Stru and Fuc

Pericardium

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* Free movement serous (watery) pericardium – lubricating fluid. Secretes watery fluid in the space between its 2 parts. Like oil. Contains hyaluronan. Heart can slide relative to the things around it. 
* Prevention of over-expansion, fibrous pericardium. 
* The part covering the heart is the visceral pericardial and is directly connected to the heart.

Hear great vessels

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* Superior vena cava – blood from head/top of body 
* Inferior vena cava – blood from rest of body 
* Pulmonary trunk
* Aorta
* Blood pumps from right ventricle to the pulmonary trunk then to the pulmonary artery. 

**Foetal circulation and the heart:** 

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* Foramen ovale: site of a flap-like valve between R and L atria. 
* Lungs are not used by foetus 
* Blood and gases exchange at placenta 
* Therefore most blood bypasses lungs by going through foramen ovale from right to left side of the heart. 
* Another route: Ductus arteriosus between pulmonary trunk and aorta. = arterial ligament 
* Foramen closes during newborn’s first breath, then seals permanently  
* Although sometimes doesn’t seal – hole in the heart 
* Ductus goes into spasm & closes - eventually fuses shut & becomes fibrous tissue  

 

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Layers of heart

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* Endocardium: lining 
* Myocardium: muscle layer 
* Epicardium: visceral pericardium. 

Structure of blood vessels

* Tunica Intima: endothelium and connective tissue 
* Tunica Media: smooth muscle and connective tissue 
* Tunica Adeventitia: Connective tissue 

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* IEL: internal elastic lamina 
* EEL: external elastic lamina 
* IEL and EEL: boundaries to tunica media 
* Smooth muscle cells arranged circularly around the vessel, controls diameter.

types of endothelium

* 3 types: continuous, fenestrated and discontinuous 

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Continuous endothelium

* Continuous: In most capillaries, exchange solutes and gases. 
* Fenerstr

Fenestrated endothelium

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* Fenestrated: Capillaries in endocrine glands, exchange larger molecules and hormones. 

Dis

Discontinuous endothelium

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* Discontinuous: In sinusoids, exchange whole cells. 
* Can turn discontinuous to continuous if under correct conditions and under induction of chemicals. 

tunical intima

* ne way flow. 
* Valves point to the heart. 

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* Arterial pulse massage helps to massage blood in veins past valves as run near each other. Muscle contraction squeezes veins and moves blood through valves. 

Circulation heart components

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* blood/haemolymph pressure: dynamic pressure produced by the pump, and hydrostatic pressure of the fluid –hydrostatic mainly constant. 
* Flow rate = pressure gradient/resistance. 

Smooth muscles altered by

* Neurotransmitters e.g. noradrenaline, acetylcholine
* Hormones e.g. adrenaline, vasopressin
* Endothelium-derived substances e.g. endothelin, NO
* Metabolites and related factors- hypoxia, CO2 and H+
* Other locally –produced factors e.g. histamine, prostaglandin

Other factors e.g. pressure, heat

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Salivary glands

* Parotid: serous 
* Submandibular: seromucous, inferior to the tongue  
* Sublingual: mucous 

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* Secretion on demand. 
* Parotic gland: Very long duct, runny serous secretion, runs over the top of chewing muscles, enters mouth by 2nd upper molar. 


* Submandibular and sublingual 

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* Hundreds of minor salivary glands: secrete continuously, keeps mouth moist

Cephalic phase

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* associated with is the response by your body to initiate the digestive process, even before the food has entered the body= CNS involved 

Layers of gut

1\. Mucosa

2\. Submucosa

3\. Muscularis externa

4\. Adventitia or serosa

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Function of TSH

allow more iodide to be actively transported into the colloid so that tyrosine is iodinated to form either MIT or DIT = T3 into T4

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SNS transmitters

 pre ganglionic - acetylcholine 

\- post ganglionic - noradrenaline 

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PNS transmitters

acetylcholine

Oral cavity regions

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* Lining = oral mucosa 
* 3 basic regions: Masticatory mucosa, specialized mucosa (tongue) and ordinary lining mucosa (everywhere else).

