Internal Systems: Circulatory System

Homeostasis

relative consistency of the internal environment

changes do occur, but they are small and kept within narrow limits

without it we die

circulatory, respiratory and digestive systems work together to maintain ____________

Internal Environment

extracellular fluid (i.e., the fluid that surrounds each cell)

Homeostatic Control System

a collection of body systems that function to maintain homeostasis

Circulatory System

transport blood throughout the body’s tissues

Respiratory System

exchange of carbon dioxide and oxygen

Digestive System

Digestion and absorption of organic nutrients, salts, and water

Three main delivery parts of the Circulatory System

1. A pump (heart)

2. Plumbing (blood vessels)

3. Fluid (blood)

Function of the Heart

to force the blood to all parts of the body

Function of Blood Vessels

to carry or hold the blood throughout its entire journey (to muscles, lungs etc.)

Major Types of Vessels

Arteries

Veins

Arterioles and Venules

Capillaries

Arteries

large blood vessels that carry oxygenated blood AWAY from the heart

must withstand pressure of blood forced through them

elasticity allows them to expand and snap back as blood passes through, this keeps blood flow in right direction, and provides additional pumping motion to help force blood through.

Veins

large blood vessels that carry deoxygenated blood TOWARD the heart

thinner walls and larger diameter compared to arteries to readily receive blood

work against gravity and rely on valves to maintain blood flow in one direction

Capillaries

extremely small blood vessels that are located within tissues; gas exchange between cells occurs here

link between arteriole and venous system

very narrow —> forces RBCs to travel through single fine (1 cell at a time)

Function of blood

to carry nutrients and oxygen most of the time; dissolved in plasma, red blood cells

8% of body weight (70kg)

5.5L = blood volume

resting cardiac output = 5L/min

circulation time = 1 min

2 types of Cardiac Circulation

Pulmonary Circulation

Systemic Circulation

Pulmonary Circulation

Pathway of blood from the heart to the lungs and back

Systemic Circulation

Route from the heart to the rest of the body

Aorta

Largest artery in the body

Three layers of Arteries

Inner Layer: Epithelial cells (one cell thick) - reduces friction allowing blood to move through smoothly

Middle Layer: smooth muscle and elastic fibers

Outer Layer: connective tissue with elastic fibres

Arterioles

Similar to arteries, smaller in diameter and carry oxygenated blood from arteries to capillaries

Purpose of thin membrane and slower pace in Capillaries

allows capillaries to exchange oxygen and carbon dioxide through diffusion

Passive Transport Diffusion

Movement of molecules from a region of high concentration to low concentration

Difference in concentrations between regions is called concentration gradient

Works well over short distances

Venules

smaller than veins, merge from capillaries to dorm veins carry deoxygenated blood

Purpose of skeletal muscles in circulatory system

contractions help push blood through removing some pressure from veins

Varicose Veins

caused by standing or sitting for a long time as it prevents skeletal muscles from squeezing blood back to heart

valves over worked resulting in blood flowing back over time

veins constantly being stretched as blood pools in them and bulge

Blood

the body’s main extra-cellular fluid

Average human has 4-6L

If blood was put into a centrifuge, it separates into…

Plasma and Formed Elements

Plasma

accounts for 55% of blood volume

Water

90% of blood

10% of blood

blood proteins, salts, hormones, glucose, vitamins, minerals, dissolved gasses and waste products

What proteins does plasma dissolve

Albumins

Globulins

Fibrinogens

Albumins

along with minerals, they play an important role in establishing osmotic pressure that draws water back into capillaries

Globulins

Produce antibodies that provide protection against invading microbes

Fibrinogens

important in blood clotting

Formed Elements

Make up 45% of blood volume

“buffy coat”

Leucocytes (white blood cells)

Platelets (cell fragments) - 1%

Erythrocytes (red blood cells) - 99%

Leukocytes (WBCs)

