Block 3 Flashcards
What are the three meninges?
Dura mater, Arachnoid, Pia
What is the location of CSF absorption into the venous system?
Dural sinuses
The dura mater is a thick layer of ___________
Thick layer of fibroblasts
What meninx is spiderweb-like and consists of a thin layer of fibroblasts that trap CSF between it and pia mater?
Arachnoid mater
What meninx consists of a single layer of fibroblasts?
Pia mater
What is the primary function of the meninges?
To protect the brain and spinal cord from mechanical injury
The flow of CSF enters what location after it passes through the cerebral aqueduct?
The Fourth Ventricle
Where does the CSF enter after the lateral ventricles?
The third ventricle, through the foramina of Monro (interventricular foramina)
Where is CSF formed?
Ependymal cells in choroid plexus, located in each of the 4 ventricles
List the 4 functions of CSF
1) Cushion brain
2) Maintain extracellular environment for neurons and glia cells
3) Waste control
4) Distribution medium for peptide hormones and growth factors that are secreted into CSF
If there is increased CSF in the skull and associated increased ventricular volume and intracranial pressure, what is the most likely cause?
Hydrocephalus
This is normally caused by an obstruction to CSF flow
Non-communicating hydrocephalus
What type of hydrocephalus is caused by impairment of absorption and can be secondary to meningitis or hemorrhage?
Communicating hydrocephalus
What are the blood-brain barrier components?
Specialized endothelial cells lined by basal lamina, astrocyte endfeet, pericytes and microglial cells
What is the importance of a functioning blood brain barrier?
To repel potentially harmful substances
What meninx fuses with the inner surface of the skull bones?
Dura mater
What ventricle is found between the two cerebral hemispheres?
Lateral ventricles
What ventricle is found at the midline of the diencephalon?
Third ventricle
What ventricle is located between the cerebellum and the dorsal surface of the hindbrain (pons/medulla)?
Fourth ventricle
Explain the flow of CSF down the pressure gradient from its site of formation at the choroid plexus
Lateral ventricles into the 3rd ventricle, through the foramina of Monro, through the cerebral aqueduct of the midbrain, into the fourth ventricle into the subarachnoid space through the foramina of Luschka
Where is CSF sampled from in most veterinary species?
Between skull and first cervical vertebra (atlas)
If the CSF fluid appears turbid, what does that indicate?
Increased cellularity (poss. infection, cancer)
Absorption of CSF tends to be pressure dependent and _________
Unidirectional
True or False
CSF fluid does not get replaced in the body
False - it is replaced several times a day
In brain capillaries, passage through intercellular clefts is blocked by what?
Tight junctions
True or False
Exchange of blood solutes is highly selective in the blood-brain-barrier
True
What surrounds the endothelium in the blood-brain-barrier?
Pericytes and astrocytes
What kind of junctions are found in the blood brain barrier?
Tight junctions
True or False
Pinocytosis is commonly seen at the blood brain barrier
False
What types of molecules can easily pass across the capillary endothelium of the blood brain barrier?
Small, uncharged, lipid soluble and unbound to proteins (ie. O2, CO2, ethanol, nicotine)
What are some examples of molecules that need specific, carrier-mediated transport mechanisms to pass through the blood brain barrier?
Glucose and some amino acids
True or False
Antibiotics and anti parasitic drugs readily pass the blood brain barrier
False - the BBB repels them
What nerve block is used to prevent closure of the eyelid/blinking?
Auriculopalpebral nerve block
What kind of nerve block would you use to perform an ophthalmic exam?
Auriculopalpebral nerve block
What are the landmarks for the auriculopalpebral nerve block?
Dorsal aspect of the zygomatic arch, or depression caudal to the mandible
This type of block is only a motor block and does NOT desensitize the eye
Auriculopalpebral nerve block
True or false
The motor nerve can be palpated
True
True or False
If you are going to enucleate the eye, you do not need to block all 4 nerves
FALSE - all 4 must be blocked
What are the main sensory nerves of the equine eye?
A) Supraborbital nerve
B) Lacrimal Nerve
C) Infratrochlear nerve
D) Zyomatic nerve
ALL
What sensory nerves do you block with a SQ injection?
