Anatomy exam 2

Separation of Chambers

interatrial septum separates the left atrium from the right atrium

the inter ventricular septum separates the left ventricle from the right ventricle

right atrium

  Pectinate muscles: ridges on the anterior wall and within the auricle

* Also seen in the left atrium.

o   Fossa Ovalis: oval depression on the interatrial septum

§  Occupies location of fetal foramen ovale---hole that shunts blood from right to left atrium in fetal life.

o   Entrances from coronary sinus (carrying blood from heart wall), superior vena cava, and inferior vena cava

o   Exit to right ventricle through right AV valve

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right ventricle

o   Trabeculae carneae: irregular muscular ridges inside ventricle wall

o   Papillary muscles: cone-shaped projections extending from internal ventricle wall (right ventricle typically has 3 of them)

§  Anchor chordae tendineae

o   Tendinous cords (chordae tendineae)

§  Thin strands of collagen fibers attaching to AV valve

o   Superior exit to pulmonary trunk through pulmonary semilunar valve

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left atrium

o   Has pectinate muscles in its auricle

o   Entrances from pulmonary veins

o   Exit to left ventricle through left AV valve

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left ventricle

o   Trabeculae carneae on internal wall surface

o   Two papillary muscles anchor chordae tendineae

o   Superior exit through to aorta through aortic semilunar valve

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pulmonary trunk/artery

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* Transports blood from right ventricle
* Splits into pulmonary arteries

aorta

transports blood from felt ventricle

superior vena cava

drain deoxygenated blood into right atrium from arms, head, neck, chest

inferior vena cava

drain deoxygenated blood from legs, feet, abdomen

pulmonary vein

drain oxygenated blood into left atrium

fibrous pericardium

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* Dense irregular connective tissue
* Attached to diaphragm and base of aorta, pulmonary trunk
* Anchors heart and prevents its overflowing.

parietal layer of serous pericardium

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* Simple squamous epithelium and areolar connective tissue
* Attached to fibrous pericardium.

visceral layer of serous pericardium

simple squamous epithelium and areolar connective tissue attach directly to the heart

trabecular carnae

irregular muscular ridges inside ventricle wall

papillary muscle

cone-shaped projections extending from internal ventricle wall

chord tendinae

thin stands of collagen fibers attaching to AV valve

tricuspid valve

between right atrium and ventricle, also called tricuspid because it has three flaps

bicuspid valve

between left atrium and ventricle, also has two flaps

coronary sinus

sits in posterior aspect of coronary sulcus

receives blood from cardiac veins and drains into right atrium

cardiac veins

great, middle, small

great cardiac vein

sits in anterior inter ventricular sulcus

middle cardiac vein

sits in posterior inter ventricular sulcus

small cardiac vein

sits posterior aspect of coronary sulcus

receives blood from cardiac veins and drains into right atrium

atrioventricular valves

·  Prevent backflow to atria

·  Right AV valve = between right atrium and ventricle; also called tricuspid

because it has three flasps

·  Left AV (mitral) valve = between left atrium and ventricle; also called bicuspid because it has two flaps

·  AV valves close when ventricles contract, force blood superiorly

· Papillary muscle and tendinous cords preventing into atria

semilunar valves

·  Prevents backflow to ventricles

·  Open when ventricles contract and blood is forced into arteries

·  Close when ventricles relax

o   Arterial pressure becomes greater than ventricular pressure

o   As blood starts to slide backward, it catches cusps and closes valves

·  Each of the two semilunar valve has three cusps

·  Pulmonary semilunar valve

*  Located between right ventricle and pulmonary trunk
* aortic semilunar valve
* located between left ventricle and the aorta
* made of endothelium-lined fibrous connective tissue cusps

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conduction of the heart

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* **Conduction system**: initiates and conducts electrical events to ensure proper timing of contractions
* Specialized cardiac muscle cells that have action potentials but do not contract
* Its activity is influenced by autonomic nervous system

parasympathetic innervation

Starts at the medulla’s cardioinhibitory center

\-   Relayed via the vagus nerve (Right=SA, Left=AV)

sympathetic innervation

Increases heart rate and force of contraction

\-   Starts at the medulla’s cardioinhibitory center

\-   Relayed via neurons from T1-T5 segments of spinal cord

sinoatrial node (SA)

  Initiates heartbeat 

Located high in the posterior wall of the right atrium

atrioventricular node (AV)

located on the floor of the right atrium (near right AV valves)

atrioventricular bundle (AV)

extends from AV node through interventricular septum

divides into left and right bundles

purkinje fibers

Extend from left and right bundles at heart’s apex

o   Course through walls of ventricles.

