Playlist

Control of Blood Flow (Nursing)

by Jasmine Clark

My Notes
  • Required.
Save Cancel
    Learning Material 2
    • PDF
      Slides Nursing Physiology Cardiovascular System Blood Vessels.pdf
    • PDF
      Download Lecture Overview
    Report mistake
    Transcript

    00:01 So now let's take a look at how we control blood flow through our vessels.

    00:06 Tissue perfusion refers to our blood flow through the body's tissues, and involves the delivery of oxygen and nutrients to, and the removal of waste from our tissue cells.

    00:18 We also have gas exchange at the lungs, absorption of nutrients in our GI tract, and urine formation in the kidneys.

    00:28 The rate of flow is precisely just the right amount to provide proper function to a tissue or organ.

    00:37 The rate of blood flow is going to be controlled by both extrinsic and intrinsic factors.

    00:43 Extrinsic controls include the sympathetic nervous system, and hormones that control the flow of blood through the whole body.

    00:52 They also act on arteriolar smooth muscles to reduce the flow to regions that need it the least.

    00:59 Our intrinsic controls also referred to as autoregulation is more of a local control of blood flow.

    01:07 Where blood flow is adjusted to meet the specific tissues requirements.

    01:12 Local arterioles that feed capillaries can undergo modification of their diameters and organs are able to regulate their own blood flow by varying the resistance of their own arterioles.

    01:27 Autoregulation or local control is going to regulate blood flow to that local area.

    01:35 An example of autoregulation is reactive hyperemia, which increases blood flow to an area due to intrinsic factors.

    01:45 There are two main types of intrinsic mechanisms that determine the final autoregulatory response at a tissue.

    01:53 We have metabolic controls and myogenic controls.

    01:58 With metabolic controls increase in tissue metabolic activities are going to result in a declining level of oxygen, as well as increasing levels of our metabolic products like H+, potassium, adenosine, or prostaglandins.

    02:16 The effects of changes on the local level cause a direct relaxation of arterioles and relaxation of our precapillary sphincters.

    02:26 This causes the release of nitric oxide as well as powerful vasodilators, our endothelial cells.

    02:36 Endothelins also released from the endothelium of our capillaries are going to be potent vasoconstrictors.

    02:44 Nitric oxide and endothelins are usually balanced unless blood flow is inadequate.

    02:51 In which case, nitric oxide is going to win control and cause vasodilation.

    02:57 Also inflammatory chemicals can cause vasodilation.

    03:05 Another type of local control are myogenic responses.

    03:09 Local vascular smooth muscles are going to respond to changes in the main arterial pressure in order to keep perfusion constant while avoiding damage to our tissues.

    03:22 In myogenic control, passive stretch is going to cause our smooth muscles to respond by constricting.

    03:30 Here, increase mean arterial pressure stretches the vessel wall more than normal.

    03:37 And turn, the smooth muscles respond by constricting and causing a decrease in the blood flow to that tissue.

    03:46 Opposite of passive stretch is reduced stretch.

    03:50 Here the decreased mean arterial pressure causes less stretch than normal.

    03:56 In response, our smooth muscles would dilate causing an increase in the blood flow to that tissue.

    04:04 We also have long-term autoregulation as part of our intrinsic controls.

    04:10 This occurs when short-term autoregulation cannot meet the tissues nutrient and requirements.

    04:17 Long-term autoregulation may take weeks or months to supply an adequate blood supply.

    04:25 The number of vessels to a region may increase by way of angiogenesis, and existing vessels may become larger.

    04:34 This is common in the heart when our coronary vessels become occluded and also in the body of people who move to high altitude areas.


    About the Lecture

    The lecture Control of Blood Flow (Nursing) by Jasmine Clark is from the course Cardiovascular System: Blood Vessels – Physiology (Nursing).


    Included Quiz Questions

    1. Circulatory shock
    2. Hypovolemic shock
    3. Vasogenic shock
    4. Cardiogenic shock
    1. Vasogenic shock
    2. Cardiogenic shock
    3. Circulatory shock
    4. Hypovolemic shock

    Author of lecture Control of Blood Flow (Nursing)

     Jasmine Clark

    Jasmine Clark


    Customer reviews

    (1)
    5,0 of 5 stars
    5 Stars
    5
    4 Stars
    0
    3 Stars
    0
    2 Stars
    0
    1  Star
    0