Lacrimal, infratrochlear, and zygomatic
True or False
You have to fully anesthetize a horse to enucleate the eye
False - Standing enucleation by blocking all 4 sensory nerves plus the retrobulbar nerve
What dental nerve block works to block everything rostral on one side of the face?
Infraorbital nerve block
This nerve block desensitizes the ipsilateral upper lip and nose
Infraorbital nerve block
If you need to desensitize teeth rostral to the 1st molar, maxillary sinus and roof of nasal cavity, what block is used?
Infraorbital nerve block
What block is used to desensitize the lower lip and lower incisors?
Mental Nerve Block
What block provides anesthesia of the mandible?
Inferior alveolar nerve block
This nerve block is often performed blindly (which is difficult and possibly risky) however, it is still safer than GA
Inferior alveolar nerve block
What dental block is used for the maxilla and sinus cavity?
Maxillary nerve block
Where is the caudal epidural administered?
Between Co1 and Co2 space
What nerve block is administered in the space palpated by moving tail up and down in a horse?
Caudal epidural
What are some techniques that can be used to verify placement of caudal epidural?
Loss of resistance/hanging drop technique (checking placement by placing a drop of the block in the hub of the needle)
What are some indications for an equine epidural (caudal epidural)?
Tail, perineum, rectum or vulva procedures
Fetotomy, obstetric manipulations
Hindlimb analgesia
For local anesthetics, what is important to limit the cranial spread of the drug?
Volume
True or False
The goal of local anesthetics in equine is to cause motor blockage of the hindlimbs
FALSE
We are avoiding hind limb ataxia/motor blockage
How much 2% lidocaine is typically used in an adult horse?
6-8 mL
Xylazine and detomidine are what type of drugs?
Alpha-2 agonists
What are some side effects of alpha-2 agonists?
Sedation, 2nd degree AV block, ataxia
True or false
Side effects of alpha 2 agonists can be reversed
True (w/ IV antagonist)
What drug provides analgesia without the risk of motor blockade?
Morphine
What drug is typically used for hind limb trauma, surgery or severe laminitis?
Morphine
What are some common side effects of morphine?
Uticaria and ileus
This analgesic can be administered via epidermal catheter for long-term analgesia
Morphine
True or False
An epidural catheter can be placed to administer local anesthetics in equine
FALSE
Local anesthetics can not be administered epidurally due to loss of motor
If the epidural catheter is advanced into the LS space what happens?
analgesia for the hindlimbs
What combination provides excellent analgesia for equine?
Alpha 2 agonist + Morphine
What is used for additional anesthesia in large animals for castration?
Intratesticular block
True or False
If an intratesticular block is used, the animal does not need sedation or GA
False
Why is lidocaine used for intratesticular blocks?
Rapid onset - quickly diffuses into spermatic cord
How much lidocaine can be used in horses for intratesticular blocks?
20 mLs
How much lidocaine can be used in small ruminants for intratesticular blocks?
2-5mL
What block should only be used for ruminant enucleation and why?
Retrobulbar block - only used for enucleations because you can perforate the eye
What nerve is blocked for dehorning purposes?
Cornual branch of zygomaticotemporal nerve
What type of block is commonly performed for goat dehorning?
Ring block around the horn
What nerve can not be realistically blocked in goats?
Cornual branch of infratrochlear nerve (it is too close to the eye)
If a laparotomy needed to be performed on a cow, which of the following blocks could be used?
a) Auriculopalpebral
b) Infraorbital
c) Line block
d) Inverted L block
e) caudal epidrual
C and D (Line and inverted L)
What are the sites of administration for an L block?
T13, L1, L2
What layers is a line block providing analgesia for?
SQ and muscular layers
In what block (Inverted L or Line) is the local being injected along the incision site?
Line block
What blocks, used for ruminant flank laparotomy, are given in the dorsal and ventral branches of T13, L1 and L2?
