Midterm 2 Flashcards
What is the function of the cardiovascular system?
To deliver oxygen, other nutrients, and remove waste.
What are the components of the CVS?
The heart, large arteries, medium sized arteries, arterioles, capillaries, venules and veins.
What are the histological differences between arteries and veins?
Arteries have a more greatly defined muscular media layer, and an internal and external elastic layer, thus giving arteries more elasticity.
- What is the histology of venous valves and their function?
These are pocket-type valves, and are made up of folds of tunic intima with a core of connective tissue covered by endothelium. These valves are anti-gravity valves, and are designed to direct blood back to the heart and prevent back flow into the lower segments.
small vessels (7-9 microns), have a thin layer of endothelium and supported by some reticular fibers. Endothelial cells are attached together by desmosomes. Pericytes are flattened branching cells in relation to outer walls of capillaries; these cells may differentiate into phagocytic or contractile cells. Type 1 Capillaries: with continuous endothelium, most common. Type II capillaries: with endothelium showing holes, fenestrated. This type is found wherever there is absorption or filtration of fluid, i.e., intestines or glomeruli.
Capillaries
True Sinusoids: larger than capillaries (40-50 microns) they are irregularly shaped and are lined with phagocytic and endothelial cells. Cells have gaps between them and the basement membrane is discontinuous, allowing blood cells to pass through. Found in the spleen and bone marrow. Sinusoidal Capillaries: lined by endothelium with wider holes than type II Capillaries, present in some endocrine glands like the pituitary and adrenals.
Blood Sinusoids
connect arterioles with venules directly, bypassing capillaries. The tunica media is very thick and contains short and thick smooth muscle fibers running in circular layers. There is no internal or external elastic fibers. When the vessels contract, they completely close the lumen and shunt blood into the capillaries; when they dilate, the blood flow bypasses the capillaries and goes directly to the venous side. These can be found in the fingertips, toes, nose, ears, lips, thyroid gland, and intestines.
Arteriovenous anastomoses or shunts
What are the layers of the heart?
The endocardium, myocardium, and epicardium.
What are the components of the conduction system of the heart?
SA node, AV node, Purkinje fibers.
- What is the location and histological structure of Purkinje fibers?
They are located in the subendocardium. They are modified cardiac fibers. The cytoplasm contains very few myofibrils.
What are the parts of the pharynx?
Nasopharynx, oropharynx, and laryngopharynx.
What are the main histological features of the pharynx?
The wall is made up mainly of skeletal muscles covered externally by a layer of CT called adventitia, containing the supplying vessels and nerves, and lined internally by a mucous membrane. The surface epithelium of that membrane is stratified squamous non-keratinized, except in the nasopharynx where it is pseudostratified columnar ciliated with some goblet cells. The underlying C.T. contains sero-mucous glands, and in the nasopharynx there occurs infiltration of lymphoid tissue to constitute the pharyngeal tonsil or adenoids.
What are the parts of the digestive tube?
Esophagus, stomach, small intestine, large intestine, appendix, and anal canal.
- What is the general structure of digestive tube?
Mucosa or mucous membrane, submucosa, musculosa, adventitia or fibrous layer.
From the mucosa: generally is a simple columnar non-ciliated. It may present depressions called pits, or elevations called villi.
Surface epithelium
From the mucosa: generally tubular in shape, lined by a variety of cells of various functions, which include digestive enzymes, mucus and endocrine secretions.
Glands
From the mucosa: is a loose areolar C.T. which supports the surface epithelium and glands. It contains blood vessels, nerves and lymphatics. It also may present lymphoid infiltration of nodular or diffuse type. Nodules may be solitary or in aggregates, e.g., Peyer’s patches.
Lamina propria or corium
From the mucosa: is made up of smooth muscle fibers arranged in two thin layers; an inner circular and outer longitudinal. Fine slips extend between the glands. It functions to move m.m. and to evacuate glandular secretions.
Muscularis mucosa
What is Meissner’s plexus and its function?
A plexus of autonomic nerves and ganglia which gives postganglionic fibers to mucosa. In esophagus and first part of duodenum, it contains mucous glands.
What are the components of the musculosa and their function?
Is made up of smooth muscles disposed in two thick layers; an inner circular and outer longitudinal. In the stomach fundus and body there is an additional innermost oblique layer of muscle fibers.
Between the circular and longitudinal layers of muscles there is a plexus of autonomic nerves and ganglia called the Myenteric or Auerbach’s plexus.
What are Myenteric plexus and its function?
It provides motor supply to the muscle fibers of the wall. The functions of the musculosa include mixing of food with enzymes and moving food from one segment to the other in the digestive tube. In some locations the circular muscle layer may become thickened to form Sphincters, e.g., pyloric and anal sphincters.
What are the components of the adventitia/serosa and their function?
Dense C.T. containing blood vessels, nerves and lymphatics. It may be covered externally by peritoneum, in which case this layer will be called serosa. The visceral epithelium of serosa is made up of mesothelial cells (simple squamous).
What are the layers of peritoneum?
It is made up of a surface layer of simple squamous epithelium called the mesothelium, and an underlying layer of connective tissue which attaches the mesothelium to abdominal walls and outer surfaces of abdominal organs.
Esophagus: describe the mucosa
Folded when empty, surface is stratified squamous non-keratinized, no glands except the beginning and end (secrete mucous). Cardiac glands at lower end secrete mucous which neutralizes the effects of reguritating stomach acid.
Muscle in the esophagus made of one longitudinal layer.
