Unit 7: Circulation

Question 1

Arteries function (structure, thickness, valves, blood direction)

Answer 1

Type of blood vessel
Structure: 3 layers. Inner layer is mostly endothelium (type of epithelial tissue), middle layer is the thickest with smooth muscle tissues, outer layer is connective tissue
Thicker than veins due to the middle layer
No valves
Carries blood away from heart to the capillaries

Question 2

Veins function (structure, thickness, valves, blood direction)

Answer 2

Type of blood vessel
Structure: Same 3 layers as arteries, but smaller muscle and connective tissue.
Thinner than arteries
Contains valves that only allow blood to flow towards the heart and prevents backward flow
Carries blood from the capillary beds to the heart

Question 3

Capillaries function (structure, thickness, valves, blood direction)

Answer 3

Type of blood vessel
Interconnects arteries to veins
Structure: Single cell thick walls that allow exchange of nutrients/wastes between blood and tissues
Extremely thin
No valves
Network of many capillaries are called capillary beds. These beds have sphincters that can close a bed. If all beds were open, blood pressure would decrease. If all beds were closed, blood pressure would increase. Only the beds that the body needs are open at a time.

Question 4

Arterioles and Venules

Answer 4

Smaller versions of arteries and veins

All the features (function & structure) are the same, but on a smaller scale

Question 5

Aorta function and structure

Answer 5

The largest artery in the human body.
Leaves the left ventricle, loops over the top of the heart (creates aortic arch), and descends along the inside of the backbone.
Branches out to deliver oxygenated blood to all parts of the body, except lungs

Question 6

Coronary arteries/veins function

Answer 6

The very first branches off the aorta are coronary arteries.
Delivers oxygenated blood to the heart muscle. Heart does not receive nutrients from the blood that goes through it since heart muscle is too thick and dense, and blood travels too hard and fast.
Coronary veins take deoxygenated blood back to the heart.

Question 7

Right and left atria function

Answer 7

Two upper, thin-walled chambers of the 4 heart chambers. Atrium is sing. for atria
Right atrium: collects blood from the vena cava
Left atrium: collects blood from the pulmonary veins

Question 8

Left and right ventricles function

Answer 8

Two lower, thick-walled chambers of the 4 heart chambers.
Right ventricle: Send blood to the lungs via the pulmonary trunk
Left ventricle: Send blood to the body via the aorta

Question 9

Septum function

Answer 9

The central wall of the heart

Separates the left and right sides of the heart preventing the mixing of blood high in oxygen and blood low in oxygen.

Question 10

Atrioventricular (AV) valves function

Answer 10

Two valves between the atria and ventricles that direct blood flow and prevent backflow of blood.
Right hand side (Tricuspids): three cusps, or flaps
Left hand side (Bicuspid/mitral): two cusps

Question 11

Chordae tendineae function

Answer 11

Strong, fibrous strings that support the AV valves as well as prevent them from inverting when the heart contracts.

Question 12

Semilunar valves function

Answer 12

Two valves between the ventricles and their two attached vessels.
Pulmonary semilunar valve (right side): Right ventricle and the pulmonary trunk
Aortic semilunar valve (left side): Left ventricle and the aorta

Question 13

Superior and inferior vena cava function

Answer 13

Largest veins in the human body.
Superior: Collects deoxygenated blood from the head, chest, and the arms into the right atrium
Inferior: Collects deoxygenated blood from the lower body into the right atrium.

Question 14

Pulmonary trunk function

Answer 14

Receives blood from the right ventricle, branching off into two vessels into the lungs

Question 15

Pulmonary arteries vs pulmonary veins function

Answer 15

Pulmonary arteries are the two branched off vessels from the pulmonary trunk that carries deoxygenated blood from the right ventricle to the lungs
Pulmonary veins are four vessels that carry oxygenated blood from the lungs to the left atrium

Question 16

Pulse

Answer 16

Pulse is the alternate expansion and recoil of arteries produced by the rhythmic contractions of the heart.

Question 17

Cardiac cycle characteristics (two step process, lub-dubb sound)

Answer 17

The beating of the heart is a two step process:
Systole- Contraction of heart
Diastole- Relaxation of heart
Each cardiac cycle (a heartbeat) lasts about 0.85s of alternating systole & diastole of the atria and ventricles
The familiar lub-dubb sound of a heartbeat is due to the closing of valves. First the closing of AV valves followed by the closing of semilunar valves.

Question 18

What does it mean when the heartbeat is said to be intrinsic? How is this possible?

Answer 18

The rhythmic contraction of the atria/ventricle is conducted by a intrinsic system, meaning it will beat without any nervous system stimulation.
This is possible as the beat is controlled by a special type of tissue called nodal tissue, which has both muscular and nervous tissue characteristics.

Question 19

Sinoatrial (SA) node location and function

Answer 19

Part of the intrinsic heartbeat conduction system
One of the nodal tissues located in the upper wall of the right atrium.
Also called the “pacemaker” as it initiates the heartbeat and sends out an excitation impulse every 0.85s. This impulse causes both atria the contract, then the impulses are sent to the AV node.

