hypoxia :oxygen defecincy at tissue level.in these slides you are going to in touch with its types ,causes effects.share whatever you wanted to say comment us . these notes are provided by our loving mam MAM SANIA .thanks to teach us mam :)

1. Hypoxia

2. Hypoxia
Oxygen deficiency at the tissue level.
Anoxia:
means absence of O2 at the tissue level.

3. Types of Hypoxia
1. Hypoxic Hypoxia - PO2 of the arterial
blood is low
2. Anemic Hypoxia - Amount of Hb. To carry
O2 is Low
3. Stagnant or Ischemic Hypoxia- Blood flow
to the tissue is low
4. Histotoxic Hypoxia – Tissue can’t utilize O2

4. Causes of Hypoxic Hypoxia
A. Low PO2 in the inspired air which include:
1. High Altitude
2. Breathing Gas mixture having Low PO2
3. Breathing in closed space
B. Decreased Pulmonary Ventilation due to Respiratory Disorders.
1. Obstructive Lung diseases e.g Asthma
2. Mechanical or Nervous Disorders (e.g. neuromuscular disorders)
3. Depression of Respiratory centre
4. Pneumothorax (air in thorcic cavity)

5. Causes of Hypoxic Hypoxia
C. Inadequate Oxygenation of Blood due to Respiratory Disorders Which
includes:
1. Impaired alveolar Diffusion e.g. Emphysema(destruction of alvoeli)
2. Non Functioning Alveoli e.g. Fibrosis
3. Pulmonary Edema
4. Lack of Surfactant . Collapse of lungs
5. Pulmonary disease
6. Abnormal alveolar ventilation-perfusion ratio (↑ physiologic dead space)
7. Diminished respiratory membrane diffusion

6. Causes of Hypoxic Hypoxia
D. Cardiac Disorders
1. Congestive Heart Failure
2. Venous-to-arterial shunts ("right-to-left" cardiac shunts)

7. Anemic Hypoxia
Reduced O2 carrying capacity due to:
1 .↓ number of RBCs
2. ↓ amount of Hb
3. abnormal hemoglobin (e.g.) Met Hb

8. Stagnant Hypoxia
Due to decreased velocity of blood flow.
General circulatory deficiency
1. CCF
2. Hemorrhagic Shock
Localized circulatory deficiency (peripheral, cerebral, coronary vessels)
3. Vasoconstriction (vasospasm) &
4. Thrombo-embolism

9. Histotoxic Hypoxia
Inability of the tissue to utilize O2.
1.Cyanide (cytochrome oxidase is completely
blocked. refers to a reduction in ATP production by
the mitochondria due to a defect in the cellular
usage of oxygen.)
2.Sulfide Poisoning
3. Vitamin B deficiency (beriberi ) tissue utilization
of oxygen is compromised.

10. Effects of Hypoxia
• death of cells
On CNS
• ↓ mental activity
• coma
• Reduced work capacity of the muscles

11. Cyanosis
• Cyanosis means blueness of skin,and its
cause is excessive amounts of
deoxygenated hemoglobin in skin blood
vessels.
• This deoxygenated hemoglobin has
intense dark blue purple color that is
transmitted through skin.

12. Cyanosis
• In general, definite cyanosis appears whenever the
arterial blood contains more than 5 grams of
deoxygenated hemoglobin in each 100 milliliters of
blood.
• A person with anemia almost never becomes cyanotic
because there is not enough hemoglobin for 5 grams to
be deoxygenated in 100 milliliters of arterial blood.
• Conversely, in a person with excess red blood cells, as
occurs in polycythemia vera, the great excess of
available hemoglobin that can become deoxygenated
leads frequently to cyanosis, even under otherwise
normal conditions.

13. Central cyanosis
• Central cyanosis is caused by diseases of the heart or
lungs or by abnormal hemoglobin types like
methemoglobin or sulfhemoglobin etc.
• This is seen commonly as bluish or purple discoloration
of tongue and linings of the mouth.
• high altitude sickness,
• pulmonary edema,
• acute sever attack of asthma,
• pneumothorax

14. Central cyanosis

15. Peripheral cyanosis
• Peripheral cyanosis results from decreased local blood
circulation in the peripheral organs, arms and legs.
• Cyanosis shows up as the levels of deoxygenated blood
rises in the small blood vessels of the fingers and toes.
• This may be seen in heart failure, shock (sluggish or
slowing of blood circulation with severe loss of blood
pressure), exposure to cold temperatures and diseases
of blood circulation.
• Limbs appear bluish and are usually cold to touch.

16. Peripheral cyanosis

17. Cough Reflex
• The bronchi and trachea are so sensitive
to light touch that very slight amounts of
foreign matter or other causes of irritation
initiate the cough reflex.
• Afferent nerve impulses pass from the
respiratory passages mainly through the
vagus nerves to the medulla of the brain.

18. Cough Reflex
• First, up to 2.5 liters of air are rapidly inspired.
• Second, the epiglottis closes, and the vocal cords shut
tightly to entrap the air within the lungs.
• Third, the abdominal muscles contract forcefully, pushing
against the diaphragm while other expiratory muscles,
such as the internal intercostals,also contract forcefully.
The pressure in the lungs rises rapidly to as much as
100 mm Hg or more.
• Fourth, the vocal cords and the epiglottis suddenly open
widely, so that air under this high pressure in the lungs
explodes outward.The rapidly moving air usually carries
with it any foreign matter that is present in the bronchi or
trachea.

19. Sneeze Reflex
The sneeze reflex is very much like the
cough reflex, except that it applies to the
nasal passageways.
The initiating stimulus of the sneeze reflex is
irritation in the nasal passageways; the
afferent impulses pass in the fifth cranial
nerve to the medulla, where the reflex is
triggered.

20. Sneeze Reflex
A series of reactions similar to those for the
cough reflex takes place; however, the uvula
is depressed, so that large amounts of air
pass rapidly through the nose,thus helping
to clear the nasal passages of foreign
matter.