ileo-caecal junction

**food present in this area after 4 hrs swallowing** 

= stomach

Stomach phases

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* Cephalic(impact brain has on digestion before digestion, smells, thoughts etc. Can increase and decrease desire for food) 
* Gastric (Stretch and chemo receptors peristalsis stimulates, gastrin release from g cells, inhibited at pH

Pancrease role

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* Secretes digestive enzymes 
* Can respond to neuronal input 
* CCK and secretin act on the pancreas, stimulating it 
* CCK bile sac contraction. Food enter duodenum, CCK is released from duodenum, slows stomach down and stimulates contraction of the gall bladder. Gall bladder squirts bile into the duodenum which emulsifies fats. Also, makes you feel full. 
* Secretin promotes the production and secretion of bile from the liver to the gall bladder. 

Secretin

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* promotes the production and secretion of bile from the liver to the gall bladder. 
* from s-cells in the duodenum

Loss of intake food signals

* CCK: Secreted in response to food, acts in the brain in hypothalamus neurotransmitter to inhibit eating, reduces appetite and inhibits eating. 
* Glucagon-like peptide-1: from intestine, in response to food. 
* Peptide YY: from intestine in response to food.  

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Peripheral hunger

* intestine releases ghrelin, peaks before you're aware of feeling, makes you feel hungry, increases food intake, secreted by endocrine cells of gastric mucosa, increases hunger, growth hormone secretion and fat stores, and also acts on **GHSR in hypothalamus** , growth hormone secretagogue receptors

 

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Long term lack of hunger

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* Leptin, insulin, oestrogen. 

Leptin

Produced by adipose tissue, leptin suppresses long-term appetite. POMC (pro-opiomelanocortin) and CART (cocaine-amphetamine-regulated transcript) are stimulated by leptin. Increases activity of melanocortin pathway

**NPY/AgRP neurons:** 

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* Suppressed by insulin and leptin 
* Stimulation releases NPY and AgRP 
* Neurotransmitters in hypothalamus 
* NPY: Activates its receptor which are GPCR, stimulates eating 
* AgRP: Binds to and inhibits MC4R (receptors), inhibits anorexigenic effects of alpha-MSH

Rumen

**Reticulo-Rumen microorganisms:** 

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* 10-20% of live weight.  
* Cows produce 150L of saliva per day. Contents are 85%-93% water.  
* Ruminal papillae = finger like projections.  
* Stratified squamous epithelium – keratinized. 

**Reticulo-Rumen microorganisms:** 

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* Fermentation produces **volatile fatty acids (VFAs) which are absorbed,** gas & more microorganisms 
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* Heterotrophic and Autotrophic (inc. methanogens) 
* Chemostat 
* Complex interrelationships – methanogens reduce efficiency but impact on growth of other species. 

Reticulum

Keratinised stratified squamous epithelium

honeycomb tripe

Omasum

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* egulates entry of food into the abomasum 
* May return food to the reticulo-rumen 
* Water and VFA absorption 

Abomasum

True stomach

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* Glandular 
* Gastric pits 
* Parietal & Chief

Cellulose digestion: 

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* **90% of cellulose digestion is in the reticulorumen** 

__**FLUID ENERGY:**__

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* Potential energy acquired from the beating of the heart
* Kinetic energy of the fluid itself 
* Potential energy of the fluid that it possesses as its position in the gravitational field 
* Fluid flows from where its total fluid energy is higher to where its total fluid energy is lower

__**HYDROSTATIC PRESSURE:**__

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* Dynamis pressure produced by the pump 
* Hydrostatic pressure of the fluid 

Open circulation

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* Incomplete system of vessels 
* Circulating fluid = haemolymph 
* Haemolymph (contains sugars and proteins) flows through vessels and freely percolates through intercellular spaces
* Heart may propel the haemolymph through vessels