Question 20

Atrioventricular (AV) node location and function

Answer 20

Part of the intrinsic heartbeat conduction system
One of the nodal tissues located in the base of the right atrium, near the septum.
Receives impulse from SA node and sends out second impulse. This second signal travels from the AS node to the branches of AS bundle before reaching the Purkinje fibers.
The combination of AS node and bundle along with the Purkinje fibers all work together to efficiently cause both the ventricles to contract.

Question 21

Parasympathetic vs Sympathetic system

Answer 21

These are the two autonomic nervous systems (not under conscious control) that extrinsically control the heartbeat.
Parasympathetic: Decreases SA and AV nodal activity when body is inactive, causing the heartbeat to slow down.
Sympathetic: Increases SA and AV nodal activity when body is active/excited, causing the heartbeat to increase
Factors like need for oxygen or blood pressure level determines which system becomes active

Question 22

Carotid arteries function

Answer 22

Branches off the aortic arch and takes blood to the head, including the brain.
Contains number of nerve endings: Chemoreceptors that detect oxygen content and Pressure receptors that detect blood pressure changes. These help maintain homeostasis.

Question 23

Jugular veins function

Answer 23

Takes blood from the head back to the superior vena cava. Does not contain valves as blood flow is through gravity.

Question 24

Subclavian arteries and veins function

Answer 24

Artery: Branches from the aorta and travels under the collarbone to carry blood to the arms.
Veins: Collects blood from the arms back to the superior vena cava.

Question 25

Mesenteric arteries function

Answer 25

Branches off from the aorta, where they branch into capillaries within intestinal villi.
Takes blood to the organs of the digestive system. Branched capillaries absorb nutrients from small intestine.

Question 26

Hepatic portal vein function

Answer 26

Hepatic: Liver
Portal: Indicates capillary beds on both ends (one within the villi of small intestine and other in the liver)
Brings blood from digestive tract to liver

Question 27

Hepatic Vein function

Answer 27

Carries blood from the liver once it has processed the blood, to the inferior vena cava.

Question 28

Pulmonary circuit

Answer 28

Circulation of blood from the heart to the lungs.
1. Blood from all regions of the body collects in the right atrium
2. Passes into right ventricle which
3. Pumps blood into pulmonary trunk
4. Trunk divides into right and left pulmonary arteries as they approach the lungs
5. Pulmonary capillaries facilitate the exchange between CO2 and O2.
6. Blood is led back into the left atrium through the four pulmonary veins.
The pulmonary circuit starts with deoxygenated blood sent to the lungs and ends with oxygenated blood returned to the heart.

Question 29

Systemic circuit

Answer 29

Circulation of blood from the heart to all parts of the body (except lungs).
1. Starts from the left ventricle with oxygenated blood
2. Pumped into the aorta which
3. Branches off into various parts of the body where
3. Capillary exchange of waste and materials occur
4. Blood is led back into the right atrium through the superior/interior vena cava
The systemic circuit starts with oxygenated blood sent to various parts of the body and ends with deoxygenated blood returned to the heart.

Question 30

Renal arteries and veins function

Answer 30

Arteries takes blood to the kidneys while the veins take blood away back to the inferior vena cava.

Question 31

Iliac arteries and veins function

Answer 31

Arteries: Aorta branches off in the pelvic area into two iliac arteries, one for each leg. Each iliac artery breaks off into another branch called the femoral artery that supplies the upper leg.
The iliac veins returns the blood back to the inferior vena cava.

Question 32

Blood pressure & systolic vs diastolic blood pressure

Answer 32

Blood pressure: The pressure of blood against the wall of blood vessel. Highest in the aorta and lowest in the venae cavae.
Systolic: Pressure when the ventricles are contracting, ejecting blood from the heart. Highest blood pressure rating.
Diastolic: Pressure when the ventricles are relaxing; heart is at rest. Lowest blood pressure rating.
Pressure is normally measured along the branchial artery on the arm. Normal reading would be 120 systolic reading / 80 diastolic reading

Question 33

How does your body adjust blood pressure

Answer 33

Body can adjust blood pressure, only to a certain extent.
Brain can instruct the body to widen arterioles thus lowering blood pressure, or narrow them to raise the blood pressure.

Question 34

Blood pressure and its relationship with total cross sectional areas

Answer 34

As cross sectional area increases, the speed of the blood decreases. As speed decreases, the blood pressure decreases.
Blood pressure is highest in arteries and lowest in capillaries. This is because capillaries have a high cross sectional area as it has many branches. The low blood speed in capillaries allow the exchange of materials between blood and tissue cells.

