week 7 Flashcards
Blood vessels/flow, BP/HR regulation + blood composition and haemostasis
Blood vessels (what they transport)
Transport:
- essential nutrients towards cells
- wastes away from cells
- regulating molecules to/from cells
- dissipation of heat
- cells & chemicals for protection/ defence
Blood vessels (how they transport)
Exchange of materials between blood & tissues
Maintaining one way flow (list 3)
Valve:
- prevent back flow
Skeletal muscle pump
- massaging effect of muscle movement on the veins and assisting in blood flow up
Respiratory pump
- breathing in decreases pressure in the chest allowing blood to flow up more easily
Blood flow
Blood volume through a vessel within a given time period
Pressure difference = hight -> low
Blood flow resistance
Flow decreases as resistance increases
- vessel diameter
- vessel length
- blood viscosity
Capillary Osmotic pressure (OPc)
- force opposing hydrostatic pressure
- mainly due to plasma proteins
Capillary Hydrostatic pressure (HPc)
force exerted by fluid pressing against a wall
Net movement
Fluids will leave capillary if net HPc is greater than OPc
- OUT>IN
Fluids will enter capillary if net OPc is greater than HPc
- IN>OUT
Capillary exchange (3 types)
Diffusion:
- water, ions and small molecules
- some ions (Na+, K+, Ca2+, Cl-) through channels
Filtration
- driven by hydrostatic pressure
- determined by size
Reabsorption
- driven by blood colloid osmotic pressure
HR
Heart Rate = beats per minute
SV
Stroke Volume = mL per beat
CO
Cardiac Output = mL per minute
Systolic BP
pressure exerted against vessel at contraction
• Identified as top number
Diastolic BP
pressure exerted at against vessel at relaxation.
• Identified as bottom number.
Pulse Pressure
difference between SBP & DBP.
Mean Arterial Pressure (MAP)
average arterial blood pressure
S + D + D
\_\_\_\_\_\_\_
3
s - systolic
d - diastolic
(Over 60 = good)
Stroke volume (3 parts)
Preload
• Stretch in muscle fibres
• More stretch… more strength….. to a limit
Afterload
• Pressure needed to open SL valves -> eject blood.
Contractility
• Force of contraction
2 Parts of ANS of the heart
SNS
increase Heart rate (chronotropic)
increase Contractility (inotropic)
PSNS
decrease Heart rate
decrease Contractility
Regulation of heart rate (2 components)
Internal
- Cardiac conduction system
External control
- Medulla oblongata
- Centres
Antagonistic control ( 2 centers)
Cardioacceleratory
Cardioinhibitory
Function of blood
Transport •oxygen,nutrients,waste,hormones, drugs •Regulation of pH and ions •body temperature, pH, fluid volume •Protection •blood loss, infection
Composition of blood
- Plasma (fluid)
•water plus proteins
•carries nutrients,hormones, gases,wastes and electrolytes - Regulation of pH and ions
•RBC, WBC, platelets
•all formedinbone marrow (stem cells)
Red blood cells + haemoglobin
- makes blood red
* binds and transports oxygen and carbon dioxide
Haemoglobin structure and function
Iron binds oxygen
•Oxyhaemoglobin
•deoxyhaemoglobin
Protein binds CO2
•carbaminohaemoglobin
RBC structure and function
- High surface to volume ratio
- quickly absorbs and releases oxygen
- Discs form stacks (roleau)
- smooth flow through narrow blood vessels
- Discs bend and flex entering small capillaries
- 7.8µm RBC passes through 4 µm capillary
White blood cells (leukocytes)
- No haemoglobin (not red)
- Have nuclei and other organelles
- Live hours-years
- Five different types
WBC functions
•defend against pathogens
•remove toxins and wastes
•attack abnormal cell
Five types of leukocytes
Neutrophil - Phagocytic -bacteria (40-70% WBC)
Eosinophil - increase in allergic reactions and parasitic infections (1-4% WBC)
Basophil - Release histamine and contain heparin (0.5-1% WBC)
Lymphocyte - B cells, T cells &NK cells (20-45% WBC)
Macrophage - AKA monocytes –enter tissues to become macrophages (4-8% WBC)
Platelets (thrombocytes)
- Fragments of very big cells (megakaryocytes)
- Circulate 9-12 days
- Removed by spleen
- 2/3 reserved for emergencies
Platelets –three functions
- Release important clotting chemicals
- Temporarily patch damaged vessel walls
- Reduce size of break in vessel wall
Haemostasis
Cessation of bleeding
Three phases
- Vascular phase
- Platelet phase
- Coagulation phase
Vascular phase
Immediate vasoconstriction:
- contract & expose basement membrane
- Release chemicals
•inc.vWF–platelets to collagen
•Stimulate smooth muscle contraction - Endothelium become “sticky”
•Seal off blood flow
Platelet phase
Begins to seal damaged vessel
Platelet adhesion
•chemicals from damaged tissue
•platelets become sticky
Platelet aggregation
•release chemotactic substances
•forms plateletplug
Coagulation phase
Begins ~30 sec after injury •Blood clotting = coagulation •Liquid blood forms gel •Cascade of reactions (dominoes) •End result = conversion of fibrinogen into fibrin
Clot retraction
- Final step
- Platelets pull on fibrin –threads contract
- Pulls torn edges of vessel closer together
- reducing bleeding & stabilising injury site
- Reduces size of damaged area •makes repair easier
Blood typing + surface antigens
Surface antigens
•cell surface proteins that identify cells to immune system
•normal cells are ignored and foreign cells attacked
Blood types
•genetically determined
•by presence/absence of RBC surface antigens A, B, Rh (or D)
Cross-reactions in transfusions
- AKA transfusion reactions
- Plasma antibody meets its specific surface antigen •Blood will agglutinate (clump) and haemolyse
- Occurs if donor and recipient blood types incompatible
