• List the components of each of the three layers that make up a typical arterial blood vessel. 
• Describe the differences in the middle layer structure between elastic and muscular arteries plus arterioles.                
• Describe the two pathways leading to the formation of a clot and the factors that initiate each of these pathways.

 

1.  

• List the four different layers or tunics associated with the digestive tract from the esophagus to the rectum and the components found in each layer. 
• For the layer facing the lumen, list the three modifications noted in the small intestine that are associated with an increase in surface area. 
• In which layer are blood and lymph vessels found?
• Describe the major differences between the stomach wall and the wall of the esophagus

 

 

1. For the four different types of nerves found in the sympathetic division of the ANS, list how the neuronal axons (preganglionic or postganglionic?) exit the spinal cord and associated nearby ganglia. Be specific about locations, structures and communicating pathways followed. Finally, list at least one target organ or structure for each type
2.  

• Describe parasympathetic and sympathetic neurons, taking into account the relative lengths of the fibers, neurotransmitters involved, and receptors that are present at the pre-post ganglionic junctions and postganglionic-target organ junctions (this does NOT include discussion of how the nerves exit the spinal cord).
• Name 5 effects of the flight-or-flight response and 5 effects that target DIFFERENT components than those named for the sympathetic effects of the rest-and-digest response.

 

1.  

• Discuss the etiology of goiter development compared to that of a normal person. 
• List the three major endocrine cell types and their secretions found in the human pancreas. 
• Name and describe the roles of the substances produced by the exocrine portion of the pancreas

 

1.  

• A CBC is ordered for you and the sample of blood has just been taken. After proper procedures are observed and centrifugation occurs, the blood is separated into two major components. Name the liquid portion, the three proteins plus four other components contained in it. 
• Name the various cellular components in the formed elements and provide at least one feature for each of them.
• Describe the flow of blood through the cardiovascular system

The artery wall is comprised of three distinct layers: the intima, media, and adventitia. The intima is the innermost of three concentric layers, and is mainly connective tissue composed of a continuous ECs monolayer directly attached to the basement membrane which consists of collagen type IV and elastin.

 

Arteries

An artery is a blood vessel that conducts blood away from the heart. All arteries have relatively thick walls that can withstand the high pressure of blood ejected from the heart. However, those close to the heart have the thickest walls, containing a high percentage of elastic fibers in all three of their tunics. This type of artery is known as an elastic artery. Vessels larger than 10 mm in diameter are typically elastic. Their abundant elastic fibers allow them to expand, as blood pumped from the ventricles passes through them, and then to recoil after the surge has passed. If artery walls were rigid and unable to expand and recoil, their resistance to blood flow would greatly increase and blood pressure would rise to even higher levels, which would in turn require the heart to pump harder to increase the volume of blood expelled by each pump (the stroke volume) and maintain adequate pressure and flow. Artery walls would have to become even thicker in response to this increased pressure. The elastic recoil of the vascular wall helps to maintain the pressure gradient that drives the blood through the arterial system. An elastic artery is also known as a conducting artery, because the large diameter of the lumen enables it to accept a large volume of blood from the heart and conduct it to smaller branches.

 

Farther from the heart, where the surge of blood has dampened, the percentage of elastic fibers in an artery's tunica intima decreases and the amount of smooth muscle in its tunica media increases. The artery at this point is described as a muscular artery. The diameter of muscular arteries typically ranges from 0.1 mm to 10 mm. Their thick tunica media allows muscular arteries to play a leading role in vasoconstriction. In contrast, their decreased quantity of elastic fibers limits their ability to expand. Fortunately, because the blood pressure has eased by the time it reaches these more distant vessels, elasticity has become less important.

Notice that although the distinctions between elastic and muscular arteries are important, there is no "line of demarcation" where an elastic artery suddenly becomes muscular. Rather, there is a gradual transition as the vascular tree repeatedly branches. In turn, muscular arteries branch to distribute blood to the vast network of arterioles. For this reason, a muscular artery is also known as a distributing artery.

 

Arterioles

An arteriole is a very small artery that leads to a capillary. Arterioles have the same three tunics as the larger vessels, but the thickness of each is greatly diminished. The critical endothelial lining of the tunica intima is intact. The tunica media is restricted to one or two smooth muscle cell layers in thickness. The tunica externa remains but is very thin.

