Lecture 16 - Circulatory Control Systems Flashcards
An abnormal increased volume of interstitial fluid in a tissue or organ is called:
Edema
True or false: under normal conditions, the volume of a tissue remains constant except for minor variation of capillary blood volume
True
How is Interstitial fluid volume controlled?
hydrostatic pressure
osmotic pressure
endothelial integrity
the lymphatic system
What are the causes of Edema?
-endothelial damage (inflammation)
-impaired lymphatic drainage
-raised blood pressure
-reduced blood osmotic pressure
-increased capillary permeability
-decreased plasma protein
What is the significance of albumin in regards to edema?
Albumin helps to retain water within the blood vessels by drawing water into the bloodstream from the surrounding tissues. A decrease in albumin concentration in the blood will result in a consequent decrease in blood osmotic pressure. This effectively lowers the osmotic pressure gradient, and less water will be drawn out of the tissues and into the blood, leaving it to accumulate in the tissues and cause edema.
How does cardiac/renal failure cause edema?
It raises blood hydrostatic pressure, and fluid will move down the pressure gradient into the surrounding tissues, where the hydrostatic pressure is lower.
What are three reasons for reduced blood osmotic pressure?
- Renal disease (loss of albumin across glomerulus)
- hepatic disease (inadequate albumin synthesis)
- malnutrition (inadequate albumin synthesis)
What are some causes of lymphatic obstruction that can lead to edema?
Tumors, fibrosis, inflammation, surgery, congenital abnormality
In order to maintain homeostasis in the cardiovascular system and respond to changes in activity, blood flow must be:
redirected to the tissues that become more active to provide enough supply
What is the only organ that receives a (relatively) constant supply of blood?
the brain
What controls cardiovascular function by adjusting HR, stroke vol, pressure, distribution, etc?
negative feedback systems of the Neural, Endocrine, and autoregulatory systems
Autoregulation of perfusion in the capillary bed is (dependent/independent) of specialized nervous stimulation or endocrine control
independent
When the body is active, does blood pH increase or decrease?
It decreases, because cells undergo cellular respiration to met the energy requirements, which creates more CO2, and subsequently H+
Increased CO2, decreased O2, increased K+, adenosine, lactate, decreased local pH, or increased local temperature will all stimulate the release of:
NO from the endothelial cells, which is a powerful vasodilator
decreased CO2, increased O2, increased pH, and decreased local temperature will stimulate the release of:
endothelins from the endothelial cells, which are powerful vasocontrictors
what happens when the precapillary sphincters contract?
Blood flows only through the thoroughfare channel, restricting passage to the rest of the capillary bed. This DECREASES blood flow
What happens when the precapillary sphincters are relaxed?
blood flows throughout the entire capillary bed, effectively INCREASING blood flow.
during vasodilation, the precapillary sphincters are:
relaxed
during vasocontriction, the precapillary sphincters are:
constricted
When blood flow is excessively high and the vessels are excessively stretched, the smooth muscle cells of the vessel can reflexively contract and decrease blood flow to that area. This is known as the:
Myogenic response
If perfusion of an organ is too low (ischemia), the tissue will experience low levels of oxygen (hypoxia). The vessel’s smooth muscle will be only minimally stretched. In response, it relaxes, allowing the vessel to dilate and
thereby increase the movement of blood into the tissue. This is known as:
The myogenic response
walls of the systemic blood vessels (dilate/constrict) in response to low O2, while the walls of the pulmonary blood vessels (dilate/constrict) under low O2
systemic = dilate, pulmonary = constrict
The cardiovascular center of the brain is found in the:
medulla
The inputs of the cardiovascular center in the brain are the _____ while the outputs are the _______
Input: cerebral cortex, limbic system, hypothalamus, sensory receptors (baro/chemo) in the periphery
Output: Autonomic NS
What are the main types of sensory receptors for cardiovascular regulation?
Baroreceptors within the blood vessels and heart chambers that respond to blood pressure
Chemoreceptors near the baroreceptors that monitor concentration of H, CO2, O2
The ______ centers slow cardiac function by decreasing heart rate via parasympathetic stimulation from the vagus nerve
cardioinhibitor
The ______ centers stimulate cardiac function by increasing heart rate and stroke volume via sympathetic stimulation from the cardiac accelerator nerve
cardioaccelerator
The ________ control contraction of the smooth muscle in the blood vessel, via sympathetic stimulation from the vasomotor nerve.
vasomotor centers
Sympathetic stimulation _____ blood pressure, and parasympathetic _________ blood pressure
increases, decreases
increased BP results in ___ baroreceptor firing, ____ stimulation of cardiac inhibitor centers, ______ stimulation of cardiac accelerator and vasomotor centres, ____ cardiac output, and ____ vasodilation
- higher baroreceptor firing
- increased cardiac inhibitor
-decreased accelerator and vasomotor - decreased cardiac output
- increased vasodilation
Describe the neural response to decreased blood pressure
baroreceptors fire less, causing increased stim of the accelerator and vasomotor centers and decreased stim of the inhibitor centers. this results in higher cardiac output (HR, SV), and increased vasoconstriction, causing blood pressure to rise
What is the chemoreceptor reflex?
Chemoreceptors detect hypoxia (low O2), hypercapnia (high co2), acidosis (high H+), and send signals to the cardiovascular center in the brain
how does the CV respond to hypoxia?
increased oxygen uptake by increasing respiratory activity and ventilation, while also increasing oxygen conservation by causing vasoconstriction (via sympathetic vasomotor activity) and decreased HR and cardiac work (via cardiac vagal activity)
T/F. Parasympathetic innervation is important in the heart and the vasculature
False. It is important in the heart, but not so much in the vasculature
Explain how the sympathetic division of neurons work
The preganglionic neurons release ACh at the synapse to bind to the nicotinic receptors on the postganglionic neurons. then the postganglionic sympathetic neurons release NE from their nerve terminals to bind the adrenergic receptors on the target tissues.
Explain how the parasympathetic division of neurons work
the preganglionic neurons release ACh at the synapse to bind the nicotinic receptors on the postganglionic neurons. Then the post neurons release ACh from their nerve terminals to bind to the muscarinic receptors on the cell membrane tissues
Heart rate and body size are _____ related
inversely. This is because smaller animals have a greater metabolic rate due to a higher SA:VOL ratio
Epinephrine and Norepinephrine are released by the adrenal medulla, and increase HR and force of contraction by acting on what type of receptor?
B1
During exercise, what happens to oxygen transport?
it remains constant, as the hemoglobin becomes 100% saturated and can’t increase anymore regardless of increased Cardiac Output
Why does HR decrease with training?
the muscles of the heart strengthen, allowing for greater force of contraction. Essentially, each beat can push more blood (an increase in stroke volume), therefore cardiac output can remain higher with lower heart rates
name some causes of coronary occlusion:
- Deposition of cholesterol causing hardening and narrowing of the arteries
- Fatty deposits also significantly reduce the diameter of the lumen
- The restriction of blood flow increases pressure in the artery, leading to damage of the arterial wall
- The damaged region is repaired with fibrous tissue which significantly reduces the elasticity of the wall
- As the smooth lining of the artery is progressively degraded, lesions form called plaques, and if these rupture, blood clotting is triggered, forming a thrombus that restricts blood flow
Risk factors for coronary heart disease
GODDESS acronym:
Genetics
obesitiy
diet
diseases
exercise
sex
smoking
