Circulatory System Flashcards
What is blood pressure?
The force exerted by blood on the muscular walls of blood vessels
Blood pressure rises and falls as the heart beats.
When is blood pressure highest?
During systole, when the heart contracts
Systolic BP ranges from 90 - 120 mm Hg.
What is systolic blood pressure?
The pressure in the arteries when the heart contracts
Normal range is 90 - 120 mm Hg.
When is blood pressure lowest?
During diastole, when the heart is at rest
Diastolic pressure ranges from 60 - 80 mm Hg.
What happens if blood thickens?
The heart pumps harder to push it
This can lead to increased blood pressure.
How does a low salt diet affect blood pressure?
Reduces water retention, thus decreasing blood volume & pressure
Salt promotes water retention, which increases blood pressure.
What role does stress play in blood pressure?
Releases hormones that constrict blood vessels, increasing resistance to flow
This can lead to higher blood pressure.
What is considered hypertension?
Blood pressure regularly rising over 140/90 mm Hg
Hypertension can lead to serious health issues.
What are the consequences of hypertension on arterial walls?
Causes tears and swelling in arterial walls
White blood cells and other substances collect around the tears.
What happens if a plaque ruptures?
A blood clot forms on the top of the tears
This can clog the artery even more.
What can blocked vessels that feed the heart cause?
A heart attack
Blocked vessels can severely impact heart function.
What can blocked vessels that feed the brain cause?
A stroke
This can lead to significant neurological damage.
What is a normal blood pressure reading?
120/80 mm Hg
This is considered a standard normal reading.
Heart murmurs
Due to a leaky valve (problem with valve closing)
Causes of hypertension
Genetics, diet (high salt intake), stress, age
ECG?
The record of electrical impulses ( changes ) in the heart
Reads the change in electrical activity in various body tissues
Compares the activities of various areas
SA node (sinoatrial node) AKA pacemaker
In wall of right atrium
Receives message from medulla oblongata and sends message to make both atria contract
Impulse travels to AV node
Factors affecting BP
-exercise
-cholesterol build up
-vasoconstriction/vasodilation (controlled by hypothalamus)
-increase/decrease blood = controlled by hormones from hypothalamus, process occurs in kidneys
Hypotension
Lower BP (systolic below 100)
Body adjusts by activating sympathetic nervous system to increase heart rate
Hypertension
Higher BP
Makes heart work harder = body adjusts by activating parasympathetic nervous system to slow heart rate
Circulatory disorders
Arteriosclerosis = (hardening of the arteries)
Atherosclerosis = (plaque buildups in arteries, blood flow very slow)
Aneurysm = (weakening of artery wall)
Varicose veins = valves become weak, allow backflow/pooling of veins
Coronary circuit plugged = cause heart attack
Types of blood vessels
Arteries
Arterioles
Capillaries
Venules
Veins
Coronary circuit
Made of blood vessels that feed the heart tissue (myocardium)
Blood vessels=coronary arteries/arterioles, capillaries, cardiac venules/veins
Heart doesn’t use the blood in inner chambers
Vascular pathway (3 main pathways from the heart)
- Pulmonary (lungs)
- Systemic (body)
- Coronary (heart)
Components of blood
- Plasma (90% H2O)
- WBC’s (leukocytes)
- RBC’s (erythrocytes)
- Platelets (thrombocytes)
Lymphatic system (3 main functions that contribute to homeostasis)
- Lymphatic capillaries absorb excess tissue fluid and return it to blood stream
- Lymphatic capillaries absorb fats from digestive tract and return to blood stream
- Lymphoid organs help defend body against disease
Lymphatic system consists of
- Lymph vessels
- Lymph nodes
- Lymphoid organs
- Lymph fluid
Intrinsic control
Each time the heart beats:
-2 atria contract simultaneously
-the 2 ventricles contract simultaneously
-all the chambers relax
Extrinsic control
-nervous stimulation may speed up or slow down heartbeat
-regulated by autonomic nervous system’s 2 divisions:
1. Parasympathetic nervous system
2. Sympathetic nervous system
Parasympathetic nervous system
Regulates normal activities. May cause heart to slow down during relaxation
Sympathetic nervous system
Responds to stress and increases blood flow to tissues - speeds up heartbeat
ECG waves
P wave occurs just prior to atrial contraction
QRS complex occurs just prior to ventricular contraction
T wave occurs after ventricular contraction
Arterioles
-small arteries
-less elastic than arteries
-selectively open and close to allow blood flow to capillaries only in areas requiring blood
Capillaries
-Smooth muscle that encircles entrance of capillary called pre-capillary sphincters
-Walls only 1 cell thick for nutrient and waste exchange
Venules
Small veins that draw blood from capillaries
Lymph fluid
Consists of water, electrolytes, lymphocytes, plasma proteins
Fluid that’s collected by lymph vessels
Blood vessel circuit
Heart —> arteries —> arterioles —> capillaries —> venules —> veins—> back to heart
Atherosclerosis
When the artery’s walls are stiffened and thickened
Lymph enters the circulatory system at?
The subclavian vein
How many heart valves would a blood cell travelling from the renal vein to the pulmonary vein pass through?
2