With a lumen averaging 30 micrometers or less in diameter, arterioles are critical in slowing down—or resisting—blood flow and, thus, causing a substantial drop in blood pressure. Because of this, you may see them referred to as resistance vessels. The muscle fibers in arterioles are normally slightly contracted, causing arterioles to maintain a consistent muscle tone—in this case referred to as vascular tone—in a similar manner to the muscular tone of skeletal muscle. In reality, all blood vessels exhibit vascular tone due to the partial contraction of smooth muscle. The importance of the arterioles is that they will be the primary site of both resistance and regulation of blood pressure. The precise diameter of the lumen of an arteriole at any given moment is determined by neural and chemical controls, and vasoconstriction and vasodilation in the arterioles are the primary mechanisms for distribution of blood flow.

Step-by-step explanation

Answers:

1.    List the components of each of the three layers that make up a typical arterial blood vessel. 

The artery wall is comprised of three distinct layers: the intima, media, and adventitia. The intima is the innermost of three concentric layers and is mainly connective tissue composed of a continuous ECs monolayer directly attached to the basement membrane which consists of collagen type IV and elastin.

 

2.    Describe the differences in the middle layer structure between elastic and muscular arteries plus arterioles.  

An artery is a blood vessel that conducts blood away from the heart. All arteries have relatively thick walls that can withstand the high pressure of blood ejected from the heart. However, those close to the heart have the thickest walls, containing a high percentage of elastic fibers in all three of their tunics. This type of artery is known as an elastic artery. Vessels larger than 10 mm in diameter are typically elastic. Their abundant elastic fibers allow them to expand, as blood pumped from the ventricles passes through them, and then to recoil after the surge has passed. If artery walls were rigid and unable to expand and recoil, their resistance to blood flow would greatly increase and blood pressure would rise to even higher levels, which would in turn require the heart to pump harder to increase the volume of blood expelled by each pump (the stroke volume) and maintain adequate pressure and flow. Artery walls would have to become even thicker in response to this increased pressure. The elastic recoil of the vascular wall helps to maintain the pressure gradient that drives the blood through the arterial system. An elastic artery is also known as a conducting artery, because the large diameter of the lumen enables it to accept a large volume of blood from the heart and conduct it to smaller branches.

Farther from the heart, where the surge of blood has dampened, the percentage of elastic fibers in an artery's tunica intima decreases and the amount of smooth muscle in its tunica media increases. The artery at this point is described as a muscular artery. The diameter of muscular arteries typically ranges from 0.1 mm to 10 mm. Their thick tunica media allows muscular arteries to play a leading role in vasoconstriction. In contrast, their decreased quantity of elastic fibers limits their ability to expand. Fortunately, because the blood pressure has eased by the time it reaches these more distant vessels, elasticity has become less important.

Notice that although the distinctions between elastic and muscular arteries are important, there is no "line of demarcation" where an elastic artery suddenly becomes muscular. Rather, there is a gradual transition as the vascular tree repeatedly branches. In turn, muscular arteries branch to distribute blood to the vast network of arterioles. For this reason, a muscular artery is also known as a distributing artery.

 

Arterioles

An arteriole is a very small artery that leads to a capillary. Arterioles have the same three tunics as the larger vessels, but the thickness of each is greatly diminished. The critical endothelial lining of the tunica intima is intact. The tunica media is restricted to one or two smooth muscle cell layers in thickness. The tunica externa remains but is very thin.

With a lumen averaging 30 micrometers or less in diameter, arterioles are critical in slowing down—or resisting—blood flow and, thus, causing a substantial drop in blood pressure. Because of this, you may see them referred to as resistance vessels. The muscle fibers in arterioles are normally slightly contracted, causing arterioles to maintain a consistent muscle tone—in this case referred to as vascular tone—in a similar manner to the muscular tone of skeletal muscle. In reality, all blood vessels exhibit vascular tone due to the partial contraction of smooth muscle. The importance of the arterioles is that they will be the primary site of both resistance and regulation of blood pressure. The precise diameter of the lumen of an arteriole at any given moment is determined by neural and chemical controls, and vasoconstriction and vasodilation in the arterioles are the primary mechanisms for distribution of blood flow.

