Cardiac and Vasculature Histo Flashcards
1
Q
What are intercalated discs?
A
- transverse junctions at ends of cells allowing electrical current through
2
Q
What are purkinje cells?
A
- modified cardiac mm cells acting as pacemaker for the heart
- Few myofibrils but high glycogen
- Larger and seen at periphery of myocardium next to endocardium
- Mostly lack T tubules
3
Q
Hallmarks of cardiac muscle?
A
- striations intercaladed discs
- central located nuclie surrounded by unstained section
- Lipofuscin granules near nucleus of some cells, lysosomal residue (part of normal aging)
4
Q
Describe fibrous pericardium?
A
- Denst CT outer covering
5
Q
Describe serous pericardium?
A
- Parietal layer of serous pericardium lining lthe inner surface of fibrous pericardium
- Visceral layer of serous pericardium covering the outer surface of heart
- Pericardeial cavity the space btw parietal and isceral layers
6
Q
Epicardium is synonymous with ___ and made up of ___
A
- Epicardium is synonymous with Visceral layer of serous pericardiuim and made up of simple squam with aerolar ct and fat
7
Q
Layers of heart wall in to out?
A
- Endocardium
- Myocardium
- Epicardium
8
Q
What does the epicardium contain?
A
- Loose aerolar CT with autonomic nerves and variable adipose tissue lined with mesothelium
- Branches of coronary arteries are embedded in adipose tissue
- Synonomyous with visceral pericardium
9
Q
Describe myocardium?
A
- Thickest layer of the heart containing:
- cardiocytes
- Nodal cardiocytes
- Myoendocrine cardiocytes
- Characterized by:
- striations
- Intercalated discs
- Lipofuscin granules
- dyad t tubule
- Mitocondria
- Atrial granules
10
Q
Where are intercalated discs located?
A
- at sites where cells meet end to end, they always coincide with Z lines
11
Q
What are the three regions of intercalated discs?
A
Transverse region
- Fascia adherens: actin filaments at ends of terminal sarcomeres insert into junction, most predominant, transmit contractile forces
- Desmosomes: provide anchorage for intermediate filaments of cytoskeleton
Longitudinal region
- Gap (nexus) junction: sites of low electrical resistance allowing excitation to pass btw cells
12
Q
Describe the dyad T tubules
A
- 1 T tubule and 1 SR cisterna
- fingerlike ingavinations of the sarcolemma found at z lines
- allows for uniform contraction of myofibrils in a cardiocyte
13
Q
What are nodal cardiocytes?
A
- modified cells w/n SA and AV node that initiate and relay electrical signals
- PSNS and SNS fibers terminate in the nodes
- only modifiy rate of intrinsic cardiac muscle contraction
14
Q
What are atrial granules?
A
- Myoendocrine cardiocytes: atrial cells that contain membrane bound granules, smaller quantities found in left atrium and ventricles
- Contain precursor for ANF (P)
- ANF targets kidneys to decrease Na and H20 retention
15
Q
Describe the endocardium in the ventricles
A
- Subendocardial layer
- thin layer of CT with sm mm
- Merges with myocardium
- Contains branches of purkinje fibers
16
Q
Endocardium in atria?
A
- Lacking subendocardial layer
- Purkinjie fibers are closer to endothelium intermixed with myocardium
17
Q
Cardiac skeleton importance?
A
- Electrical insulator btw atria and ventricles allowing atria to pump firstt
18
Q
What makes up heart valves?
A
- Core of fibroelastic CT covered by endothelium
- Continuous with cardiac skeleton
- Fibroelastic layer of endocardium condenses to form a valve ring creating central portion of the valve
19
Q
Tunica Intima?
A
- Endothelium made of a single layer of squamous cells
- Basal lamina thin EC layer made of collagen proteoglycans and glycoproteins
- Subendothelial layer made of loose CT
- internal elastic membrane membrane btw intima and media, sheet like layer of fenestrated elastic material within arteries
20
Q
what are endothelial cells?
A
- Single layer of endothelial cells form innermost part of tunica intima
- Involved in blood coagulation and thrombosis local vasodilation and constriction
- Storage granules weibel Palade body store and release von willelbrand factor role in hemostasis, and p selectin role in inflammation
21
Q
Tunica media?
