Human Physiology and Pathology
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- Created on: 15-04-13 19:22
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- Human Physiology and Pathology
- Respiration
- gas exchange needs a large surface area
- supplies O2 to the cells and collects CO2 from the cells
- lungs also have a role in the acid base balance and speech and breath control
- respiratory system also works with the circulatory system
- respiratory system made up of nasal passage, oral cavity, pharynx, larynx, trachea and lungs
- larynx contains the vocal chords and the epiglottis which closes when eating
- respiratory tract has the conducting zone and respiratory zone
- respiratory zone is from the terminal bronchioles in the conducting zone and ends at the alveoli
- conducting zone is from the larynx to the trachea, is considered dead space as its not involved in gas exchange.
- does humidify the air and trap bacteria and dust
- diaphragm contracts for inspiration and relaxes for exhilation
- nasal turbinates are bones in the nasal cavity that circulate and humidify air.
- mucociliary escalator is the system by which the respiratory tract is lined with ciliated cells and mucus lines it
- cilia move the mucus up and out of the lungs, taking dust particles with them
- gas exchange occurs in the alvelor sacs which are 250micro m in diameter
- gas exchange needs a large surface area
- alveoli make up 50-100m2 surface area.
- alveoli contain epithelial cells-type 1 and 2.
- type 2 secretes pulmonary surfactant
- have alveolar pores to allow air to circulate
- alveoli contain epithelial cells-type 1 and 2.
- alveolar ventilation is the measure of fresh air volume reaching the alveoli each minute
- uses the equation Va = (Vt X RR) - (DSV - RR)
- transpulmonary pressure is the force acting on the lungs to expand, uses equation Palv-Pip
- flow = pressure difference / R
- a low R gives a high flow
- lung compliance is the stretchiness of the lungs and determines the compliance, elasticity and surface tension forces
- use the equation compliance = change in lung volume/ transpulmonary pressure
- lungs have 2 circulations, the pulmonary and the bronchiole circulation
- controlled by chemoreceptors, there are central and peripheral chemoreceptors
- central chemoreceptors are found in the brain stem
- only increase firing with an increase in CO2 levels in the blood
- not sensitive to oxygen pressures
- peripheral chemoreceptors are found near the arteries
- increases firing rate with a decrease in oxygen levels and an increase in acids and arterial CO2 levels
- stimulates medullary inspiratory neurons and firing to motor neurons in the diaphragm and external intercostals
- in direct contact with the blood and use chemical messengers to communicate
- central chemoreceptors are found in the brain stem
- respiratory failure when PO2 is lower than 60mmHg at sea level and accompanied with raised/lowered PCO2.
- caused by drugs, head injury or stroke
- obstructive diseases when there is increased resistance to airflow which can be caused by excessive mucus
- e.g. COPD
- restrictive diseases are when the expansion of the lungs is restricted
- e.g. pulmonary fibrosis
- lung function tests anre used to diagnose
- obstructive diseases when there is increased resistance to airflow which can be caused by excessive mucus
- e.g. COPD
- obstructive diseases when there is increased resistance to airflow which can be caused by excessive mucus
- airway resistance can be increased by ******* contractions of smooth muscles, increased mucus production, inflammation of bronchiole walls
- Cardiovascular system
- 6 CV circulation systmems, cerebral, pulmonary, cardiac, hepatic, renal, systemic
- The metabolic functions are delivery of nutrients, removal of metabolites, circulation of hormones, temperature regulation
- arterial circulation takes high oxygenated blood from the heart
- CO=HR x SV
- venous circulation takes low oxygenated to the heart
- cardiac output is the amount of blood pumped by each side of the heart in one minute
- stroke volume is the amount of blood pumped by each ventricle in one contraction
- heart is surrounded by pericardium sac, protecting it and is joined to diaphragm
- cardiac muscle is highly striated with bands of actin and myosin in cross bridge formation
- 2 major types of cardiac cells, autorhythmic and contractile
- autorhythmic cells initiate action potential in rhythm cycles
- 2 major types of cardiac cells, autorhythmic and contractile
- blood in venous system has low flow, movement of skeletal muscle that aids movement of the blood
