The

Circulatory System

Part 2

Review from last class

Blood Vessels - Arteries• Arteries

– , elastic walls to withstand blood pressure generated during contraction of

– large diameter to reduce resistance to

– Do not have valves since the heart give them enough to send blood through the

• Arterioles– walls and smaller diameter

than arteries therefore cannot withstand as much

– blood flow through some organs by smooth muscle to reduce blood flowing into

Blood Vessels - Veins• Veins

– blood pressure in veins have thinner, more flexible walls than arteries &

– blood too low in veins to push blood flow therefore of skeletal muscle to squeezes veins needed to force blood through

– are found in veins that carry blood

the force of gravity

Blood Vessels - CapillariesCapillaries• cannot withstand significant

blood pressure therefore must reduce in arteries to lower blood pressure by having numerous capillaries

• extensive capillary network provides large

Capillary Exchange• Low blood velocity provides more time for diffusion across

capillary walls• Capillary exchange takes place due to the following forces:

– blood pressure: pressure higher in blood than tissues, which drives from blood plasma into tissue fluid

– osmotic pressure: solute higher in tissues than blood, which drives substances from fluid to plasma

Capillary Exchange1. blood pressure greater than osmotic pressure at arteriole end, which

drives , , , acids, ions, & hormones from blood plasma into tissue fluid & then into cells, while larger substances remain in blood plasma, e.g. red blood cells, , &

2. osmotic pressure greater than blood pressure at venule end, which drives , , & some H2O from tissue fluid into blood

The Body

Systemic Circulation

Circuits• Pulmonary Circulation

– carries deoxygenated blood from right ventricle to lungs & oxygenated blood from lungs to left atrium of heart, i.e. pathways between heart & lungs

• Systemic Circulation– carries oxygenated blood from left

ventricle through body & deoxygenated blood from body to right atrium of heart, i.e. pathways between heart & body

NOTE: volume of blood entering/exiting pulmonary circulation always equal to volume of blood exiting/entering systemic circulation

Major Arteries and Veins

• Subclavian arteries and veins• Jugular veins• Carotid arteries• Mesenteric arteries• Anterior and posterior vena cava• Pulmonary veins and arteries• Hepatic vein• Hepatic portal vein• Renal arteries and veins• Iliac arteries and veins• Coronary arteries and veins• aorta

Branches of the aorta

• Subclavian arteries:– artery

blood to the left arm– artery

blood to right arm, with a branch to the

• Carotid artery– Supplies to the

head and neck

• The vein draws blood

from the arms into the vena cava

• The jugular vein draws

blood from the and neck into the

superior

Mesenteric

• Mesenteric artery– Major artery that branches

from the aorta and supplies the small intestine, large , and pancreas with

blood

• Mesenteric vein– Carries

blood from the same organs into the vena cava

• Hepatic portal vein– It receives blood from the

stomach, , large intestine, pancreas, spleen and through the inferior mesenteric, gastric, and cystic veins. It carries the blood received from all these parts of the body to the .

– The blood that is brought to the liver by the hepatic portal vein is by the liver

• Hepatic vein– Drains cleaned and

blood from the liver into the inferior vena cava

Renal

• Renal arteries– Branch from the

– Supply kidneys with

• Renal veins– Drain blood

from the kidneys into the vena cava

Iliac

• Iliac arteries– Branches from the

and carries blood to the legs and feet

• Iliac veins– Drains blood

into the inferior vena cava

Summary

Lymphatic System

Functions

1. Returns fluids from to blood, i.e. prevents

in tissues2. Transports fats from

to blood

3. Defends body disease caused by

invaders

• When blood flows through capillaries, the molecules that are out for tissue cells to absorb are know as

• Interstitial fluid is composed of acids,

, fatty acids, coenzymes, hormones, neurotransmitters, salts, as well as waste products from the

• Not all interstitial fluid will be absorbed by , and so lymph capillaries, which surround blood capillaries, absorb this fluid, now known as