__**Closed circulation**__

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* Complete and continuous system of blood vessels 
* Fluid in vessels is blood 
* Heart propels blood through vessels
* Intercellular spaces filled with interstitial fluid (composition different from blood)
* Lymph in lymphatic vessels

p wave

atria depolarisation

t wave

re polar of ventricles

QRS complex

deplo of ventricles

PR interval

conduction via AV node

QT duration

ventricular repol and depol

Events cardiac sys

* atrial sys
* isovol contraction of ventricles
* ventricular ejection
* isovolumic relaxation
* passive filling of ventricles

Plicae circulares

folds of the submucosal folds/ allow for more villi as provide bigger surface area

Villi- mucosal folds

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Calcitonin

secreted by C-cells of the thyroid gland, it is only of minor importance in adults, it lowers the level of free plasma calcium, it inhibits osteoclast activity so bone absorption is reduced, and it increases excretion of calcium and phosphate by the kidneys

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PTH

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* Peptide hormone 
* Stored within the chief cells (in parathyroid gland)
* Half life of 5 minutes
* Secreted continuously at a low rate
* Released in **response to low blood calcium**
* Exerts it effects on bone, gut and kidneys

Vitamin D

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* Converted to 1,25 dihydroxycholecalciferol
* AKA: 1,25-dihydroxyvitamin D
* AKA: 1,25-(OH)2D3
* AKA: Calcitriol

__Actions of Calcitriol:__

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* Acts on cells on the GIT to increased production of calcium transport proteins 
* Leads to an increase in Calcium uptake from GIT, acts on cells in duodenum to increase transport
* Only mech that takes calcium into circulation
*  Vitamin D is converted into calcitriol using the enzyme 1α-hydroxylase that is activated using PTH. 
* Calcitriol (which is a steroid hormone) will then increase the production of calcium transport protein. 
* The only mechanism that can increase calcium stores
* Bone: Increasing rate of bone resorption

Adrenal medulla

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* Modified part of the sympathetic nervous system 
* Cortex made up of layers before inner medulla is met
* Enlarged and specialize sympathetic ganglion
* Secrete catecholamine hormones: adrenaline (epinephrine), noradrenaline (norepinephrine)

Hormones of Adrenal medulla

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* Secrete catecholamine hormones: adrenaline (epinephrine), noradrenaline (norepinephrine)

Adrenal cortex zones

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*  **Zona Glomerulosa** - Mineralocorticoids (Aldosterone) = (controls mineral/salts)
*  **Zona Fasciculata** – Glucocorticoids (Cortisol) = (increase blood glucose levels)
*  **Zona Reticularis** –  Gondocorticoids (Androgens) = (sex hormone)

DHEA

* Adrenal glands produce Dehydroepiandrosterone(**DHEA**), dehydroepiandrosterone sulfate (**DHEA-S**), and androstenedione.


* Testosterone (& Oestrogen) precursors
* Converted to testosterone in peripheral tissues


* Compared to testosterone, DHEA and DHEA-S bind less efficiently to the androgen receptors (weak steroids)

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* Controlled by **ACTH** (anterior pituitary)

receptors for sweet sour and salt

g protein

CORTISOL

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Mediates the body’s response to stress in response to endocrine signals, stress powerful stimulator of cortisol production, physical trauma, intense heat /cold/infection = stimulates glycogen breakdown 

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renin-angiotensin system (RAAS)

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* aldosterone
* Decreased ECF volume (hypovolaemia or hypotension) and decreased renal blood flow

  - Response to high plasma potassium

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CUSHINGS SYNDROME

* Overproduction of cortisol
* As a result of an adrenal tumour or pituitary tumour
* Redistribution of body fat
* Muscle wastage
* Thin skin, bruising abnormal pigmentation
* Changes in CHO and protein metabolism
* Hyperglyceamia
* Hypertension 

= Cortisol has weak mineralocorticoid activity

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__Conns disease:__

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really high blood pressure = xs aldosterone, normally due to a mass in outer adrenal cortex 

