Control of BF by Tissues (Humoral) Flashcards
What is the function of the circulatory system?
Meet metabolic needs of each tissue by controlling blood flow to tissue
What determines local blood flow rate?
- tissue need for O2/nutrient delivery
- CO2/H+ ion removal
The 2 ways local blood flow control occur are:
- acute control
- long-term
Acute control is achieved via which mechanisms
Vasodilation or vasoconstriction
What brings forth long-term control of blood flow?
- Changes in physical size
- number of blood vessels supplying tissue
If there are more nutrients being extracted from blood, what happens to blood flow?
Blood flow rate increases
List some factors influencing O2 supply and demand
- high altitude
- Pneumonia
- CO poisoning
- Cyanide poisoning
The local blood flow is influenced by what 2 theories?
- Vasodilator theory
- Lack of O2/Nutrient theory
Where do vasodilators act at?
- Precapillary sphincters
- Arterioles
- Metarterioles
Adenosine, CO2, Adenosine Phosphate, Histamine are dilators or constrictors?
Vasodilator
What is required to maintain smooth muscle contraction of precapillary sphincters, arterioles, or metarterioles?
Oxygen
What are the 2 states of precapillary sphincters?
open or closed
________________ is the rhythmical transition between the two states of precapillary sphincters
Vasomotion
Lack of glucose would cause what in vessels?
Vasodilation
Reactive hyperemia sets off the factors to cause what ?
Vasodilation
Autoregulation of Blood flow regulates the tissue resistance in order to ?
return blood flow to normal after an increase in arterial pressure
What are the 2 theories associated with autoregulation?
Metabolic and Myogenic
In endothelial-derived relaxing factor, what compound is released for vascular dilation to happen?
Nitric oxide
Which type of regulation is more complete and important in a chronic demand of tissue change?
Long-term control
Describe the main mechanism of long-term blood flow regulation
Change the degree of vascularity of the tissue
What is the major factor in long-term tissue vascularity changes?
Oxygen
List 3 vascular growth factors involved in angiogenesis
- Vascular Endothelial GF
- Fibroblast GF
- Angiogenin
Which type of hormones oppose angiogenesis?
Steroid hormones
List the 5 vasoconstrictors involved in humoral regulation of circulation
- Epinephrine
- norepinephrine
- angiotensin
- vasopressin
- endothelin
List the 4 vasodilators associated with humoral control
- bradykinin
- serotonin
- histamine
- PGs
*Baby Sit High Please
What is the only ion considered a direct vasoconstrictor in humoral regulation?
Calcium
Which vessels are NOT innervated by the Sympathetic system?
Capillaries, precapillary sphincters and metarterioles
What type of fibers are mainly carried by the sympathetic system?
Vasoconstrictor fibers
In what 2 parts of the brain is the vasomotor center located?
Pons and medulla
Through which nerve does the VMC transmits parasympathetic impulses to the heart?
Vagus (CN X)
Define sympathetic vasoconstrictor tone
continuous firing of the VMC vasoconstrictor center to maintain vasomotor tone
Define vasomotor tone
partial state of contraction in the blood vessels
List the 3 areas of the VMC
- vasoconstrictor
- vasodilator
- sensory
Which portion of the VMC transmits impulses through sympathetic fibers?
Lateral portion
Which portion transmits PS impulses to the heart?
Medial portion
Norepinephrine acts on ____ receptors to cause vasoconstriction
alpha
Which neurotransmitter causes vasodilation through b-receptor stimulation in adrenal glands?
Epinephrine
If you perform spinal anesthesia, which division of the nervous system is blocked to the periphery?
Sympathetic
The nervous system can cause an (increase/decrease) in AP
increase
AP control is regulated by :
Baroreceptor reflex
Carotid baroreceptors go to the VMC via ?
CN 9
Aortic arch baroreceptors go via the _______ to the VMC
CN 10
What type of feedback system is associated with the arterial baroreceptor control system?
Negative feedback system
At what pressure is a baroreceptor most sensitive?
100 mmHg
where in the medulla does the signal from the baroreceptor go?
nucleus tractus solitarium
Increased arterial pressure sends the signal in order to inhibit which VMC center?
vasoconstrictor
Describe the primary purpose of the arterial baroreceptor system
Reduce the minute by minute variation of arterial pressure
Why are baroreceptors not useful in long-term regulation of AP?
Because the receptors reset themselves in 1-2 days
Chemoreceptors are sensitive to?
O, CO2, H ions
Where do the nerve fibers of chemoreceptors pass through to go to the VMC?
Herring’s nerve and vagus nerve
What activates the chemoreflexes?
AP falling below critical level (80 mmHg), decreases O2 or excess CO2
Where does the CNS ischemia response originate?
VMC
What happens to the bv in the ischemia response?
constrict
What is another name for the CNS ischemia response?
Last-ditch stand
CNS ischemic response gets activated only when BP falls below?
60 mmHg
What is the name of the reaction that occurs when there is an increased CSF pressure in the brain that then cuts off the blood supply? It is a type of CNS ischemic response
Cushing reaction