0.9% of Buffy Coat

Produced in bone marrow and lymph glands

Immune defense and cleanup functions

Move by amoeboid movement (searches for bacteria/disease filled cells and WBC will surround it and engulf it (phagocytosis)

pus sometimes forms at the site

Pus from WBC at the site of cuts or scrapes

combo of living and dead WBCs and bacteria

Phagocytosis

used by WBC to engulf bacteria

Typed of Leukocytes

Granulocytes - grainy appearance

• Neutrophils

• Eosinophils

• Basophils

Agranulocytes - smooth appearance

• Lymphocytes'

• Monocytes

Phagocyte

general term given to any leukocyte that engulfs bacteria

Neutrophils

most abundant leukocytes found in body tissues and blood (help to engulf bacteria)

Eosinophils

found in mucous lining of digestive and respiratory tract

Basophils

aid in immunity by secreting substances that attract phagocytes to destroy pathogens

Lymphocytes

help to remember past foreign invaders and help to destroy them

Monocytes

circulate in blood stream for a few days then become bacteria destroying macrophages

Platelets (buffy coat)

0.1%

AKA thrombocytes

from megakaryocytes in bone marrow

Membrane bound fragments of cells that break apart from larger cells in bone marrow

Lifespan is 7-10 days

key role in blood clotting

Step 1 and 2 of Platelets and Blood Clotting

• Platelets encounter damaged blood vessels (rough surface) and break open

• Release ‘clotting factors’ – help platelets stick together to form a plug

  Clotting factor – thromboplastin

Step 3 of Platelets and Blood Clotting

Thromboplastin reacts with calcium and activates plasma protein prothrombin changing it to thrombin

Step 4 of Platelets and blood clotting

Thrombin converts the plasma protein fibrinogen into fibrin threads

Fibrin forms a scaffold to help repair process begin

Many fibrin strands gather at the ends of the vessel to form a mesh clot

Clots trap blood cells and prevent them from passing through a damaged blood vessel

Scab

fibrin, platelets, blood cells mesh together to seal a wound until new tissues can grow and repair the broken skin

RBCS (formed elements)

formed in the liver (fetus) and bone marrow (post birth)

no nucleus (enucleated) to keep them health

lifespan of 120 days

main function to carry oxygen

How Oxygen binds to an RBC

RBC contain hemoglobin molecules which contain 4 atoms, that each bond to an oxygen

each RBC bonds to 4 oxygen atoms

about 280 million hemoglobin molecules in a single RBC

Function of Cell Membrane

Transport oxygen into and out of the cell

Transport carbon dioxide into and out of the cell

Cause of Gas Exchange

oxygen pick-up and release factors

• concentration of oxygen

• acidity of surrounding fluid

Increased Acidity and Gas exchange

will loosen bonds between heme group and oxygen which result in released oxygen

acidity influenced by presence of dissolved carbon dioxide

Cardiac Output

the efficiency of the heart, the volume of blood pumped by each ventricle per min

usually L/min

Equal amount of blood pumped

on the right and left side of the heart

2 factors that affect Cardiac Output

stroke volume

heart rate

Stroke Volume

quantity of blood ejected by each ventricle during each contraction

the stronger the heart contractions, the greater the store volume

Blood in ventricles

not completely emptied, thus stronger contractions can eject more blood

Amount of blood leaving each ventricle while you are resting

70mL

types of Contractions AKA Systole

Cardiac Diastole

Atrial Systole

Ventricular Systole

Heart Rate

number of times the heart beats per minute

average = 72bpm

Calculation for Cardiac Output (CO)

Heart Rate x Stroke Volume

Cardiac Output and body mass

the greater the mass, the greater the cardiac output needed to supply blood to all the cells

Cardiac Output and energy

the more energy body needs (ex. while exercising) the greater the cardiac output must be

