Adipose Tissue Flashcards
What are the primary and secondary locations of adipose tissue in the human body?
Primarily beneath the skin, and secondarily around internal organs.
What percentage of body mass does adipose tissue represent in normal-weight men and women, respectively?
In men: 15–30%; in women: 20–25%.
How do adipocytes arise developmentally in connective tissue?
They are derived from primitive mesenchymal cells that differentiate into pre-adipocytes, transform into lipoblasts, and eventually mature into adipocytes.
What is the developmental sequence leading to a mature adipocyte?
Mesenchymal cell → pre-adipocyte → lipoblast → mature adipocyte.
How does the size of a mature adipocyte compare to other cell types?
It is significantly larger than most other cell types in connective tissue
In what forms can adipocytes be found within supporting tissue?
In isolation, in clumps within loose connective tissue, or as the dominant cell type in adipose tissue.
Trace the developmental origin of adipocytes from their primitive precursors.
Adipocytes are derived from primitive mesenchyme where they develop as lipoblasts.
Distinguish the role of lipoblasts in the maturation pathway of adipocytes.
Lipoblasts are the transitional cells in the adipocyte lineage, forming as pre-adipocytes accumulate fat on their way to becoming mature fat cells.
How does adipose tissue functionally differ from other loose connective tissues?
It is specialized for efficient fat storage, with adipocytes being the dominant and functionally specialized cell type.
What is the embryological origin of adipose tissue?
Adipose tissue originates from undifferentiated mesenchymal cells in the embryonic mesenchyme.
What transformation occurs in pre-adipocytes during their maturation?
They accumulate intracellular fat and differentiate into lipoblasts, which eventually become mature adipocytes.
Which other connective tissue cell type, aside from adipocytes, originates from undifferentiated mesenchymal cells?
Fibroblasts.
Under what physiological condition can mature unilocular fat cells revert to the lipoblast stage?
When a large amount of lipid is mobilized by the body.
List the three main sources from which adipocytes derive stored fat.
- Dietary fat as chylomicrons in bloodstreams; 2. Liver-synthesized triglycerides in circulation; 3. Triglycerides synthesized from glucose within adipocytes.
Why does adipose tissue possess a generally rich vascular supply?
To facilitate rapid transport and mobilization of lipids and hormones influencing fat metabolism.
The rate of lipid deposition and utilization in adipose tissue is primarily determined by _____ and _____.
Dietary intake and energy expenditure.
Which physiological systems and factors profoundly influence adipocyte fat metabolism beyond diet and energy usage?
Hormones and the sympathetic nervous system.
State four metabolic and regulatory roles of adipocytes.
- Energy storage; 2. Endocrine functions; 3. Secretion of proteins modulating metabolism; 4. Regulation of body mass in coordination with hormones like insulin.
Through secretion of several proteins, adipocytes modulate _____ and influence _____ in coordination with hormones such as _____.
Energy metabolism; general metabolism; insulin.
Identify six adipocytokines (proteins) secreted by adipose tissue.
Leptin, adipsin, resistin, adiponectin, TNF-alpha, and plasminogen activator inhibitor type 1.
Compare the anatomical distribution of adipose tissue with that of another connective tissue.
Adipose tissue is distributed throughout the body in the same general locations as areolar connective tissue.
List six specific anatomical locations of adipose tissue.
- Subcutaneous layer deep to skin; 2. Around the heart; 3. Around the kidneys; 4. Yellow marrow of long bones; 5. Padding around joints; 6. Posterior to the eyeball in the eye socket.
During tissue processing, lipid is removed from cells by _____ and _____, resulting in an empty vacuole surrounded by _____ that makes adipocytes appear as _____.
Alcohol; xylene; thin ring of cytoplasm; signet ring cells.
Explain how the microscopic appearance of unilocular adipocytes is altered by routine histological preparation.
The lipid droplet is dissolved, leaving an empty vacuole surrounded by a thin ring of cytoplasm with eccentric, flattened nuclei.
