Biology 20 AP: Unit D - Circulatory System

What are the 3 main functions of the circulatory system?

1. Transportation of gases, nutrients, and wastes

2. Regulation of internal temp. and transports hormones

3. Protection against bacteria/viruses, toxins, and blood loss from injury

What are the 3 major components of the circ. system?

1. Heart: muscular organ that pumps blood through body to generate blood flow

2. Blood vessels: veins, arteries, capillaries that act as a “roadway” for blood

3. Blood: carries nutrients, oxygen, carbon dioxide, water, and other material throughout the body

Arteries

carry oxygen-rich blood AWAY from heart to the rest of the body

exception: pulmonary arteries

contain thick-layered, elastic walls, and smooth muscle

helps keep the blood under pressure so that it can reach the furthest body parts

Veins

carry oxygen-poor blood TO the heart from the body

exception: pulmonary veins

smaller veins: venules

thin-layered walls with some smooth muscle and elastic tissue

distinguishing feature: valves (ensures one way flow of blood)

large circumference and less elasticity than arteries

muscle contractions from skeletal muscles keep blood flowing to the heart

Capillaries

very tiny vessels that join arteries to veins

location of gas, waste, hormone, and nutrient exchange

smallest blood vessels

one-cell thick

diameter that enables only one RBC to travel through at a time

allows for maximum gas exchange between blood and body cells

Vasoconstriction

narrowing of blood vessels as a result of contraction of the smooth muscle

will decrease blood flow throughout the vessel

keeps heat in

e.g. cold fingers

Vasodilation

widening of blood vessels as a result of relaxation of the smooth muscle

will increase blood flow through the vessel

releases heat

e.g. red face when running

Pulmonary circulatory system

system of blood vessels that carries DEOXYGENATED blood to the LUNGS (pulmonary) and OXYGENATED blood back to heart

function: to oxygenate blood

Systemic circulatory system

involves various arteries and veins in the BODY

the VEINS carry DEOXYGENATED blood from body tissues back to the heart
the ARTERIES carry OXYGENATED blood away from heart to body tissues

tissue capillaries: where blood becomes DEOXYGENATED and where wastes from tissues enter blood

Right and left atria (singular: atrium)

two upper heart chambers fill w/ blood returning from either body (right) or lungs (left)

Right and left ventricles

two bottom heart chambers that pump blood either to lung (right) or body (left)

Septum

thick muscular wall that separates left and right chambers of the heart

Superior vena cava

large vessel that opens into right atrium that carry oxygen-poor blood from UPPER body

Inferior vena cava

large vessel that opens into right atrium that carry oxygen-poor blood from LOWER body

Pulmonary arteries

vessels by which oxygen-poor blood passes from right ventricle to lungs for gas exchange

Pulmonary veins

vessels by which oxygen-rich blood returns from lungs to left atrium

Aorta

largest vessel in the body through which oxygen-rich blood is pumped from left ventricle to body

Tricuspid valve

helps blood flow in the correct direction from the right atrium to the right ventricle

Bicuspid valve

allows blood flow b/w the left atrium and the left ventricle

Semilunar valves

permits blood to flow into the arteries from the ventricles

prevents the backward flow of blood from the arteries into the ventricles

Systole

pumping chambers contract to push blood out

Diastole

pumping chambers relax and fill with blood

What sound does the heart make?

lubb-dubb sound

What is the lubb-dubb sound caused by?

opening and closing of the valves within the heart

What is the heartbeat set by?

the sinoatrial node/pacemaker

allow it to contract without external nerve stimulation

own nerve impulse

Sinoatrial node/pacemaker

bundle of specialized muscle cells that electrically stimulate the atria to relax and contract

right atrium

Atrioventricular node

transmits the electrical signal through specialized fibers (bundle of His & Purkinje fibers that cause contraction)

delays then relays the signal to both ventricles

ECG

monitors electrical signals through heart

P wave

electricity of contraction of atria (ventricles fill with blood)

AV valves open

semilunar valves close

QRS wave

contraction of ventricle

AV valves shut (“lubb” sound)

semilunar valves open

T wave

heart reset period

ventricles relax

AV valves open

atria fill with blood

semilunar valves close (“dubb” sound)

Blood pressure

measured by sphygmomanometer

blood being pumped through vessels cause pressure changes which corresponds with phases of the heart

Systolic pressure

maximum pressure during ventricular contraction

top #

Diastolic pressure

minimum pressure before ventricles contract again

bottom #

What is a normal resting BP?

