Circulatory system Flashcards
What are the two part of the circulatory system?
- The cardiovascular system
- The lymphoid system
What does the cardiovascular system do?
Heart and blood vessels transport blood through pulmonary circulation and systemic circulation
What does the lymphoid system do?
Lymph vessels transport excess fluid from body tissues towards the heart
What are the main components of the cardiovascular system?
- Blood
- Heart
- Blood vessels
How much blood does the average person have?
5L
What are the components of blood?
- plasma
- cells
- platelets
What is plasma made of?
- water
- plasma proteins
- ions
- glucose
- amino acids
- hormones
- waste
What are the main functions of blood?
- oxygen transport
- clotting
- transport of hormones, ions, nutrients
- move heat around body to stabilise temp
- move white blood cells to site of infection
What are the different types of white blood cells?
- Neutrophils
- Eosinophils
- Monocytes
- Basophils
- Lymphocytes
- Natural killer
What do neutrophils do?
White blood cells which engulf pathogens
What do Eosinophils do?
White blood cells involved in allergic reactions
What do monocytes do?
White blood cells which engulf pathogens/debris
What do basophils do?
White blood cells which engulf large parasitic pathogens
What do lymphocytes do?
White blood cells involved in adaptive immune response and production of antibodies
What do natural killer cells do?
White blood cells used for surveillance (e.g. for mutated cells)
What goes into the right atrium?
Deoxygenated blood from the body
What comes out of the right ventricle?
Deoxygenated blood headed for the lungs
What goes into the left atrium?
Oxygenated blood from the lungs
What goes out of the left ventricle?
Oxygenated blood transported to body
What brings blood to the right atrium?
Superior and inferior vena cava
What vessel transports blood out of the right ventricle?
Right and left branches of the pulmonary artery
What blood vessel brings blood from lungs to left atrium?
Pulmonary veins
What blood vessel brings blood to body from left ventricle?
Aorta
What do valves do?
Open and close in response to the pressure of blood as it is moved through the heart to maintain unidirectional flow of blood
What are the four valves of the heart?
- Tricuspid valve
- Pulmonary valve
- Mitral valve
- Aortic valve
Where is the tricuspid valve?
Between the right atrium and right ventricle
Where is the pulmonary valve?
Between the right ventricle and the pulmonary artery
Where is the mitral valve?
Between the left atrium and left ventricle
Where is the aortic valve?
Between the left ventricle and aorta
How does the heart contract?
- Sino-Atrial node (SAN) acts as natural pacemaker
- fires impulses 60-80bpm at rest without depending on CNS
- impulse causes contraction of atria, then contractions of ventricle
What does the sympathetic nervous system do to heart rate?
Speed it up (using sympathetic cardiac nerves)
What does the parasympathetic nervous system do to heart rate?
Slows it down (using vagus nerve)
How long does it take for blood to complete a circuit of pulmonary and systemic circulations?
Approx. 1 min
What are the different types of blood vessels?
- Arteries
- Arterioles
- Capillaries
- Venules
- Veins
What is the common 3-layer structure of blood vessels?
- Tunica intima
- Tunica media
- Tunica externa
What is the tunica intima?
The internal layer of a blood vessel made up of a smooth later of squamous epithelial cells (endothelium) on a base of collagen
What is the tunica media?
The middle of the three layers of the blood vessel structure made of smooth muscle to allow contraction to increase blood pressure
What is the tunica externa?
The outer layer of the blood vessel which protects it
What is different about the structure of capillaries compared to other blood vessels?
Only have tunica intima layer
What are the functions and features of arteries and arterioles?
Carry blood away from heart to organs
Have thick walls to withstand high blood pressure from heart
What are the two types of arteries?
- large (elastic)
- medium/small (muscular)
What are the functions and features of veins and venules?
- Carry low pressure blood back to heart
- less smooth muscle and elastin than arteries
- veins have valves, venules do not
What are capillaries made of?
Single layer of endothelial cells and a basement membrane
What is the role of capillaries?
Transport blood throughout tissues to supply with oxygen and nutrients
What are the functional features of capillaries?
- thin wall for diffusion of substances
- diameter same as red blood cell (7-8μm)
What are the different branches of the aorta?