Proximal paravertebral block
Distal paravertebral block
Inclusion of what injection site would provide better anesthesia for a flank laparotomy?
a) T12
b) L3 and L4
c) L3
d) None- you want to stay away from L3 and L4
b) L3 included for proximal block, L4 included for distal block
What is a contraindication of including L3 in a block?
If L3 and L4 are administered local block, the animal could lose motor and go down which is dangerous
What are some indications for a caudal epidermal in ruminants?
Obstetric manipulations, surgical procedures for tail, perineum, anus, rectum, vulva, vagina, prepuce, scrotum
Where is a ruminal caudal epidermal administered?
Between S5-Co1 or Co1-Co2 space
What types of drugs are used for ruminant caudal epidurals?
Local anesthetics, alpha 2 agonists, moprhine
True or False
Ruminant caudal epidurals are rarely performed
False - common and easily performed
True or False
Ruminant lumbosacral epidural should not induce loss of motor function
False - it does induce motor function
Where is the site of injection for the ruminant lumbosacral epidural?
Between L6-S1
What animals is the ruminant lumbosacral epidural used?
Immature cattle (caudal epidural in adult cattle), small ruminants, camelids, and pigs
What are the 4 techniques used for anesthesia for the teats?
Ring block
Inverted V
Cistern infusion
IV regional anesthesia
Paravertebral block of L1-L3 (L4) can provide anesthesia to what area of the udder?
Cranial aspect of udder and teats
What block provides anesthesia to the caudal aspect of the teats and udder (around anus)?
Pudendal block
Intravenous regional anesthesia (Bier Block), is used for what?
Commonly used for site of injury or disease (ie foot abscess/wound)
Why would a Bier Block be given IV versus as a local block?
Inflammation can block the effects of a local block
What side of the heart pumps blood through the lungs?
Right side of the heart
What side of the heart pumps blood through the body’s tissue and supplies O2 and nutrients, removing CO2?
Left side of the heart (Systemic)
Contraction and emptying of the heart
Systole
Relaxation and filling of the heart
Diastole
What is the primary function of the cardiovascular system?
Transport
Most of the resistance in blood vessels is due to what?
Vessel diameter
Ability to increase the volume of blood held without a large increase in blood pressure
Capacitance
What does high capacitance allow for?
High blood volume and low blood pressure; it is the ability to increase the volume of blood without a large increase in BP.
True or False
The greater the vessel diameter, the greater its resistance and blood flow.
False: The greater the vessel diameter, the great its resistance and LOWER the blood flow
What holds more volume of blood, a vein or artery?
Veins hold more volume
What tolerates higher pressure, a vein or artery?
Artery
What is the largest artery?
Aorta
Arteries deliver _______ blood to the organs.
Oxygenated
Smallest branches of arteries
Arterioles
What blood vessels have the highest resistance to blood flow?
Arterioles
Thin walled, single layer of endothelial cells surrounded by basal lamina, also the site of exchange of nutrients, gases, water and solutes between blood and tissues.
Capillaries
Thick walled blood vessels that are under high pressure
Arteries
Thin walled blood vessels with low elastic tissue but high capacity, containing the largest percentage of blood in the CV system.
Venules and veins
What blood vessels would have the largest lumen?
Veins
What cells make up the atria and ventricles, are able to shorten/lengthen, and have striated muscles specialized for contraction and impulse conduction?
Working myocardial cells (cardiomyocytes/myocardium)
Cells that exhibit automatic rhythmical electrical discharge (cardiac action potentials)
Pacemaker Cells (autorhythmic cells)
Where are pacemaker cells found?
SA and AV nodes, Purkinje fibers
Found in the conducting system of the heart, these cells carry the action potential throughout the heart
Conducting cardiomyocytes
What are the similarities between cardiac and skeletal muscles?
Fibers are striated
Myofibrils of actin and myosin
Similar sarcomere arrangement
Contain SR and T-Tubules
True or False
Cardiac muscle is usually multinucleated
False - It is uninucleated
What type of muscle has high mitochondrial density?
Cardiac muscle
What allow the cardiac muscle cells to contract in a wave-like pattern?
