Category Archives: HUMAN ANATOMY & PHYSIOLOGY

THE HEART AS A PUMP-CARDIOVASCULAR SYSTEM TUTORIAL

The Right and Left Hearts are Connected in Series, but are Folded Together to Form a Single Unit

  • The right heart pumps blood only to the lungs; its output is low pressure (25 mm Hg)
  • The left heart pumps blood to the rest of the body; its output is high pressure (120 mm Hg)
  • Because the 2 hearts are attached they beat in synchrony
  • The 2 atria receive the incoming blood- they pump extra blood into the ventricles

OXYGEN CARRIED IN BLOOD WHEN PERSON IS AT HIGH ALTITUDE-TUTORIAL PHYSIOLOGY

Oxygen Uptake in the Lungs is Increased About 70X by Hemoglobin in the Red Cells

  • In the lungs oxygen must enter the blood
  • A small amount of oxygen dissolves directly in the serum, but 98.5% of the oxygen is carried by hemoglobin
  • All of the hemoglobin is found within the red blood cells (RBCs or erythrocytes)
  • The hemoglobin content of the blood is about 15 gm/deciliter (deciliter = 100 mL)
  • Red cell count is about 5 million per microliter

Each Hemoglobin Can Bind Four O2 Molecules (100% Saturation)

MECHANISMS IN KIDNEY-TUTORIAL HUMAN PHYSIOLOGY

Section of cortex of human kidney.

Image via Wikipedia

Basic Kidney Anatomy

  • Kidneys paired, about 150 gm each
  • Urine forming units:
    • Cortex
    • Medulla (lobed: renal pyramids)
    • Cortex and medulla composed chiefly of nephrons and blood vessels
    • Supplied by renal arteries (branches of descending aorta) and renal veins (branches of inferior vena cava)
  • Urine collecting and expelling units:
    • Calyces
    • Renal pelvises
    • Ureters
    • Bladder
    • Urethra

Although the Kidneys are Tiny Organs They Receive 25% of the Cardiac Output

WHY SEX? -SEXUAL REPRODUCTION-TECHNICAL POINT OF VIEW FOR DISCUSSION

The sexual cycle
Image via Wikipedia

Sex is Very Costly

  • Large amounts of energy required to find a mate and do the mating: specialized structures and behavior required
  • Intimate contact provides route for infection by parasites (AIDS, syphillis, etc.)
  • Genetic costs: in sex you pass on only half your genes to your children
  • Males are an expensive luxury- in most species they contribute little to rearing offspring

But There are Some Advantages

  • More genetic diversity: more potential for survival of species when environmental conditions change
    • Shuffling of genes in meiosis
    • Crossing-over in meiosis

SYNAPSES AND NEUROMUSCULAR JUNCTIONS OF NEURONS-TUTORIAL

Chemical Transmitters Carry the Signal Across Synapses & Neuromuscular Junctions

  • A contact between 2 nerves is called a synapse
  • At the synapse there is a break in electrical transmission (the action potential cannot cross)- instead chemicals are released that carry the signal to the next nerve
    • The release of chemical transmitters at nerve endings was first shown by Otto Loewi in the frog heart
  • A neuromuscular junction (NMJ) is a contact between a nerve and a muscle- it is like a synapse, the action potential stops and the signal is carried by a chemical

FIGHT CANCER GO EASY

Scientists from University of Strathclyde have devised a novel way to harness natural vitamin E extract that would kill tumours within 10 days.

Using a new delivery system, the research team could mobilise an extract from Vitamin E, known ton have anti-cancer properties, to attack cancerous cells.

In the study conducted over skin cancer, the researchers found that tumours started to shrink within 24 hours and almost vanished in ten days.

They believe the tumours might have been completely destroyed if the tests had continued for longer.

When the tumours regrew, they did so at a far slower rate than previously.