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__Addison’s disease:__

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* Damage to adrenal glands, autoimmune disease or pituitary damage
* Deficits in glucocorticoids and mineralocorticoids 
* Progressive weakness, lassitude and weight loss
* Pigmentation of the skin and mucosal membranes   

Excess ACTH act on the melanocytes to produce melanin (high pigmentation) (amino acid sequence of ACTH is strikingly similar to MSH)

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T4

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* 90% of thyroid hormone released is T4
* T3 has a much greater biological activity 
* Enzymatic conversion of T4 into T3 in peripheral tissues (liver, kidneys & skeletal muscle) = peripheral conversion 
* Drug L-thyroxine = chemically T4 but authentically made 

__Hashimoto’s disease:__

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•Autoimmune disease

•Antibodies against thyroglobulin or thyroid peroxidase (attacks them)

•Interferes with thyroid hormone synthesis

•Antibodies also against TSH receptor

•Prevents stimulation of T3 & T4 release

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__Grave’s disease:__

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Abnormal antibodies that mimic TSH (thyroid gland constantly stimulated)

•  Activates TSH receptor inducing T3/T4 release

• Characterised by goitre, exopthalmos and lid retraction

 Muscle weakness, heart palpitations, irritability

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Paracrine

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* produce hormone in cell that will influence cells next to it (not in circulation)

Autocrine

produces hormone and influences itself

Endocrine

hormone that enters circulation

types of hormone

* __Steroid hormones__ = cholesterol derivatives e.g testosterone 
* __Peptide hormones__ = growth hormones, oxytocin 

__Amino acid derived hormones__ = thyroid hormones

Oxytocin

* Interaction of oxycontin with receptors raises the level of intracellular calcium in the myoepithelial cells of the mammary gland 

= only cells that express specific receptor will respond to that hormone

__Anterior Pituitary:__

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__Anterior Pituitary:__

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* Growth hormone 
* Prolactin 
* ACTH
* TSH
* FSH
* LH

Somatopause

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* Decrease in lean body mass
* Decline in bone mineral density 
* Increase body fat 

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* Pituitary dwarfism 

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* Slow growth rate below 3rd centile on age/height or bone chart 
* Poor muscle development, excess subcutaneous fat 
* In adults has no major symptoms 

gigantism

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* GH excess (gigantism): abnormally high linear growth due to excessive action of IGF while the epiphyseal growth plates are open, normal body proportions as soft tissues also affected 

Acromegaly

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* (GH xs) increase growth hormone later in life after fusion of growth plates (epiphyses), enlarged hands/feet, deep voice, diabetes, usually due to pituitary tumour  

__Ascending Sensory pathways__ 

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* Dorsal column

Spinothalamic

Spinocervical

Spinoreticular

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areas of grey area

tha

* Basal ganglia (nuclei)
* Thalamus
* Hypothalamus

Basal ganglia

* A collection of nuclei which produce regulated movements.

\-Extrapyramidal motor control: Major inputs from cerebral cortex, thalamus and brainstem 

\-Major outputs to: thalamic nuclei, cortex (via thalamus) and brainstem

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thalamus

1\.Relays sensory pathways to cerebral cortex (ascending tracts).

2\.Activating the cerebral cortex – sleep & consciousness. 

3\.Emotional effects generating autonomic activity.

4\. Co-ordination of visual and motor activity.

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hypothalamus

1\.Responds to physiological, environmental and emotional changes that affect the autonomic nervous system.

2\.Part of the limbic system:

  -  involvement in thirst, hunger, appetite.

  - reproduction and associated behaviour.

3\.   Maintenance of homeostasis (e.g. body temperature and water/electrolyte balance). 

4\.  Neuroendocrine control – the pituitary gland.

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CPGS

network of neurons which produce rhythmic behaviors 

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__M- neurons;__

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* Most fish (and amphibians) have a large M-neurone on either side of the brainstem.
*  Large neurones (cell soma 100μm diameter) 


* Detect vibration by sensory input.
* Axon of the m-neurone crosses the midline and extends throughout spinal cord.
* Collaterals contact interneurones and motor neurones at all spinal levels.

