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Paramedicine y1 > Anatomy + Physiology 2 > Flashcards

Anatomy + Physiology 2 Flashcards

1
Q

Universal characteristics of Muscles

A
  • Excitablity / responsiveness (chemical signals, stretch, electrical changes)
  • Conductivity )Electrical excitation initiate waves of excitations
  • Contractility (Shortens when stimulated)
  • Extensibility (Stretched between contractions)
  • Elasticity ( Returns to original rest lengths)
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2
Q

Skeletal muscle

A

Attached to bone via tendons. Contraction brings movement across Joints

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3
Q

Voluntary striated muscles

A

Voluntary - usually subjected to conscious control
Striated - alternating light and dark bands due to internal contractile protiens

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4
Q

Structural hierachy of skeletal muscle w/ definitions

A
  • Muscle↔Contractile organ - attached to bones with tendons. Separated from other muscles with fibrous epimysium
  • Fasicle↔bundle of muscle fibres within a muscle. supplied by nerves and blood vessles and enclosed in bibrous perimysium that separates it from neighbouring fascicles
  • Muscle fibre↔single muscle cell - slender, elongated enclosed in specialized plasma membrane (sarcolemma) . Contains densely packed bundles - myofibrils - of contractile protien filaments, multiple nuclei immediately beneath the sarcolemma and extensive network of specalized smooth endoplasmic reticulum.
  • Myofibril↔Bundle of protien myofilaments within muscle fibre. Conenctively fill most of cytoplasm. Surrounde by sarcoplasmic reticulum and mitochondria. Banded (striated) appearance due to overlap of protien myofilaments
  • Sarcomere↔Segment of myofibril from one Z disk to the next in striation pattern. Hundreds end to end to compose a myofibril. Functional, contractile unit of muscle fibre
  • Myofilaments↔fibrous protien strands that carry out contraction process - thick filaments (Myosin) and thin filaments (Actin). Thick and thin side over one another to shorten each sacromere - shortening end to end shortens entire muscle
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5
Q

Skeletal muscle cells (fibre)

A

Multiple Peripheral Nuclei

Mitochondria between myofibrils

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6
Q

SKeletal muscle Glycogen

A

Carbohydrate stored to provide energy for excerise

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7
Q

Skeletal Muscle Myoglobin

A

Red pigment - provides O2 needed for muscle activity

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8
Q

Skeletal muscle Myoblasts

A

Stem cells fuse and form muscles fibres early in development

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9
Q

Skeletal muscle Saatellite cells

A

unspecialized myoblasts between muscle fibre and endomysium. Play a role in regeneration of damaged skeletal muscle tissue

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10
Q

Muscle Fibre - Myofibrils

A

Attached to inner surface of sarcolemma. Comprised of bundles of protien fillaments

Thin - Actin
THick - myosin

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11
Q

Sarcoplasmic Reticulum - SR

A

Smooth ER network around myofibril

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12
Q

Terminal Ciserns

A

Dilated end sacks of SR that cross muscles fibre from one side to the other - Ca+ reservoir

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13
Q

T tubules

A

Tubular infoldings of sarcolemma which penetrate through cell and emerge on other side

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14
Q

Triad

A

T Tubule and two terminal cisterns associated with it

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15
Q

Muscle fibre - Sarcomeres

A

Myofilaments organized into repeating functional unis.
A bands - Dark
I bands - Light

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16
Q

Sacromere

A

Segment from Z disk to Z disk.
H Band - contains thick filaments
I band - contains thin filaments

Subdivisions::
M line- Protiens that connect neighbouring thick filaments
H Band - Region either side of M line (THICK FILAMENTS ONLY)
A band - zone of overlap

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17
Q

Actin

A

Thin filaments
Fibrous acitn - two intertwined strands
Glubular - single string w/ active site that binds to had of myosin molecule.

