Physiology II- Midterm 1 Flashcards
What 3 Systems Affect Cardiovascular System?
- Endocrine
- Nervous
- Kidneys
What type of organ receives the most blood and what are three examples?
Reconditioning organs
- Digestive
- Kidneys
- Skin
Blood flow is adjusted by _______ according to _____.
reconditioning organs, metabolic needs of organs
Which organ is least tolerant to blood flow changes?
brain
Blood flow depends on ____ and ____.
- Pressure
2. Resistance
Vascular resistance ____ flow rate while pressure gradient ____ flow rate.
decreases
increases
What is a Pressure Gradient?
pressure difference between beginning and end of vessel
What is Resistance?
measure of opposition to flow
What/how effects resistance?
- Blood viscosity (doesn’t usually change) as v increases, R increases
- Length (doesn’t change) as L increases, R increases
- Radius (most changed) as R increases R decreases
What determines viscosity?
number of RBC’s
Heart–> ____–>____–>____–>____–>____–>Heart
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
2 Functions of Arteries
- Rapid Transit from heart to organs
2. Pressure reservoir to provide driving force
Collagen provides _____strength, elastic provides ____ strength.
Tensile, elastic/stretch
What is Blood Pressure?
force exerted by blood against a vessel wall that drives blood around body
Blood Pressure Depends On…
- Volume
2. Compliance of vessel walls
Arteries are ___ complient than veins
less
What is systolic blood pressure?
- peak pressure
- exerted by ejected blood against vessel walls during cardiac systole
- around 120mmHg (“normal”)
What is diastolic Blood Pressure?
- minimum pressure
- when blood is draining into vessels downstream
- around 80mmHg (“normal”)
What is Pulse Pressure?
- pressure difference between systolic and diastolic pressure
- pulse we can feel close to skin
What is Mean Arterial Pressure?
- MAP
- average pressure driving blood forward into tissues throughout cardiac cycle
Muscular Arteries
- deliver blood to specific organs
- thick muscular media
- active in vasoconstriction
- helps regulate blood pressure
Radius supplying individual organs can be adjusted to….. How?
- distribute CO among organs depending on body’s momentary needs
- dilation increases blood flow
- constriction decreases blood flow
Arterioles
- major resistance vessels
- exist within organs
- resistance occurs in arterioles primarily
What are the two resistance mechanisms?
- Vasoconstriction (narrowing)
2. Vasodilation (enlarging)
How does vasoconstriction and vasodilation effect resistance and flow?
Vasoconstriction–> decreases flow, increases resistance
Vasodilation–> increases flow, decreases resistance
What is Vascular Tone?
2 Factors of Vascular Tone.
degree of constriction experienced by a blood vessel
- Myogenic activity of smooth muscle
- Sympathetic fibres continually release norepinephrine
What regulates flow?
Flow is never ___ or _____.
- ANS
- nonexistent/stopped
- organ/tissue dies
What are intrinsic and extrinsic factors? Local ___ and ____ influences change arterial radius.
Intrinsic–> local environment
Extrinsic –> neuronal inputs
- chemical (histamine, metabolic changes)
- physical (heat, cold, stretch, stress)
What is Active Hyperaemia?
What are the 4 causes?
- increase in organ blood flow associated with increased metabolic activity of an organ or tissue
1. Increases metabolic activity in organ
2. Decreased O2, increased metabolites in ISF of organ
3. Arteriolar dilation in organ
4. Increased blood flow in organ
What are the 7 chemical factors that cause vasodilation of arterioles?
- decreased O2
- Increased CO2
- Increased Acid
- Increased K+
- Increased Osmolarity
- Adenosine release
- Prostaglandin release
Endothelial Cells Are…
They release ___ in response to ___.
An example is ____.
- local vasoactive mediators
- locally acting chemical messengers
- chemical changes in their environment
- NO (nitric oxide)
Norepinephrine and epinephrine are ___ controls. NE is a ___ and causes ___. E is a _____ or ______ and causes ____.
Extrinsic
a, vasoconstriction
b, vasodilation
a, vasoconstriction
Local controls can _____ sympathetic vasoconstriction.
