Biology Unit 4: Homeostasis

homeostasis

ability of an organism to maintain its internal environment, despite changes in the external environment

the body uses ____ to maintain homeostasis

feedback mechanisms

two types of feedback mechanisms

negative feedback and positive feedback

negative feedback

when the response stops the stimulus

positive feedback

when the response increases the stimulus

what does your body need to keep stable

body temperautre, blood pressure, blood pH, O2 and CO2 concentration, water balance, and blood glucose

what are the 2 main body systems involved in homeostasis

endocrine and nervous system

endocrine system

series of glands that produce hormones to help maintain homeostasis, attempt at long term stability, a lower response than nervous stability

nervous system

The coordinating centre comprised of the spinal cord and brain, attempts at short-term stability, immediate response

organs of excretory system

kidneys, bladder, and liver

kidneys

water-soluble waste is formed here, as well as regulation of body pH and water levels

bladder

stores liquid waste

liver

transforms ingested toxins such as alcohol, heavy metals and waste from protein metabolism into soluble compounds that can be removed by the kidney

types of water soluble wastes

ammonia and urea

ammonia

produced by protein and DNA metabolism, it is very toxic so the liver converts it to urea

urea

100,000x less toxic than ammonia

urinary system components

renal arteries, renal veins, ureters, urinary sphincter, urethra

renal arteries

pass blood to kidneys

renal veins

remove blood from kidneys

ureters

pass urine to the bladder

urinary sphincter

controls the release of urine from bladder

urethra

the tube used to void the bladder

kidney structure components

cortex, medulla, and renal pelvis

cortex

outer layer of connective tissue of kidney

medulla

inner layer under the cortex in kidney

renal pelvis

hollow chamber which connects the kidney with the ureter

nephron

approxim ately one million small functional units of the kidney spanning the cortex and the medulla, comprised of specialized blood vessels and tubes that wrap around each other for filtering wastes from the blood and producing urine

where does making urine occur

nephrons

first step of making urine

filteration

filteration

occurs from the glomerulus to bowman’s caspule, anything small (urea) moves by difusion into bowman’s capsule

step 2 of making urine

reabsorption

reabsorption

put non-waste materials back into blood

where does glucose go in reabsorption

proximal convulated tubule

last step in making urine

secretion

secretion

occurs from PCT to DCT, maintains ion and water levels by returning excess amounts to he nephron from blood

where does water go in reabsorption

descending loop of henle

where do H+ go in reabsorption

distole convulated tubule

blood flow

renal arteries—>afferrent —> glomerulus —> efferent arteriole —> capillaries —> renal vein

flow of glucose

renal artery —> afferent artirole —> glomerulus —> bowman’s capsule —> proximal convulated tubule —> capillaries —> renal vein

afferent

carry blood toward an organ

efferent

carry blood away from an organ

what is in the blood before it enters the kidney

urea, glucose, water, NaCl, H+, K+, RBC, WBC,platelets, protein

what is in the nephron in the bowman’s capsule/glomerulus

urea, glucose, water, NaCl, H+, K+

what is in the nephron in the proximal tubule

urea, water, NaCL, H+, K+

what is in the nephron in the loop of henle

uea, H+, K+, water

what is in the nephron in the distal tubule

urea and water

what is in the nephron in the collecting duct

urea and water

the nervous system

a communication system

divisons of the vertebrae nervous system

central nervous system and peripheral nervous system

central nervous system

brain, spinal cord, coordinating centre

peripheral nervous system

nerves that carry info between the receptors, CNS, and the organs/muscles

sections of peripheral nervous system

afferent system and efferent system

afferent system

recieves input from receptors and transmits it to CNS

efferent system

carries signals to effectors (muscles and glands)

types of efferent systems

somatic nerves and autonomic nerves

somatic nerves

voluntary processes

autonoic nerves

involuntary processes

sections of autonomic nerves

sympathetic and parasympathetic

sympathetic

prepares body for action (heartrate, breathing, sweating, pupil dilation)

parasympathetic

stimulates body activities that acquire and conserve energy (digestion)

types of nervous system cells

neurons and glial cells

neurons

cells that conduct nerve impulses (functional units)

glial cells

structural support and metabolism of nerve cells (do not conduct messages)

nerve

bundle of many neurons

neuron anatomy

cell body, dendrites, axon, myelin sheath, schwann cells, nodes of ranvier, and neurilemma

cell body of neuron

nucleus and majority of cytoplasm

dendrites

projections of cytoplasm that carries nerve impulses to the body

axon

extension of cytoplasm that carries nerve impulses away from the body

myelin sheath

insulated covering (made of fat) over the axon of some nerves, preents loss of charge

schwann cells

type of glial cell that produces myelin sheath

nodes of ranvier

regularly occuring gaps between sections of the myelin sheath

neurilemma

thin membrane surrounding the axon in PNS, promotes regeneration of damaged axons

which nervous system has a greated ability to regenerate

peripheral nervous system

neurons without ___ or ____ do not regenerate

myelin sheath or neurilemma

grey matter

in brain and spinal cord, no myelin sheath, fast signal, no repair

white matter

has myelin sheath, slower signal, can repair

types of neurons

sensory neurons, motor neurons, and interneurons

sensory neurons

afferent neurons, carry impusles from sensory receptors to the central nervous system

motor neurons

efferent neurons, carry impulses from the central nervous sytem to effectors (muscles, organsm, glands… things that produce a response)

interneurons

relay neurons, link sensory neurons to moto neurons with the body, found in the central nervous system

the reflex arc

neutral circuit through the spinal cord that provides a framework for a reflex action, the simplest nerve pathway, involuntary, unconscious

what happens when your hand accidentally touches a hot stove

heat is detected by thermoreceptors in skin, nerve impulse is carried by sensory neurons to spinal cord, interneurons send singal to brain to make a conscious decision about any further actions required, motor neurons carry impulse to muscles in hand, signal causes muscles to pull hand away

resting potential

the cell membrane has a potential diffrent across the membrane, there is an overall negative charge

polarization

negative charge inside (-70mV), Na+ on outside K+ on inside

3 ways to depolarize a membrane

a stimulus arriving at a receptor cell, a chemical fitting into a receptor site, or a nerve impulse travelling down a neuron

depolarization

positive charge on inside Na+ diffuse to inside

action potential

the state of the neuron when a nerve impulse passes by (35mV)

threshold potential

-55mV

repolarization

negative charge on inside K+ moves from inside to outside, Na+ is inside

hyperpolarization

negativ charge on inside (below -70mV) Na+ on inside K+ on outside

refractory period

gradual active pumping of the ions (3 Na+ out 2 K+ in at a time) to restore resting potential, during this period no impulses can pass along that part of the membrane

how many ions does the sodium-potassium pump move

3 Na+ out 2 K+ in

first step of action potential

sodium channels open

step in action potential after sodium channnels open

sodium ions diffuse into cell (depolarization)

step in action potential after depolarization

sodium channels close while potassium channels open

step in action potential after potassium channels open

repolarization - potasssium diffuse to outside

last step of action potential

active transport is used to move potassium into the the ion and sodium out

why does the neuron become hyper polar

potassium channels are slow to close

the meninges

3 protective membranes that surround the brain and spinal cord, act as protection and support the CNS

blood brain barrier

most substances cannot leave blood stream and enter cerebrospinal fluid