Circulatory System
Divided into two halves- the blood leaving the heart
-the blood coming into the heart
Three types of blood vessels
Arteries (and arterioles)—carry blood from the heart
Capillaries—exchange materials with the tissues
Veins (and venules)—return blood to the heart
Ex 1) Contrast Veins and Arteries
Arteries
Veins
What is the main function of capillaries?
Can you think of any times, other than the example in the book, where blood might go
directly somewhere?
Wednesday
Continue activities from Tuesday
Drawing the heart
Know the function of the following before doing the drawing.
-Left atria- receives oxygenated blood lungs. Sends it to left ventricle
-Right atria- receives deoxygenated blood from the body; sends it the right ventricle
-Coronary arteries – branches from aorta- supplies ox blood to the heart tissue
-Corony veins- sends deox blood back to right atrium
-Pulmonary trunk- vessel that goes from right ventricle and branches into the L and R
pulmonary arteries, which go to the lungs
-Chordae tendineae- strings that go between the wall of the ventricles and the AV valves.
They prevent the valves from being pushed by the flow of blood into the atria.
-Left and right ventricles- large muscular pumps that send blood to the body or to the
lungs.
-Anterior and posterior vena cava- widest veins- one above and one below the heart
-Pulmonary arteries and veins-send and receive blood to and from the heart and lungs
-Atrioventricular valves-close the space between the A and V
-Semilunar valves- Either of two valves, one located at the opening of the aorta and the
other at the opening of the pulmonary artery, each consisting of three crescent-shaped
cusps and serving to prevent blood from flowing back into the ventricles. Respectively
known as the aortic semilunar and the pulmonary semi lunar valves
-Septum- dividing wall btwn the L and R of heart
Q: What would happen if you didn’t have chordae tendineae?
Q: What does the superior and inferior refer to?
Q: What is the difference between the L and R Ventricle?
Q: What is unusual about the pulmonary arteries and veins in comparison to most other
arteries and veins?
Q: When are the AV valves open? Closed?
Write out the pathway of the heart including all the above terms.
Conduction of the heart beat?
-SA node. –starts the electrical signal that makes the heart beat-every .85 seconds- sets
the beat. Spreads over both atria simultaneously
-AV node- carries the electrical signal from the atria to the ventricles
-Purkinje fibers-conducts electrical signal from top of septum to bottom of heart
-systole-contraction of ventricles-creates blood pressure
-diastole-relaxation of ventricles
Q: What happens if the SA valve isn’t working properly?
Q: Why is the sinoatrial valves known as the pacemaker?
Q: What is the relationship to the strength of the voltage and the action within the heart?
Q: What happens in the left atrium when the right atrium contracts?
Q: Think of times when your heart sped up. What was the reason?
Nervous control of heart
SA and Av nodes are connected to sympathetic and parasympathetic nerves
Sym- times of stress and activity
Acceleration of heart rate
Dilation of coronary arteries to increase flow to heart muscle
Para- times of relaxation
-slower heart rate
-reduced blood flow to heart tissue
-associated with the neurotransmitter acetylcholine
things that can affect heart rate
increase: exercise, hormones like epinephrine, thyroxine, caffeine,
decrease:
blood temperature and pressure also affect heart rate.
Systemic circulation
Major veins and arteries
Trace pathways
Kindeys- Renal
Liver- Mesenteric, hepatic portal, hepatic vein
Lungs- pulmonary
Heart- coronary
Legs- femoral, saphonous,
Hips- iliac
Arms- brachial
Shoulder- subclavian (under clavicle)
Head- carotid- difference from left and rightRight- branches off subclavion
Left- direct from aortic arch
When tracing pathway, just mention major veins and artieries, not the smaller vessels
Blood Pressure
How is it created?
How does it change?
Special terms
Systole- contraction
Ventricle systole
Diastole- relaxation
Ventricle diastole
Blood pressure measurements are the two numbers
120- systolic pressure in brachial artery
80 diastolic pressure
source of blood pressure in arteries- from ventricle systole
as blood moves further away from heart, vessles branch out and blood pressure drops.