lymphatic characteristics

some fluid leaves blood capillaries and is not reabsorbed by them

* This interstitial fluid moves into lymphatic capillaries, where it is then called lymph
* Components:
* Water, dissolved solutes, and a small amount of protein
* Sometimes cell debris, pathogens, or cancer cells

innate immunity

present at birth

* Protects against a variety of different substances (nonspecific)
* No prior exposure to substances is necessary
* Includes barriers of skin and mucosal membranes, nonspecific cellular and molecular internal defenses
* Respond immediately to potentially harmful agents

adaptive immunity

acquired/specific immunity

* Response to antigen involves specific T- and B- lymphocytes
* A particular cell responds to one specific foreign substance but not another
* Take several days to be effective

inflammation

An immediate response to ward off unwanted substances

* Local, nonspecific response of vascularized tissue to injury
* Part of innate immunity 


* Events of inflammation
* Injured tissue, basophils, mast cells, and infectious organism release chemicals that initiate a response 
* The chemicals include histamine, leukotrienes, prostaglandins, and chemotactic factors.

Bronchiotracheal tree

Composed of the trachea, the bronchi, and the bronchioles that transport air from the environment to the lungs for gas exchange.

pulmonary circulation

o   Deoxygenated blood from the right side of the heart to the lungs

o   In the lungs, the blood picks up oxygen and releases carbon dioxide

o   Blood vessels return the blood to the left side of the heart

systemic circulation

Oxygenated blood from the left side of the heart to systemic cells

o   At systemic cells (e.g., skin and muscles), blood exchanges gases, nutrients, and waste

blood vessels return blood to the right side of the heart

basic pattern

right heart→ lungs→ left heart→ systemic tissues→ right heart

electrocardiogram

Skin electrodes detect electrical signals of cardiac muscle cells

 Common diagnostic tool

p wave

reflects electrical charges of atrial depolarization originating in SA node

QRS complex

* Electrical changes associated with ventricular depolarization
* Atria also simultaneously repolarizes

t wave

* Electrical change associated with ventricular repolarization
* Two segments between waves correspond to plateau phases of cardiac action potentials (no electrical change)

p-q segment

associated with atrial cells plateau (atria are contracting)

s-t segment

associated with ventricular plateau (ventricles are contracting)

p-r interval

* Time from the beginning of the P wave to the beginning of the QRS deflection
*  From atrial depolarization to the beginning of ventricular depolarization
* Time to transmit action potential through entire conduction system

q-t interval

* Time from beginning of QRS to the end of T wave
*  Reflects the time of ventricular action potentials
* Length depends upon heart rate
* Changes may result in tacyarrhythmia (rapid, irregular heart rate)

initiation of action potential

1. Reaching threshold

\-   Slow voltage-gated Na+ channels open

\-   Membrane potential changes from -60mV to -40mV


2. Depolarization

\-   Fast voltage-gated Ca2+ channels open and Ca2+ flows in

\-   Membrane potential changes from -40mV to just above 0mV


3. Repolarization

\-   Calcium channels close and voltage-gated K+ channels open so K+ flows out

\-   Membrane potential goes back to rest value (60mV)

\-   Process begins again

contraction of cardiac muscle

1. Depolarization

\-   Impulse from the conduction system opens fast voltage-gated Na+ channels

\-   Na+ enters the cell, changing membrane potential from -90 mV to 30 mV

\- Voltage-gated channels start to inactivate


2. Plateau

\-   Depolarization opens voltage-gated K+ and slow voltage-gated Ca2+ channels

\-   K+ leaves cardiac muscle cell as Ca2+ enters

\-   Membrane remains depolarized


3. Repolarization

\-   Voltage-gated Ca2+ channels close while K+ channels remain open

\-   Membrane potential goes back to 90mV

refractory period

\-   Cells cannot fire new impulses during refractory period, and makes sustained tetanic contraction impossible

arteries

* Convey blood from heart to capillaries
* Have thicker tunica media and narrower lumen than veins
* Have more elastic and collagen fibers (spring back into shape)


* More resilient and resistant to changes in blood pressure


* Arteries branch into smaller vessels extending from heart


* Decrease in elastic fibers
* Decrease in lumen diameter
* Increase in the relative amount of smooth muscle

3 types: elastic, muscular, arterioles

elastic arteries

* Largest arteries-diameters from 2.5 to 1cm
* Conduct blood from heart to muscular arteries
* Have large proportion of elastic fibers allowing stretch and recoil


