Human Physiology

'Building blocks' are cells which grouped into tissues. Common characteristics:

• Bound by membrane (plasma). Cytoplasm is encolsed within the membrane with organelles which perform a function.
• Can break down large molecules mainly glucose and fat) into smaller ones to create energy for growth and repair 
• Have a nucleus that contain genetic info (deoxyribosenucleic acid)

During evolution cells become more specialized some contract (muscles), some conduct electricity (nerves). Some develop further and secrete substances such as enzymes or hormones

Types of tissues: Blood and lymph (classed as connective), connective tissue, nervous tissue, muscle, epithelia and glandular tissue

Prep sample for microscopic examination:

• Treat with formaldehyde or chemical (cryofixaction where tissue frozen then cut) to preserve
• cut the tissue 10-20μm using a microtome, then mount onto a slide
• Dye tissue accordingly. Place under a microscope (electron microscope used for detail or create 3D image but must be treated with heavy metal first)

Anatomical positions - assume body is erect, facing ahead, feet apart, arms by side, palms facing outwards, fingers extended. This can be done lying down face up (supine) or face down (prone)

Anatomical planes

• Sagittal plane - longitudinal (vertical) plane divides body into right and left side. If goes through mid line is called mid sagittal or median section. If not then is the parasagittal section.
• Coronal plane - vertical plane divides body into front (anterior/ventral) and back (posterior/dorsal) section
• Transverse plane - horizontal plane divides body into upper (superior) and lower (inferior)

Body CavitiesStructures contained within spaces that protect and support. The 2 major cavities are:           Dorsal Cavitiy - made up of Cranial cavity and Spinal cavity                                   Ventral Cavity - made up of Throatic Cavity, Diaphragm, Abdomino-pelvic cativy 

Anatomical direction: 

• Superior - Above - The adrenal gland lies superior to the kidney
• Inferior - Below - The diaphragm is inferior to the lungs
• Medial - Towards mid-line - The sternum is medial to the arms 
• Lateral - Away from mid-line - The kidney are lateral to the vertebral column
• Dorsal - Towards back/ behind - The dorsal columns of the spinal cord
• Ventral - Towards/ in front - The ventral roots of the spinal nerves
• Superficial - Towards surface - The epidermis is superficial to the dermis 
• Deep - Away from surface - The dermis is deep to the epidermis 
• Proximal - Close to origin - The proximal tube of the nephron is near to the glomerulus 
• Distal - Away from origin - The distal tube of the nephron is furthers from the glomerulus  Ipsilateral - On same side of body - The right eye is ipsilateral to the right ear 
• Contralateral - On opposite side of body - The right cerebral hemisphere controls the muscles on the contralateral side
• Afferent - Towards - Afferent fibres of the nervous system carry impulses towards the CNS  Efferent  - Away from - Efferent fibres of the nervous system carry impulses away from CNS

Definition:The maintenance of a stable internal environment for the preservation of the normal functioning of the cells

• Loss of homeostasis causes illness
• Heart is an example of the importance of homeostasis as depends on rhythmical and coordinated contractions of the cardiac muscles. By electrical signals which depend on conc. of Na and K ions inside and outside the cardiac muscle
• If excess K in extracellular fluid - muscle is too excitable. If too few - muscle less excitable. Conc. kept within a narrow range

• Balance between intake of food and drink and amount used or excreted.
• If protein intake is less than what being used you have negative nitrogen balance - as nitrogen is used to make amino acids which form proteins. If protein intake is greater than what is being used you have positive nitrogen balance.
• Thirst mechanism and urine production controls fluid level.
• Conc. of plasma glucose is 4-5 mmol/L between meals and rises after a meal which stimulates insulin to be released by pancreas to reduce the conc. until at normal level when it is no longer relesed. Glucose is stored as glycogen (liver/muscles) or fat (fat cells/adipose tissue). This is negative feedback.
• Glucagon increases plasma glucose by releasing glucose from its stores
• Negative feedback loop maintains level of variables within a range using sensors and receptor where info is compared by a comparator. If dont match signal sent to effector to correct it.
• Freeforward control - uses receptors to detect potential changes to minimize its effect. E.g insulin secreation happens before ingested food causes rise in blood glucose.
• You can reset negative feedback loop. E.g during exercise the loop for control of BP by barroreceptors is reset to allow unlimted amount of exercise.
• Native feedback and feedforward regulation - Short term control
• Adaptive control - Long term control. 

