MANA S2
Integumentary system

Tissue types can be distinguished by:
1) amt of intercellular space (fibres)
2) Function & appearance

1) Epithelial tissue
2) connective tissue
3) Muscular tissue
4) Nervous tissue

Epithelial tissue:
F) to protect underlying tissue and structures that may be subjected to wear and tear, drying out or damage by other living organisms
C) - cells arranged to form covering sheets or lining membranes

  • cells are predominant. amt of inter-cellular substance at minimum.

True Epithelium:
a lining membrane of the body tracts that open to the exterior
e.g. digestive, respiratory, urogenital tracts

Mesothelium:
serous lining membrane for large cavities of the body (slippery=less friction)
eg. pleura, pericardium, peritoneum

Endothelium:
inner lining of walls of blood and lymph vessels and heart, reduces friction, helps prevent blood clotting.

Connective tissue:
F) -packing and support material of the body
-plays an important role in repairing injuries by forming scar tissue to join injured parts
C) - cells far apart & separated by large amts of int substance

  • varying quantities of fibres present in int subs

different types:

  • Areolar connective tissue: fills empty spaces
  • adipose connective tissue: similar to areolar but has cells impregnated with fat
  • dense connective tissue: densely packed fibres that form elongated strands. e.g: tendons, ligaments, aponeurosis, deep fascia, intermuscular septa and neurovascular bundle.
  • cartilage: hyaline, fibrous and elastic
    -bone
    -haemopoetic tissue: forms red adn white blood cells. found in the red marrow of long bones and in internal organs like Liver.

Muscular tissue:
F) consist of highly specialized elongated cells possessing the inherent power of contraction

Skeletal muscle (striated voluntary)

  • long threadlike cells with many striations
  • muscle cells=muscle fibres
  • each fibre has many myofibrils
    -myofibril consists of overlapping filaments of the proteins myosin and actin whihc glide past each other when the fibre contracts.
  • fast and short duration contractions
  • most attatched to skeleton

Visceral muscle ( non-striated involuntary)

  • have long spindle shaped cells with no striations
  • slow and longer duration contractions
  • usually found in hollow organs eg blood vessels

Cardiac muscle (striated involuntary)

  • have branching striated cells
  • contractions rhythmic

Nervous tissue
C) has specialized characteristic of excitability and conductivity
F) Nerve impulses: all the chemical and electrical changes accompanying the transmission of an impulse.
-often generated by the stimulation of a receptor at terminal end of dendrite

  • reaches axon and then transferred to next neuron via synapse.
  • neurotransmittors released into synapse
  • direction of impulse from dendrite to axon

Neuroglia:
support tissue for nervous system

Nerouns:
cell consists of a cell body, axon and dendrite and their branches = nerve fibre

Macroscopic structure of nervous system:
-CNS
-PNS: + autonomic

composition of peripheral nervous system:
somatic and autonomic component. Spinal and cranial nerves

functional composition:
somatic afferent and efferent nerve fibers

31 pairs of spinal nerves.
cranial (8), thoracic (12), Lumbar (5), sacral (5), coccygeal (1)

unilateral area of skin supplied by a particular spinal nerve is called a dermatome

unilateral group of skeletal muscles supplied by a particular spinal nerve = myotome

Embryology:
ectoderm = nervous system (neural tube and neural crest >brain, spinal cord & peripheral ns) and epidermis
mesoderm= muscles, bones and dermis layer
endoderm= intestinal canal

mesodermal layer>segments>paired blocks of mesoderm>somites. both sides of neural tube.
3 regions in somites:

  • dermatome=dermis of skin
    -myotome=skeletal muscles
    -sclereotome=segmented parts of skeleton

Integument

Epidermis:
-stratified, keratinized epithelium
-tough, horny superficial layer

  • avascular
  • thickness depends on location

Dermis:
-underlying layer of connective tissue
-dense layer of collagen and elastic fibres = skin tone

Tension lines:
fibers in intercellular substance in dermis have a prevailing direction in the different regions of the body.
lacerations // to tension lines = heal well. lacerations acroos tension line disrupts collagen fibers = keloid
eg. stretch marks from pregnancy

blood supply to the skin

 Arteries to the skin form plexuses (network of nerves or blood vessels) in the dermis

 From these plexuses capillary vessels originate and pass into the dermal papillae

 Sympathetic nerve fibres present in the cutaneous nerves control the smooth muscle in the small arteries of the skin

vasoconstriction & vasodilation

terms

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Pleura - the covering of the lungs (visceral pleura) and of the inner chest wall (parietal pleura) which consists of a closed sac of serous membrane.

Pericardium - the membrane surrounding the heart. Consists of two parts – the outer fibrous pericardium and the internal serous pericardium.

Peritoneum - the serous membrane of the abdominal cavity. The parietal peritoneum lines the walls of the abdomen and the visceral peritoneum covers the abdominal organs.

Epidermis - the outermost layer of the skin which is divided into 4 layers.

Dermis - (corium) the true skin; the thick layer of living tissue that lies beneath the epidermis.

Mucosa - the moist membrane lining many tubular structures and cavities. Eg the nasal sinuses, respiratory tract.

Subcutaneous - beneath the skin

Skin ligaments - (L. Retinacula Curtis) numerous small fibrous bands, extend through subcutaneous tissue and attach the deep surface of the dermis to the underlying deep fascia.

Receptor - a cell or group of cells specialized to detect changes in the environment and in the sensory nervous system.

Effector - any structure or agent that brings about activity in a muscle or a gland, eg a motor nerve.

Nerve - a bundle of conducting nerve fibres that transmit impulses from the brain or spinal cord to the muscles and glands OR inwards from the sense organs to the brain and spinal cord.

Nerve fibre - the long fine process that extends from the cell body of a neuron and carries impulses.

Grey matter - nerve cell bodies

Fascia:
superficial - located between dermis and deep fascia.
-composed mostly of loose connective tissue and stored fat.
-fibrous bands extend through it.


deep fascia:
dense organised connective tissue

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