When blood leaves the capillaries, the pressure in the vessels is too low to move in back
to the heart. Pressure in veins is created by contraction of skeletal muscles that squish the
blood.
Backflow is prevented by valves
Blood and what’s in it
Blood has two main divisions
Plasma-liquid- water and other stuff
Formed elements- things that your body made- like cells and cell bits.
Plasma
3 main components
water, 90-92 % of plasma
plasma proteins- 7-8 %
salts. Less than 1 %
Role and source of main plasma components
Proteins- maintain blood volume- cannot leave capillary, means that blood is hypertonic
in capillaries compared to fluids in tissue, so they make blood draw in more water
everything else- gases, nutrients, nitrogenous wastes, others
FORMED ELEMENTS
Red Blood Cells- erythrocytes
White Blood Cells- Leukocyctes
Platelets
Source of all types- red bone marrow- view diagram p 231
Red Bloods Cells
No nucleus
Shape- biconcave disk- indented on both sides
Small- just narrowed than a capillary
Made of hemoglobin protein which carries oxygen
 Made of 4 globular proteins with an iron group in each glob
 Gives blood its red colour
 The number of hemoglobin molecules in a red blood cell is
approximated to be somewhere between 250 million to 270
million.
 each hemoglobin molecule contains 4 heme groups which can each
bind to one molecule of O2, each red blood cells carries more than
1 billion O2 molecules
Other Formed elements- students make a diagram and state the function of each type
Overall questions
What parts of the blood are responsible for maintaining blood pressure? And how?
What parts are involved I clotting?
What is the general role of WBCs?
Blood Clotting
Injury
Platelets stick to exposed tissue and try to plug hole
Platelets and damaged tissue release prothrombin activator
Prothrombin activator and Ca++ cause prothrombin to become thrombin
Thrombin and Ca++ cause fibrinogen to become fibrin thread
Fibrin threads cling to platelets and form a net that red blood cells cant pass through.
Which materials are always present in the blood?
Which materials need to be activated?
Why is it important that blood clotting occurs in steps?
Capillary Tissue exchange
What are the two pressures that influence movement of materials between capillaries and
tissues?
Blood Pressure
Created by heart
Osmotic Pressure
Created by salts and plasma proteins in caps
Results
Arterial end
Water moves out of capillaries
Middle
Glucose, amino acids, O2 move out
Co2 moves into caps
Venous End
Water moves from the tissues back into the caps
Explain the forces that are causing the water to move.
Excess water that does not go back in the cap, goes into lymphatic capillaries and is
carried from caps to the subclavian vein in the shoulder area.
Lymphtatic system
Carries fat molecules from digestive tract
Excess water from tissues
White blood cells that fight infection
Made of lymphatic veins, which also have valves
And lymph nodes, lumps of lympathic tissue that play a role in immunity
How do white blood cells get to infected tissue?
Damaged cells and other white blood cells produce histamine
Causes small windows between cap cells to open wider
This allows neutrophils and monocytes (macrophages) to squeeze through caps and get to
tissue
Col thing about some white blood cells- they can change their shape like amoebas. P 243
Fetal Circulation
Bypasses the lungs and liver
How? Page 458
Different because…
Lungs are not in use by fetus.
Blood bypasses the lungs by moving from the right atrium to the left atrium through the
oval opening or foramen ovale. This is why, especially premature babies, may be born
with a hole in their heart and have a heart murmur.
Any blood that enters the right atrium and is pumped to the pulmonary trunk will be sent
to the aorta via the arterial duct.
Blood from the mother reaches the fetus through the umbilical vein. It merges with the
inferior vena cava via the venous duct. Blood then travel through the heart and around
the body and out via the umbilical artery.
Summary
Oval opening
umbilical vein
umbilical artery
Venous duct
Arterial duct