Circulatory System Flashcards
The circulation of fluid after it leaves the vascular system and before it re-enters the vascular system
Non-vascular circulation
Secreted by the vascularized choried plexus in the brain into the ventricles of the brain and then passes into the subarachnoid spae
Cerebrospinal fluid
The cerebrospinal fluid then returns from the subarachnoid space to venous channels within the dura mater of the
Head
The circulation of cerebrospinal fluid in the subarachnoid space is an example of
Non-vascular circulation
Fluid in the cardiovascular system passes through a
Closed circuit
The pressure generated by the heart is sufficient to move blood through the
Arteries
Require externally generated pressure (such as pressure from nearby contracting skeletal muscle) and valves to move fluid
Veins
Allow fluid flow in only one direction
Vein valves
In those veins in which blood flow is resisted by high hydrostatic pressure (e.g. the lower limbs) the valves are more likely to become incompetent and result in
Impairment of venous flow and dilation of the veins (varicose veins)
Do all veins have valves?
No
The veins of the portal system and veins communicating between the veins of the face and scalp and the dural venous sinuses within the skull do not have
Veins
In veins without valves, the direction of flow is determined by the
Pressure gradient
A closed circuit
Cardiovascular system
A one-way circulatory system
Lymph vasular system
The lymph from the left side of the head, neck and thorax, the left upper limb, and everything below the diaphragm drains into the
Thoracic duct
The thoracic duct drains into the junction of the
Left subclavian vein and left internal jugular vein
The lymph from the right side of the head, neck and thorax and right upper limb drains into the
Right lymphatic duct
The right lymphatic duct drains into the junction of the
Right subclavin vein and right internal jugular vein
Lymph flows through the lymphatic channels in a direction toward the connection with the
Venous system (i.e. towards the heart)
Extracellular fluid enters lymph capillaries which then drain through
Lymphatic vessels
Contain one-way valves, just like veins
Lymphatic vessels
Interposed along the path of the lymphatic system
-have afferent and efferent vessels
Lymph nodes
Filter the lymph, trapping diseased cells, abnormal
cells, and pathogenic organisms and contain lymphocytes and other cells of the immune system
which attack these trapped cells
Lymph nodes
Transports materials from one part of the body to another
-ex: oxygen from lungs to tissues in the body
Cardiovascular system
The cardiovascular system transports
Oxygen, carbon dioxide, nutrients, and wastes
The cardiovascular system carries chemicals that provide signals from one organ to another, these are called
Hormones
Plays an important role in temperature regulation
Cardiovascular system
Heat is constantly being produced in the body by
Metabolic processes and muscle contraction
Warm blood from the interior of the body is brought to cutaneous capillary beds in the skin where heat from the blood is
Dissipated to the environment
Control how much warm blood reaches cutaneous capillary beds to lose heat to the environment
Cutaneous A-V shunts
When a shunt is OPEN, blood shunts from an artery to a vein and bypasses a cutaneous capillary bed, therefore
Less blood reaches cutaneous capillaries and less heat is lost
When a shunt is CLOSED, blood flows to the cutaneous
capillary bed and therefore
More blood reaches the cutaneous capillaries and more heat is lost
More warm blood will be allowed to reach the skin to lose heat when the environmental temperature is
Warm
Less warm blood is allowed to reach the skin to lose heat when the environmental temperature is
Cold
Allow heat from the arterial blood to transfer to the venous blood and thereby not reach the cutaneous
capillaries, thus reducing the amount of heat that is lost to the environment through the skin and thus conserving heat and reducing energy needs to produce heat
Venae Comitantes
This mechanism through the venae comitantes, found primarily in the limbs and body wall, allows for a reduction in heat loss without a
Reduction in cutaneous blood flow
The end arteries are part of the
Collateral circulation
An artery that has full responsibility for providing blood to an organ or part of an organ
Anatomical end artery
If an anatomical end artery is occluded, the region supplied by the artery undergoes
Cell death
An artery that “shares” responsibility for blood supply to a region but the “sharing” is inadequate such that occlusion also leads to cell death in the region supplied
Functional end atery
What type of arteries are branches of the coronary artery?
Functional end arteries
Allow multiple pathways for blood to reach the target tissue
Anastomosis of blood vessels
When an anastomosis is present, occlusion of one pathway results in shunting of blood to a
-therefore there is no cell death
Collateral pathway
A reversal in the direction of blood flow in one or more vesicles typically occurs when an occlusion is bypassed using
Collateral vessels
What happens to collateral vessels as the need for collateral flow develops (e.g. from a partially occluded artery)
They grow in size
For example, as one or more branches of the coronary arteries become narrowed from atherosclerosis, the quality of the anastomoses among these vessels
Increases
Anastomoses may also be present in veins, but only in veins without
Valves
Costal notching due to enlargement of intercostal arteries is seen in
Coarctation (narrowing) of the aorta
Prominent in the blood supply to cutaneous regions with large surface area
Venae Commitante
