Theme 1 : Anatomy Flashcards
atm : Thoracic cage
What is the Thoracic cage made up of?
Vertebrae and Intervertebral disc on posterior
Ribs 12 pairs round the lateral side
Sternum
Costal Cartilages for movement
What is the function of the Thoracic cage?
Protection of viscera (internal organs) and for Muscle attachment
The thoracic cage is in relation to…
Pectoral Girdle
What is the pectoral girdle made up of?
The bony structure to which the upper limb structures are attached to. They consist of the clavicle (collar bone) and the scapula (shoulder blades)
Which ribs are typical?
3-9
Which ribs are atypical?
1,2, 10-12
What does a typical rib consist of?
Head with 2 facets, Neck, Tubercle and a body shaft with a costal (subcostal) grove
Give the characteristics of a typical vertebrae
Lateral side: Heart shaped body with demi facets
On Transverse process = costal facets
On Spinous process = Inferior pointing
Intervertebral
between vertebrae
Costovertebral
Head of rib articulates with costal (demifacet) on two adjacent vertebrae and the associated intervertebral disc.
Costotransverse
Tubercle of rib articulates (forms a joint) with the transverse process of vertebrae
What is special about ribs 1st, 10, 11th and 12th
They only articulate with one vertebrae
Sternoclavicular
articulates between the clavicle (collarbone) and the sternum
Sternocostal
articulates the sternum with the costal cartilages
Interchondral
Joints between the tips of adjacent costal cartilages of ribs 6-10 (False ribs)
Costochondral
joints between costal cartilage and rib
Origin/Proximal attachment of the Pectoralis major
Clavicle, costal cartilages and sternum
Function of the Pectoralis major
Adducts on shoulder and medially rotates humerus
Innervation
Supplying nerves to an organ/part of the body
Innervation of the Pectoralis major
Lateral and Medial Pectoral nerves
Origin or Proximal attachment of the Pectoralis Minor
3-5th rib superiorly upwards
Insertion or Distal attachment of the Pectoralis Minor
coracoid process of scapula
What is the coracoid process of scapula?
bone structure that projects anteriorly and laterally from the scapular neck
Function of the pectoralis minor
Stabilises scapula
Innervation of the pectoralis minor
Medial pectoral nerve
What are the Three Layers of intercostal Muscles?
External Intercostals
Internal Intercostals
Innermost Intercostals
Origin or Proximal attachment of the Serratus anterior
1-8th/9th rib
Insertion or Distal attachment of the Serratus anterior
medial border of scapula
Function of the Serratus anterior
Protracts (extend) scapula
Innervation of the Serratus anterior
Long Thoracic Nerve
Blood supply to the thoracic wall derived from thoracic aorta to…
Posterior Intercostal arteries
Blood supply to the thoracic wall derived from the Subclavian artery to…
Anterior Intercostal arteries
Which ribs are true
1 to 7
Which ribs are false
8 to 10
Which ribs are floating
11 and 12
Superficial
towards the surface
Deep
towards the inside
Medial
towards the midline of the body
Lateral
towards the outer edge
Posterior/Anterior
front/back
Dorsal/Ventral
On all fours: back/belly surface
Inferior/Superior
lower/higher
Caudal
towards the tail end
Cranial
towards the head end
Proximal/Distal
close to the body / away from the body
Flexion
decreasing the angle of a joint
Extension
increasing the angle of a joint
Abduction
take arm away
Adduction
bring it back arm
Pronation/Supination
Upper limb only: palms facing back/palms facing upwards
Elevation / Depression
lift shoulders / bring down
Circumduction
circle arm
The inferior tip of the sternum is…
xiphoid process
Superior part of the sternum is…
manubrium
What are the different types of muscles, briefly explain them. Where they are
Smooth- in the gut and viscera
Skeletal- gross muscles, locomotor (musculoskeletal system)
Cardiac- heart beating
What are the functions of skeletal muscles?
Locomotion (moving organs/structures and voluntary movement)
And Posture
What allows skeletal muscles to perform these functions?
Contractile proteins (myofilaments) arranged as myofibrils in muscle fibres
Describe the microstructure of skeletal muscle (4 things)
Elongated, multinucleated cells
Peripheral nuclei
Grouped into bundles called fascicles
Surrounded by connective tissue
Explore the different connective tissues in the microstructure of skeletal muscle
Epimysium surround muscle
Perimysium surround a bundle of muscle fibres (fascicle)
Endomysium separate single muscle fibres from another
State the organisation of skeletal muscle (from largest to smallest)
Muscle -> Muscle fascicles -> Muscle fibres -> Myofibril -> Microfilaments
Describe what the basement membrane is made of
continuous with endomysium
What is sarcolemma to the muscle fibre?
the muscle fibre’s cell membrane
What is Sarcoplasm?
the fiber’s cytoplasm
What makes up myofibril?
Sacromeres
What are satellite cells, what do they do?
Myogenic cells that allow skeletal muscle to regenerate
What are the main types of myofilaments?
Actin (Thin)
Myosin (Thick)
What is the smallest functional unit of a skeletal muscle fibre?
sarcomere
Where are these myofilaments anchored at?
Myosin anchored at M
Actin anchored at Z
Complete the sentence:
Contraction occurs as …
the Myosin moves along the Actin
Where does shortening of skeletal muscle occur?
Between origin and insertion
What is the end result of skeletal muscle contraction?
shortening of a sarcomere
What are the FOUR parameters are used to describe skeletal muscles?
Origin
Insertion
Action
Innervation or nerve supply
What is the action of pectoralis major?
Flexion, adduction and Internal rotation of the shoulder joint
What is the action of pectoralis minor?
Protraction of the scapula
Elevates the ribs
What is the nerve supply of Biceps Brachii?
Musculocutaneous nerve
What is the action of Biceps Brachii?
Flexion of the shoulder joint
Flexion of the elbow joint
Supination of the radio-ulnar joints
What is the insertion of Biceps Brachii?
Radius
What is the origin of the long head of Biceps Brachii?
head (lateral) : Supraglenoid tubercle of the scapula
= Glenoid fossa
What is the origin of the short head of Biceps Brachii?
(medial) : Corocoid process of the scapula
What is the nerve supply of deltoid?
Axillary nerve
What is the action of deltoid?
Abduction of the shoulder joint
What is the insertion of deltoid?
Deltoid tuberosity (tubercle) of the humerus
What is the origin of deltoid?
Clavicle, acromion process and spine of the scapula
Acromion process
the top outer edge of your scapula (shoulder blade)
Spine of the scapula
a prominent ridge of bone on the posterior surface of the scapula
What is the action of Serratus anterior?
Protraction of the scapula
Holds scapula flat against the thoracic cage
Flat
parellel fibres within an apernosis
Pennate
feather like may be unipennate, bipennate or mutilpennate
Fusiform
spindle shaped with round bellie and tappered at tendons
Quadrate
four sides
What are the different types of muscle fibre arrangement?
Flat
Pennate
Fusiform
Quadrate
Circular
Multi-headed/bellied
Give an example of a muscle with circular muscle fibres
Orbicularis Oculi
Give 2 examples of a muscle with pennate muscle fibres
Deltoid and felxor digitorum
Give an example of a muscle with multi headed muscle fibres
Biceps Brachii
Give an example of a muscle with flat muscle fibres
External Oblique
Give an example of a muscle with quadrate muscle fibres
pronator quadratus
Describe how the contraction of muscles is stimulated by motor nerves
Nerve impulses travel through the motor endplate and the neuromuscular junction with the help of acetylcholine release to enter the muscle fibres
What happens when the nerve impulses enter the muscle fibres?