Adaptive control long term control. E.g increase muscle mass during physical training. Negative effects can occur E.g is have persistant high BP arteries can develop thick walls which can raise BP further, thicken walls of heart which can lead to venticular failure.

Positive feedback E.g hormonal control of uterine contractions which causes labour. 

• small contractions start putting pressure on the cervix
• increase in oxytocin - increases excitability of uterus so contraction strengths increase
• the conc. increases and contractions become stronger until baby is born.
• when baby born pressure on certix reduces, oxytocin decreases, no contractions.

Blood consists of plasma , red cells (erythrocytes), white cells (leukocytes) and platelets (thrombocytes).

Circulaing blood volume is about 7-8 % of total body weight.

• Plasma is about 4% of body weight it is 95% water 5% substances in solution and suspension mineral ions (Na, K , Ca, Cl),
• small organic molecules (aa's, fatty acids, glucose)
• plama protein (albumin account for 60% of total plama protein and globulins account for 40% of total plasma protein and divided into α, β (transport lipids + fats in blood and made in liver) and γ (antibodies produced by lymphocytes) and Fibrogen imporant in clotting 2-4% of total plasm protein and grouped with globulins).
• Its composition is kept within 'safe limits'

Formed elements of the blood (red cells, white cells and haematocrit) Red cells (small, circular, biconcave discs 7-8μm, no nucleus, thin, flexible, large SA:VOL, one mature it contain haemoglobin and can transport respiratory gases around the body)

Haematocrit - proportion of the total blood volume occupied by red cells also known as packed cell vol., centrifuge small vol. of blood in capillary tube til components packet at bottom, measure the height of the column of red cells relative to total height. viscosity of the blood increases as haematocrit increases

Red cells - small, circular, biconcave discs 7-8μm, no nucleus, thin, flexible, large SA:VOL, one mature it contain haemoglobin and can transport respiratory gases around the body

White cells (leukocytes) - larger than RBC, have nucleus, protect against disease by beings transported to sites of infection and inflammation, can pass through walls of capollaries and enter tissure by diapedesis, attack sites of infection by chemotaxi. 3 types granulocytes, monocytes and lymphocytes

Platelets (thrombocytes) - control bleeding, maintain vascular endothelium, formed by bone marrow and bud off from the cytoplam of megakaryocytes, lifespan of 10days, 2-4μm in diameter with no nucleus, discoid shape, outer regions are weakly stained by dyes and is the hyalomere(contains actin filaments which form filopodia(cellular projections)). Inner part of platelets known as granulomere stained strongly with basophilic dyes, contains granules (α-contains proteins involved in forming clots, delta contain Ca, ADP, ATP, serotonin, lambda  similar to lysosomes and contain hydrolytic enzymes)

• Neutrophils - cytoplasm not stained with eosin or basophilic dyes, 12-15μm diameter, 2-5 lobe nucleus linked with chromatin, formed in bone marrow, matured, release in blood for 6-12 hours then enter intercellular space by diapedesis where engulf+digest bacteria. 1st line of defence, eventually undergo apoptosis
• Eosinophils -granules stained red with eosin, formed with bone marrow before released in blood survive for 12-20 hours, 12-15μm diameter, bi-lobed nucleus,1-5% of total No. of WBC in adults, increase No. if have allergic condition, anti-histomine properties, congregate at sites of inflammation and worm infestation
• Basophils -12-15μm diameter, ganules stained strongly by methylene blue, segmented nucleus, least common, formed in bone marrow released in blood, secrete histamine, can be responsible for some pneumena, stimulated to secrete content of granules by IgE+cytokines
• Monocytes - 15-20μm diameter, indented nuclei, formed in bone marrow released in blood once mature. 2days after migrated to tissue where mature, long-lived (months), act as immune response by presenting antigens so can be recognized by T-lympocytes
• Lymphocytes - 25% vol.of total WBC, small (6-12μm, circle nucleus is stained as surrouned by cytoplasm, B-lymph mature in lymphoid tissue, T-lymph mature in thymus. Large (20μm off centre nucles with lots of cytoplasm, are activated B-cells short-life (hours) produce antibodies, T-cells (200+days) cell-mediated immune response.