- capillary bed has 3 types of vessels, terminal, arteriole, postcapillary venule and true capillaries
- terminal arteriole has precapillary sphincters controlling blood supply to the capillaries
- postcapillary venule connects directly to arterioles via the vascular shunt
- pulse is the pressure wave of blood
- taken as atmospheric pressure as the reference
- maximum arterial blood flow is 120mmHg and the minimum is 80mmHg
- taken as atmospheric pressure as the reference
- mean arterial pressure is the average arterial pressure over the cardiac cycle
- use CO=(MAP-CVP)/TPR or MAP = CO x TPR
- heart wall has three layers, epicardium, myocardium and epithelium
- ventricular muscle is much tcker than atrial muscle and left side has a thicker muscle than the right side
- two types of valves in the heart, atriventricular valves and semi lunar valves
- atrium and ventricules separated by atrioventricular valves, left side has two flaps of connective tissue, right side has three flaps of connective tissue
- ECG is a diagnositc tool
- Myocyte permeable to potassium not sodium
- P Wave is the atrial depolarisation
- QRS complex is the ventricular depolarisation
- ST segement is the plateau of ventricular action potential
- T wave is the ventricular repolarisation
- pacemaker cells can fire action potentials in absence of external stimulus
- increase heart rate by stimulation of sympathetic nerves, increase rate of rise of pacemaker potential
- circulating catecholamines increase rate of rise of pacemaker potential
- decrease heart rate by stimulation of parasympathetic nerve to the heart, decrease in rate of rise of pacemaker potential
- barorreceptors monitor stretch and feedback information to the cardiovascular centers in the medulla
- extrinsic control is any regulation of the heart by neural input, circulating hormones or any other factor originating from outside the organ
- INtrinsic control is when the function is regulated by factors originating from within the organ or tissue itself
- adrenaline, insulin and glucagon also affect heart rate
- ventricular contractility is the measure oof ventricles capacity for generating force
- 2 types of capillary, closed/continuous and fenestrated
- closed/continuous is present in less active tissue, have basal membrane and capillary membrane fused tight together
- fenestrated are present in active tissues to allow rapid exchange of materials
- lymphatic system mops up excess fluid in interstitial fluid
- lymph supports immune system by carrying the immune bodies
- factors affecting fluid exchange across capillary walls include capillary hydrostatic pressure, interstitial hydrostatic pressure, plasma colloidal osmotic pressure, interstitial colloidal osmotic pressure
- capillary hyrdostatic pressure forces fluid out of the capillary
- interstitial hydrostatic pressure forces fluid into the capillary
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- plasma collodoidal osmotic pressure draws fluid into the capillary
- interstitial colloidal osmotic pressure draws fluid out of the capillary
- adrenaline is a vasoconstrictor in most vascular beds but is a vasodilator in skeletal muscles
- arrythmias are abnormalities of the cardiac rhythm
- can cause sudden death, syncope, heart failure, chest pain, dizziness, palpitations
- two main types of arrythmia bradycardia and tachycardia
- Blood
- leukocytes are involved in immune response, have nuclei
- 5 types-lymphocytes, neutrophils, monocytes, eosinophils and basophils
- lymphocytes make up 20-40% of all leukocytes, three main types-T B and null
- basophils are non phagocytic cells. release histamine, heparin and other chemicals associated with allergic reactions
- monocytes are 2-8% of all the leukocytes, used in phagocytic defense
- eosinophils are 1-4% of all leukocytes, attack invaders that are too large to ingest, release toxic molecules which can damage normal tissues at the same time
- neutrophils are 50-80% of all leukocytes, are phagocytes
- 5 types-lymphocytes, neutrophils, monocytes, eosinophils and basophils
- thrombocytes are fragments of cytoplasm and have nucleus, are involved in blood clotting
- blood cells formed in bone marrow
- red blood cells are the most abundant, transports gases, no nucleus
- are biconcave, have flexible plasma membrane
- replicated every 120 days
- filtered and destoyred in the spleen
- made up of 55% plasma and 45% red and white blood cells
- haematopoiesis is blood cell production
- active bone marrow is red and found in pelvis, spine, ribs, cranium and ends of large bones
