor
engulfs pathogens & dead cells
presents antigens to lymphocytes
5%
new -> circulates blood for few hrs
migrate to tissues
become macrophages
wandering
fixed
Lymphocytes
Small WBCs involved in adaptive immunity
Types
B cells
produce antibodies
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T-cells
cell-mediated immunity
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develop into cytotoxic T cells
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NK cells
natural killer/null cell
destroy infected or cancerous cells
30%
Leukocytes Defence Function
Against Pathogens
identifies & eliminates bacteria, viruses, fungi, & parasites
Phagocytosis
engulfs & removes debris from dead or injured cells
invade pathogens
Immune System
coordinates body defence mechanisms against threats
Cancel Cell Detection & Destruction
recognize & eradicates abnormal or cancerous cells
Human vs Cow WBC
Human
more neutrophils
Cow
more lymphocytes
Identify the
major components of blood
and describe their
function
Blood
Components
Plasma
Serum
plasma from which fibrinogen and other clotting proteins have been removed
Components
Organic Molecules
Proteins
Three Classes
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Tranferrin
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6-8%
Functions
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Lipids
Glucose
Nitrogenous waste
Amino acid
Trace elements & vitamins
Ions
Electrolytes
2-4%
high conc.
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low conc.
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Gases
CO2
O2
N
Water
90%
waste
urea
bilirubin
creatinine
Hormones
Cellular Elements
Leukocytes
Neutrophils
mobile phagocytes that ingest foreign substances & pathogens
Eosinophils
produce toxic compounds directed against invading pathogens
Monocytes
Phagocytes after migrating into tissues
develop into macrophages
Basophils
tissue basophils = mast cells
Lymphocytes
Produce specific immune responses directed against invaders
Platelets
not cells, released by mechanical stress
fragment of megakaryocyte
cells fragments essential to blood clotting
produce in bone marrow
smaller than RBC
colourless
no nucleus
contain
mitochondria
smooth endoplasmic reticulum
membrane-bound vesicles
"granules"
life span
10 days
promote
clot formation
inflammation
breakdown damaged tissue
support wound healing
Erythrocytes
Hematocrit
(hct)
when animals are taken to the hospital, they look at hct
diagnose if anemic or too many blood
1 more item...
decrease = anemia
fractional contribution of erythrocytes to the blood
= height of RBCs/ Total height
Major function
transport O2 & CO2
5 billion RBC/ 1mL of blood
5L blood -> 25 trillion RBC
Shape
biconcave disk
large SA
1 more item...
Diameter
7.5-8 µm
Thickness
2-2.5 µm
Lifespan
depends on species
slower metabolism
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intense metabolism
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flexible membrane
spectrin, myosin, actin (protein)
maintain shape & flexibility
No nucleus
organelles
mitochondria
2 more items...
usually for protein synthesis
90% of glucose metabolized via glycolysis
yield lactate
excreted into blood
Content
Spectrin
part of membrane
1 more item...
Hemoglobin
globin + 4 heme groups
2 more items...
increase O2 transport
2 more items...
250 million per RBC
2,3 BPG binds
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Enzymes
Glycolytic
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Carbonic anhydrase
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44% of entire blood
vehicle for transport
Volume
8% of BW
700kg Cow -> 56L blood volume
