Dr Thomas’s Lectures Flashcards
What are the 4 main types of tissues?
Connective - binds cells and organs
Epithelial - covers exterior and lines internal cavities
Muscle - excitable, consists of skeletal, smooth and cardiac
Neural - excitable, allows propagation of nerve impulses
What are the three cell junctions?
Gap junctions - allow communication between cells
Tight junctions - hold cells together, no communication
Desmosomes - anchoring point
What is a negative feedback loop?
If the response of the affector reduces the intensity of the stimulus
What is a positive feedback loop?
When the increased stimulus makes the secretory agent secrete even more (birth example)
Which cells can change their membrane potential?
Excitable cells
What is the resting membrane potential of an excitable cell?
-70mV
Describe depolarisation
An impulse arrives and has passed the threshold, this then triggers Na+ channels to open which allows them to flood into the cell. K+ gates open and potassium then floods out of the cell.
Describe what happens in repolarisation
The Na+ and K+ channel gates close and the Na+ and k+ are pumped back into their respective resting states by active transport
What cell is responsible for myelinating cells
Oligodendrocytes
What are the cells which are acting as myelin sheath
Schwann cells
Describe what happens as AP reaches the end of a neurone
The membrane depolarisation activates calcium ion channel to open allowing them to flood in. This influx causes vesicles to move to the presynaptic membrane and release their contents to the synapse
What are the functions of the skin?
Protection
Sensation
Vitamin D production
Temperature regulation
Excretion
What are the three MAIN layers of the skin
Epidermis
Dermis
Hypodermis
What are the sub layers of the dermis?
Papillary layer - which contain blood vessels and the dermal papillae which holds the dermis and epidermis together
Reticular layer - which are more dense and elastic thanks to collagen and elastic fibres
What is the term used for wound healing?
Fibroblast proliferate
What are the layers of the epidermis
Stratum -
Corneum
Lucidum
Granulosum
Spinosum
Basale
What are the cells in the epidermis called?
Keratinocytes (90%)
Melanocytes (5%) - pigment anti UV producing
Langerhans- immune cells
Merkel - sensory
What is the chemical which hardens keratinocytes?
Keratin
What does the eccrine sweat glands do?
Open directly through pres, they eliminate waste and cool body
What is the function of the apocrine sweat gland?
They open into hair follicles
What is the function of the sebaceous glands?
Secrete sebum, which is the policy lubricant for hair and skin
How is Vitamin D produces?
UV converts a form of cholesterol to D3, which is Vit D’s precursor. Blood takes D3 to the liver and kidneys where it is converted to Vitamin D
What does the somatic nervous system control
The movement of skeletal muscles. IT IS MADE UP OF THE BRAIN, SPINE AND NERVES
Describe the process of the neural muscular junction
Synaptic vesicles transfer acetylcholine to bind to a motor end plate (ionotropic membrane). This releases sodium into the muscle continuing the action potential.
Describe cross bridge cycling
Calcium is released into the carcomere which binds to troponin. This displaces troponin which moves tropomyosin, revealing the myosin binding sites. The power stroke begins with ATP being hydrolysed, releasing a phosphate group and causing myosin to bind to these newly exposed sites and slide forward. ADP is released and the process stops until ATP is replaced on the myosin which separates the myosin from actin
What does the autonomic nervous system do?
Maintains the internal environment. Keeps homeostasis by controlling circulation, digestion and excretion.
What do visceral sensory neurones do?
Monitor temperature, pain, irritation, chemical changed and stretch in the visceral organs
What are the two divisions of the autonomic system?
Sympathetic (short) and Parasympathetic (long)
What does the spleen do?
Filters blood, destroys old RBC
What are the two lobules on the thymus
Cortex and medulla
What do the cortex and medulla lobules do?
The cortex contains many lymphocytes
The medulla is where the T cells migrate to before entering the blood
What do Basophils and mast Cells do
Release mediators to contribute to inflammation (histamines and other cytokines)
Basophils in circulation, mast cells in tissue
What do eoisnophils do?
Cytotoxic - they release substances from their granules and directly damage or kill PARASITES