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18
Q

Tropomyosin

A

Actin binding protien. Molecules that block acive sites on G actin subinits

Troponin - small calcium binding protien on each Tropomyosin

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19
Q

Myosin

A

Comprise of thick filaments.
Molecules shaped like double headed golf club - 2 chains.
Heads directed outwards
Heads on 1/2 filament angle to left, other 1/2 to right
Bar zone = no heads

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20
Q

Dystrophin

A

Linked actin to outermost myofilaments to membrane protiens that link to endomysium.
Transfers forces of muscle contraction to connetie tissue leading to tendon.
Genetic defect = myscular dystrophy

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21
Q

Titin (hehe titty)

A

Elastic filaments
Runs through core of thin filament and anchors it to Z disk and M line
- stabalize and position thick filament

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22
Q

Skeleal muscle contraction in order

A
  • Sarcomere shorten
  • H bands and I bands get smaller
  • Zones of overlap get larger
  • Z lines move closer together as thick and thin filaments slide past eachother
  • Width of A band remains constant
  • During shortening↔Dystrophin and linking protiens pull on extracellular protiens
    • Transfers pull to extracellular tissue
  • Sliding in all sarcomeres in Myofibril
  • Myofibril gets shorter
  • muscle fibre gets shorter
  • muscle gets shorter
  • produces tension
  • ONLY CONTRACT WHEN STIMULATED BY A NERVE
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23
Q

Motor neurons and motor units

A

Somatic motor neurons - nerve cells who bodies lie in brainstem and spinal cord

Somatic motor fibres - axons that lead to skeletal msucle

Motor Unity - one nerve fibre and all muscle fibres innovated by it.

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24
Q

Muscles fibres in one motor unit

A
  • dispersed throughout muscle
  • Contract in unison
  • produce weak contraction over wide area
  • Able to sustain long term contraction as motor units take turn contracting
  • Contraction usually requires contraction of several motor units at once .
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25
Q

Small motor unit

A
  • Fine degree of control
  • 3-6 muscles per neuron
  • eye and hand muscles
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26
Q

Large motor units

A
  • More strength than control
  • Powerful contractions supplied by alrge motor units with hudreds of fibres
  • Gastrocnemius has +- 1000 muscle fibres per neuron
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27
Q

Neuromuscular Junction

A

nerve fibre meets target cell - target cell is muscle cell

  • Terminal branches of nerve fibres within NMJ forms synapses with muscle fibres
  • one nerve fibre stimulates the muscle fibre at several points within MNJ
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28
Q

Nerve parts

A

Axon terminal - swolen end of nerve fibre
Synaptic cleft - gap beween axon terminal and sarcolemma

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29
Q

Electrivally excitable cells

A
  • Muscle fibers and neurons are electrically excitable
  • Cell membranes exhibit voltage changes in responce to stimulation
  • Voltage - difference in eectrical charge from one point to another
  • resting membrane potential +- 90mV in skeletal muscle cells
  • Maintained by sodium/potassiun point
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30
Q

Unstimulated resting cell

A
  • More anions (-ve) on inside of cell membrane than outside
  • anions make inside of pl asma membrane negatively cahrged by comparison to outer surface
  • plasma membrane is electrcially polarized with negative resting membrane potential
  • there are excess Na+ In extracellular fluid (ECF)
  • Excess potassium Ions (K+) in intracellular fluid.
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31
Q

Stimulated

A
  • Na+ Ion gates open in the plasma memrbrane
  • Na+ flows into cell down its electrochemical gradient
  • these cations overide the negative charges in ICF
  • depolarization↔inside of plasma membrane becomes positive
  • Na+ gates close and K+ gates open
  • K moves otu of cell partly repelled by na+ cahrge and aprtly because of concentration gradient
  • Loss of positive K+ ions turns membrane negative again - repolarization
  • this voltage shift - depolarization and repolarization - is an action potential
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32
Q

Resting membrane potential - cell not stimulated

A
  • Action potential is quick event in stimulated excitable cell
  • perpetuates itself down length of cell membrane
  • AP causes another ot happen immediatly infront of it
  • triggers another
  • wave of excitation is called a impulse
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33
Q

