larry m. frolich, ph.d. biology department, yavapai college blood everywhere— capillaries oxygen...

Larry M. Frolich, Ph.D.Biology Department, Yavapai College

• Blood everywhere—capillaries

• Oxygen for Cell Respiration

• Circulatory System– Blood Cells– Arteries and veins– Heart and Chambers

Blood, Oxygen and Circulation


Blood is everywhere…how?

• Circulatory system– Big vessels leave from

pump—heart– Divide and split to all

major parts of body:• Limbs• Head• Guts• Major organs• Body wall• Skeleton, muscles


“Stuff” moves in and out of blood

• From/to outside world– O2, CO2 in lungs– Nutrients in guts/digestive

system– metabolic wastes—

kidneys/urinary system

• From/To cells of body– Every single tissue– O2, CO2, nutrients, waste


“Stuff” moves in and out by diffusion

Inside organs, muscles, structures, bones, big vessels divide into smaller and smaller vessels and then into network-like capillary beds. This is where diffusion can happen rapidly, at the microscopic level. Then, to get blood back to heart, capillaries feed into smaller veins into larger and larger veins into major veins that return to heart


Capillaries infiltrate every tissue of the body (so blood is everywhere!)

• Why? Because the cells that make up every tissue need– Oxygen (for cellular

respiration)– Nutrients (for cell

metabolism)– Immune cells nearby (to

eliminate invading microbes)– Removal of waste (from cell

metabolism)


Capillaries—schematic view

• Very schematic view of what happens in a capillary• Arteries bring blood from heart. Veins take blood to heart.• Network of capillaries really connects artery to vein• Diffusion of needed substances only happens in microscope, thin-walled

capillaries• See next slide for more realistic view of capillary network or “capillary bed.”


Capillaries—more realistic views

More realistic drawing showing network of capillaries connecting arteries to veins and threading through tissue. Open-ended lymph capillaries pick up excess fluid from tissue and also give immune cells route back into blood circulation

Photomicrograph of stained blood vessels of retina showing intricate capillary network

Electron micrograph showing arterioles, tiniest of arteries, splitting into virtual sheet of capillary network that brings blood into very close proximity with almost every cell in the tissue.


Heart pumps blood• If more oxygen is needed, heart pumps faster• Brain, guts are big users of oxygen• But muscles under physical activity are biggest user.• During exercise, more muscles are active, more oxygen is needed so heart

pumps faster• Pulse is measure of how fast heart is pumping• Learn to measure your own pulse—you’ll need to do this for the Lab Project


Blood Pressure• Blood pressure

measures force of blood against wall of vessels

• Systolic pressure is highest point, as blood is being forced out of heart by contraction of heart muscle

• Diastolic pressure is lowest point, between heart “beats,” when heart is inactive

• Would you expect these values to be affected by physical exercise—find out in Lab Project for this unit!


Why do cells need oxygen?

• Remember Cell Respiration (breaks down glucose to make high-energy ATP bonds that can be used for cell metabolic reactions)– Glycolysis (can happen in absence of oxygen=fermentation)– Citric acid cycle– Electron transport chain


• Every step of respiration catalyzed by proteins that are coded for in the DNA

• Can you find cellular respiration on the E. coli metabolic map?


• Oxygen diffuses into blood in lungs• In lungs, bronchioles (air tubes) branch and branch, finally

ending in tiny sacs called alveoli.• Each alveolus is surrounded by capillaries• Oxygen diffuses across super-thin epithelial tissue of alveolus,

across super-thin epithelial tissue of capillary, across red blood cell membrane and is held by Hemoglobin protein molecules in red blood cells

How does oxygen get into blood?


Blood Cells

• Red blood cells are one of several types of blood cells• Each second, 3 million new red blood cells are formed by a special kind of

mitosis• Red blood cells have no nucleus or organelles. They are just full of

Hemoglobin (Hb)• Thus, Hb was one of the earliest proteins to be isolated and understood.• It’s role in sickle cell anemia also helped to unlock the genetics and

molecular structure of Hemoglobin (see web links on the course website)


Blood Cells

• White blood cells fight invading microbes as part of the immune system

• Include– Lymphocytes—recognize invaders– Monocytes and neutrophils—actually consume or engulf microbes– Basophils—release substances that trigger the other cells.


What Does C-V System do?

• Circulate blood throughout entire body for– Transport of oxygen to cells– Transport of CO2 away from cells– Transport of nutrients (glucose) to cells– Movement of immune system components

(cells, antibodies)– Transport of endocrine gland secretions


How does it do it?

• Heart is pump• Arteries and veins are main tubes (plumbing)

– Arteries Away from Heart– Veins to Heart

• Diffusion happens in capillaries (oxygen, CO2, glucose diffuse in or out of blood)


• Heart/Great Vessels--1 Route

• Smaller aa. vv.--many routes (collateral circulation)

• Capillaries—network where diffusion occurs

Overall Organization of System


Artery/Vein differencesArteries (aa.) Veins (vv.)

Direction of flow

Blood Away from Heart

Blood to Heart

Pressure Higher Lower

Walls THICKER: Tunica media thicker than tunica externa

THINNER: Tunica externa thicker than tunica media

Lumen Smaller Larger

Valves No valves Valves (see next)


Capillaries• Microscopic--one cell

layer thick• Network • Bathed in

extracellular matrix of areolar tissue

• Entire goal of C-V system is to get blood into capillaries where diffusion takes place


Two circulatory paths

Pulmonary

Systemic


GREAT VESSELS•Aorta•IVC, SVC•Pulmonary Trunk•Pulmonary Veins


Heart Chambers and Valves


Heart Chambers

• Right Atrium (forms most of posterior of heart)– Receives O2-poor blood from body via IVC, SVC, Coronary sinus

– Fossa Ovalis- on interatrial septum, remnant of Foramen Ovale

• Right Ventricle– Receives O2-poor blood from right atrium through tricuspid valve

– Pumps blood to lungs via Pulmonary Semilunar Valve in pulmonary trunk

• Left Atrium– Receives O2-rich blood from 4 Pulmonary Veins

• Left Ventricle (forms apex of heart)– Receives blood from Left Atrium via bicuspid valve– Pumps blood into aorta via Aortic Semilunar Valve to bod


Heart Valves: Lub*-Dub**• *Tricuspid Valve: Right AV valve

– 3 Cusps (flaps) made of endocardium and CT– Cusps anchored in Rt. Ventricle by Chordae Tendinae– Chordae Tendinae prevent inversion of cusps into atrium– Flow of blood pushes cusps open– When ventricle in diastole (relaxed), cusps hang limp in ventricle– Ventricular contraction increases pressure and forces cusps closed

• *Bicuspid (Mitral) Valve: Left AV valve– 2 cusps anchored in Lft. Ventricle by chordae tendinae– Functions same as Rt. AV valve

• **Semilunar valves: prevents backflow in large arteries– Pulmonary Semilunar Valve: Rt Ventricle and Pulmonary Trunk– Aortic Semilunar Valve: Left Ventricle and Aorta– 3 cusps: blood rushes past they’re flattened, as it settles they’re pushed

down (valve closed)


Another View


Location of Heart in Thorax


Fetal Circulation•No circulation to lungs

•Foramen ovale•Ductus arteriosum

•Circulation must go to placenta•Umbilical aa., vv.

larry m. frolich, ph.d. biology department, yavapai college blood everywhere— capillaries oxygen...

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