biosciences

• Cerebellum

  Balance and coordination
• T3 and T4 production

  Thyrotropin-releasing hormone released from hypothalamus, thyroid stimulating hormone released from anterior pituitary, T3 and T4 released from thyroid gland
• CNS vs PNS

  CNS: receives information, processes, responds to sensory information

  PNS: all nervous tissue outside CNS
• Pleural membrane

  Double-layered serous membrane that encloses and protects each lung. Contains pleural fluid.

  - Visceral: attached to lungs

  - Parietal: attached to chest cavity
• Small intestine

  Site of most enzymatic digestion and absorption.

  - Facilitates segmentation (mixing of chyme) and peristalsis

  - Duodenum, Jejunum, Ileum
• Oogenesis

  Sequence of events which lead to mature gametes.

  - Development begins in utero, then continues at puberty

  - One primary oocyte selected to mature each monthly cycle
• Spermatogenesis

  Production of sperm cells.

  -occurs in semiferous tubules, begins at puberty
• Pre-ovulatory phase

  Follicular changes: FSH acts on primary follicle, which develops into secondary follicle. FSH secretion causes maturation of follicle into tertiary, which secretes oestrogen.

  Endometrial changes: Oestrogen from maturing follicle causes thickening of recently shed layer of endometrium,
• Ovulation phase

  Follicular changes: Lutenising Hormone levels surge, causing rupture of mature follicle and release of ovum from ovary. Remaining follicular cells start to develop into corpus luteum.

  Endometrial changes: No large change; endometrium is still thickening
• Corpus Luteum

  Endocrine tissue which produces hormones, estrogen, and progesterone which prepares the uterine lining for receiving an embryo
• Post-ovulatory phase (successful implantation)

  Follicular changes: Corpus luteum does not degenerate.

  Embryo secretes hormone called human chorionic gonadotropin, which mimics LH and keeps corpus luteum alive until placenta develops
• Post ovulatory phase (no implantation)

  Follicular change: Remaining follicular cells have fully developed into corpus luteum, which secrete oestrogen and progesterone. Corpus luteum degenerates into corpus albicans, causing cessation of oestrogen and progesterone production.

  Endometrial change: Thickens further due to oestrogen and progesterone, top layer sheds (menstruation)
• Muscle regeneration

  - Skeletal: cannot divided after 1st year, only enlargement of existing cells. Some regeneration available

  - Cardiac: Cannot divide or regenerate

  - Smooth: Can grow in size and number, regeneration possible
• Loose connective tissue

  Loose: mostly cells, nourish and cushion epithelia, found in underlining of epithelia
• dense regular connective tissue

  Mostly fibres, enhance tensile strength and resistance to stretching in ONE DIRECTION
• dense irregular connective tissue

  Greater strength in ALL DIRECTIONS, protect organs against injury
• Fluid connective tissue

  Blood: transports nutrients

  Lymph: Drainage of excess interstitial fluid
• Collecting duct

  Filtrate is carries through osmotic gradient in renal medulla, water may be absorbed by body
• Papillary duct

  Collects filtrate from multiple collecting ducts, delivers it to minor calyx
• Types of muscle

  Skeletal: Attached to bone, voluntary movement, striated

  Cardiac: Heart tissue, involuntary movement, striated

  Smooth: Walls of hollow organs, airways and blood vessels, non-striated

  
• 4 properties of muscular tissue

  electrical excitability, contractility, extensibility, elasticity
• Proximal convoluted tubule

  Reabsorption of essential substances (mostly ions) from the filtrate back into blood.

  
• Loop of Henle

  - Descending = reabsorption of water into blood

  - Ascending = reabsorption of Na+ and Cl- from filtrate

  
• distal convoluted tubule

  Selective reabsorption and secretion occur here, most notably to regulate reabsorption of water and sodium

  
• CNS neuroglia

  - Astrocytes: most common, support and protection of neurons

  -Oligodenrocytes: maintain myelin sheath

  - Microglia: function as phagocytes, remove cellular debris

  
• Function division of GIT

  Upper: food breakdown

  - Mouth, oesophagus, stomach, small intestine

  Lower: Absorption and waster

  - Small intestine, large intestine
• pituitary glands

  - Posterior: direct extension of hypothalamus. Communication occurs via hormones sent directly from hypothalamus through neurosecretory cells

  - Anterior: Attached to posterior gland. Communication occurs via hormones related into capillaries surrounding AP.

  
• Oesophagus GIT wall layers

  1. Stratified squamous epithelium

  2. Submucosa: contains oesophageal glands secreting mucus

  3. Muscularis externa: muscle

  4. Adventitia: connective tissue
• Stomach GIT wall

  1. Simple columnar epithelium, aids in secretion

  2. Submucosa: Contains blood vessels, provides support

  3. Muscularis externa: three layers for churning and mixing

  4. Serosa: Friction-free surface

  
• Small intestine GIT

  Epithelium: Simple columnar with microvilli and goblet cells secreting mucous

  Submucosa: Contains glands secreting alkaline mucous

  Muscularis externa: Facilitate peristalsis

  Serosa: Smooth outer surface
• Large intestine GIT wall

  1. Simple columnar with goblet cells for mucous secretion

  2. Submucosa: Support, houses blood vessels

  3. Muscularis externa: Movement and compaction of faeces

  4. Serosa/adventitia: Serosa covers the peritoneal cavity, adventitia is present in retroperitoneal sections
• Posterior pituitary hormones

  Antidiuretic hormone and oxytocin
• Anterior pituitary hormones

  Short axon neurons in hypothalamus synthesise hypo-physiotropic hormones. Blood vessels carry these to AP.
• Water soluble hormones

  Cannot diffuse through plasma membrane, free hormone diffuses out of blood and binds to target cell receptor on plasma membrane surface.

  - Alters protein ACTIVITY
• Lipid soluble hormones:

  Diffuses out of blood into ECF, diffuses through plasma membrane and binds to target cell receptor in cytosol or nucleus

  - Activates genes to trigger response, alters protein SYNTHESIS
• Gonadotropic hormones

  Secreted by AP in response to gonadotropin-releasing hormone
• Lutenising hormone

  Surge causes ovulation of ovum from follicle + formation of corpus luteum
• Follicle stimulating hormone

  Stimulates follicle development
• Graded potential vs action potential

  -graded potential: small deviation from the resting membrane potential that makes the membrane either more polarized or less polarized; occurs when a stimulus causes mechanically-gated or ligand-gated channels to open or close in an excitable cell's plasma membrane

  
  

  -action potential (aka impulse): a sequence of rapidly occurring events that decrease and reverse the membrane potential and then eventually restore it to the resting state; occurs in the axon of a neuron when depolarization reaches a certain level termed the threshold (-55mV)
• 4 major brain sections

  1. Cerebrum: balance and coordination

  2. Diencephalon (thalamus, hypothalamus): Consciousness, learning

  3. Brainstem (midbrain, medulla oblongata): Breathing, heart rate, BP

  4. Cerebellum: Balance + coordination