- Ascending aorta
- aortic arch - curves over heart and gives branches for head neck and arms
- thoracic aorta - down through chest
- abdominal aorta - begins at diaphragm then divides into right and left iliac arteries
Which blood vessel do most organs receive blood from?
A descending branch of the aorta
What are the coronary arteries?
Branch off ascending aorta to provide oxygen and nutrients to heart muscle
What is atheroscleoris?
formation of hard, fatty plaques
What happens if an end artery is blocked or damaged?
Blood supply to the tissue/organ is compromised and there is no alternative vessel to provide blood
What are anastamoses?
An artery’s alternative route for blood
What vessels supply blood to the brain?
- Right and left carotid arteries
- Vertebral arteries
Define blood pressure
The pressure that blood exerts on the walls of blood vessels
Define systolic blood pressure
Maximum pressure within the large arteries when the heart muscles contract
Define diastolic blood pressure
Lowest pressure within large arteries during heart muscle relaxation
What factors affect blood pressure?
- Cardiac output
- Peripheral vascular resistance
If either increase, blood pressure will also increase
Define cardiac output
The volume of blood pumped by the heart in one minute
How is cardiac output calculated?
Heart rate x stroke volume
Define stroke volume
Amount of blood pumped out of left ventricle in one contraction
Define peripheral vascular resistance
The resistance to blood flow in the arterioles
When is there high peripheral vascular resistance?
In vasoconstriction - sympathetic stimulation causes constrictions and decreased diameter causes increased PVR so blood pressure increases
When is there low peripheral vascular resistance?
In vasodilation - reduction in sympathetic stimulation increases diameter which decreases PVR, leading to lower blood pressure
Where are baroreceptors found?
In carotid arteries and aorta
What happens if baroreceptors detect a high stretch?
This means blood pressure is high, to the brain slows the heart and causes vasodilation of arterioles
What happens if baroreceptors detect low stretch?
This means blood pressure is low, so the brain speeds up the heart and causes vasoconstriction of arterioles
What are the effects of high blood pressure?
- damage to endothelial lining of arteries increasing the risk of atherosclerotic plaques and blood clots
- left ventricular hypertrophy
- aneurysms
- damage to blood vessels in eye
- chronic kidney disease
What is and Ischaemic stroke?
85% of all strokes
A blood clot forms from a ruptures atherosclerotic plaque, blocking blood flow to an area of the brain
What is a transient ischaemic attack?
a temporary occlusion in an artery where the clot dissolves by itself
What is a hemorrhagic stroke?
Damage to blood vessels leads to leakage of blood into surrounding brain tissue
What is left ventricular hypertrophy (LVH)?
Heart must contract more to push blood through a high pressure system leading to thickening of the left ventricle
What is an aneurysm?
Thinning and bulging of arteries
What are the components of tissue fluid?
water, glucose, fatty acids, salt, oxygen
Define hydrostatic pressure
Pressure in the capillary due to the heart pumping blood through the arteries
How is tissue fluid formed?
- nutrients and oxygen dissolved in water (not hormones) are pushed out of the capillary through small gaps between endothelial cells due to blood pressure
- Because the water has moved out, the blood gets more concentrated at the venous end because still has red blood cells and proteins
- More water in tissue fluid than blood so water moves back by osmosis, and CO2 and urea also diffuses into blood
What happens to excess tissue fluid?
Taken up by lymphatic system and returned to heart
What is lymph made up of?
- Tissue fluids
- Lymphocytes
- Lipids from digestion
What do the lymph nodes do?
The lymph passes through them on the way to the heart so they can filter the lymph and detect pathogens
Where does the lymph rejoin the circulatory system?
thoracic duct empties lymph from upper and lower body and left side into the left subclavian vein
right lymphatic duct empties lymph from right upper body into right subclavian vein
What are lymph nodes?
Small organs of the lymphoid system made mostly of lymphocytes which detect pathogens or antigens in lymph
What is lymphadenopathy?
Swollen lymph nodes usually due to local infections, upper respiratory infections, TB, HIV, and rarely due to cancer
What causes inflammation?
Damage to tissue
What happens in the vascular response?
Vasodilation occurs bringing immune cells, and the endothelial cell layer becomes leaky
What are the cardinal signs of inflammation?
- heat - extra blood arriving
- swelling - more fluid moving out into tissues by hydrostatic pressure carrying immune cells
- redness - extra blood flow
- pain - due to stimulation of nearby neurons