Muscularis mucosa
Esophagus: Describe the submucosa
contain tubulo-alveolar mucous glands (esophageal glands). They facilitate the passage of a bolus of food
Esophagus: Describe the musculosa
made up of the usual two layers of muscles, but the type of muscle varies. In upper third of esophagus the muscle is skeletal, in the lower third it is smooth, and in middle third it is mixed.
Esophagus: Is the adventitia in the esophagus covered by peritoneum?
No
What are the anatomic parts of the stomach?
Fundus, body, pylorus
Fundic Glands: located at the upper constricted portion of the gland. They are short columnar cells secreting mucus to protect the m.m. surface against gastric juice.
Mucous neck cells
Fundus glands: occupying the body of the gland. They are columnar cells secreting pepsinogen for protein digestion.
Peptic or chief cells
Fundus glands: are found among the previously mentioned cells. They are circular to multisided, central rounded nuclei and acidophilic cytop-lasm. They secrete the HCl and the intrinsic anti-anemia factor.
Parietal or oxyntic cells
Fundus glands: Variable in shape, and lie between other cells and basement membrane. They stain specifically with silver and chromium salts. They are endocrine cells secreting serotonin, a vasoconstrictor and possibly gastrin, which stimulates gastric secretion.
Argentaffin or Enterochromaffin cells
Fluid that is filtered through capillary walls is called:
tissue or interstitial fluid
Tissue fluid which contains molecules of relatively large size remains behind to contitute a fluid called:
lymph
Part of the tunica intima, Variable in shape, and lie between other cells and basement membrane. They stain specifically with silver and chromium salts. They are endocrine cells secreting serotonin, a vasoconstrictor and possibly gastrin, which stimulates gastric secretion.
Endothelium
Part of the tunica intima, is made up of a single layer of flattened squamous cells lying on a basement membrane
subendothelium
Part of the tunic intima, absent in veins. It appears corrugated with many holes to allow tissue fluid to reach outer layers. It allows the wall to yield under pressure.
Internal Elastic Membrane
Tunica Media: arranged circularly around vessel. Contraction causes vasoconstriction and narros the lumen. In this way, muscle action can control the flow of blood into the blood vessels.
Smooth muscle fibers
Tunica Media: Run in between muscle fibers. Elastic fibers may fuse to form another membrane called the external elastic membrane or lamina.
Collage and elastic fibers
Tunica Media: Made up of elastic fibers that condense and separate tunica media from adventitia. Absent in veins.
External Elastic Membrane
Where are vasa vasora found?
Tunica Adventitia
small blood vessels found in adventitia in thick-walled vessels. They provide nutrition to the outer layers that fail to receive fluid which diffuses through endothelium into the inner layers.
Vasa Vasora
Large Arteries: endothelium is made up of flattened endothelial cells. Subendothelium is a wide zone. It contains collagen and many elastic fibers:
Tunica Intima
Large Arteries: The widest zone. Comprises 75-80% of the thickness. Made up of MULTIPLE corrugated fenestrated elastic membranes. Internal and external ELASTIC MEMBRANES cannot be differentiated. Smooth muscle fibers and collagen fibers occur in between the elastic membranes.
Tunica media
Large Arteries: A small layer compared to the tunica media. Made up of collagen fibers and elastic fibers. VASA VASORA supply the walls.
Tunica Adventitia
Medium-sized and small arteries: Endothelium on thin zone of subendothelium, with collagen and some elastic fibers that condense to form the internal elastic membrane.
Tunica Intima
Medium-sized and small arteries: Almost half the thickness of the wall. Called muscular layer as it is composed mostly of muscle fibers with some collage elastic fibers.
Tunica Media
Medium-sized and small arteries: Half or just less than half the thickness of the wall. It is made up of collagen fibers, elastic fibers and vasa vasora.
Tunica Adventitia
Arterioles: made up of endothelium and very thin subendothelium, which cannot be recognized microscopically but has a very prominent internal elastic membrane
Tunica Intima
Arterioles: The thickest zone, mainly muscular. Smooth muscle fibers form about 2-5 layers. Lacks external elastic membranes
Tunica Media
Arterioles: Is a very thin zone made up of collagen and some elastic fibers.
Tunica Adventitia
Type 1 Capillaries have this type of endothelium:
Continuous
Type 2 Capillaries have this type of endothelium:
Fenestrated
Represent the main connection between arterial and venous sides of circulation:
Capillaries
flattened branching cells in relation to outer walls of blood capillaries. May differentiate into phagocytic or contractile cells.
Pericytes
This is the most common capillary type:
Type 1
This type of capillary occurs where there is absorption or filtration of fluid such as the intestines and glomeruli of the kidney:
Type 2
Larger than capillaries, their diameter ranges between 40-50 microns. Tortuous and irregular outline and are lined by phagocytic and endothelial cells. Cells have gaps between them and the basement membrane is discontinuous. The gaps allow blood cells to pass through. BLOOD SINUSOIDS are found in the liver, spleen and bone marrow.
True Sinusoids
Present more commonl in some ENDOCRINE GLANDS like pituitary or adrenal. They are less tortuous than true sinusoids and their diameter is about 30 microns.
Sinusoidal Capillaries
Connect arterioles with venules directly, bypassing capillaries. The diametes is slightly larger than arterioles and the lumen is narrow.
Arteriovenous Anastomoses or shunts
Innermost layer of the heart:
endocardium
Middle layer of the heart.
Myocardium
Outermost layer of the heart.
Epicardium
