The Cardiovascular System



Respiration

___________________of the Respiratory System

Exchange of Gas (at the alveoli)

Exhaled air used in vocalization

Heat dissipation of Heat and Water

______________ Balance

________________ in Respiratory Zones

Movement of Air (Conducting zone):

–mouth/nose --> trachea --> bronchioles

–Conducts air to the respiratory zone

–Also serve to warm, humidify and filter inspired air

Gas Exchange (_________________ zone):

–Alveoli

–Site of gas exchange

Steps in Respiration:

Ventilation: breathing Movement of Air

Gas exchange: Movement of Molecules

air --> blood --> tissue

__________ utilization: Use of Oxygen

Cell Respiration Production of CO2

The Respiratory Cycle

___________ (Active negative pressure)

–Diaphragm Contracts (flattens)

–Muscles Pull the ribcage up and out

_______________ (Passive positive pressure)

–Muscles relax

–Elastic Lung tissue recoils

Gases diffuse down their pressure concentration gradients

_____ Phases of Respiration

Pulmonary ventilation – moving air into and out of the lungs

External respiration – gas exchange between the lungs and the blood

_________ – transport of oxygen and carbon dioxide between the lungs and tissues

Internal respiration – gas exchange between systemic blood vessels and tissues

Mechanisms of Breathing

Inspiration and expiration are accomplished by contraction and relaxation of striated muscle

Quiet __________________

–contraction of the diaphragm and external intercostal muscles increase thoracic volume --> increased lung volume

–intrapulmonary pressure becomes subatmospheric and air comes into t the lungs

Mechanisms of Breathing

Quiet _______________

–muscles relax --> elastic recoil of lungs and thorax decreases thoracic volume --> raise intrapulmonary pressure

–air is forced out

Forced inspiration and expiration

–contraction of accessory respiratory muscles leads to larger changes in intrapulmonary pressure

Muscles of Breathing

Pulmonary Respiration -

Lung Volumes and Capacities

Lung volumes:

–__________ (TV)

–inspiratory reserve volume (IRV)

–expiratory reserve volume (ERV)

–residual volume (RV)

Lung capacities:

–total lung capacity

–_______________ (VC)

–inspiratory capacity

–functional residual capacity

_____________________ = tidal volume x breaths/minute

Accommodation in Exercise

Increase Total Minute Volume

ν Increase the Volume in the Lungs

ν Increase the Number of Breaths per Minute

Unforced Respiratory Cycle

Forced Expiration

Forced Inspiration

____________ of Breathing

Breathing must occur in a continuous cyclical pattern to sustain life

Cyclical neural activity to the respiratory muscles

The motor neurons that stimulate the respiratory muscles are controlled by two major descending pathways:

–voluntary breathing

–involuntary breathing

Regulation of Breathing

Brainstem respiratory centers:

–a diffuse neuronal system in the medulla forms the rhythmicity center that controls automatic breathing

–respiratory areas in the pons influence breathing

Regulation of Breathing

Nuclei in the medulla control the cycle of inspiration and expiration

Dorsal respiratory group neurons (DRG neurons):

–control the diaphragm and external intercostal muscles (I neurons)

CNS Regulation of Ventilation

Negative Feedback Control of Ventilation

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Oxygen Transport

Hemoglobin

–Heme: organic pigment molecule; contains ferrous iron (Fe++)

–Globin: four polypeptide chains

Anemia

–Hemoglobin concentration is below normal

Polycythemia

–Hemoglobin concentration is above normal

Erythropoietin

–Secreted by kidneys; controls production of hemoglobin & RBCs in bone marrow

Loading/unloading reactions

Lungs: deoxyhemoglobin + O2 --> oxyhemoglobin (loading)

Tissues: oxyhemoglobin --> deoxyhemoglobin + O2 (unloading)

Factors influencing reactions

–PO2 of the environment

•High PO2 favors loading

–Affinity between hemoglobin and oxygen

•Weak bond favors unloading

Oxyhemoglobin dissociation

Blood entering the tissues contains 20 ml O2 per 100 ml blood

Blood leaving the tissues contains 15.5 ml O2 per 100 ml blood

–22%, or 4.5 ml of O2 out of the original 20 ml O2 per 100 ml blood, is unloaded to the tissues

- Oxyhemoglobin dissociation curve

–Oxyhemoglobin in the venous blood at rest functions as an oxygen reserve

Effects of pH and temperature

Bohr effect: affinity between hemoglobin and oxygen is decreased when pH is lowered and increased when pH rises

Reduced affinity = greater unloading of O2

Effect of pH on oxyhemoglobin dissociation curve (See figure 23.1)

–A shift to the right of the curve indicates a greater unloading of oxygen

Affinity between hemoglobin and oxygen is decreased when temperature increases

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