Midterm 2 Flashcards
(64 cards)
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.
