Week 2 - Homeostasis And Control Systems, Basic Tissues Flashcards
what is the foundation of homeostasis?
Negative feedback
How does negative feedback work in the body?
A sensor (e.g. baroreceptor) detects a change, which is relayed to an integrating sensor in the body, which relays a signal to an effector (muscle or gland) which then changes a variable to negate the initial change.
How is blood pressure regulated?
Baroreceptors detect changes in blood pressure, which then sends a signal down the glosso-pharyngeal nerve to the medulla oblongata in the brain. This then relays a signal via autonomic nerves to the heart blood vessels, which then accordingly adjusts the blood pressure.
What is positive feedback?
When an initial stimulus causes a response which reinforces itself (e.g. nerve action potential, ovulation, blood clotting)
What are the 2 control systems in the body?
Nervous system and endocrine system
How is the nervous system divided?
Central nervous system in spine
Somatic nerves - conscious action in skeletal muscles
Autonomic nerves - divided into parasympathetic and sympathetic nervous system.
Which regions of the spine (CNS) are allocated to which parts of the autonomic NS?
Parasympathetic - top and bottom of spine (cranial, cervical, sacral)
Sympathetic - middle (thoracic, lumbar)
Which neurotransmitters are released by the sympathetic and parasympathetic NS?
Symp - noradrenaline
Para - acetylcholine
How are the preganglionic fibres shaped in symp and parasymp?
Symp - short
Parasymp - long
(Sympathetic nervous system is a grower, parasympathetic is a shower)
How are the postganglionic fibres shaped in symp and parasymp?
Symp - long
Para - short
(Sympathetic nervous system is a grower, parasympathetic is a shower and has performance anxiety)
When is the sympathetic NS active?
Stressful situations (fight or flight)
When is the parasympathetic NS active?
Vegetative situations (rest and digest)
What are the 4 basic tissues
Epithelia, connective tissue, muscle, nervous
What is the function of epithelia?
Act as cover surfaces (e.g. skin)
Line cavities and tubes
Form glands
What is the general structure of epithelia
Loosely packed cells supported by a basement membrane
Has 2 sides - lumen / surface side (apical side), and basement membrane side (basal side)
How is epithelia classified?
Based on number of cell layers and cell shape
Cell layers
- one layer = simple
- more than one layer - stratified
Cell shape
- flat = squamous
- cube = cuboidal
- rectangle = columnar
Simple squamous epithelium (5 facts)
- flat cells
- oval nuclei
- one cell layer
- major function - gas + nutrient exchange
- location - blood vessels, alveoli
Keratinised stratified squamous (5 facts)
- flat surface cells w/ oval shaped nuclei
- many layers (stratified)
- keratin producing
- function - protection, waterproof barrier
- location - skin
Non-Keratinised stratified squamous (4 facts)
-Flat surface cells w/ oval nuclei
- many layers
- function - protection, barrier
- location - oral cavity, oesophagus
Simple cuboidal epithelium (4 facts)
Square cells w/ round nuclei
One layer
Function - secretion / absorption
Location - glands, kidney tubules
Simple columnar (5 facts)
Tall cells w oval, basally located nuclei
One layer
Function - absorption + secretion
Location - gastrointestinal tract
Surface mods - microvilli
Pseudostratified ciliated columnar epithelium with goblet cells (6 facts)
Tall
Appears stratified as some cells don’t reach free surface
All cells touch basement membrane
Mods - cilia + goblet cells
Location - trachea + large respiratory airways
Function - mucociliary escalator
What are intercellular junctions
Specialised areas of cell membrane that binds 1 cell to another
What are the 4 intercellular junctions
Desmosomes
Hemidesmosomes
Tight junctions
Gap junctions