Nerve impulse will attach to the sarcolemma and enter into the t-tubules that go down into the depth of the muscle for simultaneous contraction
Where is calcium stored and released from?
The sarcoplasmic reticulum
What is the role of calcium in the sliding filament theory?
calcium ions bind to the troponin, which alters the shape pulling the tropomyosin aside which exposing the myosin-binding sites
Where are satellite cells located?
Between the sarcolemma and basement membrane of muscle fibers
Describe the actions of satellite cells (2 points)
Normally dormant in adult muscle, but act as a reserve population of cells - Give rise to regenerated muscle and to more satellite cells
Able to proliferate and then fuse with existing muscle fibers to lay down new proteins and hypertrophy (increase in cell size)
in response to injury
What is the Jugular notch?
at the center of the superior border of the manubrium of sternum
What is the Lower costal margin?
an arch formed by the medial margin of the seventh rib to the tenth rib
What is the name of the connective tissue that all muscles of the body are surrounded by?
Fascia
Where do the breasts lie?
lie within the superficial fascia of the anterior chest wall between ribs 2 to 6
Where and how are breasts formed?
formed in the embryo by an ingrowth of ectodermal cells
Describe the breasts (externally)
circular profile with a prolongation, the axillary tail, which extends up into the axilla
Where does the nipple lie?
On the pigmented areola
What happens to the breast during puberty?
under the influence of oestrogen, there is the deposition of fat (stored in white adipose cells) in the connective tissue of the breast
Also growth in length and branching of the duct system
The breast mainly consists of fatty fibrous tissue, where is fat found?
In the connective tissue, covers the superficial surface of the gland, beneath the skin, and gives the smooth contour of the breasts
What happens to the breasts after menopause?
decrease in fat and atrophy of glandular tissue
Describe the anatomy of the breasts internally (before the menopause)
subdivided into about 20 lobes with lobules by fibrous connective tissue which contains deposits of fat
What does the fibrous connective tissue help the breasts with?
attach the breast to pectoralis major
Explain the system in the breasts
The duct system of each lobe drains through a single lactiferous duct to the nipple
Up to about 20 lactiferous ducts open separately through each nipple
Where does the breast get it’s blood supply?
Mainly from branches of the internal thoracic artery, also supplied by branches from the lateral thoracic artery and thoraco-acromial artery
What usually accompanies the distribution of the arteries in the breast?
Lymphatic vessels that drain the breast
Describe the breasts in males
Rudimentary (underdeveloped) and are formed of small ducts without lobules
What are the 2 portions of the skeletal system?
Axial and appendicular
What are the functions of the skeletal system?
Protection of organs
Supports the body
Movement
Metabolic reservoir
Production of new red blood cells
What is the skeletal system comprised of?
bone and cartilage
What are the 3 layers of the embryonic disc
ectoderm, mesoderm , endoderm
When does Bone Development (ossification) occur?
week 8 and finishes ~ 20 years
Intramembranous Ossification
The direct conversion of mesenchymal tissue into bone
Endochondral Ossification
start with a cartilaginous template (Hyaline cartilage) made from the mesenchyme is replaced by bone
Epiphyseal cartilage (type of hyaline cartilage) = allows bone to continue to grown
Bone is comprised of 4 cell types:
Osteoprogenitor cells
Osteoblasts (laying down new material)
Osteocytes (trapped within bone, maintenance of bone)
Osteoclasts = bone resorption
Bone maintenance is regulated by a dietary intake of:
Calcium
Phosphorous
Vitamins, A, C and D
What do the vitamins do to bones?
Vitamin A is essential for bone remodelling
Vitamin C is essential for connective tissue
Vitamin D is essential for calcium absorption
Bones Can be classified by their shape, embryology or region as either (5):
Long bones
Flat bones
Irregular bones
Short bones
Sesamoid bones
How many bones at birth, how many bones in adulthood?
270 Bones at birth, 206 by adulthood
What connective tissue covers the skeletal system except where articulation occurs
Periosteum
What connective tissue surrounds the cartilage
perichondrium
What is the Spongy Bone also known as?
Cancellous bone
Trabecular bone
Describe the spongy bone (3)
Irregular bony plates called trabeculae
Surrounded by red marrow
Highly vascularised
Describe the anatomy of compact bone (4)
Lamellae (concentric layers) are laid down by osteoblasts
Osteoblasts eventually become trapped in the osteoid matrix and turn into osteocytes occupying their own lacunae
Canaliculi radiate from each lacunae in which nutrients travel to the osteocytes
The haversian canal contains the neurovascular supply
what are the 3 types of joints?
Synovial, fibrous, cartilaginous
What are Synovial joints and what do they allow?
a joint capsule and a synovial cavity, they permit movement.
what are Fibrous joints connected and what does it cause?
connected by collagen and do not permit movement
What are connect Cartilaginous joints and what does it enable?
are connected by cartilage to allow some movement
Why can bone heal well?
They are vascularised tissue
What are stratified epithelium?
Cells pile on top of each other
What kind of mucous membrane is the oesophagus lined with?
White mucosa
What are squamous epithelium?
cells are flat
Where are stratified epithelium cells necessary at and why?
At sites of friction with the risk of mechanical damage
Where can squamous epithelium be found in?
Internal organs
How do squamous epithelium appear under naked eye examination?
White
Where is keratin present and what produces them?
In skin cells, by keratinocytes
What does keratin do to the skin?
Makes the skin impervious (not allowing fluid to pass through)
What connects muscle to bone?
Skeletal muscle in continuity with the tendon
What do fibroblasts produce?
Produce the protein collagen
What do fibrous tissue consist of?
long fibres containing collagen
Why is fibrous tissue important?
To form scars in healing wounds - able to do this due to its strength
What does the microscopy of fat look like after processing it in different chemicals?
Fat leaches out to leave behind the honeycomb shaped cells called adipocytes
What is the end-product of the break down of the muscle?
Brown pigment called lipofuschin
Why are intercalated discs important?
For the contractile function of the heart
Where are cells of the cardiac muscle joined together at?
Irregular junctions called intercalated discs
What is cardiac muscle also called?
Myocardium
What is the myometrium is made up of?
smooth muscle fibres ; no striations
Why are striations important in skeletal muscle?
The contractile function of the muscle cells
Where are cuboidal cells found in?
Glands which secrete specialised fluids e.g. salivary glands
Why are they called Pseudostratified Ciliated Columnar Epithelium?
all nuclei do not reach the surface
What are the larynx, trachea and bronchi lined with?
Pseudo-stratified columnar epithelium
Columnar epithelium of the large intestine consists of test tube like structures termed…
crypts (deep pit that protrudes down into the connective tissue surrounding the small intestine)
What kind of epithelium is the large intestine lined with?
Columnar epithelium
What is the function of mucus?
Protects the mucosa/lining
Traps dust particle
Acts as lubricant
What is the action of columnar epithelium?
Secretes mucus
What do columnar epithelium appear like in organs on naked eye examination?
pink/red
Name at least three of the organs squamous epithelium lines
Skin
Mouth and tongue
Oesophagus
Anal canal
Vagina
Cervix
What makes the skin protected by UV light?
Keratinised stratified squamous epithelium
What kind of stratified squamous epithelium is the oesophagus lined with?
Non-keratinised
What kind of mucous membrane is the stomach lined with?
Pink mucosa
What kind of mucous membrane is the oesophagus lined with?
White mucosa
The oesophagus joins the stomach at what junction?
Oesophago-gastric junction (OGJ)
What makes skin waterproof?
Superficial part of the skin consists of dead keratinised cells
What are the Systemic consequences of injury and inflammation?
Fever, leucocytosis, acute phase proteins
What are the local consequences of injury and inflammation?
