TEST 1 SAQ : Intro-Tissue Flashcards
Describe the negative feedback system in blood glucose and temperature homeostasis
Stimulus: Blood glucose levels rise after eating
Detected by pancreas –> releases insulin
Insulin facilitates glucose uptake by cells
Insulin stimulates liver to convert glucose to glycogen for storage
Stimulus: Blood glucose levels drop
Detected by pancreas –> releases glucagon
Glucagon signals liver to break down glycogen into glucose
Glucose released into bloodstream
Stimulus: Body temperature rises
Detected by thermoreceptors in skin and brain
Signal sent to hypothalamus
Hypothalamus activates sweating
Blood vessels dilate (vasodilation) to release heat
Stimulus: Body temperature drops
Detected by thermoreceptors in skin and brain
Signal sent to hypothalamus
Hypothalamus activates shivering
Blood vessels constrict (vasoconstriction) to conserve heat
Explain how blood clotting and child birthing work via positive feedback mechanisms.
Stimulus: Labor begins, fetus head presses against cervix
Detected by stretch receptors in cervix
Signal sent to hypothalamus
Hypothalamus releases oxytocin
Oxytocin stimulates uterine contractions
Stronger contractions push fetus against cervix
Stretch receptors in cervix further stimulated
Signal sent to hypothalamus for more oxytocin release
Positive feedback loop continues until birth
Stimulus: Blood vessel injury
Platelets adhere to site of injury
Release of chemicals (e.g., thromboxane)
Chemicals attract more platelets to injury site
Platelets release additional chemicals
Chemical cascade accelerates platelet aggregation
Formation of stable blood clot to seal wound
Positive feedback loop continues until clotting is complete
List down the types of bonds and explain each in detail.
Ionic Bonds
* Electrons are transferred /donated
* Atom losing electron – cation and atom gaining electron – anion
* Resulting ions attract each other due to opposite charges.
- Covalent Bonds
* Electrons are shared between atoms
* Types
* based on number of electrons shared (single, double, triple)
* strength of the bond (polar and non-polar)
List down the functions of lipids and proteins
Functions of Lipids
* Essential structural components of cell – cholesterol and phospholipid*
* Next source of energy next to carbohydrate; energy reserves -twice the amount of energy
carbohydrate
* Insulation - help maintain body temperature
* Cushion effect - protect body against knocks and injuries
Functions of proteins
* Support - structural proteins
* Movement - contractile proteins cause muscular contraction
* Transport -transport proteins carry gases –e.g hemoglobin
* Metabolic regulation- that catalyse chemical reactions -enzymes
* Defense – antibody, tough protein coats of skin, nails
List down the types and functions of nucleic acids
2 types
Deoxyribonucleic acid ( DNA )
Ribonucleic acid ( RNA )
Differences:
Sugar: Deoxy ribose/Ribose
Strands: Two/One
Base difference: thymine/uracil
Function: inheritance/protein synthesis
Explain the components and functions of cell membrane
Composed of:
1. Lipids
1. Phospholipids
* Major component in the cell membrane - Arranged in bilayer
* Hydrophilic (likes water) head
* Hydrophobic (hates water)Tail
2. In between phospholipid layer, have cholesterol
- Carbohydrates
- Glycolipids - made of carbohydrates and lipids
- Glycoproteins - made of carbohydrates and proteins
- Proteins
- Transmembrane proteins extends throughout the membrane from inside to outside(e.g., channels)
- Surface proteins found only on the surface (e.g., receptors)
Define osmosis? what happens to RBC in different tonic solution
ovement of water molecules from higher water concentration zone to lower water concentration zone across a semi-permeable
membrane (where solutes cannot move)
- RBC in hypotonic solution
- Water concentration of solution is more than water concentration in RBC
- Water moves into the cell
–> increased water content in cell –> cell bursts or lyses - RBC in hypertonic solution
- Water concentration of solution less than water concentration in cytoplasm
- Water moves out of the cell–>outside–>cell shrinks (crenation)
- RBC in isotonic solution
- Water concentration of solution is equal to water concentration in cytoplasm
- No water movement across the cell
List down the phases of mitosis and explain each phase.
Mitosis is divided into 4 stages, followed by Cytokinesis
o Mitosis divided into 4 stages
- Prophase
- Chromatin becomes chromosomes
- Centrioles appear at the poles – forms spindle
- Metaphase
- Chromosome line up at midplane of the cell
- Anaphase
- Chromosome pair separate –>chromatid–> pulled by spindle to poles
- Telophase
- Nucleolus & nuclear membrane for the daughter cells reappear
- Mitotic spindle disappears, chromosomes becomes chromatin
o Cytokinesis
* Cytoplasm separates
Define exocrine glands. List and briefly explain the types of exocrine glands.
Exocrine glands - glands secretes mucous/ serous / both, secrete onto epithelial surfaces
through ducts
o Merocrine secretion- Secretions produced is released as vesicles. E.g. Sweat -sweat gland
o Apocrine secretion - Part of the cell breaks and released as secretion e.g., milk - mammary glands
o Holocrine secretion - cells bursts to release the secretion. E.g Sebum - Sebaceous glands
Explain the structure, location and function of simple columnar epithelium.
Structure - single layer of tall, thin cells; nucleus towards bottom
Location - Stomach, intestinal lining, gall bladder
Functions - Secretion, absorption