 

3.    Describe the two pathways leading to the formation of a clot and the factors that initiate each of these pathways.

I.                Initial pathway (Extrinsic)

1. A cell membrane protein called tissue factor (TF), present on the outside of all human cells with the exception of red blood cells and endothelium, binds with a plasma protein, Factor VII (FVII) converting FVII to the active FVIIa.

2. The TF/FVIIa complex initiates the clotting cascade.

3. TF/FVIIa complex reacts with plasma proenzymes factor IX (FIX) and factor X (FX) converting them to active enzymes FIXa and FXa.

4. Small amounts of FXa react with prothrombin (FII) in the presence of cofactor FVa(FV is released from platelets). This produces thrombin (FIIa).

5. Thrombin catalyzes fibrin formation from fibrinogen

 

This initial pathway is independent of Factor VIII (factor missing in hemophilia A) and Factor IX (factor missing in hemophilia B). The question arises, why can't the body utilize only this pathway in the absence of Factor VIII or IX? When the body has made a small amount of fibrin, a substance known as Tissue Factor Pathway Inhibitor (TFPI) is released. This inhibitor binds to the TF:FVIIa/FXa complex, preventing further formation of factor FXa. It is thought that TFPI is released to protect against overreation of the coagulation system. At this point, the intrinsic pathway is activated.

 

II. Intrinsic Pathway

 

1. The small amount of FIIa(thrombin) formed from the initial pathway activates the inactive pro-cofactor FVIII to FVIIIa.

2. Factor FVIIIa forms a complex with activated FIXa.

3. FVIIIa/FIXa complex is responsible for the continuous formation of thrombin, which in turn cleaves fibrinogen into fibrin. This step is crucial for the formation of a durable secondary hemostatic plug.

4.    List the four different layers or tunics associated with the digestive tract from the esophagus to the rectum and the components found in each layer. 

The wall of the digestive tract has four layers or tunics:

• Mucosa
• Submucosa
• Muscular layer
• Serous layer or serosa

The mucosa, or mucous membrane layer, is the innermost tunic of the wall. It lines the lumen of the digestive tract. The mucosa consists of epithelium, an underlying loose connective tissue layer called lamina propria, and a thin layer of smooth muscle called the muscularis mucosa. In certain regions, the mucosa develops folds that increase the surface area. Certain cells in the mucosa secrete mucus, digestive enzymes, and hormones. Ducts from other glands pass through the mucosa to the lumen. In the mouth and anus, where thickness for protection against abrasion is needed, the epithelium is stratified squamous tissue. The stomach and intestines have a thin simple columnar epithelial layer for secretion and absorption.

The submucosa is a thick layer of loose connective tissue that surrounds the mucosa. This layer also contains blood vessels, lymphatic vessels, and nerves. Glands may be embedded in this layer.

The smooth muscle responsible for movements of the digestive tract is arranged in two layers, an inner circular layer and an outer longitudinal layer. The myenteric plexus is between the two muscle layers.

Above the diaphragm, the outermost layer of the digestive tract is a connective tissue called adventitia. Below the diaphragm, it is called serosa.

 

5.    For the layer facing the lumen, list the three modifications noted in the small intestine that are associated with an increase in surface area. 

The plicae circulares (circular folds) are permanent ridges in the mucosa that encircle the inside of the small intestine. The ridges force the food to spiral forward. The spiral motion helps mix the chyme with the digestive juices.

 

Villi (singular, villus) are fingerlike projections that cover the surface of the mucosa, giving it a velvety appearance. They increase the surface area over which absorption and digestion occur. The spaces between adjacent villi lead to deep cavities at the bases of the villi called intestinal crypts ( crypts of Lieberkühn). Glands that empty into the cavities are called intestinal glands, and the secretions are collectively called intestinal juice.

Microvilli are microscopic extensions of the outer surface of the absorptive cells that line each villus. Because of their brushlike appearance (microscopically), the microvilli facing the lumen form the brush border of the small intestine. Like the villi; the microvilli increase the surface area over which digestion and absorption take place.