A mass of dead (necrotic) tissue
Remnants of inflammatory cells
Remnants of initial stimulus
What options are available to sort out the consequences of injury and inflammation?
Resolution (scavenging) of the inflammatory response
Regeneration
Repair (or incomplete regeneration) by connective tissue deposition (fibrosis) resulting in a fibrotic scar
Describe the process of Resolution (scavenging) of the inflammatory response
Resolution occurs always and is sometimes enough to clear the area of inflammation/damage
Complete restoration of the tissue to its normal state is called ‘restitutio ad integrum’
Achieved by macrophages
Describe how macrophages are formed and what do they act as/do?
Circulating blood monocytes migrate into tissues as macrophages / histiocytes
Some monocytes go to specialised capillary areas in the liver, bone marrow and spleen called sinusoids
Here, the macrophages act as a filter tissue to remove abnormal molecules or cells (e.g. old red blood cells)
Macrophages clear offending stimuli, dead tissue and produce growth factors for the proliferation of various cells in the healing response
Where can I find macrophages?
Mostly at sites of inflammation (acute or chronic)
All normal tissues contain macrophages / histiocytes
List and explain the 5 activities of macrophages
Chemotaxis
=Migration towards damaged tissues
Hypertrophy
=Histiocytes become larger and accumulate more cell organelles and enzymes
Pseudopodia
=Active movement
Pinocytosis
=Ingest fluid from their surroundings
Phagocytosis
=Ingest larger particles, molecules or cells
What do activated macrophages/histiocytes develop?
receptors for abnormal molecules or abnormal cells (foreign or own)
What happens if resolution and scavenging does not heal injury?
healing by
option B. regeneration or by
option C. repair becomes necessary
Describe regeneration, which tissues can do this?
Regeneration of surface epithelium
May result in restitutio ad integrum
Cannot regenerate complex structures like hands
Using adult stem cells
Labile tissues e.g. skin, mucosa of GI tract
Stable tissues e.g. liver, kidney, endothelium
Describe repair, where can it occur?
Does NOT result in restitutio ad integrum but in scarring
Permanent tissues e.g. heart
What determines the mechanism of healing in regeneration
The type of tissue (and the type and extent of injury)
What is regeneration dependent on?
on limited damage and the preserved integrity of the extracellular matrix (scaffolding) or basement membrane.
Otherwise, regeneration is usually impossible and healing by repair (scarring) occurs.
Where can I find adult stem cells?
Stem cell pools in tissues (e.g. crypts of the colonic epithelium, bone marrow, hair follicles, epidermis)
What kind of capacity and replication does adult stem cells have?
Prolonged self renewal capacity and asymmetric replication
What can bone marrow stem cells transdifferentiate into?
neurons, liver cells and others
What is the condition that allows Liver tissue to regenerate from stem cells ?
if the stromal reticulin scaffolding remains intact
How can Epithelial tissues replenish themselves ?
by increasing in stem cell divisions and shortening of cell cycle time
.
.
Why does healing by repair result in scarring?
A response by fibroblasts to patch the damage with fibrosis thus forming a fibrotic scar
Describe the basic sequence of repair of tissues
Haemostasis and blood clotting
Inflammation
Formation of granulation tissue (angiogenesis + fibroblast prolif.)
Formation of connective tissue/scar
Remodeling of the scar
Final scar
What is angiogenesis?
the development of new blood vessels
What are the processes of angiogenesis? (6)
Vasodilatation (acute inflammatory response, histamine, NO)
Degradation of the BM of adjacent local blood vessels - sprout
Migration of endothelial cells and recruitment of endothelial precursor cells from the bone marrow
Proliferation of endothelial cells
Maturation of endothelial cells into tubes
Development of blood vessel walls
Describe the formation of granulation tissue
Angiogenesis + proliferation of fibroblasts (via TGF-beta)
Resulting in granulation tissue formation composed of new blood vessels, fibroblasts and remaining inflammatory cells (usually neutrophils)
New vessels are leaky contributing to oedema/swelling/tumour
Why does granulation tissue need collagen?
To give it strength before the formation of granulation tissue
list systemic impairments of healing
Age
Anaemia
Infection / sepsis
Drugs (steroids, cytotoxics, antibiotics)
Soft tissue genetic disorders (Ehler’s Danlos, Marfan’s, …)
Diabetes mellitus (many blood cells shrink owing to altered osmotic pressure)
Malignancy
Malnutrition
Obesity
Vit C deficiency
Trace mineral deficiencies
Trauma and shock
Uraemia
What local factors impair healing?
Local infection
Foreign body
Haematoma - a collection of blood which is located outside the blood vessels. They can be found under the skin within a soft tissue and display as a purple coloured bruise.
Denervation - a procedure that aims to permanently stop a nerve transmitting pain.
Poor blood supply or perfusion (the passage of fluid through the lymphatic system or blood vessels to an organ or a tissue.)
Mechanical stress or iatrogenic (relating to illness caused by medical examination or treatment) stress
Necrotic tissue
Site (lip vs foot)
What problemscan cause impede healing?
Local and systemic factors may impede healing
.
.
Describe the process of scar remodeling
Interactions of collagen deposition and degradation by matrix metalloproteinases (MMPs)
Collagen changes to type I collagen
The blood vessels disappear
Contraction of the scar tissue
What do fibroblasts produce during scar formation? What is it controlled by?
ECM proteins (e.g. collagen, elastin)
Mainly controlled by transforming growth factor beta (TGF-beta)
What does growth factors from macrophages induce?
migration and proliferation of fibroblasts into the granulation tissue
Mainly controlled by fibroblast growth factors (FGFs)
Granulation tissue is…
weak and oedematous (relating to or affected with edema : abnormally swollen with fluid)
What are the complications of wound healing? (4)
defiecient, excessive
Deficient scar formation leading to dehiscence or ulceration
Excessive scar formation (e.g. keloid)
Abdominal adhesions (e.g. Crohn’s disease, appendicitis)
Contractures (often in burns)
Describe the cardiovascular system and its circulations
Some arteries carry deoxygenated blood
Arteries carry blood away from the heart
Veins carry blood towards the heart
pulmonary circulation (heart and lungs)
systemic circulation (heart and body)
List the major chambers of the heart
Right atrium to right ventricle – pulmonary circulation
Left ventricle to left atrium – systemic circulation
Describe the Heart Wall’s Microstructure
- Epicardium (visceral pericardium) - outside
- Myocardium - cardiac muscle – m for middle
- Endocardium - lines the chambers – endoskeleton (inside)
Describe the structure of cardiac muscle
Striated appearance – formed by sarcomeres
Intercalated discs
Normally 1 nucleus per cell - humans
Branching pattern
What are the 2 intercalated discs found in the myocardium?
Fascia adherins and desmosomes – anchor cells together
Gap junctions – cardiac action potentials
Describe the function of cardiac muscle
Involuntary control
Beat in unison by ID
Coordinated movement
Spread of excitation
Describe the structure of smooth muscle
Not striated
One central nucleus per cell
Found in walls of tubular structures and hollow viscera
Describe the function of smooth muscle
Involuntary control
Regulates the diameter of blood vessels
Propels liquids and solids – responsible for peristalsis
Expels contents
List the major lobes of the lungs
Left:
2 lobes
Oblique (diagonal/slanting) fissure – between lobes
Right:
3 lobes
horizontal and oblique fissures
Left smaller than right
Describe the respiratory tree
Trachea
Main bronchi
Secondary (lobar) bronchi – into different lobes
Tertiary (segmental) bronchi
Bronchioles
Alveoli
Distinguish what are branches and tributaries
arteries createbranchesand veins are created fromtributaries
e.g. (branch different to tributary - tributes into the thoracic cage instead of branching out of veins)
Is the right subclavian vein a branch or tributary and to what?