Neruomuscular toxins and paralysis

A
  • toxins can interfere with synaptic function - paralyzem uscles
  • some pesticisdes contain cholisterase inhibitors
    • bind to acetylcholinestrae and prevent it from degrading ACh
    • Spastic paralysis - state of continual contraction of muscles - suffocation
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34
Q

Teatnus / lockjaw

A

Form of spastic paralysis cauased by toxin Clostridium Tetani

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35
Q

Flaccid paralysis

A

Muscles are limp and cannot contract

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36
Q

Butolism

A

Food poisoning caused by neruomsuclar toxin secreted by the bacterium colstridum botulinum

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37
Q

Exccitation

A
  • Excitation↔process in which nerve action potential lead to muscle action porentials
    • Action potential arrives at synaptic terminal
    • scetylcholine is relaseased
    • permeability of membrane changes and triggers ACh
    • ACh molecules cross synaptic cleft and bind to ACh receptors on Sarcolemma
    • Na+ ions rush into sarcolemma generate action potential
    • K+ moves out of cell - concentration gradient
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38
Q

Excitation - contracting coupling

A

events that link action potentials on sarcolemma to activation of myofilaments - preparing them to contract
- Action potential spreads along each T tubule (lie between two ends of sarcoplasmic reticulum
- In resting state tropmyosin srands cover active sites on thin filaments
- Prevents cross-bridge formation
- Ca+ binds to and cahnges shape of troponin molecule
- Troponin molecule roles tropomyosin from active sites

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39
Q

Contraction

A
  • Contraction↔muscle fibre develops tension and may shorten
    • Energised (ADP) myosin heads bind to active sites of F actin
    • Formation of cross bridges
    • contraction cycle begins
      • Myosin head pivots towards M line - requires energy. REFERED AS A POWER STROKE
      • Breaking of new ATP - breaking of cross bridge.
40
Q

Relaxation

A

stimulation ends - muscle fibres relaxes and returns to resting length
- Cessation of nervous stimulation and ACh release.
- ACh breakdown by Acetylcholinesterase (AChE)
- Reabsorption of Ca ions by sarcoplasmic reticulum
- Free myosin head splits ATP int ADP and phosphate group
- Energy released cocks Myosin head
- cycle can now be repeated
- ATP binds to myosin head and breaks link to action
- Active site now free.

41
Q

Length tension relationship

A

amount of tension generateed by a muscle depending on how stretched or shortened it was before it was stimulated
- If overally shortened before stimulation - weak contraction results as thick filaments approached Z discks
- if to stretched before stimulated - weak contraction results as minimal overlap between thich and thin filaments in minimal corss bridge formation
- Optimum resting length produces greatest force of muscle contracts↔Nervous system maintains muscle tone (partial contraction) to ensure that resting muscles are near this length

42
Q

Rigor Mortis

A
  • Hardening of muscles and stiffening of body
  • Starts 3-4 hours after death
  • teriorating sarcoplasmic reticulum releases Ca+2
  • Allows Ca+2 to enter cytosol
  • Ca+2 activates Myosin actin cross bridging
  • muscle contracts, but cannot relax
  • Muscle relaxation requires ATOP - No longer produced after death
  • Fibres remain contracted until Myofilaments begin to decay
  • Rigor mortis peaks +- 12 hours after death
  • Diminishes over next 8-60 hours.
43
Q

Threshold

A

Minimul voltage neccessary to generate an action potential in muscle fibre and produce contraction

44
Q

Twitch

A

cycle of contraction and relaxation when stimulus is at threshold or higher

45
Q

Latent Period

A

very bried delay betweein stimulus and contraction
- Time required for excitation, excited Contraction coupling, and tensing of elastic Components of muscle

46
Q

Contraction phase

A

time when muscle generates external tension
- Force generated can overcome load and cause movement

47
Q
A
  • Relaxation phase↔time when tension declines to baseline
    • SR reabosrbs Ca+2 myosin released actin adn tension decreases
    • Takes Longer than contraction.
48
Q

Integumentary system

A

Skin and accessory organs (hair nails + glands).
Largest and heaviest organ - thick and thin

49
Q

Thick skin (location, accessories and epidermis thickness)

