3 Active Transport - Weeblychssciencedavis.weebly.com/.../3_active_transport.pdfActive Transport...
Transcript of 3 Active Transport - Weeblychssciencedavis.weebly.com/.../3_active_transport.pdfActive Transport...
Active Transport & Homeostasis
Life Science: Molecular
Membrane ProteinsTransporters are transmembrane proteins that use energy to move molecules across a membrane.
Active TransportLow Concentration
Cell Membrane
High Concentration
Low Concentration
Cell Membrane
High Concentration
Active transport is the movement of molecules through a membrane against a concentration difference.
Protein pumps use energy to move molecules such as calcium, potassium, and sodium ions across the membrane against a concentration gradient. – sodium-potassium pump
• pumps sodium out • pumps potassium in
Transmembrane Pumps
Active Transport
Active TransportLarger molecules can be transported by movements of the cell membrane known as bulk transport. – Endocytosis is the process of taking material into the
cell by infolding of the cell membrane. • phagocytosis - cell eating • pinocytosis - cell drinking
– Exocytosis is a process of releasing large amounts of materials from the cell.
Active Transport
Homeostasis• Homeostasis means maintaining a constant
internal environment. • Cells need to maintain a narrow range of
conditions to stay alive. – temperature – pH – salinity – minerals – glucose
Hypothalamus• Hypothalamus = master nerve control center
➡ receives information about internal conditions from nervous system
➡ releases hormones to maintain homeostasis
• Pituitary gland = master endocrine gland ➡ secretes broad range of hormones
to regulate other glandsin the body hypothalamus
pituitary
Chemical Controls➡ Neurotransmitters released by neurons ➡ Hormones released by endocrine glands
axon
endocrine gland
receptor proteins
target cell
receptor proteins
hormone carried by blood
neurotransmitter
Feedback• There are two ways to maintain homeostasis
– Positive feedback – Negative feedback
Maintaining Homeostasis
high
low
hormone 1
lowersbody condition
hormone 2
gland
specific body condition
raisesbody condition gland
Negative FeedbackModel
Blood Osmolarity
Osmoregulation
osmoreceptors inhypothalamus
nephron
nephron
ADH
promoteswaterreabsorption
increase thirst
renin
promotessodiumreabsorption
high salt
pituitary
angiotensin
adrenalgland
aldosterone
nephron (JGA)
low blood pressureJuxtaGlomerular Apparatus