The right subclavian VEIN is a TRIBUTARY of the brachiocephalic vein
Is the left subclavian artery a branch or tributary and to what?
The left subclavian ARTERY is a BRANCH of the aorta
What is the micro structure of blood vessels?
Tunica intima
Tunica media
Tunica adventitia (externa)
Describe the structure and function of Tunica intima
Lined by endothelium – monolayer of squamous epithelial cells that covers entire vascular system
Connective tissue
Reduces friction for blood flow
Describe the structure and function of Tunica media
Primarily smooth muscle
Connective tissue- elastic and collagen fibres
Controls size and shape of artery
Describe the structure and function of Tunica externa (adventitia)
Outer connective tissue layer- primarily collagenous
Can contain nerves and vessels (nevi vasorum – nerves of the vessels and vasa vasorum – vessels of the vessels)
Connects artery to surrounding structures
What are large elastic arteries?
conducting = Those nearest the heart (aorta and pulmonary arteries)
What is the main feature of large elastic arteries?
contain much more elastic tissue (elastin) in the tunica media than muscular arteries
What is the size of a large elastic artery?
Large diameter (>10mm)
What is the function of a large elastic artery?
- accommodates surges (powerful forward or upward movement) in blood
Give examples of large elastic arteries
the aorta, subclavian, and common carotid arteries
What are Medium Muscular Arteries?
Distributing arteries - other arteries (smaller) that are not large elastic arteries
What is the size of medium muscular arteries?
Smaller diameter (0.5mm-10mm)
What is the main feature of medium muscular arteries?
Tunica media contains a thick layer of smooth muscle (lots)
What is the function of the medium muscular artery?
Vasoconstriction and vasodilation send the blood where it needs to go in the body
What are the examples of medium muscular arteries?
femoral and popliteal arteries
What are the sizes of Small Arteries and Arterioles?
small arteries: (0.3mm-0.5mm) arterioles: microscopic - ≤0.3 mm
What is the main feature of small arteries and arterioles?
Tunica media predominantly smooth muscle, 1-2 cell layers in thickness
What is the function of small arteries and arterioles?
Tonus (the constant low-level activity of a body tissue) dictates degree of filling of capillary beds
What is the size of Capillaries?
Microscopic (5-10µm)
What is the main feature of capillaries?
Endothelial layer only (no tunica media or externa)
What is the function of capillaries?
Allow exchange between blood and extracellular fluid
What are the 2 types of capillaries?
Continuous- uninterrupted endothelium = most common
Fenestrated- pores (fenestrae) – high amount of exchange
e.g., endocrine glands, the intestines, pancreas and kidney
What is the size of the venules?
Microscopic (8-100µm)
What is the main feature of venules?
Very thin tunica externa and media
What is the function of venules?
Drain capillary beds
What is the size of a vein?
1mm -> 10mm
What is the main feature of veins?
Tunica media thinner and large veins have well developed tunica adventitia/ externa
Give 3 examples of veins
femoral, popliteal and great saphenous veins
What are Venous Valves?
Inward projection of intima, strengthened by collagen and elastic fibres
Semi lunar cusps attached to the venous wall
Where can’t you find venous valves?
Absent in thorax and abdomen
What can the dilation of veins lead to?
Dilation of veins can mean valves don’t close, resulting in varicose veins (swollen and enlarged veins)
Superficial veins do not have corresponding…
arteries e.g., great saphenous vein.
Arteries and veins work together to…
Turn blood against gravity
Give me an example of when arteries and veins are incorporated together
Smaller arteries in the middle to propel venal blood flanked by 2 veins enclosed in a sheath e.g., brachial artery and brachial veins
What are the 2 veins found flanked with smaller arteries called?
Venae comitantes
Why are arteries in the middle of brachial and arteries and veins?
The external forces support the venous blood vessels from the arteries andthe muscles contractingto help propel the blood against gravity.
What factors aid the return of blood against gravity?
Valves
Arteriovenous pump
Respiratory pump
Musculovenous pump
What is Deep Vein Thrombosis?
a blood clot that develops within a deep vein in the body
What causes deep vein thrombosis?
Long periods of inactivity are one cause of venous stasis (slow blood flow in the veins)
.Where arteries are surrounded by multiple veins this can act as…
a counter-current mechanism to heat regulation
What is the connections of vessels?
Anastomoses
What can anastomosis do?
Uniting of arteries or veins
Creates un-interrupted circulation
Can provide collateral circulation
What can you find at the end of arteries? And give examples for each
Anatomic (true) end artery - no anastomoses. E.g., the Central artery of retina
Functional (potential) end artery - ineffectual anastomoses. E.g, Coronary arteries of the heart
What is occlusion?
the blockage or closing of an opening, blood vessel, or hollow organ due to necrosis
what can occlusion cause?2 places with 2 concequences
Central artery of retina
Occlusion = blindness
E.g., Coronary arteries of the heart
Occlusion can cause myocardial infarction (heart attack)
Describe the Venous (Hepatic) Portal System
Venous blood high in products of digestion
Veins from the spleen, stomach and intestines drain into the liver via the hepatic portal vein
Filtered by the liver, blood then drains into the hepatic veins and into Inferior Vena Cava to be returned to the heart
Where can I find Eccrine sweat glands?
occur over most of the body and open directly onto the skin’s surface
.
.
What are the 3 ways tissue can grow?
maa
Multiplicative:
Increase in cell number by mitotic division
Auxetic:
Increase in cell size
Accretionary:
Increase in extracellular tissue
Explain what growth is? (formula)
Increase in cell number – Decrease (cell death)
What does cell turnover permit?
maintenance of continuously growing tissues (e.g. skin, intestinal mucosa) and healing (injury, disease)
What happens our proliferative ability as we grow older?
Fetal development shows rapid growth and constant programmed cell death (apoptosis)
In adults, many tissues loose proliferative ability (permanent cells)
Describe the ability of a labile cell to proliferate and give examples of labile cells
continuous proliferation
high cell turnover
short lifespan
epithelial cells
white blood cells
Describe the ability of a stable cell to proliferate and give examples of stable cells
good regeneration ability
low cell turnover
longer lifespan
Hepatocytes can go back to the cell cycle
facultative divider
What does ‘facultative divider’ mean?
Some cell undergoing this Go phase may have the option of coming out of it to undergo mitosis
Describe the ability of a permanent cell to proliferate and give examples of permanent cells
little / no regeneration
very low / no cell turnover
long lifespan, cannot go back to cell cycle
neurons
cardiac / skeletal muscle
red blood cells
terminal differentiation
What is differentiation?
selective expression of genes that determine this journey that May occur in several stages to acquire a specialized function or morphology
What does Injury generally depend on?
duration and the severity of the stimulus
Irreversible cell injury can lead to …
necrosis or apoptosis
Name the 4 adaptive processes
hypertrophy
hyperplasia
atrophy
metaplasia
What is hypertrophy?
Increase in cell size owing to increase in structural components
The only adaptive response available to permanent cells
What does the increased workload from hypertrophy activate?
PI3K/AKT and G-coupled pathways
Give examples of physiological hypertrophy
Hypertrophy of skeletal muscle through training
Uterine hypertrophy owing to hormone stimulation
Hypertrophic smooth muscle in pregnancy
Give examples of Pathological hypertrophy
Cardiac hypertrophy owing to hypertension or valvular disease
Bladder hypertrophy owing to prostatic enlargement
What is hyperplasia?
the enlargement of an organ or tissue caused by an increase in the reproduction rate of its cells, often as an initial stage in the development of cancer
What are the requirements for hyperplasia to occur?