Question 35

Changes in circulation with regular exercise (7)

Answer 35

1. Heart muscle becomes stronger and more efficient
2. Ventricular chambers become bigger, pumping more volume of blood
3. Wall thickness of wall chambers increase, meaning it can exert more pressure which means it doesn’t have to pump as often
4. Number of capillaries increase within the working muscles, increasing blood flow to these muscles
5. Arteries become more flexible, can actually reverse some of the effects of atherosclerosis
6. Decrease in LDL, which deposits cholesterol in arteries and increase in HDL which helps body get rid of excess cholesterol
7. Individuals with normally high blood pressure experiences lower blood pressure

Question 36

Cardiovascular diseases: Atherosclerosis

Answer 36

Accumulation of fatty materials beneath the inner lining of arteries. Such deposits are called plaques, mainly being cholesterol buildup.
Plaques can protrude into the lumen of the vessel and interrupt blood flow.
Plaques can also cause clots to form. Stationary clots are thrombus, clots that move along with the blood are called embolus. Thromboembolism is a clot that was carried in the bloodstream but now stationary. This is serious and must be treated.

Question 37

Cardiovascular diseases: Stroke

Answer 37

When a small cranial arteriole (in the head) bursts or is blocked by an embolus.
Prevents sufficient oxygen flow, causing a portion of brain to die, followed by paralysis or death.

Question 38

Cardiovascular diseases: Heart attack

Answer 38

When a coronary artery is blocked, and a portion of heart muscles dies due to a lack of oxygen.

Question 39

Cardiovascular diseases: Hypertension

Answer 39

When blood pressure is high, meaning systolic reading is greater than 140 or the diastolic reading is greater than 90.
Sometimes called silent killers as it may not be detected until a stroke/heart attack occurs.
Can cause considerable damage to blood vessels, heart, brain and kidneys.

Question 40

Cardiovascular diseases: Hypotension and some factors

Answer 40

When blood pressure is low, meaning systolic reading is lower than 90 or the diastolic reading is lower than 60.
Can result in a lack of nutrients getting to their destinations in time. If the brain is not getting enough oxygen, it may result in fainting.

Question 41

3 main functions of the lymph system

Answer 41

1. Lymphatic capillaries take up excess tissue fluid and return it to the bloodstream
2. Lacteals absorb fats from the digestive tract and transport them to the bloodstream
3. The lymph system helps defend the body against disease
   These functions are done by a type of white blood cells called lymphocytes, found in lymph vessels and organs

Question 42

Lymph

Answer 42

The fluid inside lymphatic vessels. Forms when lymph capillaries drain tissue fluid which is mostly water with other substances like protein, nutrients, and enzymes.

Question 43

Edema

Answer 43

Localized swelling caused by accumulation of tissue fluid that has not been collected by the lymph system.
Can cause tissue damage and eventual death.

Question 44

Lymph vessels structure and function

Answer 44

Lymph capillaries: tiny vessels consisting of simple epithelial cell wall, takes up extra tissue fluid.
Lymph veins/venules: Same structure as cardiovascular veins and venules, also containing valves so lymph flow is maintained.

Question 45

Spleen function

Answer 45

Largest lymph organ
Produces lymphocytes which filters the blood of foreign particles
Stores excess blood; when blood pressure is too high it stores the blood to lower it, when blood pressure is too low it contracts and adds blood to the bloodstream to increase it

Question 46

Lymph node function

Answer 46

Contains lymphocytes that filter the lymph fluid of any viruses/bacteria

Question 47

Thoracic vs Right lymphatic duct functions

Answer 47

Both transports lymph back into the circulatory system
Thoracic duct: Returns lymph collected from the left side of head/neck, left arm, and rest of the body below chest area to the left subclavian vein
Right lymphatic duct: Returns lymph collected from the right side of head/neck and right arm to the right subclavian vein

Question 48

Red bone marrow and thymus gland functions

Answer 48

Site of production and maturation of lymphocytes
Red bone marrow: Produces both B-lymphocytes and T-lymphocytes. Matures B-Cells.
Thymus gland: Matures T-cells. Becomes smaller with age.

Question 49

Four unique features of a fetal circulation system

Answer 49

1. Oval opening: Opening between the 2 atria that allows blood flow directly from the right to the left atrium. Allows blood to bypass the lungs, as they do not work yet
2. Arterial duct: Connection between the pulmonary trunk and the aorta, again allowing blood to bypass the non-functional lungs
3. Umbilical artery/vein: Arteries carry waste, CO2 and urea to the placenta from the fetus. Veins carry nutrients, O2, glucose and amino acids to the fetus from the placenta
4. Venous duct: Connection between the umbilical vein and the vena cava, allowing blood to bypass the liver.
5. Placenta: Organ developed in uterus during pregnancy. Exchanges materials with fetus.

Question 50

Changes in fetal circulation at birth

Answer 50

Oval opening and arterial duct close to allow blood circulation to the now functional lungs.
Venous duct is closed as baby is no longer connected to mother and blood does not need to bypass the liver
Umbilical artery/vein are cut off once the baby is delivered, external part dropping off to leave belly button.