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This figure shows how leukocytes respond to chemical signals from injured cells. The top panel shows chemical signals sent out by the injured cells. The middle panel shows leukocytes migrating to the injured cells. The bottom panel shows macrophages phagocytosing the pathogens.
Leukocytes exit the blood vessel and then move through the connective tissue of the dermis toward the site of a wound. Some leukocytes, such as the eosinophil and neutrophil, are characterized as granular leukocytes. They release chemicals from their granules that destroy pathogens; they are also capable of phagocytosis. The monocyte, an agranular leukocyte, differentiates into a macrophage that then phagocytizes the pathogens.

Classification of leukocytes

When scientists first began to observe stained blood slides, it quickly became evident that leukocytes could be divided into two groups, according to whether their cytoplasm contained highly visible granules:

  • Granular leukocytes contain abundant granules within the cytoplasm. They include neutrophils, eosinophils, and basophils (you can view their lineage from myeloid stem cells in [link] ).
  • While granules are not totally lacking in agranular leukocytes    , they are far fewer and less obvious. Agranular leukocytes include monocytes, which mature into macrophages that are phagocytic, and lymphocytes, which arise from the lymphoid stem cell line.

Granular leukocytes

We will consider the granular leukocytes in order from most common to least common. All of these are produced in the red bone marrow and have a short lifespan of hours to days. They typically have a lobed nucleus and are classified according to which type of stain best highlights their granules ( [link] ).

Granular leukocytes

The  left image shows a neutrophil, the middle image shows an eosinophil, and the right image shows a basophil.
A neutrophil has small granules that stain light lilac and a nucleus with two to five lobes. An eosinophil’s granules are slightly larger and stain reddish-orange, and its nucleus has two to three lobes. A basophil has large granules that stain dark blue to purple and a two-lobed nucleus.

The most common of all the leukocytes, neutrophils    will normally comprise 50–70 percent of total leukocyte count. They are 10–12 µ m in diameter, significantly larger than erythrocytes. They are called neutrophils because their granules show up most clearly with stains that are chemically neutral (neither acidic nor basic). The granules are numerous but quite fine and normally appear light lilac. The nucleus has a distinct lobed appearance and may have two to five lobes, the number increasing with the age of the cell. Older neutrophils have increasing numbers of lobes and are often referred to as polymorphonuclear    (a nucleus with many forms), or simply “polys.” Younger and immature neutrophils begin to develop lobes and are known as “bands.”

Neutrophils are rapid responders to the site of infection and are efficient phagocytes with a preference for bacteria. Their granules include lysozyme    , an enzyme capable of lysing, or breaking down, bacterial cell walls; oxidants such as hydrogen peroxide; and defensins    , proteins that bind to and puncture bacterial and fungal plasma membranes, so that the cell contents leak out. Abnormally high counts of neutrophils indicate infection and/or inflammation, particularly triggered by bacteria, but are also found in burn patients and others experiencing unusual stress. A burn injury increases the proliferation of neutrophils in order to fight off infection that can result from the destruction of the barrier of the skin. Low counts may be caused by drug toxicity and other disorders, and may increase an individual’s susceptibility to infection.

Questions & Answers

What is metatarsal
Ndotenyin Reply
bone of the foot is known as metatarsal
the term "mental" pertain to which of the following a. chin b.navel c. ear d. nose e. skull
cris Reply
what are the three many components of the lymphatic system?
Milica Reply
those are...... organ, tissue and blood capillary or vessals
anatomical terms and use them appropriatly in the language of anatomy of anterior body landmarks
Teody Reply
what is human anatomy?
rascal Reply
lts stady structured human body's
what is the study of how the body functions?
what is abdomipelvic cavity?
david Reply
where can we find the short bones
Chidi Reply
Carpal bones are examples of short bones
what is blood supply
on upper limb and lower limb
carpal bones
during pregnancy which would more increase size the mothers abdominal or pelvic cavity?
Nurmalyn Reply
pelvic cavity I think
What is anatomical position
define the main directional terms of the body
cris Reply
during physical exercise respiratory rate increace two student are discussing the mechanisms involved. student A claim they are positive feedback and student B claim negative feedback do you agree with student A or B and why
what is the physiology of circulation
please I mean the physiology of criculation
blood flow refers to the movement of blood through the vessels from arteries to the capillaries and then to the veins
during pregnancy, which would more size the mother's abdominal or pelvic cavity? explain
cris Reply
list and define the three plane of devision of the body
complete the following statements using correct directional terms for human being. 1. the navel is________to the nose 2. the heart is______to the breastbone(sternum) 3 the ankle is______to the knee 4 the ear is______to the eyes.
1. superior 2. posterior 3. superior 4. lateral
anterior fuerior
name the system of the body and its function
cris Reply
11 system are human body 1.integumentary system 2. skeletal system 3. muscular system 4. nervous system 5. endocrine system 6. cardiovascular system 7. lymphatic system 8. respiratory system 9. digestive system 10. urinary system 11. reproductive system male and female.
during pregnancy, which would more size the mother's abdominal or pelvic cavity? explain
how the body maintain hormeostasis in terms of bloodglucose level
cris Reply
It releases hormones from the pancreas insulin and glucagon
why human blood pressure high
amin Reply
fear, anxiety, sickness
why in mothers womb the foetus head is in anus direction?
As it seems the position downside n if we did such position thn soon we got vomiting then how foetus stay in downward position long time?
What is red blood cell
A type of blood cell that is made in the bone marrow and found in the blood. Red blood cells contain a protein called hemoglobin, which carries oxygen from the lungs to all parts of the body. Checking the number of red blood cells in the blood is usually part of a complete blood cell (CBC) test. It
red blood cell are the most numerous blood cells.they comprise about 99% of all blood cells red blood cells are non nucleated it has red colour due to present to hemoglobin.
Thanks for the answers
how will you promote quality of life in ptb patient using the 14 basic needs and 21 nursing problems?
rOx Reply

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