Requires cells to be able to divide = labile or stabile cells
Permanent cells cannot undergo hyperplasia
Often hyperplasia and hypertrophy occur together, what are the mechanisms of hyperplasia?
Growth factor and stem cell activation?
What are the 2 types of physiological hyperplasia?
HORMONAL
hyperplasia which increases the functional capacity (e.g. breast development and breast feeding)
COMPENSATORY
hyperplasia when tissue was lost (e.g. partial liver resection or bone marrow hyperplasia in bleeding)
What usually causes Pathological hyperplasia?
excess hormonal stimulation of the cells
Give examples of Pathological hyperplasia
Endometrial hyperplasia owing to excess oestrogen
Prostatic hyperplasia owing to excess androgens
Virus induced hyperplasia in warts (HPV)
What causes pathological hyperplasia to develop into neoplasia?
increased cell turnover increases the risk of genetic aberrations/mutations and thus neoplasia
What is atrophy?
Reduction of the size of cells (and cell organelles)
Reduction of cell numbers (apoptosis)
Usually both at the same time
What is the mechanism involved in atrophy?
Degradation of cellular organelles/proteins by ubiquitin-proteasome pathways
Describe what Pathological atrophy can cause (5)
Denervation of muscle (e.g. trauma, poliomyositis)
Vascular atrophy of the brain
Malnutrition / starvation
Disuse atrophy of muscle or bone in immobilisation
Pressure atrophy owing to adjacent mass effect (e.g. tumour)
What is Metaplasia?
Reversible change where one differentiated cell type/tissue is replaced by another differentiated cell type/tissue
Adaptive response to a change in environment
Where can metaplasia occur?
Seen in epithelium but possible in mesenchymal tissues (soft tissues)
It’s NOT a change of phenotype/morphology of an already differentiated cell
What is the mechanism involved in causing metaplasia?
Stem cells differentiate along a different pathway owing to a change in the local microenvironment and/or colonization by differentiated cells from nearby tissues
Describe Physiological metaplasia in the cervix
The cervix changes its shape over the monthly cycle (fluid content of the stroma).
The vagina has an acidic microenvironment.
Thus: Metaplasia of cervical endocervical simple columnar epithelium to…
ectocervical stratified squamous epithelium (can deal with acid conditions better)
Give examples of pathological metaplasia
Metaplasia from bronchial ciliated columnar epithelium to
stratified squamous epithelium in response to smoking
Metaplasia from oesophageal stratified squamous epithelium to
columnar epithelium in response to acid reflux (Barrett’s oesophagus)
Osseous metaplasia within muscles after trauma (myositis ossificans)
describe Pathological bronchial metaplasia
The ciliated pseudostratified columnae epithelium of the bronchus changes into (keratinizing) stratified squamous epithelium. Reduces columnar and replaced to squamous =
In the wrong place
The protective functions of mucin production and ciliary motion are lost
Increased risk of neoplasia
What are the process examples of Reversible cell injury
Reduced oxydative phosphorylation and depletion of ATP
Changes in ion concentrations and osmotic influx of water result in cell swelling
Changes in intracellular organelles (e.g. mitochondria) and the cytoskeleton
Increasing eosinophilia
Give examples of irreversible cell injuries
Lysosome rupture and autodigestion
Denaturation of proteins
Membranes rupture
Nuclear changes: Karyolysis/karyorrhexis and pyknosis – changes and breaks up to small nuclei
What can irreversible cell injury result to?
This results in cell death – rupture of the surface of the cell leads to:
Leakage of cellular components into the blood allow detection of injured tissues:
e.g. troponin (heart), transaminases (liver)
What are the Principal pathways of cellular death which differ in morphology, mechanism and role in disease?
Apoptosis:
Programmed cell death (normal, but may be abnormally high in disease), no inflammation
Necrosis:
ALWAYS PATHOLOGICAL, inflammation
Necroptosis:
Shows features of both (very new concept)
Pyroptosis:
Apoptosis with fever and IL-1 signalling (new conc)
What is necroptosis?
Shows features of both necrosis and apoptosis
What is pyoptosis?
Apoptosis with fever and IL-1 signalling
Name the properties of necrosis (5)
Regional
Cells swell
Nuclei shrink (pyknosis)
Cell membrane ruptures
Cell contents leak
Name the properties of apoptosis (5)
Local
Cells shrink
Nuclei fragment
Membrane intact but altered
Apoptotic bodies (blebs)
What causes necrosis and what does it cause?
Pathogens
Causes inflammatory response
What causes apoptosis and what does it cause?
Physiological or pathological causes
Causes no inflammation
What is the Mechanism of necrosis?
ATP depletion Causes Mitochondrial damage
= Influx of calcium
Since the Accumulation of oxygen radicals causes Increased membrane permeability
= DNA and protein damage
= Drop in ph (lactic acid)
What can the mechanism of necrosis cause?
This acidic environment can cause saponification of fatty acids and accumulation of Ca2+
= calcifications as a long term concequence
What does the macroscopic pattern of Coagulative necrosis look like?
Shape and architecture of necrosis are preserved for some time - maintained
E.g. ischaemic infarction of the kidney
Yellow bit – abnormal = necrosis
What does the macroscopic pattern of Liquefactive necrosis look like?
Shape quickly lost, liquified, viscous, soft lesion
E.g. ischaemic infarction of the brain – abscess formation
Also in bacterial infection/abscess formation owing to lytic enzymes of the acute inflammatory response
What does the macroscopic pattern of caseous necrosis look like?
Cheese-like appearance
Usually mycobacterial (TB) in the lung (the photo)
What is gangrene?
a condition in which blood flow (and thus oxygen) is restricted or reduced in a part of the body causing tissues to die
What are the 2 types of gangrene?
Dry gangrene caused by ischaemia and Wet gangrene caused by bacteria
Why is ischaemia worse than hypoxia?
Because in hypoxia alone, anaerobic glycolysis can continue.
In ischaemia, no metabolites are available and no waste metabolites are removed
What is ischaemia?
absence of oxygen because blocked blood flow
What does hyperthermia do?
Hypothermia reduces the metabolic needs of tissues and reduces inflammation and cell swelling
What is ‘ischaemia reperfusion injury’ ?
Where restoration of blood flow exacerbates (worsens) tissue damage
Give 5 examples of Physiological apoptosis
Programmed apoptosis in embryogenesis
Involution of hormone dependent tissues after hormone withdrawal (e.g. menstrual cycle)
High turnover tissues (e.g. intestinal epithelium)
Elimination of self-reactive/ autoimmune lymphocytes
Programmed apoptosis of inflammatory cells at the end of the inflammatory response (e.g. neutrophils)
What is the speed of a Human cell turnover?
~1.000.000 cells per second
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Describe the extrinsic pathway of apoptosis
Name : death receptor mediated pathway
Receptor-ligand interactions with ligands Fas or TNF receptor activate a cascade of adaptor proteins which activates Initiator caspases – caspase 3
Which leads to the substrate cleavage and formation of a cytoplasmic bleb
Describe the intrinsic pathway of apoptosis
Name: the mitochondrial pathway
Cell injury causes: growth factor withdrawal, DNA damage, and protein misfolding (ER stress)
This is sensed by BCL2 family receptors which activate processes in the mitochondria to activate initiator caspases – caspase 3
Which leads to the substrate cleavage and formation of a cytoplasmic bleb
What are the 3 mechanisms of acute inflammatory
acute inflammation cannot be achieved without these 3 components
1 Vascular dilatation (vasodilatation)
2 Increased vascular permeability and extravasation of fluid – leakiness of the vessels, creating gaps, cells can go through
3 Emigration of leukocytes, primarily neutrophil polymorphs
What is the aim of the pathophysiology of acute inflammation?