There is no ____ innervation to arterioles.
- override
- parasympathetic
The Cardiovascular Control Centre is located in ____ and is the integrating centre for ____.
medulla of brain stem, BP regulation
Vasopressin and Angiotensin II control ____.
fluid balance
Describe a Capillary
- smallest blood vessel (single file RBCs)
- exchange site for blood and tissues
- thin walled
- small radius
- branched
- slow velocity of blood
- close to target tissues
Where does exchange occur in capillaries?
between endothelial cells
3 Typesof Capillaries and Example Locations
- Continuous
- have tight junctions
- e.g. skin, muscles
- Fenestrated
- more permeable
- e.g. kidneys, intestines, hormone tissues
- Sinusoidal
- incomplete basement membrane
- e.g. liver, bone marrow, lymphoid
What are capillary pores?
- water-filled gaps
- at junctions between cells
- permit water-soluble
- size varies between organs
How do lipids and proteins exchange between capillaries and tissues?
Lipids–> pass through lipid bilayer (pass readily)
Proteins–> vesicular transport too big to diffuse (e.g. hormones)
What proteins do not pass through capillaries? Why?
plasma proteins, because no mechanisms of transport
Two types of passive exchange
- Passive Diffusion
2. Bulk Flow
What is Bulk Flow? What is it for?
-not metabolic (no energy exchange)
-movement of fluid from blood to ISF and back
-through capillary pores
-ultrafiltration and reabsorption
distributes ECF
What are the Starling forces?
What do they influence?
- Capillary Blood–> hydrostatic pressure
- Plasma–> colloid osmotic pressure
- Interstitial Fluid–> hydrostatic pressure and colloid osmotic pressure
- Bulk Flow
What is Hydrostatic Pressure?
force exerted by fluid pressing against a wall
Where does most filtration occur?
filtration=fluid out
arterial end because pressure is higher
What is Colloid Osmotic Pressure?
- force opposing hydrostatic pressure
- created by plasma proteins
- does not vary across capillaries
If BP increases fluid moves ____ via bulk flow. If BP decreases fluid moves ___ via bulk flow.
into interstitial space, into plasma space
Define…
- Lymphatic System
- Initial Lymphatics
- Lymph
- Lymph Vessels
- Networks of one way vessels allowing fluid to be returned from ISF to blood
- Small, blind-ended, terminal vessels permeating almost every tissue
- ISF entering a lymphatic vessel
- convergence of initial lymphocytes that enter into venous system near entrance to RA. One way
4 Functions of the Lymphatic System
- Return of Lymph
- Defence against disease
- Transport absorbed fat
- Return filtered proteins
What is Edema, and what are its four causes?
- swelling of tissues due to accumulation of ISF
1. Decrease in concentration of plasma proteins
2. Increase in permeability of capillary wall
3. Increased venous pressure
4. Block of lymph vessels
Veins
- return blood to heart
- large radius and little resistance
- blood reservoir (60% of blood is in veins at any given time)
- walls are thinner
- little smooth and elastic tissue
- more collagen than elastin
Five Factors that Increase Venous Return
- driving pressure around 15mmHg
- sympathetic venous vasoconstriction
- skeletal muscle activity
- respiratory activity
- effect of cardiac suction
What is the purpose of venous valves?
mechanically prevent back flow of deoxygenated blood
Three Primary Determinants of Blood Pressure
- Cardiac Pressure
- Total Peripheral Resistance
- Mean Arterial Pressure
Mechanisms of blood pressure regulation
Baroreceptors- arterial pressure sensors (increased action potentials as MAP increases)
-e.g. carotid sinus, aortic arch
How does the ANS effect heart functions?
- changes cardiac output
- changes blood vessel size (resistance to flow)
What does sympathetic drive regulate?
- Arteriolar diameter (TPR)
2. Venular diameter (CO)
What does the PNS regulate?
heart rate
What are the steps of Baroreceptor Reflex?