A

Plams of hands/soles of feet
sweat glands

Sweat glands, NO hair follicles or Sebacenous glands

Epidermis - 0.5mm thick

49
Q

Thin skin (location, accessories and epidermis thickness)

A

Rest of body (Not soles/palms)

Hair follicles, sebaceous glands and sweat glands

Epidermis +/- 0.1mm thick

50
Q

Functions of the skin

A

Resistance to trauma/infection
H2 barrier (prevents h2 getting in) - tight junctions between cells (prevents dehydration)
Uv radiation + harmful chemicals
Vitamin D synthesis (First step - liver and kidneys complete)

51
Q

Epidermis - outer stratified squamous epithelium

A

Keritinized (tough protein)
layered + flat cells.
MAIN CELL = Keratinocytes
No blood vessels - nutrients fro diffusion from underlying connective tissue.
Nerve endings and receptors for touch/pain

52
Q

Layers of epidermis (Deepest to top)

A
  1. Stratum basale - single layer stem cells + keratinocytes. Migrate to surface to replace lost cells - also contains melanocytes nad tactile cells
  2. Stratum spinosum - several layers of keratinocytes + desmosmes and tight junctions
  3. Stratum granulosum - 3-5 layers of flat keratinocytes (dark staining keratohyalin granules)
  4. Stratum lucidum - thin + pale layer only in thick skin - keratinocytes packed with clear protein eleidin.
  5. Stratum corneum - surface layer - several layers (up to 30) of dead scaly keratinized cells.
53
Q

Keratinocytes

A

synthesis keratin - produced by mitosis of stem cells. needs abundant Oxygen and nutrients - once away from Blood vessels, itosis cannot occur

54
Q

Melanocytes

A

Synthesise pigment melanin - sheilds DNA from UV radiation (only in stratum basale)

55
Q

Dendric cells

A

Macrophages, originate in bone marrow - guard against pathogens (Stratum spinosum + stratum granulosum)

56
Q

Tactile cells

A

Touch receptor cells associated w/ dermal nerve fibres - base layer of epidermis

57
Q

Dermis

A

Connective tissue layer under epidermis - 0.2mm to 4mm.

Mainly collagen + blood vessels, sweat glands, sebaceous glands and nerve endings
Hair follicles + nail roots.
FOrms wavy boundary with epidermis
DERMAL PAPILLAE - Upward finger like extension of dermis.
- Prominant wave on fingers - finger prints

58
Q

Dermis layers

A

Papillary layer - superficial zone - thin areolar tissue in and near dermal papilla (allows mobility of leukocytes and other defence cells)

Reticular layer - deeper, thicker layer. Dense irregular connective tissue. (stretch marks - tears in collagen fibres)

59
Q

Hypodermis

A

Deep connective tissue layer below dermis - not considered apart of the skin, but associated with it)

Subcutaneous tissue - more areolar and adipose tissue than in dermis. Pads the body and binds skin to underlying tissues

Abundant blood vessels - common injection sites

60
Q

Skin disorders

A

Ichthyosis - inherited, shedding process inhibited (can result in overheating)

Eczema - chronic inherited inflammatory skin condition w/ dry itchy and reddening of skin

Exfoliative dermatitis - excessive shedding of skin

61
Q

Skin colour

A

Melanin produced by melanocytes - accumulates in keratinocytes

Eumelanin - brownish black
Pheomelanin - reddish yellow

Haemoglobin - pink/red hue to skin

Carotene - yellow pigment aquired from egg yolks / orange/ yellow vegetables

62
Q

Hair

A

Slender filament of keratinized cells gorwing from follicle in skin
- not on palms/ soles.