To maximise the movement of plasma proteins and leukocytes out of the circulation and into the site of the insult
How does Vascular smooth muscle relax rapidly in Vascular dilation of acute inflammation?
mediated by histamine and nitric oxide
Describe what vasodilatation does in acute inflammation.
Increased amount of blood BUT slower flow in the area of vasodilatation
neutrophil emigration
This results in stasis of blood and an increase in hydrostatic pressure beyond normal levels - oedema
What is oedema
a build-up of fluid in the body which causes the affected tissue to become swollen
What are the signs of Vascular dilation acute inflammation?
cardinalrules
Rubor (redness)
Tumour (swelling, oedema)
Calor (heat)
What do Histamine and nitric oxide also activate?
typesof cells not in inflammation, in angiogenesis
endothelial cells
Describe what vascular permeability does in acute inflammation.
= Injurous stimuli like thermal burns or some microbial toxins cause endothelial damage
= contraction of endothelium
= vascular permeability increases
= cells, proteins, and mediators leak
= increase in tissue osmotic pressure
= more oedema
= rapid/long-lived
What is exudate
Endothelium cells change configuration
= increased interendothelial spaces
Exudate is fluid that leaks out of blood vessels into nearby tissues and may ooze from cuts or from areas of infection or inflammation
vasodilation and stasis still occur
What is transudate
fluids that pass through a membrane or squeeze through tissue or into the extracellular space of tissues
increased hydrostatic pressure
Decreased colloid osmotic pressure
What are the diseases caused because of transudate? and why
increased hydrostatic pressure (venous outflow obstruction e.g congestive heart failure)
Decreased colloid osmotic pressure (decreased protein synthesis e.g. liver disease and protein loss e.g. kidney disease)
What is the difference between the fluid content of exudate and transudate?
Exudate – high protein content and may contain some white and red blood cells
Transudate – low protein content and few cells
What is difference between exudate and transudate?
“Transudate” is fluid buildup caused by systemic conditions that alter the pressure in blood vessels, causing fluid to leave the vascular system.
“Exudate” is fluid buildup caused by tissue leakage due to inflammation or local cellular damage.
Phagocytic leukocytes (mainly neutrophils but also macrophages) leave the vasculature in the following 3 steps:
Margination and rolling along the vessel wall
Adhesion to the activated endothelium
Emigration through the vessel wall into the surrounding tissues
Describe the process of Margination and rolling along the vessel wall
Leukocytes are displaced peripherally by a central axial column of erythrocytes.
In stasis, more leukocytes assume a peripheral position next to the endothelium (margination).
Transient connections occur between the leukocytes and the endothelial cells (rolling).
Proteins involved: Selectins which may be upregulated by Tumour necrosis factor (TNF) and Interleukin 1 (IL-1).
What mediates and upregulates Adhesion to the activated endothelium?
Mediated by integrins (VCAM-1, ICAM-1) which are also upregulated by TNF and IL-1.
What mediates Emigration through the vessel wall into the surrounding tissues?
Mediated by CD31/PECAM-1
How does a leukocyte move?
Contractile cytoplasmic microtubules
and Changes in cytoplasmic fluidity
Where does the movement of leukocytesgo towards (think of chemicals) and where do they tend to move to? (more…)
Movement occurs towards high concentrations of chemical mediators = chemotaxis
Move to direction with more mediators
What are the mediators of Vasodilatation in acute inflammation?
Histamine, Nitric oxide, prostaglandins
What are the mediators of Increased vascular permeability in acute inflammation?
Histamine, Complement C3a and C5a, bradykinin, leukotrienes
What are the mediators of Chemotaxis and leukocyte recruitment in acute inflammation?
Tumor necrosis factor (TNF), Interleukin 1 (IL-1), Complement C3a and C5a
What are the mediators of fevers in acute inflammation?
TNF, IL-1, prostaglandins
What are the mediators of pain in acute inflammation?
Prostaglandins, bradykinin
What are the mediators of Tissue and cell damage in acute inflammation?
Lysosomal enzymes from leukocytes, ROS, Nitric oxide
What are the beneficial effects of inflammation? (8)
Degradation of bacteria and toxins
Fever (pyrexia) via hypothalamus thermoregulation
Stimulation of immune response
Haematological changes (leukocytosis, anaemia)
Facilitation of transport of drugs
Delivery of nutrients and oxygen
Initiating healing
Fibrin formation
What are the harmful effects of inflammation? (6)
Digestion of normal tissues
Constitutional symptoms (malaise, nausea, anorexia)
Swelling
Weight loss
Inappropriate inflammatory response
Fever
What are the clinical effects of acute inflammation?
Serous inflammation and effusion (in excess)
Fibrinous inflammation
Purulent inflammation and abscess formation
Ulceration
What are the 3 outcomes of acute inflammation?
Complete resolution/restoration = restitutio ad integrum
Healing by scarring
Progression to chronic inflammation
What is chronic inflammation?
As a consequence of acute inflammation
= often Primary chronic inflammation in autoimmunity
Long-lasting inflammation
What are the symptoms of chronic inflammation?
Persistent infections (e.g. viral or fungal infections)
Inability to heal (e.g. chronic peptic ulcer of the stomach)
Immune-mediated inflammatory diseases (e.g. Crohn’s disease, glomerulonephritis)
Prolonged exposure to toxic agents (e.g. silicosis of the lung)
What are the cells of chronic inflammation?
T-lymphocytes (CD3 positive)
B-lymphocytes (CD20 positive)
Plasma cells
Macrophages
Eosinophil polymorphs
Mast cells
Fibroblasts
Antibodies
Complement
Mediators
Few neutrophil polymorphs
Little fluid exudation (leakiness of the vessel)
What is granulomatous inflammation?
A distinctive pattern of chronic inflammation
collection of activated epithelioid (epithelium-like) macrophages
It may be surrounded by lymphocytes or not (naked granulomas e.g. in sarcoidosis)
It may show central necrosis (e.g. mycobacterium) or not
What could epithelioid macrophages do in granulomatous inflammation?
Epithelioid macrophages may fuse to form multinucleated giant cells
What are Glands formed from?
Glands are formed from specialised cuboidal/columnar epithelial cells with a secretory ability/function.
Glands are never squamous.
What are the 2 types of glands?
Some glands have a duct or they secrete onto a surface = exocrine glands
Some don’t have a duct and Secretion into the blood
= endocrine glands
Give examples of endocrine glands
Anterior pituitary
Thyroid
Parathyroid
Pancreas (Islets of Langerhans)
Adrenal glands
In the thyroid what do the blood capillary and thyroid follicles look like?
blood capillaries - white-looking irregular shapes
thyroid follicles - big pink circular structures
In the anterior pituitary, what do the blood capillary and secretory cells (different types) look like?
Blood capillary - pink blobs
Secretory cells - cells with purple nuclei
What are the properties of Skin?
The largest organ of the body
About 5kg (around 15% of body weight)
2m2 surface area
Covers the entire surface with continuity at mucocutaneous junctions (e.g. eyes, mouth, anus, vulva/vagina, urethra)
Continuously renewing and repair
What are the properties of the skin?
Mechanical barrier
Waterproofing
Protection from injury
Protection from infection
Cushioning and insulation
Sensory functions
What are the functions of the skin?