- Baroreceptors monitor BP
- Action potentials are produced in cardioregulatory/vasomotor centres in medulla oblongata
- Decreased parasympathetic stimulation of heart, increasing heart rate
- Increased sympathetic stimulation increases heart rate and stroke volume
- Increased sympathetic stimulation increases vasoconstriction
Describe Baroreceptor Reflex
- short-term adjustments
- occur within seconds (rapid response)
- change made by CO and TPR
- mediated by ANS
- influences HR, veins, arterioles
- if BP deviates for a few days a new set point is in place
What is a longterm regulator of blood pressure?
blood volume influenced by salt/water balance
What are the three main components of blood?
- Erythrocytes
- Leukocytes
- Platelets
What are thrombocytes?
- platelets
- cell fragments
- used in homeostasis
- produced in bone marrow
What is Hematocrit?
percentage of cells that are RBCs
What makes of the Buffy coat after centrifuging?
platelets
What are the three components of Plasma?
- water
- proteins
- organic molecules
What are the three groups of plasma proteins?
- Albumins
- most prevalent
- colloid osmotic pressure
- bind substances
- Globulins
- transport hormones and cholesterol
- aid in blood-clotting
- immunoglobulins (antibodies)
- inactive before input
- Fibrinogen
- forms fibrin threads for clotting
Constituent of Blood:
Function of Water
- transport medium
- carries heat
Constituent of Blood:
Functions of Electrolytes
- membrane excitability
- osmotic distribution of fluid between ECF and ICF
- buffer pH changes
Constituent of Blood:
Functions of Nutrients, Wastes, Gasses, Hormones
- transported in blood
- blood gas CO2 plays a role in acid-base balance
Constituents of Blood:
Functions of Plasma Proteins
- exert osmotic pressure for distribution of ECF between vascular and interstitial compartments
- buffer pH changes
Blood Constituents:
Function of Albumins
- transport many substances
- contribute to colloid osmotic pressure
Blood Constituents:
Functions of Alpha and Beta Globulins
- transport water insoluble substances
- clotting factors
- inactive precursor molecules
Blood Constituents:
Functions of Gamma Globulins
-antibodies
Blood Constituents:
Functions of Fibrinogen
inactive precursor for the fibrin meshwork of a clot
Describe Erythrocytes
- transport O2 to tissues
- remove CO2 from blood
- thin and biconcave
- large surface area
- very flexible
- no nucleus or organelles
- no DNA or RNA
- have enzymes and hemoglobin
Why are Erythrocytes so flexible?
they have to fit into capillaries which are smaller than they are
What are the two enzymes in RBCs and what do they do?
- Glycolytic Enzymes
- anaerobic resp
- need glycolysis for ATP
- Carbonic Anhydrase
- CO2 transport
- catalyses CO2 into HCO3-
Describe Hemoglobin
- Hb
- found only in RBCs
- contain pigment
- ion
- red when oxygenated
- blue when deoxygenated
- carries O2
- combines with CO2, H+ from CO2 rxn, Co, NiO2
What are the two components of hemoglobin and what do they do?
- Globin
- protein
- four folded poly-peptide chains
- Heme
- four iron groups
- each bound to one poly-peptide
What is Erythropoiesis?
erythrocyte production
Describe the production sites of erythropoiesis in each stage of life
- Intrauterine
- yolk sac -developing liver and spleen
- bone marrow when developed - Childhood
- bones (RBM) - Adults
- sternum (RBM)
- ribs (RBM)
- ends (upper of long bone) (RBM)
How does the spleen contribute to erythropoiesis?
removes old RBC’s from blood
Describe the progression of cell development in erythropoiesis
- —————————–BONE MARROW—————————–
1. Pluripotential Stem Cell
2. Erythroid
3. Normoblast
4. Reticolocyte - ————————————-Blood————————————-
5. Erythrocyte
4 Steps of Control of Erythropoiesis
- Kidneys detect decreased O2 carrying capacity
- kidneys secrete erythropoietin hormone
- Erythropoiesis stimulated
- Increased O2 carrying capacity relieves initial stimulus through negative feedback
Cells committed to become RBCs….
undergo proliferation and maturation causing them to lose their nucleus and organelles and gain Hb
What is the life span of a RBC?
120 days
Blood types are categorized by…
the type of antigen present on the RBCs