Topic 5a - Homeostasis... Flashcards
What internal conditions are under homeostatic control?
[gases] eg. O2, CO2
temp
[salt]
pH
Ectotherms…?
fish, reptiles, amphibians
Endotherms…?
mammals, birds
Behavioural mechanisms in ectotherms…?
sunbaking & burrowing
Behavioural mechanisms in endotherms…?
shivering, elevating metabolic rate, sweating/panting
Re. thermoregulation in humans, what are the 2 phases?
phase 1 - behavioural
phase 2 - physiological
What are examples of human physiological phases of thermoregulation in response to decreased & increased core temperature…?
Decreased temp - vasoconstriction, increased metabolic rate, shivering, hair raised
Increased temp - vasodilation, decreased metabolic rate, sweating, hair lowered
What structures comprise the integumentary system?
skin, hair, nails, sensory receptors, various glands
What structures comprise the endocrine system?
hormone-secreting glands & organs including hypothalamus, pituitary, thyroid, pancreas, adrenals, ovaries, testes
What are the 4 tissue types?
Epithelial
Connective
Muscle
Nervous
What is epithelial tissue…?
Sheets of tissue lining the external & internal surfaces of the body:
skin
lining of GIT
lining of circulatory system
What’s under epithelial tissue?
proteinaceous basement membrane
Cells lining the lungs…?
Simple epithelium - flattened cells & basement membrane
Cells lining the trachea…?
Simple epithelium - mucous-producing cells with cilia & basement membrane
Cells lining the skin…? (outer to inner)
Stratified epithelium - dead cells, flattened dying cells, differentiating cells, dividing cells, basement membrane
Characteristics of connective tissue…?
lots of fluid & proteins (mainly collagen)
Connective tissue embedded in the … component?
fluid
What are the 3 main types of connective tissue?
- loose (forms membranes with epithelial cells)
- dense (ligaments & tendons)
- specialised (cartilage, bone, adipose, blood etc)
Different muscle tissues…?
skeletal
cardiac
smooth
In nerve tissue, … provides support & produces … that controls propagation of electrical signals?
glial cells provide support & produce insulation (myelin)
Organs are…?
composed of at least 2 types of tissue that function together (usually all 4 tissue types are found)
Tissue cells of the epidermis contain…? (most superficial layer)
dead cells
living epidermal cells
What lies within the dermis…? (middle layer) (think skin diagram)
hair follicles, sebaceous gland, sensory nerve endings, sweat glands, muscle (pulls hairs upright), arterioles & venules
What lies in the subdermal & connective & adipose tissue layer? Bottom layer
adipose and vasculature
Different forms of cell-cell communication…?
direct
synaptic
paracrine
endocrine
Outline direct communication… eg?
cells in direct contact
ions flows to and fro via gap junctions
eg. cardiac cells
Outline “remote” communication…
- mediated by chemicals released by one cell type & received by another
- receptor proteins in target cells bind to chemical signal
- secreted substances only influence target cells
Example of synaptic communication…?
neurotransmitters that transmit signals from cell to cell
Outline paracrine hormones… eg?
chemicals released cause response in nearby cells - localised & short-lived
eg. prostaglandins
Outline endocrine hormones… eg?
chemicals secreted into the bloodstream - target cells can be far away from secreting cells
effects can be long or short-lived
eg. insulin
3 main classes of hormones…? eg?
peptides (eg. insulin)
modified AAs (Noradrenaline)
steroids (testosterone)
2 basic types of hormonal response mechanism…?
peptide & modified AAs
steroids
Describe how peptide & modified AA hormones work…
bind to receptor on membrane of target cell -> activates 2nd messenger system (cAMP) -> activates other enzymes -> enzymes catalyse specific reactions -> product
Describe how steroids hormones work…
diffuses thru plasma membrane -> binds to receptor in nucleus (or to one in cytoplasm that carries it into nucleus) -> hormone-receptor complex binds to DNA & causes RNA polymerase to bind to promoter site for gene -> transcription (DNA -> mRNA) -> mRNA fucks off into cytoplasm, attaches to ribosome & synthesises specific protein