Immune functions
UV protection
Thermoregulation
Vitamin D metabolism
Personal, social and sexual significance
Storage of calories/energy
Describe the layers the skin
Epidermis (epithelium of ectodermal origin)
Dermis (connective tissue of mesodermal origin)
Subcutaneous adipose tissue
Describe the structure of hair-bearing skin
Epidermis = epithelium
Dermis = supportive stroma
Subcutaneous tissue = subcutaneous fat
Meissner corpuscle = fine touch sensation (top of dermis)
Pacinian corpuscle = vibration sensation (middle of dermis)
Sweat glands (exocrine)
Sebaceous glands (exocrine)
next to it is = arrector muscle of hair
The hair follicle holds the hair shaft
With hair matrix and papilla of hair follicle with blood vessels = subcutaneous artery, vein and nerve
Where can you find thick, glabrous and hairless skin?
Fingers, palms, toes, soles, lips, labia minora, glans penis
Where can you find Thin, hairy skin?
Everything else
What is Pilosebaceous units?
The hair follicle, hair shaft and sebaceous gland
Describe the structure of hair-less skin
Thick keratin layer
Epidermis = epithelium
Dermis = supportive stroma
Subcutaneous tissue = subcutaneous fat
Meissner corpuscle = fine touch sensation (top of dermis)
Pacinian corpuscle = vibration sensation (middle of dermis)
Sweat glands (exocrine)
Sebaceous glands (exocrine) except palms of the hands and soles of the feet.
Describe the Epidermis
Keratinising stratified squamous epithelium
Composed of keratinocytes undergoing terminal differentiation (approx. 1 month)
What is in between the epidermis and dermis?
Basement membrane (collagen layer) at the junction with the dermis
What are the four layers of the epidermis?
Horn cell layer (stratum corneum, no nuclei) - waterproofing
Granular cell layer (statum granulosum) - bits of nuclei
Prickle cell layer (stratum spinosum) - mechanical strength
Basal cell layer (stratum basale) - replenishing
What are the cell types in the epidermis? What is their functions?
Keratinocytes
: Mechanical protection, waterproofing, keratinocyte-derived endogenous antibiotics (defensins and cathelicidins)
Melanocytes
: UV-light protection for DNA = melanin pigment
Langerhans cells
: Immune function (sentinel cells)
Merkel cells
: Sensory function (light touch)
How do keratinocytes mature in the epidermis?
Basal cell layer -> Prickle cell layer as spinous cells -> granular cell layer -> horn cell layer as cornified cell
What helps the cells of the epidermis to be held together between layers?
Desmosomes
What is Squamous cell neoplasia?
Non-melanoma skin cancer is a group of common skin cancers that are usually easy to treat.
Symptoms of non-melanoma skin cancer include a red lump or a flat, scaly patch = too much exposure to the sun
What is the precursor of squamous cell neoplasia?
Dysplasia (an increase in abnormal cell growth or development) of
squamous carcinoma in-situ (the earliest form of squamous cell skin cancer in the epidermis)
Where is the origin of melanocytes?
the neural crest (S-100+ proteins)
What are melanocytes?
Melanocyte is a highly differentiated cell that produces a pigment melanin inside melanosomes
They are not epithelial cells
Stuck to the basement membrane
Describe the action of melanocytes
Melanin, formed in melanosomes
One melanocytes delivers melanin to
36 keratinocytes via dendrites
Keratinocytes are pigmented
Keratinocytes phagocytose the tips of melanocyte dendrites
Melanin provides protection against UV
What is Melanoma?
A type of skin cancer. It develops from melanocytes.
often a new mole or a change in the appearance of an existing mole due to over exposure of the sun
Where do Langerhans originate from?
Originate from the bone marrow (CD1a + marker)
- not easily seen on HE stained slides
What are Langerhans cells?
Dendritic (like melanocytes)
Antigen-presenting cells, immune sentinels surveying the microbiome of the skin
What are Merkel cells?
Merkel cells mediate tactile sensation/light touch
Associated with sensory nerve endings
Not recognizable in normal sections
What are Meissner corpuscules?
mechanoreceptors of “glabrous” (smooth, hairless) skin
Located in the dermal papillae
Tactile sensation
What is the Basement membrane comprised of?
Collagen type IV
What is the function of the basement membrane?
Resistance to shearing forces
Interdigitating pattern = mechanical resilience and strength
Control of epithelial – mesenchymal/stromal interactions (e.g. invasion in neoplasia)
tying together epidermis and dermis
What does it mean to be invasive?
Invasive if breaks through the basement membrane
Why is the basement membrane important in disease?
Without it = Increased skin fragility and impaired wound healing
Control of invasion in SCC (Squamous cell carcinoma) and melanoma
Integral in development and healing
Name a Blistering disease of the skin that targets the basement membrane
Bullous pemphigoid
Name an autoimmune disease of the skin that targets the basement membrane
Dermatitis herpetiformis
Name a genetic disease of the skin that targets the basement membrane
Epidermolysis bullosa
What is the Dermis?
Dense connective tissue (collagen, elastin, extracellular matrix)
What is in the dermis?
Papillary dermis - the superficial layer, lying deep into the epidermis
Mostly extracellar matrix - Nerves, blood vessels, lymphatics, histiocytes, mast cells, plasma cells, lymphocytes
Mechanoreceptors, thermoreceptors, Meissner and Pacinian corpuscles (sensory)
Subcutaneous fat
Epidermal appendages
Reticular dermis - the bottom layer of your dermis
What is the Epidermal appendages?
Pilosebaceous units
Sweat glands
Apocrine glands
What does the papillary dermis (also known as dermal papillae) influence?
Ridges form the fingerprints
Mainly from Interdigitating pattern = mechanical resilience and strength
What does overexposure of the sun cause?
increase in elastin
Describe what is composed in the Skin appendages
Pilosebaceous unit
= hair + sebaceous glands + smooth muscle / arrector pili muscles
Sweat glands: eccrine or apocrine
Nails
Where is hair made?
Hair follicle
What do sebaceous glands do?
lubricates hair to grow in the appendage
Natural moisturizer from secreted oils from sebaceous glands – sebum
What is Basal cell carcinoma?
Most common malignant skin cancer
Tumour of hair follicle origin
Invasive and locally destructive but very unlikely to metastasize
Will continue to grow locally
Related to sun exposure (UV light)
Local destructive growth
What is Eccrine spiradenoma?
an uncommon benign tumor of skin adnexa originating from eccrine glands
Nodules - round and quite big
Where can I find Apocrine sweat glands?
Axilla
Groin
Nipple
Eyelids
External ear canal
What is the difference between the secretion of eccrine and apocrine sweat glands?
apocrine - Fatty oil secretion not the same as sebum, less watery more oily
.
.
What happens to the embryo at week 3?
the embryo (bilaminar disc) develops further by forming 3 distinct layers (this process is known as gastrulation) Initiated by primitive streak
What does the epiblast become at week 3?
all three germ layers
What happens to the hypoblast at week 3?
replaced by cells from the epiblast and becomes endoderm then degenerates
Describe what happens at the start of week 3 when the embryo (bilaminar disc) develops further by forming 3 distinct layers (this process is known as gastrulation)
Initiated by primitive streak.
Two layers have already formed (epiblast and hypoblast).
The epiblast becomes known as ectoderm
The hypoblast is replaced by cells from the epiblast and becomes endoderm
The epiblast gives rise to the third layer the mesoderm.
The hypoblast degenerates. The epiblast gives rise to all three germ layers.
What does the Paraxial Mesoderm differentiate into?
further differentiation into paired blocks of tissue- somites
42-44 pairs eventually formed
What do somites differentiate into?
form dermomyotomes and sclerotomes
What do Dermomyotomes form?
connective tissue and skeletal muscle
What do Sclerotomes form?
bone and cartilage- vertebral arch
What does the Intermediate Mesoderm develop into?
Urogenital system – kidneys, gonads, urogenital ducts and associated glands
Describe the composition of the mesoderm from nearest to the notochord to the furthest away
Paraxial, Intermediate, Lateral plate
What is the lateral plate mesoderm continuous with?
the amniotic sac and yolk sac
What Are the 2 layers that the mesoderm splits into?
