Respiratory and Circulatory

Systems Bio 171 – Week 11

Learning Objectives • Describe the mechanics of breathing

• Describe the path of blood flow in the four-

chambered heart

• Describe the structure and function of red blood

cells, white blood cells, capillaries, veins, and

arteries

• Understand how the respiratory and circulatory

systems work together; their purpose and function

• Understand the importance of surface area:volume

ratios on respiration

Respiratory and Circulatory

Systems • Cells need O2, get rid of

CO2—these tasks are

completed by respiratory and

circulatory systems.

• Respiratory—gas exchange

between the surface of

organism and the

environment

• Circulatory—connects all cells

with the environment

• During respiration gases

diffuse between environment

and organism

Lungs and Respiration • Thoracic cavity

• Diaphragm contracts, expands thoracic cavity

• Expansion creates negative pressure (partial vacuum) pulling air into nostrils, mouth, and then lungs

• Intercostal muscles between ribs also contract to expand the chest and suck air into lungs

Exercise: Exhalation occurs by relaxing your diaphragm and intercostal muscles. To force more air from your lungs, you must use our abdominal muscles. Place your hand near your belly button and force as much air out of your lungs as possible. What happened to your abdominal muscles when you exhaled?

Respiratory Organs

• Gills—designed for

water breathing, dense capillary beds that

function in external resp. • Extracts dissolved oxygen

from water

• Thin membranes dry out if

not kept moist

Respiratory Organs

• Lungs—air breathing, elastic

bags w/in body (volume

expands/decreases),

connected to environment

via the trachea, paired

organ

Respiratory Organs • Gas bladder —control buoyancy, sometimes

vascularized and function to respire • Single, dorsal to digestive tract, no distinction between systemic and

pulmonary circulation

• Homologous to lungs

• Found in ray-finned fishes (class Actinopterygii) but not cartilaginous

fishes (class Chondrichthyes; e.g., sharks and rays)

Respiratory System

• Cutaneous—respiration through skin, important for

amphibians

Respiration - Mammals • In mammals lungs are

filled via aspiration

pump (ventilation): o Air is sucked in by low

pressure created around

lungs; rib cage and

diaphragm

o Lungs expand, fill with air

• Air enters Trachea

• Trachea -> Bronchi ->

Bronchioles

• Bronchial tubes

terminate into thin-

walled air sacs, called

alveoli, where gas

exchange occurs

Bronchial and Pulmonary Diseases

• Pneumonia – Alveoli fill with thick fluid, making gas exchange difficult

• Emphysema – Alveoli burst and fuse into enlarged air spaces; surface area for gas exchange is reduced.

• Asthma – airways are inflamed due to irritation and bronchioles constrict due to muscle spasms.

• Bronchitis – Airways are inflamed due to infection or irritant. Coughing brings up mucus and pus.

Circulatory System • Transports gases between sites of internal and

external respiration

• But also: o Thermoregulation

o Carries glucose to active organs

o Carries hormones, immune system cells

• Cardiovascular system—includes blood, vessels,

and heart

Circulatory System • Blood vessels

o Arteries—away from heart

o Veins—toward the heart

o Capillaries—tiny vessels connecting the two

• Generally arteries carry O2

rich blood and veins O2 poor,

but not always o Pulmonary artery carries O2 poor blood

from heart to lung, pulmonary vein

carries O2 rich from lungs to heart

• Two circuits: Pulmonary and

Systemic

Circulatory System • Blood flows through arteries via pressure

from heart beats

• Veins have one-way valves, flow is

accomplished largely by muscle

contraction

• Mammals have a double circulation: o Systemic: body

o Pulmonary: lungs

Circulatory System – The Heart • Pump that moves blood through

vessels

• Mammals—four chambered heart o No mixing of O2 rich and O2 poor blood

o Divided circ. allows for separate blood pressures

• Atria receive blood from veins

• Ventricles pump blood into arteries

• Right atrium receives blood from body, then to right ventricle, which pumps blood to lungs

• Left atrium receives blood from the lungs, then to left ventricle, which pumps blood to body

Circulatory System – The Heart • Blood passes through

atrioventricular valves to the ventricles o Tricuspid (R) and Bicuspid (L)valves

• Blood passes through semilunar valves to leave the ventricles o Pulmonary semilunar valve

o Aortic semilunar valve

• Right atrium receives blood from body, passes through tricuspid valve to right ventricle, which pumps blood to lungs through the pulmonary semilunar valve to lungs

• Left atrium receives blood from the lungs, passes through bicuspid valve to left ventricle, which pumps blood through the aortic semilunar valve to body

Circulatory System – The Heart • Superior/inferior venae cavae - Blood

from body to right atrium

• Pulmonary Artery - Blood from R Ventricle to Lungs o Oxygen-poor!

• Pulmonary Veins - Blood from Lungs to L Ventricle o Oxygen-rich!

• Aorta - Blood from L Ventricle to body

• Right atrium receives blood from body through the superior or inferior vena cava, passes through tricuspid valve to right ventricle, which pumps blood to lungs through the pulmonary semilunar valve into the pulmonary artery to lungs

• Left atrium receives blood from the lungs through the pulmonary veins, passes through bicuspid valve to left ventricle, which pumps blood through the aortic semilunar valve to the aorta and to the rest of the body

Tracing Blood Through the Body

Gas Exchange • Occurs in capillaries

o One cell thick

• Occurs through

diffusion across a

concentration

gradient o High Low concentration of

O2

Today • Respiratory and

Circulatory dissections o Fetal Pig

o Sheep Hearts

• Do all pig dissections then

do hearts

• Pages 68-103!

• Surface Area and

Volume Handout

• Turn in both handouts

and graphs from the

SA:V handout!

Surface Area:Volume Handout

• Estimate SA and volume for a bacterium, protistan, red-backed salamander, fetal pig, human

• Calculate SA:V ratio

• Two graphs: V (x-axis) x SA (y-axis) for each species and log(V) x log(SA)

• Choose preserved lizard, plethodontid photo, or live plethodontid to measure

Photos by Alex Figueroa (http://afigs.weebly.com/)

Family Plethadontidae: Lungless Salamanders

• Lack lungs; respire through skin and tissue in mouth

• Have 3-chambered heart: 2 atria, 1 ventricle

• 439 species, originated in the Appalachian Mountains (US!)

• Appalachian region has the highest biodiversity of salamanders in the world

• ~10 species in New York State

• Plethodon cinereus – Red-backed Salamander

• Polymorphic – “red-backed” and “lead backed” colors

• Find on Staten Island! Check under logs in deciduous forests

Photos by Alex Figueroa (http://afigs.weebly.com/)