U7 - circulatory system Flashcards
Circulatory system
- delivers oxygen and nutrients to body cells
- remove carbon dioxide and other waste products
- circulates cells of the immune system
- closed system
arteries
- blood flows out of the heart into the arteries
- walls are thick and elastic: contain a layer of muscle
- carry blood from heart to tissues
Arterioles
- small arteries branch into arioles
- small ver of arteries: muscle walls
- carry blood from arteries to cappillaries
Capillaries
- arterioles lead to networks of capillaries
- narrow vessels to fit single blood cells
- thin walls, only a cell layer
- carry blood from arterioles to venules within the tissues
Venules
- cappillary beds drain into venules
- walls are thin because they contain less muscle then arterioles
- carry blood from capillaries to veins
Veins
- many venules drain into a larger vein
- contain less muscle then arteries
- contain valves
- carry blood from venules to heart
Portal systems
- portal veins are special vessels that carry blood between capillary beds
- have thin walls and valves like veins
Heart
- muscle is involuntary
- heart cells contract on their own
- two pumps, right (lungs), left (body)
- each pump made of two chambers atrium, and ventricle
- septum divides them
Right side of the heart
- venous blood returns
- anterior, posterior vena cava connect to right atrium
- blood is pumped out of right ventricle into pulmonary trunk which splits into right and left pulmonary arteries
Left side of the heart
- blood returns from lungs
- right, left pulmonary veins connect to the left atrium
- blood is pumped out of left ventricle into aorta
AV valves
- prevent back flow from ventricles to atria
- valves open when atria contracts
- when ventricle contracts valves close
semi lunar valves
- prevent back flow from aorta and pulmonary trunk into ventricles
- open when ventricles contract
- close when ventricles relax
external anatomy
- on the front and sides of the heart are
vessels which give it a rich blood supply
blood flows to both sides of the heart through
right and left coronary arteries, and drains
into the right and left coronary veins
Pulmonary vs systematic circulation
-pulmonary: venous blood is pumped into right side to lungs release CO2 and pick up O2
-systematic: – oxygenated blood is
pumped from the left side to the body
tissues to release O2 and pick up CO2
path of blood cells
aorta → body → vena cava → R atrium → right AV valve → R ventricle → pulmonary semi-lunar valve → pulmonary artery → lungs → pulmonary vein → L atrium → left AV valve → L ventricle → aortic semi-lunar valve → aorta
heartbeat is coordinated to three special nerve regions
sinoatrial (SA) node – in the upper wall of
the right atrium; sets the rhythm, causes
atria to contract, and stimulates AV node
atrioventricular (AV) node – in the base of
the right atrium, delays signal slightly before
stimulating Purkinje fibers
Purkinje fibers – within the septum and the
ventricles, cause ventricle contraction
sequence of heartbeat
SA node begins heartbeat signal every 0.85
seconds (~70 per minute), causing atria to
contract
when this signal reaches the AV node it is
slightly delayed for the atria to empty
signal passes into Purkinje fibers, which
cause the ventricles to contract from the
bottom to the top
blood pressure in lungs
systolic – higher pressure caused by heart
contraction
diastolic – lower pressure caused by heart
relaxation (and artery elasticity)
normal B.P. = 120/80 (systolic/diastolic)
abnormal blood pressure
hypertension – blood pressure is too high
systolic > 140 or diastolic > 90
caused by many factors: obesity, excessive salt,
and genetics
hypotension – blood pressure is too low
systolic < 90 or diastolic < 60
caused by low blood volume, weak heart
contraction and dilation of the blood vessels
Measurement of arm blood pressure
blood pressure is measured by an inflatable
cuff around the arm
when the pressure in the cuff matches
systolic pressure, blood supply is cut off
the cuff is then deflated until blood begins
flowing again, this is the diastolic pressure
major arteries
aorta – carries blood from the left ventricle
to the rest of the body
L+ R coronary arteries – carry blood from
the aorta to the sides of the heart
L+R carotids – carry blood from the aorta