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*  Unilateral muscle contraction.

cerebellum

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* **Vestibulocerebellum** = balance 
* **Spinocerebellum** – body raised off the ground
* **Neocerebellum** – connected to the cerebral cortex for motor coordination

Knee jerk tendon

Stimulate patellar tendon

kne

Knee jerk pathway

1\.Stimulate patellar tendon

2\.Activates stretch receptors or muscle spindles within the extensor muscle. 

3\.Activates sensory nerve.

4\.   Extensor muscle (quadriceps) contracts 

5\.   Flexor muscle (hamstring) relaxes.

Reciprocal inhibition occurs

in the spinal cord (interneuron = B on the diagram). There is no involvement of the brain

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Molluscan brain

buccal - feeding

cerebral - coordination

pleural - respiration

pedal - movement

Proprioceptors

Receptors monitoring  muscles and joints 

a) muscle spindles, b) Golgi tendon organs c) joint receptors

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__Chordotonal organ__ 

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is a stretch **receptor** which has its own tendon,

movement, detect position of the joint and the speed of movement. 

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tric receptors

 similar to the ampullae of  Lorenzini

•Producing the electric discharges is   

   energetically expensive

•  They can also be detected by some 

    predators

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Gonadal sex

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* XY/ZZ for testes and XX/ZW for ovaries

__Follicle development - stage 1__ 

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* Primordial follicles (present at birth)
* Primary oocyte, enclosed by single layer flattened follicular/granulosa cells and basal lamina= collagen type 4
* At puberty primordial follicles are stimulated = primary follicles 

__Stage 2:__

follicle

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* uni - layered 
* Oocyte enlarges and follicular cells increase in size = cuboidal 
* Oocyte produces zona pellucida (glycoproteins, important to build spermatozoa) = glycoproteins, important in binding of spermatozoa
* __Multi-layered:__

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* follicular/granulosa cells increase in number to increase thickness 
* Stratified 
* Zona pellucida assembled 

stage 3 follicle

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* Secondary follicle 
* Spaces develop containing follicular fluid = coalesce to form a cavity 
* Production of oestrogen by granulosa cells

stage 4 follicle

* Graafian (teritary) follicle 
* Antrum , large fluid filled cavity 
* Surrounded by **corona radiata** = “glowing crown”; nutrition

ovulation

* Proteolytic activity stimulated by gonadotropin (LH) = breakdown of collagen that surrounds it
* Oocyte expelled into entrance of the uterine tube 

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__Corpus Luteum__

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* ‘yellow body’

= Endocrine function follicular cells release progesterone and oestrogen, contain lots of apotsis tissues= breakdown if not fertilized → becomes scar tissues/copus albicans

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Collagen

Type 1: forms most connective tissues 

Type 2: cartilage only 

Type 3: prominent in embryonic tissues and tissue repair 

Type 4: forms flat sheets in basal lamina -> contains globular ends and normal ends that interact to form a web 

Type 5: does not exist 

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ABP

from sertoli cells targeted by FSH, binds to testosterone and promotes spermatogenesis in the seminiferous tubule, direct inhibition the production of GnRH 

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bone anatomy

Metaphysis - the site where bones will elongate/allow for growth.

 

Endosteum - inner tissue lining. Made up of connective tissue - mostly collagen. Highly cellular - responsible for breaking down and building the bone.

Periosteum - much more fibrous. Essential in healing. Made up of collagen and blood vessels.

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* __Epithelium of uterine tubes:__ 

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* 2 cell types : secretory (peg) (watery secretion for gamete nourishment), ciliated (cilia beat rate increases in response to oestrogen)

Oestrogen

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* Essential for ova maturation and release
* Establishment of female secondary sexual characteristics
* Essential for transport of sperm from vagina to fertilisation site
* Contribute to breast development in anticipation of lactation

Progesterone

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* Regulates the development of the endometrium
* Important in preparing suitable environment for nourishing a developing embryo/foetus
* Contributes to breasts’ ability to produce milk

follicular phase

28 days

produce oestogen