to maintain a “steady state” or internal balance regardless of external environment. Body temperature, blood pH, glucose concentration, etc.....
Stimulus Triggers a response
Most homeostatic control systems function by negative feedback, where buildup of the end product shuts the system off.
but do not usually contribute to homeostasis.
Hastens the response to an action.
blood flow in the skin decreases, lowering heat loss. Narrowing of blood vessels.
Blood Vessels dilate, facilitating heat loss.
moves the respiratory medium over the respiratory surface. Such as fish gills.
Animals can use air or water as a source of O2, or respiratory medium
• Animals require large, moist respiratory surfaces for exchange of gases between their cells and the respiratory medium, either air or water
• Gas exchange across respiratory surfaces takes place by diffusion
• Respiratory surfaces vary by animal and can include the outer surface, skin, gills, tracheae, and lungs
If two solutions are isosmotic, the movement of water is equal in both directions. Osmoconformers are usually this.
If two solutions differ in osmolarity, the net flow of water is from the hyposmotic to the hyperosmotic solution
expend energy to control water uptake and loss in a hyperosmotic or hyposmotic environment
consisting only of some marine animals, are isosmotic with their surroundings and do not regulate their osmolarity
must expend energy to maintain osmotic gradients
– Essential amino acids
– Essential fatty acids
are required by cells and must be obtained from dietary sources, can not be produced by the organism
Is the breakdown of substances within the cytoplasm of a cell.
animals feed by secreting enzymes through the cell membrane onto the food. The enzymes catalyse the digestion of the food into molecules small enough to be taken up by passive diffusion, transport orphagocytosis.
• The female gonads, the ovaries, lie in the abdominal cavity from birth
• Each ovary contains many follicles, which consist of a partially developed egg, called an oocyte,surrounded by support cells
• Once a month, an oocyte develops into an ovum(egg) by the process of oogenesis
• Spermatogenesis is production of mature sperm
• Sperm are small and motile and are produced throughout the life of a sexually mature male
After about 500 cycles, human females undergo menopause, the cessation of ovulation and menstruation
• Menopause is very unusual among animals
• Menopause might have evolved to allow a mother to provide better care for her children and grandchildren
Animal hormones are chemical signals that are secreted into the circulatory system and communicate regulatory messages within the body.
are chemical signals that travel over short distances by diffusion
- Local regulators help regulate blood pressure, nervous system function, and reproduction
- Paracrine and autocrine signaling
• Pheromones are chemical signals that are released from the body and used to communicate with other individuals in the species
• Pheromones mark trails to food sources, warn ofpredators, and attract potential mates
signals act on cells near the secreting cell
signals act on the secreting cell itself
A tropic hormone regulates the function of endocrine cells or glands.
(TSH) (FSH) (LH) (ACTH)
• Non tropic hormones target non endocrine tissues
• Nontropic hormones produced by the anterior pituitary are – Prolactin (PRL): Melanocyte-stimulating hormone (MSH):influences skin pigmentation in some vertebrates and fat metabolism in mammals
central nervous system
is the part of the nervous system consisting of the brain and spinal cord.
peripheral nervous system
The peripheral nervous system (PNS) is the part of the nervous system that consists of the nerves and ganglia outside of the brain and spinal cord.