- cytokines include colony stimulating factors, interleukins, stem cell factors, thrombopoietin and EPO
- three categories for plasma proteins-albumins, globulins and fibrinogen
- globulins are proteins that transport lipids, steroid hormones and are important in blood clotting
- albumins made in liver,
- fibrinogen is made in the liver
- haemostasis is the process of blood clotting
- 3 main steps, vasoconstriction, formation of platelet plug and blood coagulation
- platelets are activated by contents in intracellular granules
- INflammation is the response to injury or infection
- mediators of inflammation are prostaglandins, leukotrienes, histamine, platelet activating factor, ATP, serotonin, bradykinin, substance P and CGRP
- Immunity is classified into humoral snd cell mediated immunity
- Humoral immunity is the production of antibodies to tag bacteria and other forgein matter for removal from the body
- cell mediated immunity is the destruction of infected or abnormal cells
- immune system is a collection of cells, tissues and molecules that mediate resistance to infections
- consists of lymphatic tissues and leukocytes
- lymphoid tissue made of bone marrow, thymus, spleen, lymph nodes and tonsils
- central and peripheral lymphoid tissue
- peripheral is the spleen, lymph nodes, tonsils, adenoids, appendix and peyers patches
- central is the bone marrow and thymus
- central and peripheral lymphoid tissue
- B cells have antibodies marking invaders for destruction. can secrete antibodies
- T cells directly damage forgein cells when in contact. Includes helper T cells, cytotoxic T cells and suppressor T cells
- Null cells/natural killer cellsare important against viral infections. Fast acting
- recognize abnormal/infected cells, cause lysis by secreting perforins
- Mast cells reside in mucosal and connective tissues/skin, releasing histamine and other inflammatory mediators
- Lymph nodes filter the blood and lymph.
- antigen presenting cells capture and present antigens here, activating B and T cells
- dendritic cells are phagocytes and can activate certain types of T cell. transport antigens to the lymph nodes
- macrophages involved in phagocytosis. secrete toxic chemicals. present antigens to T cells and secrete cytokines
- spleen filtersthe blood and lymph
- the immune response is the coordinated reaction of these cells and molecules to infectious microbes
- non specific immunity is always present in healthy individuals
- the non specific defences include inflammation, interferons, natural killer cells, skin, sebum, mucous membranes,
- Specific immunity stimulated by microbes invading tissues and has slower response to microbes
- pathogens are viruses, bacteria, fungi, protozoa, multicellular parasites
- non specific immunity is always present in healthy individuals
- inflammation is a series of events where proteins, fluids and phagocytes in an injured or infected area are accumulated
- neutrophils and macrophages anre involved
- four signs are redness, heat, swelling and pain
- interferons are proteins secreted by leukocytes and virus infected cells
- 3 types, alpha, beta and gamma
- alpha and beta secreted when a viral nucleic acid enters host cell. kills host cells and induces death in neighbouring cells
- gamma secreted by T cells and NK cells, inhibits viral replication
- also enhanced phagocytosis, boosts antibody production in B cells, activates NK cells and cytotoxic T cellsand inhibits cell division
- 3 types, alpha, beta and gamma
- complement system is part of the non specific response, has two pathways of activation
- alternate and classical pathways
- classical is binding antibodies to bacteria and is part of specific defense mechanisms
- alternate is binding to carbohydrates on the bacterial cell walls, part of nonspecific immunity
- alternate and classical pathways
- antibodies are made of two heavy and two light chains, with a constant region and a variable region which gives specificty
- 5 classes of antibody, IgM, IgD, IgG, IgE and IgA
- antibodies can neutralize, agglutinate, opsonize, activate complement and enhance NK activity
- opsonization is when the binding of the antibodies enhances the phagocytosis
- neutralization is when the binding blocks the antigen activity
- agglutination is when the antibodies bind to the pathogen, clumping it togethre
- complement activation is when the antibodies activate the complement cascade resulting in lysis of the cell
- antibodies can neutralize, agglutinate, opsonize, activate complement and enhance NK activity