* Helps propel blood through arteries during diastole


* E.g., aorta, pulmonary trunk, common carotid, common iliac arteries

muscular arteries

* Medium arteries- diameters from 1cm to .3mm
* Distribute blood to specific body regions
* Muscle allow vasoconstriction and vasodilation
* Elastic tissue in two layers


* Internal elastic lamina between tunica intima, tunica media
* External elastic lamina between tunica media, tunica externa


* Most named arteries: brachial artery, coronary arteries

arterioles

* Smallest arteries-diameters of .3mm to 10 micrometers
* Larger arterioles have three tunics
* Smaller arterioles have only thin endothelium and a single layer of smooth muscle
* The smooth muscle is usually somewhat constricted (vasomotor tone)
* Regulate systemic blood pressure and blood flow

capillaries

* Microscopic porous blood vessels
* Exchange substances between blood and tissues
* Contain only tunica intima (no subendothelial layer)


* Composed of endothelium and basement membrane


* Thin wall allows for rapid gas and nutrient exchange
* Small vessels connecting arterioles to venules
* Average length = 1mm
* Average diameter= 8-10 micrometers
* Wall consists of endothelial layer on basement membrane
* A thin wall and small diameter are optimal for the exchange between blood and tissue fluid

3 types: continuous, fenestrated, sinusoid

capillary beds

* Groups of capillaries functioning together
* Fed by metarteriole- a vessel branch of an arteriole

true capillaries

* Vessels branching from metarteriole
* Make up the bulk of the capillary bed

capillary beds

* Precapillary sphincter: smooth muscle ring at the true capillary origin


* Sphincter relaxation permits blood to flow into true capillaries
* Sphincter contraction causes blood to bypass the capillary bed


* At any time, only1/4 of body’s capillary beds are open

perfusion

amount of blood entering capillaries per unit time per gram of tissue (mL/min/g)

vein

* Transport blood from capillaries to heart
* Have thicker tunica external and larger lumen than arteries
* Have less elastic and collagen fibers


* Wall collapses if no blood in vessel


* Smallest veins- diameters of 8 to 100 micrometers
* Companion vessels with arterioles
* The smallest venules are postcapillary venules
* Large's venules having all three tunics
* Merge to form veins
* Prevent blood form pooling in the limbs; ensure flow toward heart

tunica intima

* The innermost layer of the vessel wall
* Endothelium of simple squamous epithelium
* The subendothelial layer of areolar connective tissue

tunica media

* The middle layer of the vessel; circularly arranges layers of smooth muscle cells with elastic fibers.


* The contraction causes vasoconstriction: narrows the lumen
* Relaxation causes vasodilation: widens lumen

tunica externa

* The outermost layer of the vessel; is areolar connective tissue with elastic and collagen fibers
* Helps anchor vessel to other structures
* May contain vasa vasorum


* Small arteries are required to supply very large vessels

arterial blood pressure

**Diastolic pressure** occurs when ventricles relax

·  Lowest pressure generated in arteries

·  Recorded as the lower number of blood pressure ratio

\-   **Pulse pressure**: pressure in arteries added by heart contraction

·  Equals the difference between systolic and diastolic blood pressure

·  Reflects elasticity and recoil of arteries

·  Pulse pressure allows for palpation of a throbbing pulse in elastic and muscular arteries

capillary blood pressure

Pressure no longer fluctuates between systolic and diastolic

\-   Needs to be high enough for the exchange of substances

\-   Needs to be low enough not to damage vessels

\-   Arterial end of the capillary at about 40 mm Hg

\-   Venous end of the capillary is below 20 mm Hg

\-   Accounts for filtration and reabsorption at respective ends

venous blood pressure

Venous return of blood to the heart depends on pressure gradient, skeletal muscle pump, and respiratory pump

\-   Venous pressure is low and not pulsatile

\-   Pressure gradient is small

skeletal muscle pump

As muscles contract, veins are squeezed

\-   Blood is pushed and valves prevent backflow

\-   Blood is moved more quickly during exercise

\-   Blood pools in leg vein with prolong inactivity

resistance

the friction blood encounters

Due to contract between blood and vessel wall

\-   Opposes blood flow

\-   **Peripheral resistance**: resistance of blood in blood vessels (as opposed to the heart)

\-   Affected by viscosity, vessel length, lumen size

neural regulation of blood pressure

**The cardio acceleratory center** is the origin of sympathetic pathways

·  Paths extend to the SA node

·  Activity increases heart rate and force of contraction

·  Increases overall total cardiac output and blood pressure

\-   **The cardio inhibitory center** is the origin of parasympathetic pathways

·  Extends to SA and AV nodes

·  Activity decreases heart rate and slow conduction of electrical signals

baroreceptors

\-   Nerve endings that respond to a stretch of the vessel wall

\-   Located in tunica externa of the aortic arch and carotid sinuses

\-   Firing rate changes with blood pressure changes

\-   Baroreceptor reflexes are best for quick changes in BP, but are ineffective for long-term BP regulation

