Circulatory system

Components of a Circulatory System

Three fundamental features in all circulatory systems:

1.A fluid that transports materials throughout the body

2. A network of tubes in which the fluid circulates

3.A pump that pushes the fluid through the tubes

Functions of a circulatory system

• delivers oxygen, nutrients, and hormones to cells

• carries metabolic wastes away from cells to the lungs and kidneys

• Helps distribute heat to maintain constant body temperature in warm-blooded animals

Why the need for circulation?• Unicellular organisms (bacteria, sponge, algae) do not

have a circulatory system. Use surface for exchange

•In larger multicellular organisms, body cells cannot move and do not come in contact with the external environment.•A circulatory system develops as an evolutionary adaptation

Open (circulatory) Systeme.g. insect, crustaceansno closed vessels - blood bathes the cells directlyNo distinction between blood and interstitial (tissue) fluid have one blood vessel that has chambers called sinusesHemolymph: mixture of blood and tissue fluids

e.g. earthworms, frogs, birds, humans need faster blood flow to get O2 to all cells

blood contained in a network of true blood vessels that separate blood from tissues and interstitial fluidblood circulates in only one direction

Closed (circulatory) System

Blood and its functions

• carry nutrients, O2, CO2

• equalize body temperature

• transport hormones & antibodies

• helps clotting

• removes wastes

Disturbing?

Components of Blood

Blood

• average 4-5L in a human body

• Blood is a connective tissue

• When centrifuged, blood separates into two major components:

• Plasma(55%)

• Formed elements (45%)

Blood’s components1. Plasma•Fluid part of the blood

–92% water–1% ions (Ca 2+, Na+, K+, Cl-, etc.)–7 % proteins (albumins, globulins, fibrinogen)Serum = plasma –( fibrinogen +clotting factors)

2. Cellular components: RBC, WBC, and platelets

To fill in the info on slide 13-17; use the provided summary table on Cellular component of blood.

Your table should look like the page on the right here

Description Function

Red Blood Cell (erythrocytes_)99% of Cellular Components

tiny biconcave disks (135 RBC = 1mm)Made from stem cells in bone marrowLack mitochondria and nucleiStored in spleenConstantly being destroyed and replaced (~120 days)

Carry O2 & CO2

Have iron-containing protein called hemoglobin (~ 280 mill/1 RBC) specializing at transporting O2

1 hemoglobin can bind 4 O2

Thalassemias and Anemia are conditions ofabnormal haemoglobin and haemoglobin shortage, respectively

2. Cellular Components (previously called Formed elements)

White Blood Cell (Leucocytes)

Produced in the bone marrowDo have nuclei5-9 mill./1cm3 of bloodMany different types1. Neutrophils2. Basophils3. Eosinophils4. Lymphocytes5. Monocytes

• Defend against diseases and infections

• Function in allergic reactions

• Produce antibodies stimulated by binding of foreign particles

• Phagocytize (i.e. engulf) to destroy invaders

• Leukemia – cancer of the wbc (wbc can’t stop dividing)

2. Cellular Components of Blood (Cont)

Pus

2. Cellular Components of Blood (Cont)

Platelets (thrombocytes)

Fragments of cells 1-3um; no nucleiBreak down after 7-10 days

Responsible for blood clottingPrevent excessive blood lossHemophilia – Sex-linked condition resulting in excessive bleeding

How blood clots? https://www.youtube.com/watch?v=--bZUeb83uU

Let’s go to the ER: https://www.youtube.com/watch?v=cFmmmj6a2sY

The Heart

Ventricle: heart chamber that pumps blood to the body

Atrium: heart chamber that receives blood from the body

Septum (a wall of tissue)

Pathway of blood flow through the heart

Deoxygenated blood from rest of body to right atrium via superior and inferior vena cava right atrium right ventricle pulmonary artery lung where blood picks up O2 left atrium via pulmonary veins left ventricle oxygenated blood left heart via aorta to rest of the body

Blood from upper body

Blood from lower body https://www.youtube.com/watch?v=KSbbDnbSEyM

Cardiac (heart) SystemCirculates blood through tissues of the heart.

Pulmonary (lung) System

Circulates blood from heart, to lungs, & back to heart

Systemic SystemSupplies nutrients, O2 to body cells except for heart and lungsAlso picks up CO2

Blood Vessels

Red – Arteries (Oxygen rich

blood)

Blue – Veins (Oxygen poor

blood)The largest blood vessel has a diameter of 3 cm, the smallest between 5-10um•Three major types of blood vessels: arteries, veins and capillaries

carry blood away from heart usually O2 rich (Except for pulmonary artery)

connective tissue and muscle - walls elastic and thick Pre-capillary sphincters control blood flow

Arteries

Arterioles = smaller arteries

Vasoconstriction:Decrease arterioles’ diameters restricting blood flow prevent heat loss to environment

Vasodilation:Increase arterioles’ diameters increasing blood flow facilitates heat loss to cool down(Flushing)

Veins carry blood to the heart usually O2 poor (Except for

pulmonary vein) Thinner walls and not elastic as

arteries valves push blood towards heart smooth surface

Varicose vein:Are veins that lose their elasticity as we ageLeads to blood pooling in the legs that results in bulging conditionWhen sitting or standing for a long time

Blood flow in veins Less pressure than arteries

(A)Small muscles surrounding the veins contract and relax to squeeze blood along the veins.

(B)One-way valves inside the veins prevent blood from flowing backward due to the pull of gravity

Arteries and Veins

Capillaries•Found in the muscles and lungs•Thin, semi-permeable wall- only a single cell layer thick•Very narrow; blood cells move through in single file•Cover a large surface area: no body cell is more than 2 cells away from a capillary•Movement of blood through capillaries is controlled by pre-capillary sphincters

Capillaries in the hand can leak excess fluid accumulates in the tissues due to an allergic

reaction

• Carries blood away from the heart

• Branch into arterioles

• Small veins• Converge into veins

Veins•Carries blood towards the heart

• Small arteries• Branch into capillaries

• Site of gas, nutrient and waste exchange

• Converge to form venules