Heart rate during exercise

150-180bpm

How fitness impacts stroke volume and heart rate

people in better shape have a strong heat so then is an increases strong volume and as a result heart rate is lowered

Heart

muscular organ that functions as a pump

able to contract to force blood out of heart

• has chambers that receive and deliver blood, has valves to direct blood flow

Tissues of the Heart

Endocardium

Myocardium

Endocardium

smooth tissues that lines the inside of the heart

speeds up blood flow as it prevents anything from sticking and allows blood to flow smoothly

Myocardium

muscle tissues that allows heart to contract and contains own pacemaker and nervous tissues that responds to stimuli to control the heart

Smaller Blood Receiving Chambers

Left & Right Atrium

Larger Blood Delivery Chambers

Left & Right Ventricles

Pulmonary circulation

part of the circulatory system that carries deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart. It involves the pulmonary arteries, capillaries in the lungs, and pulmonary veins.

Valves of the Heart

prevent backflow of blood as it leavers the previous valve

Atrioventricular Valves and Semi-Lunar Valves

Atrioventricular Valves

separates atria and ventricle

Tricuspid

Bicuspid/Mitral

Tricuspid Valve

separates right atrium and right ventricle

has 3 flaps

Bicuspid/Mitral Valve

separates left atrium and left ventricles

Semi-Lunar Valves

semi-moon shapes

Aortic valve

Pulmonary valve

Aortic semi-lunar valve

separates left ventricle and aorta

Pulmonary semi-lunar valve

separates right ventricle and pulmonary artery

Atrial Septal Defect

a hole in the heart

type of congenital heart defect in which there is an abnormal opening in the dividing wall between the upper filling chambers of the heart (the atria)

What causes your heart to beat

Sinoatrial node (pace maker)

Sinoatrial node

located in the right atrium and maintains in ternal pumping rhythm by causing muscle to contract and pump out the blood. Stimulates atria first, impulse then is conducted to the ventricles through a form of the junction box

Junction Box

called the atrioventricular (AV) node

Artificial Pacemaker

Electronic device inserted under skin to help heart beat regularly and at an appropriate rate. Has leads that travel through a large vein to the heart which send electric impulses to the heart to tell it to beat.

The heart cycle

consists of 2 phases of relaxation (diastole) and contraction (systole)

Diastole

diastolic pressure when blood pressure is reduced since heart is relaxed. Valves open to allow blood to flow into ventricles. Blood flows into all 4 chambers

Systole

blood is forced from heart so ventricles contract . Blood travels through pulmonary trunk and aorta. Systolic pressure since blood pressure increases (goes faster as pushed)

Heart sounds from systole

tricuspid and bicuspid valves close to prevent blood flowing back to atria (lub sound).

Aortic and pulmonary semi-lunar close (dub).

Average Systolic:Diastolic

120mmHg : 80 mmHg

RBC diffusion with lungs

RBC enter lungs with low concentration, oxygen from lungs (high concentration) diffuses into RBC’s

RBC diffusion with muscles

Muscles have low oxygen concentration so oxygen diffused from RBC (high concentration) to muscles

Oxygen concentration and gas exchange

weakens bonds between heme group and oxygen, causes release of oxygen

Gas Exchange and cellular respiration

Alot of carbon dioxide is released from tissue, so higher acid, so more oxygen released from RBC into tissue. OR alot of oxygen is used by tissues, so low concentration of oxygen, weakens bonds in RBC and more oxygen is released from RBC. Oxygen carred by the blood is released at the same rate as the cells’ rate of respiration 

Erythropoiesis

regeneration of RBC’s, erythropoietin hormone involved

Function of Blood - Transport

minteral and nutrients (from digestive system), hormones (from endocrine system), gases (from respiratory system), waste products (from cellular processes amino groups from de-amination of amino acids from protein)

Vasodilation

Function of blood - temperature regulation. Blood vessels widen to increase blood flow near body surface, helps promote heat dissipation if core body temp is too high