Ward Round Notes

Skeletal muscles contain muscle fibres which span the whole length of the muscle. These are made up of subunits called sacromeres containing thick myosin filaments and thin actin filaments. Thick and thin filaments slide towards each other during contraction, the total effect of multiple sacromeres contracting leads to the shortening of the muscle. 

Membrane potential Membrane potential refers to the net difference in charge on each side of a selectively permeable membrane  due to an imbalance of cations and anions. This difference has the potential to become electrical energy (current) which is produced when ions move down an electrochemical gradient.  In the body, a membrane potential exists between the intracellular fluid and the extracellular fluid (ie almost all cells and the extracellular fluid surrounding it). Membrane potential is measured in milivolts (mV) in the body. It is always measured with the inside (ICF) relative to the outside (ECF). 

  Symptoms of pregnancy Pregnancy leads to many symptoms which would be considered an illness or disease at other times. These symptoms are caused by hormonal changes which help create an optimum environment for the fetus and to support the increasing needs of the mother and child. Symptoms shown in pregnancy include anaemia, breathlessness, pelvic pain, swollen legs, increased urination, flushing, nausea, backaches, increased pigmentation, swollen or tender breast, and tiredness. Effects of fetus to the respiratory system There is an increased utilization of oxygen due to the fetus. (about 20% at term) The expanding uterus limits the movement of the maternal diaphragm. This leads to feelings of breathlessness

Fetal circulation  As a fetus’s lungs, kidneys and GI tract are not functional before birth, the fetus receives oxygen, nutrients and removes wastes via the maternal circulatory system. This is done through the placenta where the maternal blood and the fetus’ blood are bought in close contact. Due to a fetus’ different oxygen needs and supply, the fetal circulation is adapted such that unused parts of the body do not receive excess blood whist other areas are depleted. This is occurs via 3 shunts: l           Ductus venosus l           Foramen ovale l           Ductus Arteriosus

The cranial nerves The face is supplied by 3 branches of the tri gemminal nerve, and the back of the head is supplied by the cervical nerves. the spinal nerves C1-8 supplies the  back of head and upper limbs C3-4 supplies the shoulder. C6, 7 and 8 supplies the hand from lateral to medial. T1-12 supplies the trunk  T1 supplies the anterior medial surface of the arm. T4 is at the level of the nipples and T10 is at the level of the umbellicus L1-5 supplies the anterior leg and lower back. L2 supplies the pocket shaped areas L 3 supplies the knee S1 supplies the lateral side of the foot S2 supplies the back of leg S3 supplies the penis.

Control of serum calcium levels Bone is made up of hydroyapatite and a fibrous framework. Ca 3 (PO 4 ) 2 + Ca(OH) 2 à Ca 5 (PO 4 ) 3 (OH) Tricalcium phosphate + calcium hydroxide à hydroxyapatite Bone is maintained by osteo C lasts which ‘ C rush’/breaks down bone and osteo B lasts which B uild bone. The breaking down of old bone is also called bone resorption and the formation of new bone is called ossification . This constant relaying of bone helps reshape bones, and repair micro-damages as well as injuries. This continuous bone remodeling is called bone turnover. In adults the rates of bone formation and bone breakdown is usually almost equal. Calcium levels in the body are regulated by parathyroid hormone, calcitonin and vitamin D. The levels of calcium in blood is carefully controlled in the short term, and the total levels of calcium in the body also needs to be constantly maintained. The regulation of calcium is mainly carried out by Parathyroid hormone, whi...

When calcium is low: The parathyroid gland secretes parathyroid hormone Parathyroid hormone increases osteoclast activity and more calcium and phosphate is released into the blood stream from the bone.  Parathyroid hormone also increases secretion of phosphates by the kidneys, and also increases calcium reabsorption.  This causes an instant increase in serum calcium levels.  Parathyroid hormone also works on the kidney to increase the rate of vitamin D activation. Activated vitamin D (calcitriol) is needed for calcium absorption.  Increased calcitriol levels increase the absorption of calcium from the terminal ileum of the small intestines.  This leads to an increase in serum calcium and restores the total amount of calcium in the body in the long term. calcitriol also increases bone sensitivity to parathyroid hormone further increasing amount of calcium in blood.  The parathyroid glands are sensitive to changes in serum calcium, therefor...

The male reproductive system consists of the testes, a series of ducts, accessory glands and supporting structures. Sperm is produced in the testes. It then flows into the epididymis where it is stored, before it is propelled through a series of ducts to the exterior. The sperm matures within the ducts. Accessory sex glands secrete substances necessary to protect the gametes and to facilitate their movement along different portions of the ducts. The supporting structures play several roles including the delivery of sperm into the female reproductive tract and the support of the testes.

Unlike oogenesis, spermatogenesis occurs at puberty. Spermatogenesis occurs in the seminiferous tubules of the testes, and takes between 65 and 75 days to occur. However about 300 million sperm complete spermatogenesis each day. Spermatogenesis begins with spermatogonia (spermatogonium s.)  found beneath the basement membrane of the seminiferous tubules. The spermatogonia are sperm cells which are undifferentiated and undergo mitosis. The cells which remain near the basement membrane remain as a reservoir of undifferentiated cells, whereas those which loose contact squeeze through a blood-testis barrier and differentiate into primary spermatocytes .

Oogenesis The production of female gametes begins before birth. Primordial germ cells migrate from the yolk sac of the embryo to the gonads (reproductive organs), where they differentiate into oogonia. Oogonia undego multiple mitotic divisions, and are arranged in clusters surrounded by a layer of epithelial/follicular cells by the end of the 3 rd month of development. The oogonia continues to divide, however some of them start meiosis, arresting at the diplotene stage of meiosis 1(stage when crossing over occurs). These are now called primary oocytes. The number of germ cells in the ovaries reaches its maximum at about 5 months of gestation, at around 7 million. After 5 months, a portion of oogonia and primary oocytes begin to degenerate becoming atretic. By the 7 th month, most cells hav degenerated except for those near the surface, these have all entered meiosis 1 and most are surrounded by a layer of epithelial cells. A primary oocyte together with the epithelial cells is c...