• Testes which are connected via the epididymis and the vas deferens to the urethra (muscular tube which opens at tip of penis)
• Testes and epididymis are site of sperm production and maturation occur at 34°C (hence why located outside the abdominal cavity in scrotum)
• Vas deferens - runs from rach testis to join the urethra at base of bladder
• Urethra conveys urine and sprem to the exterior
• During sexual intercourse sperm is released from the penis via the urethra by an ***********
• Ejaculated sperm is contained in about 5ml of seminal fluid

• Each testis has a coiled tube called a seminiferous tubule which is where sperm is produced
• Sperm is produced from the mitotic division of a spermatogonia which is produces many spermatocutes which undergo meiosis to produce haploid spermatids
• These are embedded in sertoli cells where they differentiate into sperm cells under the influence to FSH
• maturation of the sperm from inactive to active takes place in the epididymis
• within the connective tissue surrounding the seminiferous tubules are leydig cells which under the influence of LH are responsible for the production of testosterone
• Testosterone acts in the testis to promote spermatogenesis and is responsible for the development and maintanence of secondary sexual characteristics (E.g beard growth) and sexual behaviours
• sperm are produced throughout the reproductive life of the male but gradually drops with age

• They have ovaries which are linked via Fallopian tubes to the uterus and thren through the cervix and vagina to the exterior
• Ovaries are within the abdominal cavity
• Ova are released from the ovaries, eventually drawn into the fallopian tube by ciliated cells
• Fallopian tubes enter the uterus (pear-shaped muscular sac, lining supports fertilised ovum during baby development)
• The uterus opens via the cervix into the vagina which opens to the exterior
• Vagina acts as a receptacle for erect penis during sexual intercourse (copulation) and as a birth canal during birth (parturition)

• is the production of ovum
• Female germ cels undergo mitotic division
• At birth the ovaries contain 1 million primary oocytes these cell arrested in the 1st stage of meiotic division. Only 200-400 of these will be released as mature ova and be able to be fertilised, rest with degenerate
• small number of the primary oocytes become surrounded by a layer of granulosa cells to form primary follicle
• during menstrual cucle a single follicle matures and released its oocytes during ovulation
• oocytes and its protective layer form the ovum
• This cycle is under hormonal regulation and the cycle stops during pregnancy and following menopause (happens after 50 years where no more follicles are available to mature)

• menstration marks end on one menstral cycle and neginning of the next
• involves shredding of the lining of the uterus along with some blood
• last about 28 days
• During 1st phase, onset of menstration, levels of FSH are raised, follicles begin to mature
• As they mature they secrete oestrogen more which stimulates the lining of the uterus proliferate
• as follicles mature on becomes more dominant and other regress
• at about 14 days, rising oestrogen levles trigger rise in LH production which causes ovulation
• follicle then turns into a corpus luteum which secretes progesterone
• this stimulates further growth of the uterus lining
• towards the end of the menstrual cucle one of two things will happen: successful fertilisation of released ovum and it will implant into the lining OR no fertilisation so the corpus luteum will stop hormone production so the lining will degenerate and shed which signals menstruation and start of a new cycle

• Copulation - insetion of erect penis into the vagina for the purpopse of *********** and delivery of seminal fluid containing 150-600 million sperm into the femal reporductive tract
• Sperm use their flagella to drive themselves through the cervix into the uterus and into the fallopian tubes where fertilisation occurs
• only 100 sperm complete journey successfully. on their way they undergo capacitation which allows them to penetrate and fertilise the ovum
• when sperm encounters the ovum it passes through the glycoprotein coat and its head fuses with the cell membrane of the oocyte
• this triffers the oocyte to alter the structure of its wall to prevent other sperm from entering and allow meiotic division to occur
• halpoid sperm and oocyte nuclei fuse to create a diploid cell
• conception has occurred

• following fertilisation the ovum begins to divide and creates a small ball of cells known as blastocyst this will eventually form embryo and a placenta
• in early stages the blastocyst secretes hCG which signals the corpus luteum not to regress and prevent uterine lining to shed
• hCG is detected on pregnancy test
• blastocyst lies in the uterine cavity for 72 hours before attaching and invading the uterine wall by implantation
• blastocyres continue to divide to form a hollow ball of cells this will form placenta and inner mass of the fetus
• as it burrows further it causes ells in uterine wall to help form the placenta
• placenta consists of blood vessels from the fetus in close proximity with blood from the mother, this allows exchange of oxygen, carbon dioxide, nuterients, waste
• fetus will spend 9 months in the uterus
• during first 1st trimester (3 months) most of vital organs are formed
• remaining 6 months are where growth happens

• number of factors such as endocrine signals and mechanical stretching of the uterus labour occurs
• contractions of the uterus stimulated by release of oxytocin (from posterior pituitary) which increase as labour progresses
• contractions are accompanied by relaxation and dilation of the cervix and vagina to allow for passage of the baby