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
What do neutrophils do?
They kill/ingest bacteria
What are the substances reabsorbed and filtered by the kidney
Water
NaCl
Glucose - unless glucose is <200mg/100ml in blood
H+
Urea - 2/3 out, 1/3 reabsorbed
Toxic substances
Interlobular artery -> afferent arteriole -> Glomerulus -> efferent arteriole -> peritubular capillaries
Route of blood in the nephron
Bowman’s capsule -> Proximal CT -> Loop of Henle -> Distil CT -> Collecting ducts
What is the point where the afferent artery joins with the glomerulus?
Juxtaglomerular apparatus
How does water move in the body?
Through salt movement concentration gradients and hydrostatic forces
Peritubular capillaries which surround the nephron reabsorb contents inside to take back into the body
Excretion =
(Filtered+secreted)-reabsorbed
What are the three layers of filtration membrane
Endothelial cells, basement layer, podocyte
What components can’t go through the bowman’s capsule
Proteins - due to basement membrane being negatively charged
Cells
Anything bigger than 7nm can’t go through
What is Hematuria?
Blood in urine
Countercurrent multiplier further reabsorbs NaCl and H2O
What is the structure of of the nephron
Glomerulus, bowman’s capsule, Proximal CT, Loop of Henle, Distil CT, Collecting Duct
Reabsorption of NA
Lumen high concentration gradient to tubule cell, so moves passively (facilitated diffusion), then from the tubule cell Na is actively transported to the interstitial fluid, where it then again follows a gradient into the peritubular capillary
What does ANP do? (Atrial natriuretic peptide)
Increased of excretion of Na+, less reabsorbed in kidney (released from right atrium when blood volume increases)
Somatic system is…
Voluntary, you have control over it
Bladder is hollow and is surrounded by smooth muscle
The detrusor muscle is responsible for…
Contracting which pushes the urine out of it in coordination with the bladder neck opening
What causes the voiding phase of the bladder?
When the bladder has reached it’s max stretching a signal is sent to the brain. Voluntary signals relax the external sphincter and the detrusor muscle contracts
What are the male reproductive organs?
Testes and penis
What are the other components of the male reproductive system?
Ducts - epididymis, ductus deferens, urethra
Glands - seminal vesicles, prostate
The testis contains:
Seminiferous tubules - produces sperm
Rente testis
Epididymis - maturation of sperm
Ductus deferens
Ledig cells - produces testosterone
What are the gonads?
The ovaries or testes
Describe spermatogenesis
Spermatagonia -> mitosis -> spermatocytes -> meiosis -> spermatids -> differentiation -> spermatozoa
The cells from seminiferous tubules move from there, through the rete testis and are stored in the epididymis
The Endometrium membranes are
Stratum compactum
Stratum spongiosum
Stratum basale - thing that is released during menstruation
Where does fertilisation occur?
Ampulla
What are the three main hormones in reproduction
Oestrogens
Androgens
Progestogens
Where is progesterone generated?
Corpus luteum, if fertilisation is successful then placenta also does
Where is testosterone generated?
Testes (leydig cells), ovaries, placenta, adrenals
Where is
During inspiration the thoracic volume increases, so the pressure decreases, which means it is lower than the pressure outside so air is sucked in
During expiration the thoracic volume decreased, so the pressure increases, which means the pressure inside is lower than atmospheric pressure so air moves out
Respiration of signals from respiratory centre in medulla oblongata cause the contraction of the intercostal muscles moving the diaphragm down which increases thoracic cavity
Respiratory volumes and capacities
Volumes - amount of air movement during different portions of ventilation
Capacities - sums of two or more respiratory volumes
What is tidal volumes
The amount of gas which is expired/inspired in one breathing cycle
What is the inspirators and expiratory reserve volume?
The amount of air which can be breathed in forcefully beyond tidal volume
The amount of air which can be forced out past tidal volume
Capacity is two or more volumes together
Total lung capacity is the vital capacity + residual volume
Peak expiration flow measures…
How quickly you can blow air out of your lungs
Measure in L/min
Ventilation is the ability to get air to the alveoli
Perfusion is the ability to ensure blood gets to the alveoli
Gas exchange is dependent on…
Thickness of membrane
Surface area of membrane
The partial pressure of the gases that go through the membrane
Blood in tissue has a lower partial pressure for O2 and a higher one for CO2, why is that?
The blood is deoxygenated as it has been used, this allows for o2 to diffuse into the blood from the lungs as there is a concentration gradient. O2 in greater supply in lungs than in deoxygenated blood
Chemical control of breathing is due to…
CO2 levels in blood
Increase in H+ ions increases ventilation
Parasympathetic releases what neurotransmitter?
Acetylcholine
Sympathetic system releases what neurotransmitter?
Noradrenaline to adrenergic receptors
Inspiration is a… active or passive process?
Active, muscle contracts
Expiration is… active or passive?
Passive, muscle relaxation
Static measurements measure how much air can be inhaled/inhaled can be used to find out if you have a…
Restrictive airway diseases
Dynamic measurements measure air flow which can help you identify a…
Obstructive airway disease
What are symptoms of asthma?
Shortness/ variable breathlessness
Chest tightness or pain
Wheezing
