Levels of organisation in the body and homeostasis Flashcards
Define anatomy
The branch of science that deals with the bodily structure of living organisms
Define physiology
The branch of science that deals with the normal functioning of living organisms and their systems and organs Basically how the body works, and how it responds to internal and external challenges
Levels of organisation in the body (smallest to biggest)
Molecules Cells Tissues Organs Systems Organism
Molecules
The chemical level of organisation
Functions cells can perform
Protection Secretion Exchange Absorption Communication Movement
Can a single cell perform every task cells are required to do?
No They are specialised to their own task
Functions of the plasma membrane
Physical barrier Compartmentalises the cell Regulates exchange with the environment Gives structural support Attachment site of proteins Transmits electrical and chemical signals Secretes and takes up substances
Ways that substances can cross the plasma membrane
Simple/passive diffusion Facilitated diffusion Exocytosis Endocytosis
Tissues
Groups of cells with similar structure and function
The four types of tissue
Epithelial Connective Nervous Muscular
Types of epithelial tissue
Can be either simple or stratified: Squamous Cuboidal Columnar Pseudostratified
What makes simple epithelial tissues simple?
One cell thick
What do the epithelial cells sit on?
Basement membrane
Epithelial tissue that is more than one cell thick
Stratified
Types of connective tissue
Connective tissue proper Fluid connective tissue Supporting connective tissue
Types of connective tissue proper
Loose Dense
Types of fluid connective tissue
Blood Lympth
Types of supportive connective tissue
Bone Cartilage Adipose tissue
Types of nervous tissue
Neurones Glial cells
What makes up a huge proportion of the brain? What is the percentage?
Glial cells 90%
Types of glial cells
Schwann cells Oligodendrocytes Astrocytes Microglial cells
Types of muscular tissue
Skeletal muscle Cardiac muscle Smooth muscle
Which type of muscle do we have control of?
Skeletal muscle
What type of muscle makes up the heart?
Cardiac muscle
What type of muscle makes up blood vessels?
Smooth muscle
Organ definition
Collection of tissue types with specific structure and function
Examples of organs
Heart Lungs Kidneys Stomach Thyroid gland
Systems definitions
Organs with complementary functions
11 systems
Integumentary Cardiovascular Respiratory Digestive Skeletal Muscular Nervous Endocrine Lymphatic Urinary Reproductive
Define organism
The functional entity that is able to breathe, move, feed, reproduce….. idependantly
What does the internal environment refer to?
The fluid surrounding cells
What are cells surrounded by in the body?
Extracellular fluid
What is extracellular fluid?
Interstitial fluid Plasma Surrounds cells
Homeostasis
Biological self-regulation The ability of the body to maintain a condition of dynamic equilibrium within the the internal environment when dealing with external changes
Examples of things controlled by homeostasis
Concentration of ions (Na+…) Concentration of nutrients Concentration of blood gases Physical characteristics of blood (pressure, volume…)
Normal range of blood glucose
3.5 - 6.0 nM
Normal range of blood osmolarity
280 - 295 mOsM
Normal range of body temperature
36.5 - 37.5 oC
Normal range of atrial blood pressure
120/80 mmHg
Normal range of atrial pO2
80-100 mmHg
Normal range of atrial pH
7.35 - 7.45
What does p stand for in pO2
Partial pressure The amount of pressure that a gas exerts
Steps in homeostatic mechanism
Change in controlled variable This is registered by sensors Sensors send messages via the afferent pathway to the CNS This sends a message via efferent pathways to the effectors Effectors cause a response to return the variable to equilibrium
Negative feedback
Homeostasis Reacts to a change in a controlled variable to re-establish equilibrium
Example of negative feedback (increase in blood pressure)
Increase in blood pressure detected by receptors in blood vessels CNS responds and lowers heart rate This causes decrease in blood pressure Equilibrium restored
How would you describe the equilibrium in homeostasis
Dynamic It fluctuates small amounts around a set value/s
Feed-forward regulation
Homeostasis Predictive mechanism Can use behavioural cues to predict how it should respond to the expected change
Example of feed-forward regulation
Eat food Signal sent predicting rise in glucose levels Insulin released slightly early to break down glucose straight away
Positive feedback
Homeostasis Escalates a change in variable to make it greater Aims to reach an end point When the end point is reached the stimulus disappears and feedback stops
Most common form of feedback in homeostasis
Negative
Examples of physiological changes of homeostatic control
Cardiovascular variables during exercise (heart rate to supply more oxygen) May be changes throughout the day to give circadian changes
What if there are changes that cause conflicting responses?
The body prioritises other variables above others
Example of prioritising is homeostasis
Salty diet causes the body to hold onto more water Causes an increase of blood pressure as osmosis causes water to remain in the blood, increasing it’s volume and pressure
Pathological changes in homeostasis
Pathogens can delude the body’s control centre to believe variables should be different Causes response that isn’t need and could be dangerous Or can just lose control/be unable to affect changes
Examples of pathological changes in homeostasis
Fever - make the body believe body temperature should be higher Cancer - loss of control of cell division Circulatory shock - hypotension following haemorrhage as body tries increase blood pressure by raising heart rate, but failing
How cells communicate with each other
Direct (cell-to-cell): mechanical, chemical, electrical Paracrine/autocrine Endocrine Neural Neuroendocrine
Pseudostratified epithelial tissue
Gives appearence that it is stratified because how crowded the cells are
Image of simple epithelial tissues:
Squamous
Cuboidale
Columnar
Image of pseudostratified epithelial tissue
Image of stratified epithelial tissue
