Homestatis And Excretion Flashcards
Suggest how excretion may occur in simple organisms such as amoeba?
Diffusion / contractile vacuole
Name two excretory products other than water and give a location in body in which it is produced?
Urea - liver
Co2 - cells [respiration]
What is the effect of an increase in metabolic rate in response to falling external temperatures?
Generates heat
What term is used to describe animals that can vary their metabolic rate significantly?
Endotherms
Suggest how animals that cannot significantly vary their metabolic rate may respond to falling external temperatures?
Hibernate
What is piloerection?
Erector muscles contract causing hairs to stand up on skin
How is piloerection an important response to falling external temperatures?
A layer of warm air is trapped close to the skin and this layer of air acts as an insulator, reducing heat loss in the body
Explain how vasoconstriction can be an important response to falling external temperatures
Less blood flows close to the surface as blood vessels contract and there is reduced heat loss
What is the main source of heat for an endotherm?
Metabolism
What is the relationship between an endotherm’s body temperature and environment temperature
Environment temp - affects enzyme activity which is required for metabolism
What is the main source of an ectotherm’s body heat?
Environment
Suggest a relationship between an ectotherm’s body temperature and environment temperature?
They gain or lose heat from or to environment [temp]
State how the liver contributes to homeostasis
By the absorption of glucose
Release of glucose
State how the lungs contribute to homeostasis
Excretes water and co2
State how nephrons of kidneys contribute to homeostasis
Excretion of water and salts
Suggest an advantage of being an endotherm
Activity independent of env temp
Adaption of ectotherm
Butterflies and moths may orient their wings to maximize exposure to solar radiation in order to build up heat before take-off
Why is there a drop in body temperature late at night?
Human body temp drops when sleep due to inactivity
Why do children typically have higher body temperatures than adults?
Growing - more cell division
High metabolism
Mention one method of excretion in flowering plants
Through stomata [O2]
Name the blood vessel that supplies blood to the kidney and from which blood vessel does it arise from?
Renal artery and from aorta
In which cavity are the kidneys located?
Abdomen / abdominal
Name one substance other than water excreted in the urine
Urea
Salts
Give a feature of a kidney that indicates it is an exocrine gland?
Does not produce hormones
A sample of urine was found to contain protein, is this normal and why?
No, because protein molecules are too big
A sample of urine was found to contain glucose, is this normal?
No, reabsorbed in liver
After a long session of heavy exercise, an athletes urine is likely to be concentrated and low in volume, why?
Lost water through sweating therefore after level in blood plasma would be low. This produces ADH which causes collecting ducts to become more permeable to water and so extra water is reabsorbed into blood plasma which reduces salt concentration
Name the substance in which urea is derived from
Protein
Name a substance in which co2 is derived from
Carbohydrate
From which blood vessel is the afferent arteriole derived from?
Renal artery
Where in the kidney is the bowmans capsule located?
Cortex
[this is where filtration takes place]
Name a group of biomolecules in the blood which are too large to pass through the filtration system of the nephron
Proteins
Suggest situations which may result in a drop in water content of the blood
Do not drink enough water, high salt intake, Infection, hot conditions
Give a precise target area for ADH and how does it reach this target area
Distal tubule
In the blood
Explain golmerular filtrate
Plasma that has entered bowmans capsule
Explain why red blood cells are normally absent from glomerular filtrate?
Too big to pass through
The concentration of glucose is the same in plasma as in glomerular filtrate, how?
Small, so can pass through
Why is glucose normally absent from urine?
Reabsorbed
Describe the role of ADH [vasopressin] in human excretion
Controls the volume of water re-absorbed in the collecting ducts
What is meant by the term homeostasis?
The maintenance of a constant internal environment of an organism
Distinguish between excretion and egestion
Excretion - removal of waste products of metabolism from body
Egestion - removal of unabsorbed material from body
Graph between body temp and environmental temp on page 86
Which of the plots relates to the dog and why?
Temperature is relatively stable - endothermic
Describe the role of the skin in controlling body temperature
Cold conditions - retains heat
1) piloerection
Erector muscled contract causing hairs to stand up and trap a layer of warm air close to the skin. This layer of air acts as an insulator for reducing heat loss
2) vasoconstriction
Less blood flows close to the surface as blood vessels contract and there is reduced heat loss
Hot conditions - skin reduces heat
1) sweat
produced and when it evaporates it removes heat from body
2) vasodilation
greater blood flow through superficial capillaries - more blood flows close to surface which results in heat loss
What is an endotherm?
Generate their own heat from metabolic reactions eg, birds and mammals
Where in the nephron does filtration take place?