63
Q

Structure of Hair

A

Bulb↔A swelling at the base of a hair follicle where hair originates in Dermis - only living hair cells are in or near bulb

Root↔the remainder of the hair in the follicle

Shaft↔the portion above the skin surface

Hair matrix↔region of mitotically active cells immediately above papilla - hair growths centre

Dermal papilla↔Bud of vascular connective tissue encase by bulb - only source of nutrition for hair

Hair receptors↔Sensory nerve fibres entwining follicles

Piloerector muscle (arrector pili)↔smoothe muscle attaching follicle to the dermis - contracts to make hair stand on end - goosebumps

64
Q

Skin apendages - Nails

A

Clear derivates of stratum corneum - thin dead cells packed with hard keratin

Nail plate - hardp art of the nail, free bit hangs over fingertip (nail body attached to finger, nail root, under skin)

Nail fold surrounding rising skin around nail

Nail groove - separates nail fold from nail plate

Nail bed - skin under naiN

65
Q

Sweat glands

A

Apocrine sweat glands - groin/anal region, areola, beard area in men - near hair follicles. milky sweat + pheromones.

Merocrine sweat glands- most numerous, dese on palms, soles + forehead. Simple tubular glands + watery perspiration

66
Q

Sweat

A

Protein free filtrate of blood plasma - 99% water with a ph of 4-6

500ml/day

67
Q

Mammary glands

A

Produce milk - develop during pregnancy and lactation
MODIFIED APOCRINE SWEAT GLANSD - Rich secretion

68
Q

Skin cancer

A

§ Basal cell carcinoma
□ Most common type and least dangerous - seldom metatasizes
□ Forms from cells in stratum basale
□ lesion is small shiny bump with central depression and beaded edges
§ squamous cell carcinoma
□ Arises from keratinocytes of stratum spinosum. Lesions usally on scalp, ears, lower lip or back of hand.
□ raised reddened scaly appearance later formed a concave ulcer
□ cahnce of recovery good with early detection and surgical removal
□ tends to metastasize to lymph nodes - may become lethal
§ malignant melanoma
□ Cancer arises from melanocytes <5% of skin cancers - most deadly form.
□ Can be successfully removed if caught early, but if metastasizes it is usually fatal
□ Greatest risk factor - familial history
Highest incidence in men, redheads and people who had severe sunburn as a child

69
Q

Burns

A

Leading cause of accidental death

First degree burns
□ Only involve epidermis
□ Redness, slight edema and pain
□ heal in days

Second degree burns
□ Partial thickness burn - involves part of dermis
□ May appear red, tan or white - blistered and painful
□ two weeks to several months to heal and may leave scars

Third degree burn
□ Full thickness burn - involves epidermis, all of dermis and often some deeper tissue.
□ Often requires skin grafts
needs fluid replacement, infection control, supplemental nutrition

70
Q

stages of healign a skin wound

A

§ Several vessels bleed into cut
§ mast cells and damaged cells release histamine
§ histamine dialates blood vessels and makes capillaries more permeable
§ blood plasma seeps into wound carrying antibodies and clotting proteins
§ Blood clot forms↔Knits edges of cut together. Inhibits spread of pathogens
§ Forms scab that temporarily seals wound and blocks infection
§ Macrophages phagocytise and digest tissue debris
§ New capillaries sprout from nearby vessels.
§ Deeper portion of cloinfiltrated by capilaries and friblasts
§ Transforms into soft mass called granulation tissue
§ macrophages remove blood cot
§ fibroblasts deposit new collagen
§ begins 3-4 days after injury and lasts up to two weeks
§ Epithelial cells multiply and migrate beneath scab - tissue regenerates
§ underlying connective tissue undergoes fibrosis
§ Scar tissue may or may not show through epithelium
Remodeling phase begins several weeks after injury and may last up to 2 years

71
Q

Blood

A

Connective tissue.
Plasma - liquid in blood
cells - forms elements of the blood

72
Q

Function of the blood.