- 5 classes of antibody, IgM, IgD, IgG, IgE and IgA
- major histocompatibility complex marks cells as self
- two classes of MHC, class 1 present on all nucleated cells, Class 2 present in macrophages, activated B and T cells and thymus cells
- leukocytes are involved in immune response, have nuclei
- Hormones
- steroid hormones are lipids that enter a target cell
- are slow acting and long lived
- peptide hormones bind to a cell surface receptor on a target cell
- are fast acting and short lived
- endocrine glands release hormones into the blood
- adrenal gland, thyroid gland, pituitary, role and control of anterior pituitary, endocrine pathways
- responsive hormones include adrenalin, cortisol and thyroxine
- prostaglandins are local hormones released from blood vessels and platelets and dont travel great distances
- the sympathetic medullary system controls the adrenal gland
- pheromones are used for sexual attraction and have other roles in synchronization
- exocrine glands release hormones into a duct
- trophic hormones come from the pituitary
- stimulate growth
- chromaffin cells make adrenalin
- adrenalin raises blood glucose, suppresses insulin secretion and stimulates glucagon secretion
- adrenaline and noradrenaline both increase heart rate, dilates voluntary muscle arterioles, constrict arterioles in skin, gut, dilates bronchi
- adrenalin has two receptors, alpha and beta
- hypothyroidism symptoms include lethargy, weakness, obesity, bracycardia, dry skin
- anterior pituitary produces growth hormone, thyroid stimulating hormone, FSH, LH and ACTH
- adrenal cortex made up of zona reticularis, zona fasciculata, zona glomerulosa
- cortisol suppresses the immune system
- hyperthyroidism symptoms include high temperature, nervous, hyperactive, underweight, tachycardia, flushed moist skin
- hormones in thyroid gland are derived from iodination of thyroglobulin
- 2 main thyroglobin groups are thyroxine and tri-iodothyronine
- thyroid gland needed to regulate temperature, growth and development and nervous system activity
- there are thyroid hormone receptors on nuclei of most cells
- infundibulum connects the pituitary to the hypothathalamus, contains nerves and vessels
- osteoid contains crystals of calcium and phosphate, made of osteoclasts and osteoblasts
- osteoblasts are bone forming cells and produce new matrix which is mineralised
- osteoclasts are large multinucleate cells that secrete H+ cand hydrolytic enzymes. used in bone resorption
- pituitary has 2 lobes the anterior at the front and the posterior in the back
- parathyroid hormone controls amount of calcium in the body
- the calcium receptors on secretory cells detect extracellular calcium concentration
- can stimulate osteoclasts to resorb bone, kidney stimulation and intestinal uptake
- the calcium receptors on secretory cells detect extracellular calcium concentration
- calcitonin inhibits osteoclasts reducing bone absorption
- hormone secretion controlled by ions, nutrients, neurotransmitters and other hormones
- peptide hormones are made as preprohormones, then cleaved to prohormones then are activated
- steroid hormones are derived from cholesterol
- in females the mullerian ducts develop and the wolffian ducts regress
- sex hormones are involved in sex differentiation, gametogenesis, behaviour, menstrual cycle, pregnancy, birth and lactation
- for the first six weeks of gestation the gonads are indifferent
- under paracrine action
- SRY genes only present on Y chromosome as it is used to develop testes
- stimulate release of mullerian inhibiting substance and testosterone. causes mullerian ducts to regress
- interstital cells/leydig cells respond to LH, producing testosterone
- leydig and sertoli cells work together as part of the sperm production process
- sertoli cells all held together by tight junctions, nourish developing sperm
- leydig and sertoli cells work together as part of the sperm production process
- oxytocin has roles in birth, feeding infant, promoting contrations in uterus, helps to expel milk after birth
- lactation uses various placental hormones, prolactin
- when the ovarian cycle ceases the ovaries are unresponsive to FSH and LH, dont secrete oestrogen and progesterone
- steroid hormones are lipids that enter a target cell
- Renal system
- kidney is used to maintain extracellular fluid so it is at constant level, regulates plasma ionic composition, plasma volume, osmolarity, pH, removes metabolic waste products, excretes H+ urea, creatin, secretes erythropoietin, renin and activates vitamin D3.
