BIO210Y5 Lecture Notes - Lecture 19: Atrioventricular Node, Sinoatrial Node, Purkinje Fibers

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blushrat11

15 Jul 2018

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Step 1: pacemaker impulse generation: the first step of cardiac conduction is impulse generation. The sinoatrial (sa) node(also referred to as the pacemaker of the heart) contracts, generating nerve impulses that travel throughout the heart wall: this causes both atria to contract. The sa node is located in the upper wall of the right atrium: it is composed of nodal tissue that has characteristics of both muscle and nervous tissue. Step 3: av bundle impulse conduction: the impulses are then sent down the atrioventricular bundle. This bundle of fibers branches off into two bundles and the impulses are carried down the center of the heart to the left and right ventricles. Step 4: purkinje fibers impulse conduction: at the base of the heart, the atrioventricular bundles start to divide further into purkinje fibers, when the impulses reach these fibers they trigger the muscle fibers in the ventricles to contract.

Related Questions

1) The external layer of the heart wall is the

Multiple Choice

endocardium.

myocardium.

epicardium.

parietal pericardium.

2) Check all that are characteristics of cardiac muscle.

Check All That Apply

Cells are long and cylindrical.

Cells are short and branching.

Cells have multiple nuclei at the periphery of the cell.

Cells have one or two nuclei in the center of the cell.

They are composed of thick and thin filaments.

The functional contractile unit is the sarcomere.

3) Match the chamber of the heart with the structure(s) from which it receives blood.

Coronary sinus

Pulmonary veins

Right atrium

Left atrium

Match each of the options above to the items below.

Right atrium

Right atrium Open choices for matching

Right ventricle

Right ventricle Open choices for matching

Left atrium

Left atrium Open choices for matching

Left ventricle

4) The less extensive distribution of T-tubules contributes to the more delayed onset and prolonged contraction of cardiac muscle tissue compared to skeletal muscle tissue.

True or False

5) The cells of the ___________ act as the heart's pacemaker, which establishes the pace for cardiac activity.

Multiple Choice

atrioventricular (AV) node

sinoatrial (SA) node

atrioventricular (AV) bundle

Purkinje cells

6) Match the cardiac vein with its description.

Travels close to the right marginal artery

In posterior interventricular sulcus

In anterior interventricular sulcus

In the posterior portion of cornary sulcus

Match each of the options above to the items below.

Great cardiac vein

Great cardiac vein Open choices for matching

Middle cardiac vein

Middle cardiac vein Open choices for matching

Small cardiac vein

Small cardiac vein Open choices for matching

Coronary sinus

7) Parasympathetic innervation to the heart comes from the medulla oblongata via the left and right ___________ nerves.

8) Check all that are components of the sympathetic innervation of the heart.

Check All That Apply

Cervical sympathetic ganglionCervical sympathetic ganglion

Spinal cordSpinal cord

Vagus nerve (CN X)Vagus nerve (CN X)

Cardiac nerveCardiac nerve

Sympathetic postganglionic axon

9) Check all that occur during ventricular contraction.

Check All That Apply

The AV valves open to allow blood to enter the ventricles from the atria.The AV valves open to allow blood to enter the ventricles from the atria.

The semilunar valves remain closed to prevent backflow of blood into the ventricles.The semilunar valves remain closed to prevent backflow of blood into the ventricles.

The semilunar valves open to allow blood to flow into the large arteries.The semilunar valves open to allow blood to flow into the large arteries.

The AV valves close to prevent backflow of blood into the atria.

Select 30 medical terms from the articles.

Complete the table in this document, like the Summary Tables in your textbook.

In the first column list the medical term.

In the second column, list any prefixes and define them.

In the third column, list the root and define it.

In the fourth column, list any suffixes and define them.

In the fifth column list the exact definition of the term.

NOTE: You many not use any medical terms that appear in any of the summary tables in your textbook.

Make sure to include references to the articles your terms come from.

1: Facelift Anatomy

With age, characteristic changes occur in the central third of the face. ^[¹^] A youthful midface is characterized by prominent cheeks and a smooth transition between the lower eyelid and cheek. Structural, soft tissue, and skin changes develop as wrinkles and creases, progressive ptosis, and general atrophy of the structures.

Pessa confirmed the changes seen in the bony structures of the face, and these include a downward migration of cephalometric points. ^[²^] The downward migration manifests as a change in soft tissue volume. The effects of gravity and repeated animation of the face also directly affect the soft tissue that overlies the mimetic musculature.

The results of magnetic resonance imaging (MRI) evaluations have helped to determine that the mimetic muscles themselves remain intact; however, the attachment to the overlying soft tissue and skin changes. The repeated action of smiling results in deepening of the nasolabial fold at the point at which the superficial musculoaponeurotic system (SMAS) inserts into the dermis.

2: Pancreas Anatomy

Embryology

The pancreas develops as 2 buds (outpouchings) of endoderm from the primitive duodenum at the junction of the foregut and the midgut. A small ventral bud (pouch) forms the lower (inferior) part of the head and the uncinate process of pancreas, whereas a large dorsal bud (pouch) forms the upper (0) part of the head as well as the body and tail of the pancreas. The ventral bud rotates behind the duodenum dorsally from right to left and fuses with the dorsal bud, and the duct of the distal part (body and tail) of the dorsal bud unites with the duct of the ventral bud to form the main pancreatic duct (of Wirsung). Because the common bile duct (CBD) also arises from the ventral bud, it forms a common channel with the main pancreatic duct. The remaining proximal part (head) of the duct of the dorsal bud remains as the accessory pancreatic duct (of Santorini).

3: Conduction System of the Heart

The conducting system of the heart consists of cardiac muscle cells and conducting fibers (not nervous tissue) that are specialized for initiating impulses and conducting them rapidly through the heart (see the image below). They initiate the normal cardiac cycle and coordinate the contractions of cardiac chambers. Both atria contract together, as do the ventricles, but atrial contraction occurs first.

The conducting system provides the heart its automatic rhythmic beat. For the heart to pump efficiently and the systemic and pulmonary circulations to operate in synchrony, the events in the cardiac cycle must be coordinated.

4:Spleen Anatomy

Overview

The spleen is an organ shaped like a shoe that lies relative to the 9th and 11th ribs and is located in the left hypochondrium and partly in the epigastrium. Thus, the spleen is situated between the fundus of the stomach and the diaphragm. The spleen is very vascular and reddish purple in color; its size and weight vary. A healthy spleen is not palpable.

Development

The spleen develops in the cephalic part of dorsal mesogastrium (from its left layer; during the sixth week of intrauterine life) into a number of nodules that fuse and form a lobulated spleen. Notching of the superior border of the adult spleen is evidence of its multiple origin (see the image below)

5:Lung Anatomy

Development

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BIO210Y5 Lecture Notes - Lecture 19: Atrioventricular Node, Sinoatrial Node, Purkinje Fibers

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