A

§ Transportation↔Dissolved gases, nutrients, hormones and metabolic wastes
§ Regulation of pH and ion composition of interstial fluids
§ Restriction of fluid loss at injury sites - clotting
§ defence against toxins and pathogens
stabilisation of body temperature

73
Q

Haeme - recycling of red blood cells

A

○ Macrophages of liver, spleen and bone marrow monitor quality and engulf old RBC’s
○ Each component of haemoglobin molecule is recycled
○ Globular proteins dissembled into amino acids and released for other cells to use
○ Heme units are stripped of ion and turned into biliverdin (green in bruises)
○ Biliverdin is turned into bilirubin (orange/yellow in jaundice) and transported to liver- excreted as bile

74
Q

blood antigens

A

○ Type A↔Surface antigen A only
○ Type B↔Surface antigen B only
○ Typpe AB↔Surface antigen A and B
Type O↔Neither surface antigen or AB

75
Q

Blood antibodies

A

○ Type A↔Anti-B antibodies in plasma
○ Type B↔Anti-A antibodies in plasma
○ Type AB↔Neither Anti-A/B antibodies in plasma
Type O↔Both Anti-A/B antibodies in plasma

76
Q

Haemolytic disease of the newborn

A

arise when Rh-neg. woman is carrying Rh-pos. fetus. When fetal and maternal blood mix at delivery - antepartum haemorrhage, amniocentesis - the mother recognises fetus Rh antigens as being foreign
○ Mixing of blood can stimulate mothers immune system to produce anti Rh antibodies - sensitisation
○ if mother has another rh pos. fetus her anti Rh antibodies cross placenta and attack fetus RBCS

77
Q

The THorax

A

○ RIB CAGE
○ Wall comprises↔12 Thoracic vertebrae (posteriorly), sternum (anteriorly) and rubs (Anterolaterally)
○ Inlet - root of neck‒ and outlet - diaphram.
○ Encloses heart and lungs - some protection for spleen , liver and kidney.
Provides atachement for pectoral girdle and upper limbs. Able to contract and expand during respiration

78
Q

Sternum

A

○ Bony plate anteriro to the heart - palpable (subcutaneous) in parts.
○ Three parts
§ manubrim
§ body - gladiolus
§ xiphoid process
Other features↔jugular notch and manubriosternal junction/joint - sternal angle

79
Q

The Ribs

A

○ 12 pairs
○ articulate posteriorly with bodies and transverse processes of vertebrae
○ articulate anteriorly with their costal cartilages
○ costal cartialges - hyaline cartilage - to attach rib to sternum.
○ Costochondral joints classified as priamry cartilaginous joints

80
Q

Ribs anatomy

A

○ Head↔portion of rib that articulates w/ bodies of thoracic vertebrae. - superior and inferior articular facets
○ Neck↔narrow portion distal to the head
○ tubercle↔wider, rough area distal to the neck. - articulates with transverse costal facet of vertebra
○ Angle↔lateral curve of rib
○ Shaft↔long sloping blade like portion of rib. - costal groove on inferior margin of shaft
True ribs↔Ribs 1-7. Each articulate with sternum via costal cartilage
False ribs↔ribs 8-12. Connects to costal cartilage of above ribs. forms costal margin.
Floating ribs↔ribs 11-12. No cartilaginous connection to sternum. No connections to costal cartilages above. No tubercles. No attachments to transverse processes of vertebra

81
Q

Chest cavity + contents

A

○ Contains
§ Right and left lungs and pleural cavities
§ heart and great vessels - centrally, in mediastinum
§ trachea, oesophagus, nerves
Mediastinal boundaries
○ Anteriorly↔sternum
○ posteriorly↔vertebral column
○ inferiorly↔diaphragm
superiorly↔thoracic inlet

82
Q

Mediastinal subdivisions

A

○ T4 plane
§ Arching aorta
§ tracheal bifurcation
§ azygos vein enters SVC
§ thoracic duct crosses vertebral column
○ Inferior mediastinum
§ Further subdivided by fibrous pericardium into
□ Anterior mediastinum
□ Middle mediastinum
□ Posterior mediastinum
□ Pericardium
□ heart
roots of great vessels

83
Q

Pulmonary circuits

A

○ Major divisions of circulatory system
○ Pulmonary circuit↔right side of heart - carries blood to lungs for gas exchange and back to heart
§ Oxygen poor blood arrives at inferior and superior venae cavae
§ Blood sent to longs via pulmonary trunk
○ Systemic circuit↔Left side of heart - supplies oxygenated blood to all tissues of body and returns it to heart
§ Fully oxygenated blood arrives from lungs via pulmonary veins
§ Blood sent to all organs of the body via aorta

