P.H.Y.S.I.O.

Regions of the brain Cerebrum - temporal, parietal, occipital, frontal lobes Cerebellum - cauliflower responsible for proprioception Diencephalon - hypothalamus (homeostatic control and neuroendocrine coupling) and thalamus (direction of sensory information to cerebral cortex) Brainstem - mescenphalon (hearing and sight), pons (inspiration), medulla oblongata (cardiovascular and respiratory centre) Receptors for general senses Nociceptors : pain and itch Thermoreceptors : temperature Chemoreceptors: chemicals, e.g. CO2 concentration Mechanoreceptors : tactile, baroreceptors and proprioceptors Ways of adaptation to a stimulus Tonic receptors : adapt slowly, always active Phasic receptors : rapidly adapting, switch off after a while Somatosensory pathway Somatosensory pathways are for the direction of information from general senses to the somatosensory cortex in the cerebrum. There are three pathways: Spinothalamic pathway (anterior and lateral) deliver...

Gigantism Overproduction of growth hormone in infants - adolescents Acromegaly Gigantism in adults (enlargement of mandible, growth of hands and feet) Goiter Enlargement of the thyroid gland Cretinism Congenital hypothyroidism (underproduction of thyroid hormone) which occurs in infants (protruding tongue, delayed puberty) Aldosteronism Overproduction of aldosterone (from zona glomerulosa) Myxoedema Hypothyroidism in adults (decreased mental ability, sparse, dry hair, puffy body areas) Grave's disease Hyperthyroidism (protrusion of eyeballs, heat intolerance, fatigue and weakness) Hypocalcaemia Too little parathyroid hormone (excitability of muscle tone, e.g. Chvostek's and Trousseau's sign) Hypercalcaemia Too much parathyroid hormone (depression of neuromuscular activity, softening of bones) Rickets Vitamin D3 deficiency with reduced bone density Cushing's Syndrome Increased ACTH or glucocorticoids...

Epidermal and Dermal Wound Healing Epidermal Wounding Healing: Basal cells of epidermis break contact with the basement membrane Cells enlarge and migrate across the wound, which is stimulated by epidermal growth factor (EGF) Migration of cells stops due to contact inhibition Relocated cells divide to build new epidermal layers and thicken epidermis Deep Wound Healing (into dermis and/or subcutaneous layer): Inflammatory phase : blood clot forms loosely binding wound edges, causing inflammation Migratory phase: clot becomes a scab, epithelial cells migrate beneath the scab to bridge the wound, fibroblasts migrate and form collagen Proliferative phase: extensive growth of epithelial cells beneath the scab, collagen fibres randomly deposited, blood vessels grow Maturation phase: collagen fibres become organised, epithelium is restored to normal thickness, scab sloughs off Photo damage There are three types of photo light, some which are blocked and some which ...

What is the dermis? The dermis is a connective tissue layer divided into two layers; papillary and reticular. The papillary layer is the more superficial layer composed of areolar tissue . It contains small capillaries, lymphatics and sensory neurons, as well as tactile corpuscles to detect light touch. The reticular layer is composed of dense irregular connective tissue (collagen, elastic fibres, connective tissue proper). It contains larger blood vessels, lymph vessels and sensory neurons and receptors called lamellated corpuscles (pressure and vibration receptors). The reticular layer shows us 'skin turgor', which determines hydration. NOTE: the hypodermis connects the dermis to underlying tissue. It is loose connective tissue with fat cells and large blood vessels. There is an absence of any vital organs or structures. Hair Hair, also termed pili, is composed of columns of dead keratinocytes held together by extracellular proteins. Parts of hair include: ...

What is the integumentary system? Basically, the skin! The integumentary system comprises a cutaneous membrane (skin), as well as accessory structures including hair, nails and exocrine glands. The skin has several functions: Protects underlying tissues and organs Excretes salts, water and organic wastes Maintains body temperature (insulation and evaporation) Synthesises vitamin D3 Detects touch, pressure, pain and temperature The skin is made up of three general layers: The epidermis : outer, thinner layer composed of epithelium (4-5 layers) The dermis : inner, thicker layer composed of connective tissue (2 layers) The hypodermis ( subcutaneous) layer: fat store with blood vessels and Pacinian corpuscles Below is a summary of the layers of the epidermis : Stratum corneum : dead keratinocytes arranged in multiple layers which are continually shed and replaced from deeper strata cells, water resistant Stratum lucidum:  exists in thick skin on...

So what do B cells do? B cells are responsible for antibody-mediated immunity, where pathogens are outside of the cell. B cells differentiate into plasma cells, producing specific antibodies to attack pathogens. There are millions of B cell populations, each with different antibody molecules. Antibody-mediated immunity is also called humoral immunity and is present from birth. Antibody-mediated immunity involves 3 steps:   1.   Sensitisation Sensitisation is when antigens bind to antibodies on an inactive B cell, making it sensitised. Recall that B cell membranes also contain Class 2 MHC proteins, which help in sensitisation by presenting the foreign antigen on the plasma membrane. The B cells is then on 'standby' until a helper T cell activates it.   2.   Activation Helper T cell binds to the class 2 MHC protein on the B cell, recognising the antigen and releasing cytokines to stimulate replication of the B cell and enhance antibody production...