\-   **If blood pressure decreases**

·  Vessel stretches declines and baroreceptor firing rate decreases

·  Sympathetic pathways increase cardiac output

·  Inhibits parasympathetic activity

·  Activates the vasomotor center to increase vasoconstriction

·  The increase in cardiac output and resistance raises blood pressure

\-   **If blood pressure increase**

·  Vessel stretches and baroreceptor firing rate increase

·  This causes the cardio acceleratory center to send less signals along sympathetic pathways

·  Stimulate the cardioinhibitory center to activate parasympathetic pathways to SA and AV nodes of the heart

·  Decrease in cardiac output and resistance lowers blood pressure

hormonal regulation of blood pressure

**Aldosterone**

·  Helps maintain blood volume and pressure

·  Released from adrenal cortex

·  Release triggered by several stimuli, including angiotensin 2

·  Increases absorption of sodium in ions and water in the kidney

\-   **ADH**

·  Helps maintain or elevate blood pressure

·  Increases water reabsorption in kidneys maintain blood volume

·  Stimulates thirst center to increase fluid intake

\-   **ANP**

·  Stimulates vasodilation

·  Increases urine output

·  Mechanism for blood pressure homeostasis involve cardiac output, resistance, and blood volume

brachiocephalic trunk

* Bifurcates into right common carotid and right subclavian arteries
* Right common carotid supplies right side of head and neck
* Right subclavian supplies right upper limb and some thoracic structures

common carotid artery

* Supplies left side of head and neck
* Travel parallel to trachea- one on each side
* Divide into external carotid artery and internal carotid artery
* **External carotid artery supplies structures external to skull**
* **Internal carotid artery supplies internal skull structures**

superior thyroid artery

thyroid gland and larynx

ascending pharyngeal artery

pharynx

lingual artery

tongue

facial artery

face

occipital artery

posterior scalp

maxillary artery

teeth, gums, nasal cavity, mastication, muscles, meninges

superficial temporal artery

parotid gland, part of the scalp

anterior and middle cerebral arteries

brain

ophthalmic artery

eyes and surrounding structures

vertebral arteries

come off subclavian arteries

* Travel in transverse foramina of cervical vertebrae
* Enter skull through the foramen magnum
* Merge to form the unpair basilar artery
* The basilar artery divides into posterior cerebral arteries (posterior cerebrum)

cerebral arterial circle

circle of willis

* Important arterial anastomosis around sella turcica
* Formed by posterior cerebral, posterior communicating, internal carotid arteries, anterior cerebral, and anterior communicating artery
* Equalizes blood pressure in brain
* Provides collateral channels if one vessel becomes blocked

left subclavian artery

supplies left upper limb and some thoracic structures

descending thoracic aorta

* Formed by aortic arch curving inferiorly
* Has several branches supplying thoracic wall and viscera

descending abdominal aorta

* Formed by descending thoracic aorta inferiorly
* Supplies abdominal wall and organs

left and right common iliac arteries

* Formed by descending abdominal aorta at 4th lumbar vertebra where abdominal aorta splits
* Each of these splits into an internal (pelvic structures) and external (lower limb) iliac artery

cranial cavity

* Some blood drains to vertebral veins
* Most blood drains through dural venous sinuses: large modified veins between two layers of dura mater

internal thoracic artery

* Emerges from the subclavian artery
* Anterior thoracic wall and mammary gland
* Branches include six anterior intercostal arteries
* Branches include musculophrenic artery
* Becomes superior epigastric

internal thoracic vein

* Receives blood from anterior intercostal veins
* Receives blood from musculophrenic and superior epigastric veins
* Drains into the brachiocephalic vein

epigastric artery

a branch of external iliac

anastomoses with superior epigastric artery

inferior epigastric vein

merges with external iliac vein

supreme intercostal artery

branch of costocervical trunk

branches into first and second posterior intercostal arteries

lumbar arteries

* Posterior abdominal wall
* Fiver pairs branch off the abdominal aorta

median sacral artery

unpaired artery extending form bifurcation of aorta in pelvis

bronchial arteries

supply bronchi and bronchioles

tiny branches off descending thoracic aorta

bronchial veins

drain into azygos and pulmonary veins

esophageal arteries

several small branches off descending thoracic aorta