• lymph capillaries: narrow, thin–walled vessels that collect fluid from tissues

• lymph: fluid within lymphatic system, i.e. fluid that enters through capillaries

• lymphatic veins: collects lymph from capillaries and fluid to blood through veins in neck (right of left vein)– contraction of skeletal

muscle moves lymph therefore require one–way

to move lymph in one direction, i.e. similar to veins in

system

• lymph nodes: filters lymph and produce

white blood cells that destroy invaders in lymph– located along lymphatic

veins

Fetal Circulation

Features of Fetal Circulation• Nutrients and waste are exchanged through

the – Fetus receives O2 and nutrients from mother

through , while CO2 and waste from fetus removed by mother through

• Pulmonary circulation not required because fetus receives oxygenated blood from mother– Fetus does not use its lungs for gas exchange

• Structures required to bypass pulmonary circuit:

1. : connects right and left atria, which reduces blood flow into right ventricle

2. : connects pulmonary trunk to aorta, which reduces blood flow into pulmonary arteries

3. : connects umbilical vein at liver to posterior vena cava, which reduces blood flow through liver

By the End of this Section you should be able to:

• identify and give functions (including where blood is coming from and going to, as applicable) for each of the following:

– left and right atria– left and right ventricles– coronary arteries and veins– anterior and posterior vena cava– aorta– pulmonary arteries and veins– pulmonary trunk– atrioventricular valves– chordae tendineae– semi-lunar valves– septum

• recognize heart structures using both internal and external diagram views

• describe the location and functions of the sinoatrial (SA) node, atrioventricular (AV) node, and Purkinje fibres

• describe how the autonomic nervous system increases and decreases heart rate and blood pressure

• differentiate between systolic and diastolic pressures

• describe hypertension and hypotension and their causes

• identify and give the function (including where the vessel is carrying blood from and where it is carrying blood to) of each of the following:

– subclavian arteries and veins– jugular veins– carotid arteries– mesenteric arteries– anterior and posterior vena cava– pulmonary veins and arteries– hepatic vein– hepatic portal vein– renal arteries and veins– iliac arteries and veins– coronary arteries and veins– aorta

• describe and differentiate among the five types of blood vessels with reference to characteristics such as

– structure and thickness of vessel walls– presence of valves– direction of blood flow (toward or away from the heart)

• differentiate between pulmonary and systemic circulation with respect to oxygenation or deoxygenation of blood in the vessels involved

• demonstrate a knowledge of the path of a blood cell from the aorta through the body and back to the left ventricle

• relate blood pressure and blood velocity to the total cross-sectional area of the five types of blood vessels

• describe capillary-tissue fluid exchange• identify and describe differences in structure and circulation

between fetal and adult systems, with reference to umbilical vein and arteries, oval opening, venous duct, arterial duct

• describe the shape, function, and origin of red blood cells, white blood cells, and platelets

• list the major components of plasma• explain the roles of antigens and antibodies

describe the functions of the lymphatic system • identify and give functions of lymph

capillaries, veins, and nodes

Mandatory Vocabularyanterior vena cava, antibody, antigen, aorta, arterial duct atrioventricular valve, autonomic nervous system, atrioventricular (AV) node, blood, blood pressure, blood velocity, blood vessel, capillary-tissue fluid exchange, carotid artery, chordae tendineae, coronary artery, coronary vein, diastolic pressure, fetal circulation, heart rate, hepatic portal vein, hepatic vein, hypertension, hypotension, iliac artery, iliac vein, jugular vein, left atrium, left ventricle, lymph capillaries, lymph node, lymphatic system, lymphatic veins, mesenteric artery, oval opening, plasma, platelets, posterior vena cava, pulmonary arteries, pulmonary circulation, pulmonary trunk, pulmonary veins, Purkinje fibres, red blood cell, renal artery, renal vein, right atrium, right ventricle, sinoatrial (SA) node, semi-lunar valve, septum, subclavian artery, subclavian vein, systemic circulation, systolic pressure, total cross-sectional area, umbilical artery, umbilical vein, valve, veins, venous duct, vessel wall, white blood cell