to the sides of the head
L+R subclavians – carry blood from the aorta to arms
major arteries
mesenteric – carries blood from the aorta
to the organs of the digestive system
L+R renal – carry blood from the aorta to
the kidneys
L+R iliac – carry blood from the aorta to the
legs
L+R pulmonary – carry blood from the right
ventricle to the sides of the lungs
major veins
L+R jugular – carry blood from the sides of
the head to the subclavian vein
L+R subclavian – carry blood from the
arms to the anterior vena cava
L+R coronary – carry blood from the sides
of the heart to the vena cava
A+P vena cava – carry blood from the head
and arms (anterior) and lower body
(posterior) to the right atrium of the heart
major veins
L+R iliac – carry blood from the legs to the
posterior vena cava
L+R renal – carry blood from the kidneys to
the posterior vena cava
hepatic – carry blood from the liver to the
posterior vena cava
hepatic portal – carry blood from the small
intestine to the liver
pulmonary – carry blood from the lungs to
the left atrium
Arteries blood flow
- bp is highest in aorta
- ## total cross sectional area of arterioles is greater than arteries, and the BP decreases
Capillaries blood flow
- huge TCA, blood pressure and velocity plummet
- gives time for nutrients to be exchanged
Vein blood flow
- blood returns to TCA, and Bp increases
-
short term blood pressure control
- blood pressure is controlled by the autonomic nervous system
- if Bp is too low, muscles in arteries contract and decrease internal diameter of the vessel
- BP is too high, muscles in arteries relax and diameter increases
long term blood pressure control
- altering blood volume
- ## blood volume and blood pressure increase
Capillaries tissue-fluid exchange
- capillaries are location of exchange between blood and tissue fluid
- nutrients, oxygen diffuse from blood to tissue fluid
- wastes and carbon dioxide diffuse from tissue fluids into the blood
- fluid enters and leaves the blood due to balance between osmotic and blood pressure
Lymphatic system
- not all fluids are absorbed on venue side
- throughout capillaries are extensions of lympathic system called lymph capillaries
- walls of lymph capillaries have holes and catch lymph in them
Lymphatic system functions
- collect excess tissues from fluid and return to blood
- pick packaged lipids from intestinal villi and carry them to the blood
- works with immune system to fight off infection
Lymph Cappilarries
- tiny vessels with closed ends, found throughout cappilarory beds
- walls are very thin and have lots of gaps
Lymph Veins
-lymph capillaries join to form larger lymph veins
- collect in two large ducts that drain into the right and left subclavian veins
-
Lymph nodes
- small swellings along the lymph vein
- each node is divided into lobes which are filed with immune cells
- lymph is cleaned by immune cells in node
Immunity
- physical barriers: skin and mucous membranes mechanically prevent entry
- non specific: white blood cells that target foreign objects and consume them through phagocytosis
- specific: white blood cells designed to fight certain kinds of pathogens
antigens
any molecule, usually protein or carbohydrate, that causes an immune response
antibody
- y shaped proteins that bind to specific antigens, produced in membranes of specific immune cells
- immune system remembers and continues to produce them
function of blood
- supply nutrients to tissues (oxygen, glucose, amino acids, etc)
- remove waste from tissues
- carries immune systems, blood clotting agents, hormones
Composition of blood
- Plasma (55%)
- 92% water - maintain blood volume, dissolves remaining components
- 7% proteins
- 1% dissolved gases, nutrients, wastes, hormones, vitamins. - Cells (45%)
- red blood cells - 4,6 Milly
- white blood cells - 5,000-10,000
- platelets - 150,000 to 300,000
Formation of blood cells
- created in marrow of your bones
- stem cells in marrow are capable of turning into different blood types
- one kind of stem cell develops into red blood cells, platelets, and non specific white blood cells
- another kind develops into white blood cells of immune systems
Red blood cells
- cells that contain haemogobling to contain 02 and CO2
- lack nucleus and organelles
- shape is biconcave disk, allows them to move easily through capillaries and increase general surface area