84
Q

Histology (anatomy) of blood vessles

A

§ Tunica intima - innermost
§ tunica media - middle
tunica adventitia - outer

85
Q

Anatomy of the heart

A

○ Hollow four chambered fibromuscular pump
○ Right and left atria and right and left ventricles
Base, apex, surfaces and borders

□ Outer fibrous pericardium↔Outer collagenous, inelastic sac. Fused to central tendon of diaphragm and adventitia of great vessels. Attached by ‘ligaments’ to sternum - variable. Securely anchored heart within thorax
□ Parietal serous Pericardium↔Lines the fibrous pericardium and reflects on to surface of the heart
□ Visceral serous pericardium

86
Q

Chambers of the heart

A

○ Right and left atria↔superior in position. receive blood returning to heart. Auricles (seen on surface) - extensions of chamber
Right and left ventricles↔inferior in position. Pump blood into aorta and pulmonary trunk

87
Q

Atriums

A

○ Openings for veins - venae cavae, pulmonary veins
○ Reveive venous blood from systemic and pulmonary circulations
○ Blood reservoir - weak pump

Right atrium
§ Musculi pectinati.
§ Crista terminalis - suculus terminalis
§ Limbus fossa ovalis + Fossa ovalis
§ cusps of tricuspid valve
§ Openings for↔Superior/inferior vena cavae and Coronary sinus
○ Left atrium
§ Openins of 4 pulmonary veins.
§ Cusps of bicuspid valve.
Roughened auricle

88
Q

Ventricles

A

○ Thick muscular chambers - cardiac muscle
○ receive blodo from atria via AV openings.
○ Pump blood into systemic and pulmonary circulation
○ Features
§ Trabeculae carneae
§ valve cusps
§ chordae tendinae
§ papillary muscles
aortic/pulmonary opening

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Q
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90
Q

Atrioventricular valves

A

○ Collagenous tissue lined with endothelium. Control blood flow from atria to ventricles
○ Right AV has three cusps - tricuspid valve
○ Left AV has two cusps - mitral or bicuspid valve
Chordae tendinae - attach to valves. Prevents AV valves from flipping back into atria when ventricles contract. Each papilalry muscle has 2-3 attachments to heart wall - distribute physical stress, coordinate timing of electrical conduction and provide redundancy

91
Q

Semilunar valves

A

○ Conenctive tissue lined with endothelium. Control flow into aorta and pulmonary trunk
○ Pulmonary semilunar valve↔between right ventricle and pulmonary trunk
aortic semilunar valve↔between left ventricle and aorta

92
Q

Blood flow through the chambers

A

○ In a typical cycle↔followign ventricular contraction, ventricles relax. Pressure inside ventricles drop. Semilunar valves close as blood flows back into ventricles from great vessels. AV valves open - blood flows from atria into ventricles
○ Ventricles contract↔AV valves close as blood attempts to back up into atria. Pressure rises inside of ventricles. Semilunar valves open and blood flows into great vessels
○ Opening and closing of all heart valves - passive.
○ Close when backward pressure gradient pushes blood back
○ open when forward pressure gradient pushes blood forwards
○ I.E. Opening and closing due to pressure differences between chambers.
○ Flimsy AV valves dont require to much pressure to close. Semilunar valves have fibrous nodles in centre - stronger back pressure for short duration

93
Q

Structure of cardiac muscle

A

○ Cardiomyocytes↔short, thick branched cells
○ striations of actin and myosin - as in skeletal muscle
○ Central nucleus surrounded by light staining mass of glycogen
○ intercalated discs - join cardiomyocytes end to end

94
Q

The conduction system of the heart

A

○ Specialised muscle cells that control and coordinate heart beat
○ cardiac muscle contracts on its own - auto-rhythmicity (without stimulation)
○ Maximum heart rate is 230bpm - maximum rate that AV node can conduct impulses.
§ Comprises an internal pacemaker and nerve like conduction pathways through myocardium

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Q
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96
Q
A

Paramedicine y1 (4 decks)

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