Week 7 human body systems - tissues and homeostasis Flashcards
Main types of tissue
-Connective tissue
-Epithelial tissue
-Muscle tissue
-Neural tissue
Connective tissue
Binds cell and organs: protects
support and integration
Epithelial tissue
Covers exterior, lines internal
cavities & some glands
Muscle tissue
Excitable, contracts: skeletal
(voluntary), smooth, cardiac
Neural tissue
Excitable: allows propagation of
nerve impulses that communicate between different parts of body
Tissue support
-Extracellular Matrix (matrix)
-Cell Junctions: hold cells together
Extracellular matrix
-Material synthesized and secreted by the cells of a tissue
-Proteoglycans (glycoproteins) and insoluble protein fibre (collagen, fibronectin, laminin)
-Very abundant in connective tissue
Cell Junctions
-Cell adhesion
molecules (CAMs)
membrane-spanning
proteins
-Cell junctions
-Gap/Communicating
-Tight
Connective tissue
Support / protect/ connect
Cells dispersed in matrix (proteoglycans & insoluble proteins)
May be watery or mineralised
True connective tissues
-Loose connective
tissue
-Dense connective
tissue
Loose connective tissue
-Adipose (fat)
-Reticular (soft organs)
Dense connective tissue
Regular:
-Tendon (muscle to
bone)
-Ligament (bone to
bone)
Irregular:
-Dermis
Supportive connective
tissue
-Cartilage
-Bone
Cartilage
-Hyaline
-Elastic
-Fibrocartilage
Fluid connective
tissue
-Blood
-Lymph
Epithelia
Protect/Regulate exchange
-One or more layers of cells
-Base: thin layer of matrix (basal lamina/membrane )
Epithelia Functions - Exchange
Simple, thin flattened cells (squamous),
gaps/pores
- e.g., rapid gas exchange
- Blood vessels (also called
endothelium) / lung
Epithelia Functions - Transporting
Simple, cuboidal or columnar
-Allow specific molecules to
be transported across them
Epithelia Functions - Cilated
Sweep fluids across surface
-Line respiratory trace/ female reproductive
Epithelia Functions - Protective
Prevent exchange
-Stacked layers of cells
-e.g., epidermis (skin)
Homeostasis
Physiologically, keeping the body’s environment in a state of
equilibrium within “normal limits”
Control of homeostasis
-Physiological response
-Reverses a change in a
controlled condition
Negative feedback loop
Negative feedback brings a system back to its level of normal functioning
Regulated variables maintained within their acceptable (normal) range by physiological control mechanisms kick in if the variable moves too far from
its set point, or optimum value
Regulation
Oscillations around a set point
Detectors have a threshold
-Minimal stimulus to set response in motion
Control: short distance or long
distance
Control systems - long distance
Input signal (stimulus) -> Intergrating system -> Output signal -> response
Intergration centres
Brain: Key
-Negative feedback: the response reduces the intensity of the stimulus the system is operating
-Positive feedback: the response enhances or intensifies the stimulus
-Examples of integrators: include the hypothalamus and the
pituitary (regions of the brain)
Long distance control - negative feedback
1) Stimulus - produces a change in variable
2) Receptor - detects change
3) Input - information sent along afferent pathway to control centre
4) Output - information sent along efferent pathway to effector
5) Response - effector feeds back to reduce the effect of stimulus and returns variable to homeostatic level
Afferent
Towards a centre
Efferent
Away from a centre
Circadian rhythms
Body temp set point changes throughout day (oscillations around set point occur)
Positive feedback loop
Not homeostasis
Positive feedback enhances or accelerates output created by an activated stimulus
-Strengthens or reinforces a change in a controlled condition
-Physiological response of effector reinforces the initial change
-Continues until interrupted by a
mechanism external to the loop
Outside factor required is to shut off positive feedback cycle
Reflex control
Reflex control consists of a
stimulus, an integrating centre
and a response