- live for four months, then are consumed by heme groups and excreted as bile pigments
white blood cells
- responsible for non and specific immunity
- have nucleus and lack haemogoblin
platelets
- cell fragments involved in blood clotting
- when blood vessel is damaged, platelets pile up in a hole and release chemicals that activate clotting enzymes in plasma
- long protein threads form, trapping RBC and platelets in clot
Fetal circulation
- lungs are filled with fluid and don’t function
- blood is carried in the umbilical chord to the placenta, where fetal capillaries are bathed in the mothers blood
- gases, waste, and nutrients are exchanged, and blood returns to fetus back through umbilical chord
Umbilical vein and arteries
umbilical cord contains three blood vessels
- umbilical vein - brings oxygen and nutrients back to the fetus from the placenta
- umbilical arteries - branches of the lilac arteries, carrying deoxygenated blood and waste to the placenta
Oval opening fetus
- opening between right and left atria in heart
- allows oxenegated blood from umbilical vein to bypass pulmonary circulation and go straight into the systemic
- normally closes before birth
venous and arterial ducts
provide quicker path for blood from umbilical vein to body
- venous ducts - connect umbilical vein to posterior vena cava, bypassing liver
- arterial ducts - connect pulmonary artery with aorta, allowing oxynegated blood to bypass lungs and left side of the heart
Five types of blood vessels found in the body
Arteries, Arterioles, Capillaries, Venules, and Veins.
structure of arteries and arterioles
Arteries: -blood out of the heart goes into arteries
- they have thin and elastic walls, a layer of muscles
- carry blood to tissues
Arterioles: - smaller ver of arteries
- carry blood from arteries to capillaries
Structure of Veins and Venules
Veins: - thin walls - valves - carries blood to heart Venules: - thin walls - carry blood from capillaries to veins
Function of valves in veins?
To prevent blood from flowing back down the vessel
Function of left and right atria
- Deoxynegated blood enters the right atria through anterior and posterior vena cava. Oxygen rich blood from the lungs enters left atrium through pulmonary vein.
Function of left and right ventricles?
Blood is pumped out of left ventricle into aorta.
Blood is pumped out of right ventricle into pulmonary trunks.
why is left ventricle more muscular?
higher forces needed to pump blood through the systemic circuit (around the body) compared to the pulmonary circuit.
Function of coronary arteries and veins?
Blood flows to both side of the heart through coronary arteries. Blood drains into left and right coronary veins.
What is role of anterior and posterior vena cava
vein that carries de-oxygenated blood from the lower body to the right atrium of the heart.
Biggest artery connected to the heart
aorta, from the heart’s left ventricle.
Name the valves found in the heart, where in the heart are they located?
Atrioventrical valves are between atria and ventricles.
Semi-lunar valves prevent back flow from aorta and pulmonary trunk
What are chord tendinae
tendons that prevent AV valves from collapsing outward
Location of hepatic portal vein?
carries blood from small intestine to the liver, located between the two
Where are SA and AV node located?
AV node is between the ventricles, and SA node is between the atriums
average systolic and diastolic blood pressures?
systolic - 120
diastolic - 80
why is BP and BV being low in capillaries and advantage
Fluid can leave and enter blood because of the balance between osmotic and blood pressure
what is Bp and Op at the capillaries
BP - due to large TCA of capillaries blood pressure drops, it moves out of the blood
OP - blood is hypertonic, it moves into the blood
BP and OP at arteriolar end of capillaries
BP = 30 mmHg out OP = 21mmHg in
BP and OP at venue end of capillaries
BP = 15 mmHg out OP = 21 mmHg in
Why is BP and OP different at two ends of the capillaries
- BP is higher at the arteriolar end because it is where the fluid moves into the tissue
- OP is higher at the venue side because the fluid moves back into blood
how is lymph moved in lymph system?
collected by lymph capillaries and move through lymph vessels and veins