Bowmans capsule or glomerulus
Give the part of the nephron where the reabsorption of amino acids occurs
Proximal tubule
Give two features of the nephron that aid filtration
Large surface area
Efferent arteries narrowed than afferent
Note one reason why homeostasis is important in the human body
Allows organisms to survive efficiently in an environment that is constantly changing
Draw a diagram of a section through human skin to show two structures involved in temperature regulation
What are the structures
Erector muscle - contracts [piloerection]
Sweat glands - produce sweat [evaporates]
What is meant by an ectotherm?
Gain or lose heat from/to their environment eg, fish, snakes, lizards
How is co2 and urea removed from the body
Co2 - lungs
Urea - removed by kidneys and transferred to bladder
What internal conditions need to be controlled and how
Temperature [piloerection,vasoconstriction,vasodilation, sweat]
Water content
Inc by drinking, lost by sweating and urea
Blood glucose
Inc and dec by hormones
What is adipose formed from?
Excess fat
Why does temperature need to be regulated?
Temperature regulates the rate of chemical reactions in the body (esp. enzyme controlled reactions)
•High temps ►can damage enzymes
•Low temps ►slow down reactions
What are the three layers of the epidermis of the skin
Cornified layer - contains dead cells full of keratin which are continuously being worn away
Granular layer - keratin is formed here
Malphigian layer - contains cells that are constantly dividing by mitosis to replace cellslost from the cornified layer. It also produces melanin(brown or black pigment in skin) which protects skin against harmful effects of UV radiation.
What are the three parts of the skin?
Epidermis
Dermal
Adipose
What does the dermis contain in the skin?
Sweat glands
Sebaceous glands
Blood vessels
What tissue does the dermal part of the skin consist of
Connective tissue which contains collagen for strength
What are the functions of the skin?
-Protection
[protects body from damage, protects body from the entry of pathogens]
-Release of sebum oil
[keeps skin soft and supple and prevents it from drying out, keeps hair moist and flexible]
-Vitamin production [skins exposure to u.v light causes production of vitamin D]
-Sense organ [contains receptors which allows to act as an organ of touch]
-Excretion [sweat glands - sweat is excreted]
Where are sebaceous glands more commonly found?
Face and scalp
The excessive production of sebum oil may lead to what?
Acne
What receptors does skin have
Temperature, pain and pressure receptors
What is sweat made up of?
Salts, water and tiny amounts of urea
Role of excretory system in relation to homeostasis
Regulating body temperature
Removing waste products of metabolism from the body
Regulating water and salt levels in body
What are the organs of excretion?
Lungs
Kidneys
Skin
What is the function of renal arteries in relation to the urinary system
carry blood rich in waste and O2 into the kidneys
What is the function of renal veins in relation to the urinary system
carry clean, deoxygenated blood away from the kidneys
What is the function of the kidney?
- Filter waste products from the blood e.g. urea, salts and water [ this happens in the cortex]
- They reabsorb useful materials the filtrate [ this happens in the cortex and the medulla]
- osmoregulation
- maintain blood at PH 7.4
What is the function of the ureter
Transports urine from the kidneys to bladder
What is the function of the bladder?
Stores urine
What is the function of the urethra?
Carries urine out of the body
Why must deammination occur?
Excess Amino Acids may become poisonous in body
What is deamination?
is the breakdown of excess Amino Acids to urea in the liver
How is urea carried out of the liver?
By the blood stream
What are nephrons?
Structures found in the kidney that make urine
Where are nephrons found?
In the cortex of the kidney
What are the two processes for the formation of urine
Filtration
Selective re-absorption
Describe filtration of blood in nephron
Blood that is high in waste and oxygen enters glomerulus under high pressure.
Part of the blood is forced into the lumen of bowman’s capsule forming the glomerular filtrate which consists of H20, glucose, amino acids, salts, urea, uric acid [theres no blood cells or large proteins present]
The blood pressure in the glomerulus is much higher than normal, why?
- Blood in the arteriole is under high pressure
- Incoming afferent arteriole is wide
- Outgoing efferent arteriole is narrower (the difference in size increases the already high pressure
Describe re-absorption in nephron
Substances taken from the filtrate back into the blood
Proximal convoluted tubule - all glucose and amino acids and a lot of NaCl by active transport and a large percentage of water by osmosis
Loop of henle - h20 by osmosis
Distal tubule - H20 by osmosis controlled by ADH
Collecting duct - H2O by osmosis controlled by ADH
Where does reabsorption and filtration take place in kidney?
Cortex
What term is used to denote the functional unit of kidney?
Nephron
What term is used to denote the dilute solution produced by nephron in early stages of process of urine formation
Glomerular filtrate
Where is ADH produced?
Pituitary gland
Which precise area of the functional unit of the kidney does ADH target?
Collecting duct
