Session 5: Exocrine glands & connective tissue Flashcards
What is osteogenesis imperfecta?
- An inherited genetic brittle bone disease. It is autosomal dominant.
- Mutated collagen fibres do not knit together or not enough produced or both
What are the 7 signs and symptoms of osteogenesis imperfect?
- Weakened bone (fractures are common)
- Short stature
- Presence of blue sclera
- Hearing loss
- Hypermobility due to loose joints
- Flat or arched feet
- Poor teeth development
What is scurvy?
Vitamin C deficiency leads to synthesis of abnormal collagen that lacks usual strength
Associated with inability to heal wounds & bone fractures
What are the 6 signs and symptoms of Scurvy?
- Gum disease & tooth loss
- Bruising of skin & hair loss
- Bleeding
- Poor wound healing
- Weakness & fatigue
- Impaired bone development in young
What is Marfan’s syndrome?
Autosomal dominant disorder in which expression of fibrillin 1 gene is affected such that elastic tissue is abnormal.
What are the 4 signs and symptoms of Marfan’s syndrome?
- Abnormally tall patients
- Arachnodactyly - abnormally long arms, legs & fingers
- Frequent joint dislocation
- Risk of aortic rupture
Describe loose connective tissue.
- Contains many cells
- Few collagen fibres
- Much ground substance
- Viscous consistency
Describe dense connective tissue.
- Contains few cells, almost all are fibroblasts
- Many collagen fibres
- Little ground substance
Split into regular & irregular
Describe regular & irregular dense connective tissue.
- Regular = collagen fibres are arranged in parallel bundles & densely packed. Fibroblasts between fibroblasts - withstand stress in a single direction. Seen in tendons, ligaments & aponeuroses.
- Irregular = collagen fibres are arranged in bundles orientated in various directions - withstand stress in multiple directions. Seen in submucosa of intestines & reticular layer of dermis
What are the 8 functions of the liver?
- Storage of metals & lipid soluble vitamins & sugars
- Anabolism of more than 60% of boy’s proteins eg plasma proteins
- Amino acid synthesis
- Haemopoiesis in embryo/foetus from week 5 to week 32
- Catabolism of drugs, hormones, haemoglobin, toxins, sugars & damaged RBCs after splenectomy
- Bile production
- Filtering cell debris from the blood
- Modifies hormones for excretion or function
What are myoepithelial cells made of? What is their function?
Myosin and actin.
They contract and squeeze the contents of a mucous cell into ductile system through lumen
What are fibroblasts?
Cells that synthesise the ECM, collagen & ground substance, producing the structural framework of connective tissue.
What are mast cells?
Granulocyte-containing immune cells.
What does brown adipose tissue do?
provides insulation & energy reserve, in neonates = generation of heat
What does adipose tissue do?
= padding & shock absorber, insulation & energy reserve
What is ground substance?
A viscous, slippery substance with a water content composed primarily of proteoglycans =
What are proteoglycans?
Large macromolecule consisting of a core protein with glycosaminoglycans (GAGs) attached. GAGs attract water to form a gel that permits diffusion but resists compression.
How do GAGs resists compression
GAGs attract water to form a gel that permits diffusion but resists compression.
What is hyaluronic acid?
A type of glycosaminoglycan (GAG) that binds to the proteoglycan core protein to form huge hydrophilic macromolecules which resist compression without inhibiting flexibility.
Main GAG in cartilage.
What is the importance of Vitamin C?
Required for the intracellular production of procollagen which is converted to collagen molecules outside of the cell and aggregate to form the final collagen fibres.
What is the structure of Type 1 collagen?
Triple helix of alpha chains
What do elastin fibres do?
Allow tissue to recoil after stretch or distension.
What are macrophages?
Phagocytic antigen presenting cells
What are 6 functions of connective tissue?
- Wound healing
- Defence against infection
- Storage reserve fuels and cells
- Protection - provides a cushion between tissue
- Transportation - medium for the diffusion
- Binding and supporting eg holding skin, organs and tissue together
What are reticular fibres? What do they do?
Type of fibre composed of type 3 collagen secreted by reticular cells.
They can cross-link to form reticulin which provides a supportive framework for soft tissue eg liver and bone marrow
What are the types of cells found in the liver?
Kupffer cells, stellate (ito) cells and hepatocytes
What are kupffer cells? What are 2 of their functions?
Specialised macrophages that make up the sinusoidal lining
Functions:
- trap and phagocytose any damaged/aged erythrocytes that were missed by the spleen
- after splenectomy, take over removal of 120 day old erythrocytes
What are stellate (ito) cells? What do they do?
Cells full of vacuoles containing Vitamin A in the cytoplasm
Functions:
- in liver cirrhosis they lose their vitamin A storage capability and differentiate into myofibroblasts
- synthesis and deposit collagen within the perisinusoidal space resulting in liver fibrosis
What is the function of bile?
Emulsify fats and assists in vitamin K absorption from small intestine
How does the hepatic blood supply work?
It connects the SI and liver.
- Nutrients from the stomach and SI are absorbed in the first capillary bed then hepatocytes detoxify nutrients of toxins in liver
What type of gland is the submandibular gland?
Mixed gland -> serous, mucous and mixed acini which secretes thick mucus and thin enzyme contained in saliva
- Compound tubuloacinar
What is the function of striated ducts?
Prevent water loss
What type of gland is the parotid gland?
Acinar, serous exocrine
Contains acini and striated ducts
What occurs in mumps?
Viral infection causing swelling of side of head due to blockage of striated duct cause fluid accumulation (parotid gland)
Which cells secrete mucus?
Goblet cells - they produce mucin and secrete them onto epithelial surface where they dorm mucus.
Where are mucus cells found?
Jejenum, line ducts of simple tubular glands in the large intestine and respiratory tract
They support the removal of foreign particles
What is the importance of mucus?
Lubricates, protective barrier, aids the movement of foreign particles & substances along epithelial cell surfaces.
Describe serous glands.
- Produce thin, watery secretion containing proteins, antibodies & zygomens.
- Contain large striated ducts
- Cell contain round, central nuclei
- Stain dark due to the presence of zygomens
Describe mucous glands.
-Produce thick, viscous secretions containing mucin
- Contain small, striated ducts
- cells contain flattened nuclei against basement membrane
- Stain light due to mucin.