In microscope preparation of uniocular adipocyte, the lipid droplet is dissolved, leaving an empty vacuole surrounded by a thin ring of cytoplasm with _______ nuclei.
eccentric, flattened
What potential artifact can occur during histological slide preparation of adipose tissue?
The remaining cytoplasmic rim may rupture and collapse, distorting the tissue architecture.
State three major physical or mechanical roles of adipose tissue beyond energy metabolism.
Thermal insulation, filling spaces between tissues and stabilizing organs, and acting as shock absorbers (especially in soles and palms).
Adipose tissue, due to its poor conductivity, contributes significantly to _____.
Thermal insulation of the body.
Which specific subcutaneous role does adipose tissue perform in body aesthetics?
It shapes the surface of the body.
Explain how adipose tissue provides mechanical protection in specific body regions.
It forms protective pads that absorb shock, particularly in high-impact areas like the soles and palms.
What are the two major types of adipose tissue and what distinguishes them?
White (unilocular) and brown (multilocular) adipose tissue.
White and brown adipose tissues differ in ___, ____, ___ and _____
They differ in structure, location, color, and pathologic characteristics.
What percentage of body weight does white adipose tissue represent in well-nourished adults?
In males: up to 20%, in females: up to 25%.
Where is white adipose tissue primarily distributed in the body?
It is distributed throughout the body, particularly in the deep layers of the skin.
White adipocytes are ____ when isolated but become _____ when closely packed in adipose tissue.
Spherical; Polyhedral.
What is the main function of white adipocytes in the body?
Long-term energy storage.
What is the typical size range of white adipocytes?
50 to 150 µm in diameter.
How much of the weight of a white adipocyte is made up by lipid?
85% of the cell’s weight is made up of lipid.
What does the term “unilocular” mean in relation to white adipocytes?
Storage of triglycerides in a single large lipid droplet or in a single locus.
What factors influence the color of white adipose tissue?
It varies from white to dark yellow depending on diet, particularly the presence of carotenoids.
White adipose tissue is absent in the _____, _____, _____, and the entire _____ of the external ear (without the ____).
Eyelids; penis; scrotum; auricle without the lobule.
How does the distribution of white adipose tissue differ between males and females?
Distribution is partly regulated by sex hormones and adrenocortical hormones, leading to different patterns in males and females.
How does the distribution of white adipose tissue change with age?
In newborns, it has a uniform thickness across the body.
What are the three primary functions of white adipose tissue?
- Energy storage; 2. Thermal insulation; 3. Cushioning against mechanical shock (e.g., around kidneys).
Describe the structural characteristics of white adipose tissue at the cellular level.
Fat is stored as lipid droplets that fuse into a large droplet, displacing the nucleus to one side, and reducing the cytoplasm to a small peripheral rim.
What is the appearance of the cytoplasm in white adipocytes under microscopy?
Pink-stained cytoplasm.
In white adipocytes, the lipid droplet has an _____ outline, with numerous _____ droplets at the periphery in the process of fusion.
Irregular; small.
What is the relationship between the lipid droplet and the plasma membrane in white adipocytes?
The lipid is not bounded by a membrane.
What organelles are most notably found in the cytoplasmic rim of white adipocytes?
Mitochondria.
What surrounds each adipocyte in white adipose tissue?
Each adipocyte is surrounded by an external lamina.
In the extracellular tissue adjacent to white adipocytes, a _____ cytoplasmic process and _____ can be seen.
Fibroblast; collagen fibrils.
What can be observed in an electron micrograph of two adjacent white adipocytes?
The large lipid droplets have an irregular outline with small lipid droplets at the periphery, and the lipid is not membrane-bound.
What is the relative size of the blood capillaries in relation to white adipocytes?
The dimensions of blood capillaries are much smaller compared to the surrounding adipocytes.
______ amounts of brown adipose tissue are found in human adults.
Only small.
What is the primary role of brown adipose tissue in newborn mammals and some hibernating animals?
Body temperature regulation.