120(systolic) / 80 (diastolic)

What is the main indicator of a healthy/unhealthy heart?

Heart rate

Cardiac output

indicator of how much oxygen is being delivered to the body

measured in mL/min

heart rate x stroke volume

Heart rate

number of beats per minute (bpm)

Stroke volume

amount (mL) of blood forced out of heart with each beat

Arteriosclerosis

thickening of artery walls causing hardening and loss of elasticity

Atherosclerosis

build-up of plaque on interior walls of artery

causes narrowing/blockage

increased BP

decreased blood flow

type of arteriosclerosis

What are the two main components of blood?

plasma

formed portion

Plasma

fluid consisting of water, dissolved gases, proteins, vitamins, minerals, hormones, and wastes

Formed portion

red blood cells (erythrocytes), white blood cells (leukocytes), and platelets

Red blood cells (RBCS) / Erythrocytes

NO NUCLEUS

oxygen carrying-capacity depends on a number of RBC present and amount of hemoglobin

transport oxygen from the lungs to the body's tissues and carry carbon dioxide waste back to the lungs for exhalation

Hemoglobin

iron-containing pigment/protein found inside erythrocyte

allows large amounts of oxygen to bind and some carbon dioxide

Anemia

condition where a person has too few RBCS or hemoglobin

causes fatigue

causes: acute bleeding, lack of iron in diet, bone marrow damage, or chronic disease

White blood cells (WBCs) / Leukocytes

have a nucleus

3 types

What are the 3 types of WBCs and their functions?

1. granulocytes: neutrophils, basophils, eosinophils; stay in blood stream

2. monocytes: can exit blood stream and become specialized macrophages

3. lymphocytes: produce antibodies that tag and incapacitate pathogens

the first two engulf & destroy bacteria and foreign bodies

Platelets

cell fragments that form when cells and bone marrow break apart

key role in blood clotting

enzyme: thromboplastin

What does plasma consist of?

water: ~92%

blood proteins (fibrinogen, serum albumin): ~7%

organic substances (urea, organic nutrients): ~0.1%

inorganic ions: ~0.9%

Leukemia

cancer of WBCs

two main types: myeloid and lymphoid

Hemophilia

inherited, life-threatening disorder

causes: insufficient blood clotting proteins

treated with coagulation protein injectioins

Why do athletes train at high altitudes?

thinner air

lower oxygen pressure

lead to higher RBC count = more hemoglobin for oxygen saturation

What other body systems is blood transport connected to and how?

1. Digestion: capillaries in small intestinal wall absorb nutrients

2. Respiration: capillary beds in lungs allow for gas (and other chemical) exchange

3. Urinary: metabolic wastes, mineral ions, and other waste products are carried by blood to kidney for excretion

Homeostatic Regulation

blood coming to skin from interior is usually warmer than skin therefore difference in temp. creates a heat gradient

vasodilation/constriction

Countercurrent heat exchange

deep arteries and veins are adjacent to each other therefore warmer blood (~37) from core exchanges heat with cooler extremities

Capillary action

walls are single cell think

location of nutrient, waste, and gas exchange via diffusion = slow blood flow

Capillary bed

vast network of capillaries found in most tissues and major organs

will “open” or “close” depending on metabolic activity taking place (e.g. digestion vs. muscles)

Interstitial fluid

any material exchanged between capillaries and cells must pass through

Edema

swelling caused by “leaky” capillaries into interstitial spaces

Blood transfusions

transfer of blood from one person to another

Antigens

specific proteins that are embedded in the membrane of RBC

used for ID

Antibodies

specific proteins found in blood plasma

What are antigens & antibodies part of and how?

natural immune response system

when RBCs with a specific antigen come into contact with plasma that has the matching antibody, it causes agglutination which means they are incompatible and cause major organ damage

Agglutination

clumping of RBCs

Rhesus factor

another group of antigens that can be found in the membranes of RBCs

Rh positive

antigen present

Rh negative

antigen not present

Risk of Rh negative individuals

most Rh negative people will NOT have antibody present UNLESS they have been exposed to the Rh-factor during transfusion or pregnancy

Antigens & antibodies (A, B, O)

A: antigen A & anti-B antibody

B: antigen B & anti-A antibody

AB: both antigen A and B & no antibodies (universal recipient)

O: no antigen & both anti-A and B antibody (universal donor)