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Flashcards in Histology Deck (41)
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Thre major layers of the heart?

  1. the inner endocardium of endothelium (and subendothelial connective tissue!)
  2. the myocardium of cardiac muscle
  3. the epicardium (connective tissue with many adipocytes and covered by mesothelium)


What 4 characteristics are found in the epicardium?

  1. Mesothelium
  2. Connective tissue
  3. Autonomic nerve bundles
  4. Adipose tissue


What is the function of the cardiac conducting system?

What are the 4 parts in order?

Modified cardiac muscle fibers that stimulates rhytmic contraction (heartbeat)

  1. Sinoatrial (SA) node (pacemaker)
  2. Atrioventricular (AV) node
  3. Atrioventricular bundle (of His) (in interventricular septim)
  4. Purkinje Fibers


How do Purkinje fiber differ from contractile fibers (3)?

  1. larger diameter
  2. abundant glycogen (therefore pale staining)
  3. closer to the endothelium



What is the cardiac skeleton?

Three functions of the cardiac skeleton?

The cardiac skeleton is dense fibrous/irregular connective tissue primarily found in the endocardium

  1. anchoring and supporting heart valves
  2. provides firm points of insertion for cardiac muscle
  3. coordinates heartbeat by acting as electrical insulation between atria and ventricles


Three layers/tunics of blood vessels?

  1. intima
  2. media
  3. adventitia


In an artery, the thickest layer is the _1_ and the lumen is _2_. In a vein, the thickest layer is the _3_ and the lumen is _4_. In a vein, the intima forms _5_ IOT restrict backflow.  _6_ contain no tunics and only endothelium.

  1. media
  2. narrow
  3. adventitia
  4. large
  5. valves
  6. capillaries


Just as the heart wall is supplied with its own _1_ arteries for nutrients and oxygen, large vessels usually have __ 2 __  (arterioles, capillaries and venules in the _3_ tunic and outer part of the media.

  1. coronary
  2. vaso vasorum
  3. adventitia


In arteries and large veins, the intima includes a prominent limiting layer made of elastin. What is the name of this layer?

Internal  elastic lamina


3 types of microvasculature?

1. Arterioles

2. Capillaires

3. Venules (drain capillaries)


What type of blood vessel is this?

1. endothelium present

2. 1-3 layers of smooth muscle

3. Thin connective tissue adventitia




What blood vessel type is this?

1. Resists and controls blood flow to capillaries

2. Major determinant of systemic blood pressure



What type of blood vessel is this?

1. Endothelium present

2. Pericytes in Media

3. No adventitia



What type of blood vessel exchanges metabolites by diffusion to and from cells?



What type of blood vessel is this?

1. Endothelium present

2. scattered smooth cells in media

3. no adventitia

Venule (no valves present!)


What blood vessel drains capillary beds and allows leukocytes to exit vasculature?



Flow of blood through metarterioles (smaller arteriole branches) is regulated by smooth muscle cell bands called what?

Precapillary sphincters


What is the purpose of arteriovenous shunts in skin?

They allow (through vasoconstriction) arterioles to bypass the capillary networks and connect directly to venules.


Where are venous portal systems found? What is their purpose?

In the liver and anterior pituitary gland.

Allows molecules entering the blood at the first set of capillaries to be delivered quickly and at high concentrations to surrounding tissues at the second capillary bed.


Where is the arteral portal system found?

In the kidneys.


What are the three types of capillaries?

1. Continuous

2. Fenestrated

3. Discontinuous or sinusoids


Function of a continuous capillary?

has many tight junctions so all exchange occurs through cells


Function of a fenestrated capillary? Where is it usually found?

Has small pores/fenestrations through cells IOT allow for greater exchange across endothelium. Also has a continuous basement membrane.

Commonly found in organs where molecular exchange is important: endocrine organs (hormone uptake), intestinal walls, choroid plexus.


Characteristics of a sinusoid? Where are these commonly found?

1. Larger lumen

2. Large spaces between endothelial cells

3. Discontinuous basal lamina

Usually located in organs where exchagne occurs readily between tissue and blood: bone marrow, liver and spleen.


Where do white blood cells enter damaged or infected tissues?

Postcapillary venules


What are the functions of pericytes?

  1. They contract IOT facilitate blood flow.
  2. Can produce smooth muscle and connective tissue during microvasculature remodeling or repair.


name 5 functions of the cardiovascular system:

  1. supply oxygen via RBCs
  2. supply/remove metabolic fuels and end products
  3. distribute and remove excess heat
  4. immune functions (includes lymphatic circulatory system)
  5. body fluid regulation (endocrine substances)


what are the 5 priorities of the cardiovascular system?

  1. maintain homostasis
  2. maintain blood pressure
  3. deliver adequate cardiac output (keep pumping)
  4. supply nutrients to match metabolic demands
  5. assure exchange at capillaries


the cardiovascular system consists of what to systems?

  1. blood vascular system
  2. lymphatic vascular system


the blood vascular system has two paths called:

1. systemic circulation

2. pulmonary circulation