Amniotic sac mesoderm- Somatic layer = Parietal layer
Yolk sac mesoderm- Splanchnic layer = visceral layer
What do mesodermal cells become?
bones,muscles connective tissue
What happens in day 1 of fertilization? (5)
Sperm and Ovum meet in Uterine Tube (usually ampulla) 12-24 hours after ovulation.
Penetration of Corona radiate and Zona pellucida
Fusion and 2nd meiotic division
Acrosome reaction makes ovum impermeable to other sperm
End- Zygote- has diploid (46 chromosomes)
What happens in days 2-3 of fertilization? (5)
Cleavage is the rapid process of mitotic divisions
First mitotic division is around 30 hours post fertilization.
By day 3, 16 cell embryo
Each cell is known as a blastomere.
Solid sphere is known as a morula.
What happens in days 6-7 of fertilization? (5)
Bilaminar Disc- As the embryo starts to implant it forms two layers.
Inner cell mass differentiates into two layers: epiblast and hypoblast.
These two layers are in contact.
Hypoblast forms extraembryonic membranes
Epiblast forms embryo
Amniotic cavity develops within the epiblast mass
What is a morula?
Solid sphere of blastomeres
Describe the structure of the cavity morula that develops
Cavity – blastocyst
The outer layer of the blastocyst thins out and becomes the trophoblast
The rest of the cells move (are pushed up) to form the inner cell mass.
Inside is the blastocoele
What does trophoblast help with?
form the placenta
.
.
What is the Bilaminar Disc?
formed when the inner cell mass forms two layers of cells, separated by an extracellular basement membrane. The 2 layers
What are the 2 layers the Inner cell mass differentiates to?
Hypoblast forms extraembryonic membranes
Epiblast forms embryo
What develops within the epiblast mass?
Amniotic cavity
What is derived from the hypoblast?
exocoelomic membrane
What does the Extraembryonic hypoblast/membrane (exocoelomic membrane) create?
The Yolk Sac contains nutrients that supply the embryo before the placenta functions.
What happens in week 2 of fertilization?
Blastocyst has reached the uterine cavity
Need for oxygen, nutrients and removal of waste
Corpus luteum produces progesterone to maintain endometrium
Go through 4 stages of implantation
What are the 4 stages of implantation
1.Shredding/Hatching of the zona pellucida
- Apposition to ensure embryonic pole is in contact
- Adhesion via molecular communication
- Invasion into the maternal uterine tissue (maternal decidua)
What does implantation initate?
Implantation initiates a decidual reaction which causes the maternal cells to contribute to the placenta
What does the Outer layer of cells of the blastocyst become?
trophoblast
What does the trophoblast differentiate to?
differentiates into cytotrophoblast and the syncytiotrophoblast
What is the cytotrophoblast?
a single layer of cells and is the inner part.
What is the syncytiotrophoblast?
the outer layer and where it invades becomes known as the syncytium. Syncytiotrophoblasts secrete HCG
What happens at week 4 of development of a foetus?
the flat disc has to fold into 2 directions
Fold Longitudinally (cephalocaudal) (day 21) = begins so that head and tail are brought closer.
Fold Laterally (transverse) (day 18) = brings the amniotic cavity down, creating the future gut tube inside the peritoneal cavity.
What does the ectoderm form?
Forms the external surfaces, and how the body interacts with its external environment.
It forms the nervous system and the epidermis of the skin.
What does the mesoderm form?
Mesoderm-Forms the major part, the bones, muscle, connective tissue, forming most of the cardiovascular system, lymphatic system, reproductive system, kidneys, linings of the body cavities and the dermis of the skin.
What does the endoderm form?
Forms the lining of tracts, e.g. the GI tract, in the lungs and respiratory passages and organs such as the pancreas and liver, urethra, bladder and some glands e.g. thymus, thyroid.
Where is the mesoderm found/formed?
Either side of the notochord (an embryonic midline structure - circlular)
What are the 3 parts of the mesoderm?
paraxial, intermediate and lateral plate
Explain the ability of a liver cell in terms of regeneration and repair.
Stable - high turnover cells
terminology - Tumour
‘Swelling’, now commonly a synonym for ’neoplasm’ or ‘cancer’
Neoplasia
AUTONOMOUS ‘new growth’ of ABNORMAL cells
Carcinoma
malignant neoplasm of epithelial tissue
Sarcoma
malignant neoplasm of connective tissue or muscle
Lymphoma
malignant neoplasm of lymphocytes
Leukaemia
malignant neoplasm of leukocytes (or other blood cells)
Melanoma
malignant neoplasm of melanocytes
‘-oma’
= neoplasm (may be benign or malignant)
squamous cell papilloma = benign squamous cell neoplasm
squamous cell carcinoma (SCC) = malignant squamous cell neoplasm
Neoplasia:
Clonal, abnormal, excessive, disorganized cellular proliferation which is
non-responsive to normal growth controls owing to genetic abnormality
= autonomous growth
Clonal - describe its process in terms of neoplasms
This process begins with one (or more) cells becoming abnormal and all further cell generations are clones of this original one. Over time neoplasms however can change!
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.
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What are the classifications of cancer?
Behaviour - benign, borderline, malignant
Histogenesis - cell of origin
Differentiation and transdifferentiation - how well does the tumour resemble the cell/tissue of origin?
does the tumour show other tissues as well?
Molecular classification - specific genetic or molecular abnormality
Are tumours clones? Are they individuals? What does their histology/morphology correlate with?
Yes, Yes, clinical behavior
What are the three sub-classifications of behaviour of tumours?
benign
= no metastasis, no invasion, no destruction BUT pressure
borderline
= local invasion and destruction BUT no metastasis
malignant
= invasion and risk of metastasis
Describe borderline neoplasms
Limited invasion and local destructive growth
Very unlikely to metastasize
Often curable
2 examples of borderline neoplasms
Serous borderline tumour of the ovary
Basal cell carcinoma of the skin
Describe what are malignant neoplasms
Invasion of surrounding tissues
Infiltrative, poorly defined borders
Usually grow relatively rapidly
Variable differentiation (similarity to tissue of origin)
METASTASIS (the ultimate proof that a tumour is malignant)
Give examples of malignant carcinomas
colonic adenocarcinoma
breast adenocarcinoma
renal clear cell adenocarcinoma
What is haematogenous metastasis?
Spread by way of veins or rarely arteries
Metastasis is what causes most mortality from neoplasms
What is lymphatic metastasis?
Spread by way of lymphatic channels
This often involves lymph nodes
Describe direct spread of metastisis using an example
E.G carcinomas of the ovary
mesothelioma of the pleura(lining of lungs)
At any site, a malignant neoplasm may be …
primary or secondary
Give an example of haematogenous metasis
haematogenous liver metastasis
Give an example of lymphatic metastasis
colonic lymph node metastasis
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Describe the colorectal adenoma carcinoma sequence
Normal epitheliu to initial adenoma caused by APC gene
Initial adenoma to Intermediate Adenoma caused by K-RAS gene
Intermediate adenoma to Late adenoma caused by Loss of long arm of chromosome 18 (DCC gene mutation)
Late adenoma to Cancer caused by Loss of short
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Carcinosarcoma
Malignant neoplasm with both - endometrial carcinoma and sarcoma
Teratoma
Neoplasm comprises many different tissues not normally present at the site
Adenoma
a benign (noncancerous) tumor. Adenomas start in the epithelial tissue, the tissue that covers your organs and glands.
Adenocarcinoma
a malignant tumour formed from glandular structures in epithelial tissue.