Multilocular tissue cells are ____ and _____ than unilocular adipose cells.
Polygonal; Smaller.
What is the difference in structure between brown adipocytes and white adipocytes?
Brown adipocytes are smaller, polygonal, and contain multiple lipid droplets, whereas white adipocytes are larger and store fat in a single large droplet.
Nucleus in brown adipose cell is ___ and ____.
spherical and central.
What components are found in the cytoplasm of brown adipocytes?
A great number of lipid droplets of various sizes, a spherical and central nucleus, and numerous mitochondria with long cristae.
Brown adipose tissue receives direct _____ innervation.
Sympathetic.
Why does brown adipose tissue appear brown under macroscopic examination?
The mitochondria in brown adipose tissue are rich in cytochromes, which give it a brown color.
What is the percentage of brown adipose tissue in human newborns?
2-5% of body weight in human newborns.
Where is brown adipose tissue mainly located in humans?
Primarily around the shoulder blades and kidneys.
The nuclei in brown adipocytes are _____ and _____ located, with a significant quantity of _______ cytoplasm surrounding them in comparison white nuclei of white adipose tissue.
larger; eccentrically located; strongly eosinophilic cytoplasm surrounding the nuclei.
In brown adipocytes, the stored lipid is contained within _____ droplets, unlike the ____ droplet in white adipocytes.
Multiple; single.
What happens to the lipid droplets in brown adipocytes during routine histological tissue processing?
The lipid droplets are dissolved, leaving behind a characteristic appearance of the cells.
What is the role of mitochondria in brown adipocytes?
Mitochondria in brown adipocytes contain numerous, closely packed cristae and are rich in cytochromes, playing a role in oxidative energy production. The cytochromes are responsible for brown colour of brown adipose tissue.
Energy produced by mitochondria in brown adipose tissue is for ATP production. T or F
False.
The energy produced by mitochondria in brown adipose tissue is dissipated as _____
Heat.
How does brown adipose tissue generate heat in response to cold?
Nerve impulses release epinephrine, which stimulates lipase in adipocytes to release fatty acids, which are metabolized to produce heat.
The name of the transmembrane protein present in mitochondria of multilocular adipocytes.
Thermogenin.
What is the role of the protein thermogenin in brown adipocytes?
Thermogenin, a transmembrane protein, is involved in the process of heat production in brown adipocytes.
Describe the distribution of brown adipose tissue in hibernating animals compared to humans.
In hibernating animals, it is more abundant (as part of a hibernating gland), while in humans it is mainly found in newborns and greatly reduces with age.
The mitochondria in brown adipocytes are involved in the _____ energy production chain.
Electron transport.
What is the physiological outcome when brown adipose tissue produces heat in response to cold exposure?
Warmed blood circulates throughout the body, helping to maintain body temperature.
What anatomical feature distinguishes brown adipose tissue’s rich blood supply?
A rich network of capillaries is found between the brown adipocytes.
What is the key function of brown adipose tissue in animals and newborns that is not shared by white adipose tissue?
Heat production, crucial for thermoregulation in response to cold environments.
Functions of white adipocytes are ____, _____ and ____; brown adipocytes majorly functions for _____
White: energy store, thermal insulator under the skin, shock absorber for e.g kidney. Brown: heat production.
Define obesity based on percentage above ideal body weight.
A person is considered obese if their body weight is at least 20% higher than it should be.
Obesity is a condition where a person has accumulated so much body fat that it might ______________.
Have a negative effect on their health.
A person is considered obese if their body weight is at least ____% higher than it should be.
20.
Name the syndrome characterized by abdominal obesity, lipid changes in blood, hypertension, insulin resistance, and a proinflammatory/prothrombotic state.
Metabolic syndrome.
What type of benign tumors can unilocular adipocytes form?
Lipomas.
What is the name of the rare malignant tumor derived from adipocytes?
Liposarcoma.
True or False: Liposarcomas are common in humans.
False. Liposarcomas are infrequent in humans.