- urinary system made up of kidneys, ureters, bladder and urethra
- ureters conduct urine from the kidneys to the bladder
- the bladder is an expandable organ that stores urine until it is expelled from the body
- urethra is used to excrete urine from the bladder to outside of the body
- kidneys are endocrine organs that secrete erythropoietin, stimulate bred blood cell production
- kidneys secrete renin which is needed for production of angiotensin II
- Angiotensin II is a hormone involved in regulating salt and water balance needed for long term blood pressure
- kidneys secrete renin which is needed for production of angiotensin II
- receives 20% cardiac output at rest, is less than 1% of body weight and uses 16% ATP
- kidney is bean shaped and around 115-170g. has three regions
- renal cortex is the outer granulated layer
- renal medulla is a cone shaped tissue with masses called renal pyramids
- renal pelvis is the central cavity that is continuous with the ureter
- kidney is bean shaped and around 115-170g. has three regions
- kidney is bean shaped and around 115-170g. has three regions
- renal cortex is the outer granulated layer
- renal medulla is a cone shaped tissue with masses called renal pyramids
- renal pelvis is the central cavity that is continuous with the ureter
- 1 million nephrons per kidney, made of renal corpuscle and renal tubule
- renal corpuscle is formed from two parts-glomerulus and bowmas capsule
- glomerulus is a tangled capillary network for filtration
- bowmans capsule is the enclosing chamber made of two layers. it receives the filtrate and the inflow to renal tubules
- renal tubule made of proxiaml tube, loop of henle, distal convoluted tubule and collecting duct
- loop of henle is a U shaped structure that has a descending limb to allow water to leave and an ascending limb that pushes out salt
- collecting ducts serve to carry urine to the renal pelvis
- proximal convoluted tubule is an epithelial layer with a brush border of microvilli to allow reabsorption of filtrate components
- 2 types of nephron, cortical and juxtamedullary
- juxtamedullary has a long loop of henle that extends into the medulla.
- responsible for medullary osmotic gradient
- cortical have short loop of henle and are most numerous
- juxtamedullary has a long loop of henle that extends into the medulla.
- renal corpuscle is formed from two parts-glomerulus and bowmas capsule
- nephron function is to carry out basic renal exchange processes
- involved in secretion, reabsorption and glomerular filtration
- glomerular filtration is when the water and small molecules move from the glomerulus to the glomerular capsule while large molecules and formed elements remain in the glomerular blood
- involved in secretion, reabsorption and glomerular filtration
- juxtamedullary apparatus is part of the distal tubule that comes into contact with nephron's afferent and efferent arterioles
- two componenets, macula densa and granular cells or JG cells
- macula densa are specialized clusters of tubule epithelial cells, monitor level of salt contained in fluid within tubule
- granular cells are specialized cells in the wall of afferent arterioles and have cytoplasmic granules containing renin
- two componenets, macula densa and granular cells or JG cells
- renal arteries enter the kidney at hilus direct from aorta and the renal veins exit at the hilus
- Respiration
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