 

6.    In which layer are blood and lymph vessels found?

Submucosa

 

7.    Describe the major differences between the stomach wall and the wall of the esophagus

 

Layers of Esophageal Wall

The esophageal wall contains four layers:

• mucosa—surface epithelium, lamina propria, and glands
• submucosa—connective tissue, blood vessels, and glands
• muscularis (middle layer)
• upper third, striated muscle
• middle third, striated and smooth
• lower third, smooth muscle
• adventitia—connective tissue that merges with connective tissue of surrounding structures

1. Mucosa
2. Submucosa
3. Muscularis
4. Adventitia
5. Striated muscle
6. Striated and smooth
7. Smooth muscle
8. Lamina muscularis mucosae
9. Esophageal glands

Layers of Stomach Wall

Layers of the stomach wall, among others, include serosa, muscularis, submucosa, mucosa. The three layers of smooth muscle consist of the outer longitudinal, the middle circular, and the inner oblique muscles. Construction of these muscles helps mix and break the contents into a suspension of nutrients called chyme and propels it into the duodenum.

1. Serosa
2. Tela subserosa
3. Muscularis
4. Oblique fibers of muscle wall
5. Circular muscle layer
6. Longitudinal muscle layer
7. Submucosa
8. Lamina muscularis Mucosae
9. Mucosa
10. Lamina propria
11. Epithelium
12. Gastric glands
13. Gastric pits
14. Villous folds
15. Gastric areas (gastric surface)

 

 

8.    For the four different types of nerves found in the sympathetic division of the ANS, list how the neuronal axons (preganglionic or postganglionic?) exit the spinal cord and associated nearby ganglia. Be specific about locations, structures and communicating pathways followed. Finally, list at least one target organ or structure for each type

9.    Describe parasympathetic and sympathetic neurons, taking into account the relative lengths of the fibers, neurotransmitters involved, and receptors that are present at the pre-post ganglionic junctions and postganglionic-target organ junctions (this does NOT include discussion of how the nerves exit the spinal cord).

10. Name 5 effects of the flight-or-flight response and 5 effects that target DIFFERENT components than those named for the sympathetic effects of the rest-and-digest response.

Parasympathetic - rest and digest

Sympathetic - fight or flight responses

 

11. Discuss the etiology of goiter development compared to that of a normal person. 

Goiter is any abnormal enlargement of the thyroid gland. The condition has various causes, with the most common worldwide being iodine deficiency. In the US, however, Hashimoto's and Graves' disease are more common etiologies. Goiters can be classified based on their morphology, function, or dignity (benign or malignant). Symptoms depend on etiology and are often absent. However, patients may present with hyperthyroidism or hypothyroidism. Large goiters may also cause obstructive symptoms due to compression of the trachea and/or the esophagus. Diagnosis is established based on clinical examination, laboratory tests, and imaging techniques. Management depends on the underlying condition and may include administering iodine (for treating nontoxic euthyroid goiter) or performing surgery (e.g., for treating local compression or thyroid cancers).

 

12. List the three major endocrine cell types and their secretions found in the human pancreas. 

There are three types of endocrine cells; alpha cells which secrete glucagon, beta cells which secrete insulin, and delta cells which inhibit the secretion on glucagon and insulin.

 

13. Name and describe the roles of the substances produced by the exocrine portion of the pancreas

The pancreas contains exocrine glands that produce enzymes important to digestion. These enzymes include trypsin and chymotrypsin to digest proteins; amylase for the digestion of carbohydrates; and lipase to break down fats.

 

14. A CBC is ordered for you and the sample of blood has just been taken. After proper procedures are observed and centrifugation occurs, the blood is separated into two major components. Name the liquid portion, the three proteins plus four other components contained in it. 

Human blood serum contains about 7 percent protein, two-thirds of which is in the albumin fraction; the other third is in the globulin fraction.

15. Name the various cellular components in the formed elements and provide at least one feature for each of them.

The formed elements are cells and cell fragments suspended in the plasma. The three classes of formed elements are the erythrocytes (red blood cells), leukocytes (white blood cells), and the thrombocytes (platelets).

 

16. Describe the flow of blood through the cardiovascular system

Blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. As the atrium contracts, blood flows from your right atrium into your right ventricle through the open tricuspid valve.

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