Intercalated discs
True or False
Cardiac muscle fuse into a single multinucleated fiber during embryonic development
False - it is a functial syncytium
True or False
Cardiac myocytes branch during development and bind to other myocytes
True
True or False
Fibers remain separated as distinct cells with their sarcolemma, but are also electrically separate to each other.
False - they are electrically CONNECTED to each other through intercalated discs (the rest of the above statement is true)
Part of the sarcolemma, contains 2 cell-cell junctions (Gap junctions and desmosomes)
Intercalated disk
Provide mechanical strength and anchor the end of the cardiac muscle fibers together
Desmosomes
What is the normal/primary/natural pacemaker of the heart?
SA node or sinus node
Where is the SA node located?
Right atrium
Where are slower pacemakers located?
AV node and Bundle of His-Purkinje system
Small strip of specialized cardiac muscle cells (pacemaker cells)
Sinus node (SA node)
True or False
The SA nodes have numerous contractile muscle filaments
False - they have almost none
What is the movement of the action potential (from where to where)?
SA node –> Atrial walls –> AV node
What delays impulse conduction from the atria to the ventricles?
AV node
Located in the posterior wall of the right atrium, immediately behind the tricuspid valve
AV node
AV node fibers have fewer GAP junctions for what reason?
Slower ion movement between cells, which allow the atria to empty their blood into the ventricles before ventricular contraction begins
AV-Bundle passes downward in the ventricular septum and divides into left and right bundle branches that are found where?
Beneath the endocardium
The AV-Bundle allows only forward conduction from what to what?
From the atria to the ventricles
Atria muscle is separated from ventricular muscle by what?
continuous fibrous skeleton
True or False
The transmission velocity in the ventricular purkinje system is fast
True
Special purkinje fibers lead the AV node impulses through the what into the what?
Through the AV-Bundle (bundle of His) into the ventricles
The ends of Purkinje fibers penetrate the muscle mass and become continuous with what?
Cardiac fibers
Part of the heart that is oriented dorsocranially
Base
Part of the heart that points ventrocaudally and to the left
Apex
What view of the heart is called the auricular surface?
The left view
What view of the heart is called the atrial surface?
The right view
Separation of the atria and ventricles, often containing fat and encircles the base of the heart
Coronary groove
Separation of the ventricles
Interventricular grooves
AV valve cusps/leaflets that originate from the outer ventricular wall
Marginal or Parietal cusps
AV valve cusps/leaflets that originates from the interventricular septal wall
Septal cusps
What anchor cusps to the inner walls of the ventricles?
Chordae tendineae
What secure the chardae tendineae to the inner walls of the ventricles?
Papillary muscles
What closes during systole to prevent backflow of blood into the atria?
AV valves
What side of the heart receives deoxygenated blood from systemic cirulation and send blood into pulmonary circulation?
The right side
What side of the heart receives oxygenated blood from the pulmonary circulation and send blood into the systemic circulation
Left side
The right atrium receives blood from what?
The cranial and caudal vena cava (and venous return from the heart muscle)
The right ______ pumps blood into the right _________ through the right _______ _________
The right atrium pumps blood into the right ventricle through the right AV valve
Right ______ contracts to send blood to the lungs through the __________ trunk & _________ arteries
The right ventricle contracts to send blood to the lungs through the pulmonary trunk and pulmonary arteries
The ________ semilunar valve prevents backflow of blood from the pulmonary trunk into the right ventricle during _______
The pulomonary semilunar valve prevents backflow of blood from the pulmonary trunk into the right ventricle during diastole
Oxygenated blood travels back to the heart through the _______ veins into the left ______ which then pumps blood into the left ______ through the left _____ ______
Oxygenated blood travels back to the heart through the pulmonary veins into the left atrium which then pumps blood into the left ventricle through the left AV valve (mitral valve)
Left ventricle contracts to send blood through the _____ ______ valve and into the ________ out to the rest of the body (and to supply the heart muscle itself)
Left ventricle contracts to send blood through the aortic semilunarvalve and into the** aorta**out to the rest of the body
The _____ _____ valve prevents backflow of blood from the aorta into the left ventricle during ______
The **aortic semilunar **valve prevents backflow of blood from the aorta into the left ventricle during diastole.