A
- Extends from IEM to EEM layer of elasin separating the tunica median and adventitia
- Circumfrentially arranged layers of smooth mm
- thick in arteries
22
Q
Tunica adventitia (externa)?
A
- Longitudinally arragned collgenous tissue with few elastic fibers
- Merges with losoe CT surrounding vessels
- Ranges from thin in arteries to thick in veins
23
Q
What is vaso vasorum?
A
- Supply blood to vascular tunics themselves fuond in large arteries and veins
- Nervi vasorum ANS input controling contraction of vascular sm mm
BOTH found in tunica adventita
24
Q
Describe large elastic arteries
A
- Largest vessel
- Elastin forms concentric sheets btw mm cell layers
- sm mm synthesizes collagen elastin and gorund substance of ECM
- Pinkish purple color from the elastin fibers
25
Muscular Medium arteries?
* **Prominent internal elastic membrane**
* recogonizable External elastic membrane is present
* Sm mm cells arranged in spiral fashion
* Relatively thick tunica adventitia
* More smm mm and less elastin than elastic arteries
26
Describe small arteries and arterioles?
* Distinguished by sm mm layers in tunica media
* Small arteries have up to eight layers and IEM
* Arterioles have 1-2 layers and may or may not have IEM
27
What does PSNS and SNS do for arterioles and what is their function?
* flow regulators for capillary beds
* Sympathetic innervation to tunica media causes vasoconstriction
* Parasympathetic innervation to media causes vasodilation
28
What is the function of capillary beds?
* Site of metabolic exchange
* Diameter smaller than RBC
29
3 types of capillaries?
* Continuous
* Fenestrated
* Sinusoidal
30
What are continuous capillaries?
* Most common type
* Tight occluding junctions sealing off intercellular clefts
* Exchange occurs via diffusion or transcytosis
* Continuous basement membrane
* Found throughout body
31
What are fenestrated capillaries?
* Located in organs wehre exchange with blood is important
* Tight jxns with fenestrations along endothelium, continuous basement membrane
* allows greater exchange across endothelium but limited to size of macromolecule
* Found in Endocrine glands and sites of fluid/metabolite absorption (kidney and gallbladder)
32
What are sinusoidal capillaries?
* Located where exchange of macromolecules and cells must openly occur
* Large fenestrations along endothelial cells
* Open exchange occurss and large cells can move through
* Partial discontinuous basement membrane
* Found in bone marrow spleen liver
33
What are metarterioles?
* first branch off of the arterioe supplying tissues
34
What are precapillary sphincters?
* Regulate blood flow through true capillaries
35
What are true capillaries?
* Branch from metarteriole lacking smooth mmuscle
* Pericytes may be present
* perivascular contractile cells with branching cytolplasmic processes controlled by NO
36
Compare veins to arteries.
* **Veins have thinner walls than arteries**
* **Lumen is larger than artery**
* **Lumen of veins is usually collapsed**
37
Describe postcapillary venules
drain capillaries no true tunica media
38
What layer in the veins has the valves?
Tunica intima
39
Describe muscular venule.
* Have 1-2 layers of sm mm in tunica media
* thin adventitia
40
Describe small veinss
* Has all three tunics
* RUnica media is 2-3 layers
* Thicker tunica adventita
41
What type of vein does a DVT typically occur in?
Medium vein
42
Describe medium veins
* Travels with muscular ateries
* Thicker tunica adventitia
* Wall is often folded around large lumen
* Contains valves
43
Describe large veins
* Thickest layer is tunica adventitia
* collagen elastic fibers and fibroblasts found in adventitia
* Contains longitudinal sm mm cells
* Tuncia media is thin
* Tunic aintima is thin and blends with media
44
Describe the lymphatic capillaries.
* Close ended tubes found among capillary beds
* Oerlapping endothelial cells forming one way valve for collecting lymph
* Incomplete basal lamina increases permeability
45
Where do lymphatic capillaries drain?
Collecting lymphatic vessels
46
Where does thoracic duct empty?
junction of subclavian and internal jugular vein on the left