Valve located between the right ventricle and pulmonary arteries (trunk)
Pulmonary Semilunar Valve
Valve located between the left ventricle and the aorta
Aortic Semilunar Valve
If you are auscultating the left side of a dog, what are the three valve sounds you may listen for and where specifically are they?
P = pulmonary valve (3rd IC space)
A = Aortic valve (4th IC space)
M = Mitral (left AV) (5th IC space)
If you are auscultating the right side of a dog, what valve are you listening for and where is it located?
The tricupsid/Right AV (4th IC space)
What sound are you hearing at the beginning of systole that is the “lubb” sound?
S1
What sound are you hearing that is the “dupp” sound?
S2
The closure of the left and right AV valves produces what sound?
The S1 or “lubb”
The closure of the aortic and pulmonic semilunar valves produce what sound?
The S2 or “dupp”
True or False
You should be able to hear the sound of blood flow from one structure to the next in normal dogs and cats?
False - blood flow from one structure to another is normally silent in normal dogs and cats
What sounds are not normally heard in normal small animals, but can be heard in some large animals normally?
S3 and S4
What is an example of a cause of an ABNORMAL S3 sound?
Congestive heart disease / DCM
What is an example of a cause of an ABNORMAL S4 sound?
Hypertrophic Cardiomyopathy (HCM)
Where is the thymus located?
In the cervicothoracic area, starting from dorsal sternal aspect towards ventral cervical area (sometimes more thorax vs cervical depending on species)
Less discrete lymphoid aggregations
Tonsils
This lymphatic organ is placed at the level of the abdominal cavity in relationship with the stomach. It has importance in storage, release, and concentration of erythrocytes and produces lymphocytes and monocytes
Spleen
Found in the course of blood vessels, these small lymphatic bodies resemble lymph nodes but have no lymphatic vessels (absent afferent/efferent lymphatics).
Hemal nodes
True or False
All animals have hemal nodes
False
In what species are hemal nodes typically found?
Sheep
These structures may represent an intermediate stage between a lymph node and the spleen
Hemal node
Found in some animals in relation to their abdominal and thoracic viscera
Hemal node
Present in many mucous membranes (larynx, intestine, prepuce, and vagina) and do NOT have capsules
Diffuse lymphatic tissue and lymphatic nodules
In what lymph tissue are capsules present?
Lymphatic organs
What are the lymphatic organs?
Lymph nodes, spleen, thymus gland
What lymph tissue is found in connective tissue of almost all organs?
Diffuse lymphatic tissue
What lymph tissue is found singly or in clusters?
Lymphatic nodules
What are the lymphatic nodules that occur in the mucosa that lines the ileum?
Peyer’s patches
What is the role of the lymphatic circulatory system?
Collects interstitial fluid, waste material, and others (like viruses and bacteria) that are in the body tissues outside the bloodstream
What is lymph?
Ultrafiltration of blood plasma
What is the difference between lymph and blood plasma?
Lymph has less protein as it is ultra-filtered
Lymph vessels draw up the lymph fluid from around the cells to send it towards the _______. There, lymph fluid collects into a large vessel that drains into the ______ ____ ____ that opens in the heart.
Chest, cranial vena cava
Without the lymph vessel, what would happen to lymph fluid?
It would build up and cause swelling
Contain immune cells that help fight infection by attacking and destroying germs that are carried through the lymph fluid
Lymph nodes
What vessels lead into a lymph node?
Afferent lymphatic vessels
What vessels lead out of a lymph node?
Efferent lymphatic vessels
True or False
Afferent vessels become Efferent vessels
False
Efferent vessels become afferent vessels
What are the lymph nodes of the head?
Parotid, lateral retropharyngeal, and mandibular
What are the lymph nodes found in the neck?
Superficial cervical (pre-scapular)
Lymph node situated caudo-ventrally to the angle of the mandible, in the angle between the masseter muscle and mandibular salivary gland
Mandibular lymph center
Usually a single lymph node, situated near the base of the ear, close to the tempo-mandibular joint
Parotidian lymph center
